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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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367b8112fe
Move all header files for xtensa to arch/xtensa/include and platform and variant header files to the appropriate arch/xtensa/platforms/ and arch/xtensa/variants/ directories. Moving the files gets also rid of all uses of symlinks in the Makefile. This has been completed already for the majority of the architectures and xtensa is one out of six missing. Signed-off-by: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Chris Zankel <chris@zankel.net>
1959 lines
45 KiB
ArmAsm
1959 lines
45 KiB
ArmAsm
/*
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* arch/xtensa/kernel/entry.S
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*
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* Low-level exception handling
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 2004-2007 by Tensilica Inc.
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*
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* Chris Zankel <chris@zankel.net>
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*
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*/
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#include <linux/linkage.h>
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#include <asm/asm-offsets.h>
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#include <asm/processor.h>
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#include <asm/thread_info.h>
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#include <asm/uaccess.h>
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#include <asm/unistd.h>
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#include <asm/ptrace.h>
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#include <asm/current.h>
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#include <asm/pgtable.h>
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#include <asm/page.h>
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#include <asm/signal.h>
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#include <asm/tlbflush.h>
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#include <variant/tie-asm.h>
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/* Unimplemented features. */
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#undef KERNEL_STACK_OVERFLOW_CHECK
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#undef PREEMPTIBLE_KERNEL
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#undef ALLOCA_EXCEPTION_IN_IRAM
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/* Not well tested.
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*
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* - fast_coprocessor
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*/
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/*
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* Macro to find first bit set in WINDOWBASE from the left + 1
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*
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* 100....0 -> 1
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* 010....0 -> 2
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* 000....1 -> WSBITS
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*/
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.macro ffs_ws bit mask
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#if XCHAL_HAVE_NSA
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nsau \bit, \mask # 32-WSBITS ... 31 (32 iff 0)
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addi \bit, \bit, WSBITS - 32 + 1 # uppest bit set -> return 1
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#else
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movi \bit, WSBITS
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#if WSBITS > 16
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_bltui \mask, 0x10000, 99f
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addi \bit, \bit, -16
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extui \mask, \mask, 16, 16
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#endif
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#if WSBITS > 8
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99: _bltui \mask, 0x100, 99f
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addi \bit, \bit, -8
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srli \mask, \mask, 8
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#endif
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99: _bltui \mask, 0x10, 99f
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addi \bit, \bit, -4
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srli \mask, \mask, 4
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99: _bltui \mask, 0x4, 99f
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addi \bit, \bit, -2
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srli \mask, \mask, 2
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99: _bltui \mask, 0x2, 99f
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addi \bit, \bit, -1
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99:
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#endif
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.endm
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/* ----------------- DEFAULT FIRST LEVEL EXCEPTION HANDLERS ----------------- */
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/*
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* First-level exception handler for user exceptions.
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* Save some special registers, extra states and all registers in the AR
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* register file that were in use in the user task, and jump to the common
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* exception code.
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* We save SAR (used to calculate WMASK), and WB and WS (we don't have to
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* save them for kernel exceptions).
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*
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* Entry condition for user_exception:
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*
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* a0: trashed, original value saved on stack (PT_AREG0)
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* a1: a1
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* a2: new stack pointer, original value in depc
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* a3: dispatch table
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* depc: a2, original value saved on stack (PT_DEPC)
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* excsave1: a3
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*
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* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
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* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
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*
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* Entry condition for _user_exception:
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*
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* a0-a3 and depc have been saved to PT_AREG0...PT_AREG3 and PT_DEPC
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* excsave has been restored, and
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* stack pointer (a1) has been set.
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*
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* Note: _user_exception might be at an odd adress. Don't use call0..call12
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*/
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ENTRY(user_exception)
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/* Save a2, a3, and depc, restore excsave_1 and set SP. */
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xsr a3, EXCSAVE_1
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rsr a0, DEPC
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s32i a1, a2, PT_AREG1
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s32i a0, a2, PT_AREG2
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s32i a3, a2, PT_AREG3
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mov a1, a2
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.globl _user_exception
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_user_exception:
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/* Save SAR and turn off single stepping */
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movi a2, 0
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rsr a3, SAR
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xsr a2, ICOUNTLEVEL
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s32i a3, a1, PT_SAR
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s32i a2, a1, PT_ICOUNTLEVEL
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/* Rotate ws so that the current windowbase is at bit0. */
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/* Assume ws = xxwww1yyyy. Rotate ws right, so that a2 = yyyyxxwww1 */
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rsr a2, WINDOWBASE
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rsr a3, WINDOWSTART
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ssr a2
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s32i a2, a1, PT_WINDOWBASE
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s32i a3, a1, PT_WINDOWSTART
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slli a2, a3, 32-WSBITS
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src a2, a3, a2
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srli a2, a2, 32-WSBITS
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s32i a2, a1, PT_WMASK # needed for restoring registers
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/* Save only live registers. */
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_bbsi.l a2, 1, 1f
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s32i a4, a1, PT_AREG4
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s32i a5, a1, PT_AREG5
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s32i a6, a1, PT_AREG6
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s32i a7, a1, PT_AREG7
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_bbsi.l a2, 2, 1f
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s32i a8, a1, PT_AREG8
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s32i a9, a1, PT_AREG9
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s32i a10, a1, PT_AREG10
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s32i a11, a1, PT_AREG11
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_bbsi.l a2, 3, 1f
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s32i a12, a1, PT_AREG12
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s32i a13, a1, PT_AREG13
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s32i a14, a1, PT_AREG14
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s32i a15, a1, PT_AREG15
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_bnei a2, 1, 1f # only one valid frame?
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/* Only one valid frame, skip saving regs. */
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j 2f
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/* Save the remaining registers.
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* We have to save all registers up to the first '1' from
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* the right, except the current frame (bit 0).
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* Assume a2 is: 001001000110001
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* All register frames starting from the top field to the marked '1'
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* must be saved.
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*/
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1: addi a3, a2, -1 # eliminate '1' in bit 0: yyyyxxww0
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neg a3, a3 # yyyyxxww0 -> YYYYXXWW1+1
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and a3, a3, a2 # max. only one bit is set
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/* Find number of frames to save */
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ffs_ws a0, a3 # number of frames to the '1' from left
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/* Store information into WMASK:
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* bits 0..3: xxx1 masked lower 4 bits of the rotated windowstart,
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* bits 4...: number of valid 4-register frames
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*/
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slli a3, a0, 4 # number of frames to save in bits 8..4
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extui a2, a2, 0, 4 # mask for the first 16 registers
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or a2, a3, a2
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s32i a2, a1, PT_WMASK # needed when we restore the reg-file
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/* Save 4 registers at a time */
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1: rotw -1
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s32i a0, a5, PT_AREG_END - 16
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s32i a1, a5, PT_AREG_END - 12
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s32i a2, a5, PT_AREG_END - 8
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s32i a3, a5, PT_AREG_END - 4
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addi a0, a4, -1
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addi a1, a5, -16
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_bnez a0, 1b
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/* WINDOWBASE still in SAR! */
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rsr a2, SAR # original WINDOWBASE
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movi a3, 1
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ssl a2
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sll a3, a3
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wsr a3, WINDOWSTART # set corresponding WINDOWSTART bit
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wsr a2, WINDOWBASE # and WINDOWSTART
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rsync
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/* We are back to the original stack pointer (a1) */
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2: /* Now, jump to the common exception handler. */
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j common_exception
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/*
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* First-level exit handler for kernel exceptions
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* Save special registers and the live window frame.
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* Note: Even though we changes the stack pointer, we don't have to do a
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* MOVSP here, as we do that when we return from the exception.
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* (See comment in the kernel exception exit code)
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*
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* Entry condition for kernel_exception:
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*
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* a0: trashed, original value saved on stack (PT_AREG0)
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* a1: a1
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* a2: new stack pointer, original in DEPC
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* a3: dispatch table
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* depc: a2, original value saved on stack (PT_DEPC)
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* excsave_1: a3
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*
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* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
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* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
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*
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* Entry condition for _kernel_exception:
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*
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* a0-a3 and depc have been saved to PT_AREG0...PT_AREG3 and PT_DEPC
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* excsave has been restored, and
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* stack pointer (a1) has been set.
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*
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* Note: _kernel_exception might be at an odd adress. Don't use call0..call12
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*/
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ENTRY(kernel_exception)
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/* Save a0, a2, a3, DEPC and set SP. */
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xsr a3, EXCSAVE_1 # restore a3, excsave_1
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rsr a0, DEPC # get a2
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s32i a1, a2, PT_AREG1
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s32i a0, a2, PT_AREG2
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s32i a3, a2, PT_AREG3
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mov a1, a2
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.globl _kernel_exception
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_kernel_exception:
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/* Save SAR and turn off single stepping */
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movi a2, 0
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rsr a3, SAR
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xsr a2, ICOUNTLEVEL
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s32i a3, a1, PT_SAR
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s32i a2, a1, PT_ICOUNTLEVEL
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/* Rotate ws so that the current windowbase is at bit0. */
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/* Assume ws = xxwww1yyyy. Rotate ws right, so that a2 = yyyyxxwww1 */
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rsr a2, WINDOWBASE # don't need to save these, we only
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rsr a3, WINDOWSTART # need shifted windowstart: windowmask
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ssr a2
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slli a2, a3, 32-WSBITS
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src a2, a3, a2
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srli a2, a2, 32-WSBITS
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s32i a2, a1, PT_WMASK # needed for kernel_exception_exit
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/* Save only the live window-frame */
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_bbsi.l a2, 1, 1f
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s32i a4, a1, PT_AREG4
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s32i a5, a1, PT_AREG5
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s32i a6, a1, PT_AREG6
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s32i a7, a1, PT_AREG7
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_bbsi.l a2, 2, 1f
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s32i a8, a1, PT_AREG8
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s32i a9, a1, PT_AREG9
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s32i a10, a1, PT_AREG10
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s32i a11, a1, PT_AREG11
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_bbsi.l a2, 3, 1f
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s32i a12, a1, PT_AREG12
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s32i a13, a1, PT_AREG13
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s32i a14, a1, PT_AREG14
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s32i a15, a1, PT_AREG15
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1:
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#ifdef KERNEL_STACK_OVERFLOW_CHECK
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/* Stack overflow check, for debugging */
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extui a2, a1, TASK_SIZE_BITS,XX
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movi a3, SIZE??
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_bge a2, a3, out_of_stack_panic
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#endif
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/*
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* This is the common exception handler.
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* We get here from the user exception handler or simply by falling through
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* from the kernel exception handler.
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* Save the remaining special registers, switch to kernel mode, and jump
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* to the second-level exception handler.
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*
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*/
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common_exception:
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/* Save some registers, disable loops and clear the syscall flag. */
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rsr a2, DEBUGCAUSE
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rsr a3, EPC_1
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s32i a2, a1, PT_DEBUGCAUSE
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s32i a3, a1, PT_PC
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movi a2, -1
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rsr a3, EXCVADDR
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s32i a2, a1, PT_SYSCALL
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movi a2, 0
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s32i a3, a1, PT_EXCVADDR
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xsr a2, LCOUNT
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s32i a2, a1, PT_LCOUNT
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/* It is now save to restore the EXC_TABLE_FIXUP variable. */
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rsr a0, EXCCAUSE
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movi a3, 0
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rsr a2, EXCSAVE_1
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s32i a0, a1, PT_EXCCAUSE
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s32i a3, a2, EXC_TABLE_FIXUP
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/* All unrecoverable states are saved on stack, now, and a1 is valid,
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* so we can allow exceptions and interrupts (*) again.
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* Set PS(EXCM = 0, UM = 0, RING = 0, OWB = 0, WOE = 1, INTLEVEL = X)
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*
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* (*) We only allow interrupts if PS.INTLEVEL was not set to 1 before
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* (interrupts disabled) and if this exception is not an interrupt.
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*/
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rsr a3, PS
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addi a0, a0, -4
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movi a2, 1
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extui a3, a3, 0, 1 # a3 = PS.INTLEVEL[0]
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moveqz a3, a2, a0 # a3 = 1 iff interrupt exception
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movi a2, 1 << PS_WOE_BIT
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or a3, a3, a2
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rsr a0, EXCCAUSE
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xsr a3, PS
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s32i a3, a1, PT_PS # save ps
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/* Save LBEG, LEND */
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rsr a2, LBEG
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rsr a3, LEND
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s32i a2, a1, PT_LBEG
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s32i a3, a1, PT_LEND
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/* Save optional registers. */
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save_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT
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/* Go to second-level dispatcher. Set up parameters to pass to the
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* exception handler and call the exception handler.
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*/
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movi a4, exc_table
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mov a6, a1 # pass stack frame
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mov a7, a0 # pass EXCCAUSE
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addx4 a4, a0, a4
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l32i a4, a4, EXC_TABLE_DEFAULT # load handler
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/* Call the second-level handler */
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callx4 a4
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/* Jump here for exception exit */
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common_exception_return:
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/* Jump if we are returning from kernel exceptions. */
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1: l32i a3, a1, PT_PS
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_bbci.l a3, PS_UM_BIT, 4f
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/* Specific to a user exception exit:
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* We need to check some flags for signal handling and rescheduling,
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* and have to restore WB and WS, extra states, and all registers
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* in the register file that were in use in the user task.
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* Note that we don't disable interrupts here.
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*/
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GET_THREAD_INFO(a2,a1)
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l32i a4, a2, TI_FLAGS
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_bbsi.l a4, TIF_NEED_RESCHED, 3f
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_bbci.l a4, TIF_SIGPENDING, 4f
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l32i a4, a1, PT_DEPC
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bgeui a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 4f
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/* Call do_signal() */
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movi a4, do_signal # int do_signal(struct pt_regs*, sigset_t*)
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mov a6, a1
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movi a7, 0
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callx4 a4
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j 1b
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3: /* Reschedule */
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movi a4, schedule # void schedule (void)
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callx4 a4
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j 1b
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4: /* Restore optional registers. */
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load_xtregs_opt a1 a2 a4 a5 a6 a7 PT_XTREGS_OPT
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wsr a3, PS /* disable interrupts */
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_bbci.l a3, PS_UM_BIT, kernel_exception_exit
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user_exception_exit:
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/* Restore the state of the task and return from the exception. */
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/* Switch to the user thread WINDOWBASE. Save SP temporarily in DEPC */
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l32i a2, a1, PT_WINDOWBASE
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l32i a3, a1, PT_WINDOWSTART
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wsr a1, DEPC # use DEPC as temp storage
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wsr a3, WINDOWSTART # restore WINDOWSTART
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ssr a2 # preserve user's WB in the SAR
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wsr a2, WINDOWBASE # switch to user's saved WB
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rsync
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rsr a1, DEPC # restore stack pointer
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l32i a2, a1, PT_WMASK # register frames saved (in bits 4...9)
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rotw -1 # we restore a4..a7
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_bltui a6, 16, 1f # only have to restore current window?
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/* The working registers are a0 and a3. We are restoring to
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* a4..a7. Be careful not to destroy what we have just restored.
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* Note: wmask has the format YYYYM:
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* Y: number of registers saved in groups of 4
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* M: 4 bit mask of first 16 registers
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*/
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mov a2, a6
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mov a3, a5
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2: rotw -1 # a0..a3 become a4..a7
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addi a3, a7, -4*4 # next iteration
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addi a2, a6, -16 # decrementing Y in WMASK
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l32i a4, a3, PT_AREG_END + 0
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l32i a5, a3, PT_AREG_END + 4
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l32i a6, a3, PT_AREG_END + 8
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l32i a7, a3, PT_AREG_END + 12
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_bgeui a2, 16, 2b
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/* Clear unrestored registers (don't leak anything to user-land */
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1: rsr a0, WINDOWBASE
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rsr a3, SAR
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sub a3, a0, a3
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beqz a3, 2f
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extui a3, a3, 0, WBBITS
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1: rotw -1
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addi a3, a7, -1
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movi a4, 0
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movi a5, 0
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movi a6, 0
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movi a7, 0
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bgei a3, 1, 1b
|
|
|
|
/* We are back were we were when we started.
|
|
* Note: a2 still contains WMASK (if we've returned to the original
|
|
* frame where we had loaded a2), or at least the lower 4 bits
|
|
* (if we have restored WSBITS-1 frames).
|
|
*/
|
|
|
|
2: j common_exception_exit
|
|
|
|
/* This is the kernel exception exit.
|
|
* We avoided to do a MOVSP when we entered the exception, but we
|
|
* have to do it here.
|
|
*/
|
|
|
|
kernel_exception_exit:
|
|
|
|
#ifdef PREEMPTIBLE_KERNEL
|
|
|
|
#ifdef CONFIG_PREEMPT
|
|
|
|
/*
|
|
* Note: We've just returned from a call4, so we have
|
|
* at least 4 addt'l regs.
|
|
*/
|
|
|
|
/* Check current_thread_info->preempt_count */
|
|
|
|
GET_THREAD_INFO(a2)
|
|
l32i a3, a2, TI_PREEMPT
|
|
bnez a3, 1f
|
|
|
|
l32i a2, a2, TI_FLAGS
|
|
|
|
1:
|
|
|
|
#endif
|
|
|
|
#endif
|
|
|
|
/* Check if we have to do a movsp.
|
|
*
|
|
* We only have to do a movsp if the previous window-frame has
|
|
* been spilled to the *temporary* exception stack instead of the
|
|
* task's stack. This is the case if the corresponding bit in
|
|
* WINDOWSTART for the previous window-frame was set before
|
|
* (not spilled) but is zero now (spilled).
|
|
* If this bit is zero, all other bits except the one for the
|
|
* current window frame are also zero. So, we can use a simple test:
|
|
* 'and' WINDOWSTART and WINDOWSTART-1:
|
|
*
|
|
* (XXXXXX1[0]* - 1) AND XXXXXX1[0]* = XXXXXX0[0]*
|
|
*
|
|
* The result is zero only if one bit was set.
|
|
*
|
|
* (Note: We might have gone through several task switches before
|
|
* we come back to the current task, so WINDOWBASE might be
|
|
* different from the time the exception occurred.)
|
|
*/
|
|
|
|
/* Test WINDOWSTART before and after the exception.
|
|
* We actually have WMASK, so we only have to test if it is 1 or not.
|
|
*/
|
|
|
|
l32i a2, a1, PT_WMASK
|
|
_beqi a2, 1, common_exception_exit # Spilled before exception,jump
|
|
|
|
/* Test WINDOWSTART now. If spilled, do the movsp */
|
|
|
|
rsr a3, WINDOWSTART
|
|
addi a0, a3, -1
|
|
and a3, a3, a0
|
|
_bnez a3, common_exception_exit
|
|
|
|
/* Do a movsp (we returned from a call4, so we have at least a0..a7) */
|
|
|
|
addi a0, a1, -16
|
|
l32i a3, a0, 0
|
|
l32i a4, a0, 4
|
|
s32i a3, a1, PT_SIZE+0
|
|
s32i a4, a1, PT_SIZE+4
|
|
l32i a3, a0, 8
|
|
l32i a4, a0, 12
|
|
s32i a3, a1, PT_SIZE+8
|
|
s32i a4, a1, PT_SIZE+12
|
|
|
|
/* Common exception exit.
|
|
* We restore the special register and the current window frame, and
|
|
* return from the exception.
|
|
*
|
|
* Note: We expect a2 to hold PT_WMASK
|
|
*/
|
|
|
|
common_exception_exit:
|
|
|
|
/* Restore address registers. */
|
|
|
|
_bbsi.l a2, 1, 1f
|
|
l32i a4, a1, PT_AREG4
|
|
l32i a5, a1, PT_AREG5
|
|
l32i a6, a1, PT_AREG6
|
|
l32i a7, a1, PT_AREG7
|
|
_bbsi.l a2, 2, 1f
|
|
l32i a8, a1, PT_AREG8
|
|
l32i a9, a1, PT_AREG9
|
|
l32i a10, a1, PT_AREG10
|
|
l32i a11, a1, PT_AREG11
|
|
_bbsi.l a2, 3, 1f
|
|
l32i a12, a1, PT_AREG12
|
|
l32i a13, a1, PT_AREG13
|
|
l32i a14, a1, PT_AREG14
|
|
l32i a15, a1, PT_AREG15
|
|
|
|
/* Restore PC, SAR */
|
|
|
|
1: l32i a2, a1, PT_PC
|
|
l32i a3, a1, PT_SAR
|
|
wsr a2, EPC_1
|
|
wsr a3, SAR
|
|
|
|
/* Restore LBEG, LEND, LCOUNT */
|
|
|
|
l32i a2, a1, PT_LBEG
|
|
l32i a3, a1, PT_LEND
|
|
wsr a2, LBEG
|
|
l32i a2, a1, PT_LCOUNT
|
|
wsr a3, LEND
|
|
wsr a2, LCOUNT
|
|
|
|
/* We control single stepping through the ICOUNTLEVEL register. */
|
|
|
|
l32i a2, a1, PT_ICOUNTLEVEL
|
|
movi a3, -2
|
|
wsr a2, ICOUNTLEVEL
|
|
wsr a3, ICOUNT
|
|
|
|
/* Check if it was double exception. */
|
|
|
|
l32i a0, a1, PT_DEPC
|
|
l32i a3, a1, PT_AREG3
|
|
l32i a2, a1, PT_AREG2
|
|
_bgeui a0, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f
|
|
|
|
/* Restore a0...a3 and return */
|
|
|
|
l32i a0, a1, PT_AREG0
|
|
l32i a1, a1, PT_AREG1
|
|
rfe
|
|
|
|
1: wsr a0, DEPC
|
|
l32i a0, a1, PT_AREG0
|
|
l32i a1, a1, PT_AREG1
|
|
rfde
|
|
|
|
/*
|
|
* Debug exception handler.
|
|
*
|
|
* Currently, we don't support KGDB, so only user application can be debugged.
|
|
*
|
|
* When we get here, a0 is trashed and saved to excsave[debuglevel]
|
|
*/
|
|
|
|
ENTRY(debug_exception)
|
|
|
|
rsr a0, EPS + XCHAL_DEBUGLEVEL
|
|
bbsi.l a0, PS_EXCM_BIT, 1f # exception mode
|
|
|
|
/* Set EPC_1 and EXCCAUSE */
|
|
|
|
wsr a2, DEPC # save a2 temporarily
|
|
rsr a2, EPC + XCHAL_DEBUGLEVEL
|
|
wsr a2, EPC_1
|
|
|
|
movi a2, EXCCAUSE_MAPPED_DEBUG
|
|
wsr a2, EXCCAUSE
|
|
|
|
/* Restore PS to the value before the debug exc but with PS.EXCM set.*/
|
|
|
|
movi a2, 1 << PS_EXCM_BIT
|
|
or a2, a0, a2
|
|
movi a0, debug_exception # restore a3, debug jump vector
|
|
wsr a2, PS
|
|
xsr a0, EXCSAVE + XCHAL_DEBUGLEVEL
|
|
|
|
/* Switch to kernel/user stack, restore jump vector, and save a0 */
|
|
|
|
bbsi.l a2, PS_UM_BIT, 2f # jump if user mode
|
|
|
|
addi a2, a1, -16-PT_SIZE # assume kernel stack
|
|
s32i a0, a2, PT_AREG0
|
|
movi a0, 0
|
|
s32i a1, a2, PT_AREG1
|
|
s32i a0, a2, PT_DEPC # mark it as a regular exception
|
|
xsr a0, DEPC
|
|
s32i a3, a2, PT_AREG3
|
|
s32i a0, a2, PT_AREG2
|
|
mov a1, a2
|
|
j _kernel_exception
|
|
|
|
2: rsr a2, EXCSAVE_1
|
|
l32i a2, a2, EXC_TABLE_KSTK # load kernel stack pointer
|
|
s32i a0, a2, PT_AREG0
|
|
movi a0, 0
|
|
s32i a1, a2, PT_AREG1
|
|
s32i a0, a2, PT_DEPC
|
|
xsr a0, DEPC
|
|
s32i a3, a2, PT_AREG3
|
|
s32i a0, a2, PT_AREG2
|
|
mov a1, a2
|
|
j _user_exception
|
|
|
|
/* Debug exception while in exception mode. */
|
|
1: j 1b // FIXME!!
|
|
|
|
|
|
/*
|
|
* We get here in case of an unrecoverable exception.
|
|
* The only thing we can do is to be nice and print a panic message.
|
|
* We only produce a single stack frame for panic, so ???
|
|
*
|
|
*
|
|
* Entry conditions:
|
|
*
|
|
* - a0 contains the caller address; original value saved in excsave1.
|
|
* - the original a0 contains a valid return address (backtrace) or 0.
|
|
* - a2 contains a valid stackpointer
|
|
*
|
|
* Notes:
|
|
*
|
|
* - If the stack pointer could be invalid, the caller has to setup a
|
|
* dummy stack pointer (e.g. the stack of the init_task)
|
|
*
|
|
* - If the return address could be invalid, the caller has to set it
|
|
* to 0, so the backtrace would stop.
|
|
*
|
|
*/
|
|
.align 4
|
|
unrecoverable_text:
|
|
.ascii "Unrecoverable error in exception handler\0"
|
|
|
|
ENTRY(unrecoverable_exception)
|
|
|
|
movi a0, 1
|
|
movi a1, 0
|
|
|
|
wsr a0, WINDOWSTART
|
|
wsr a1, WINDOWBASE
|
|
rsync
|
|
|
|
movi a1, (1 << PS_WOE_BIT) | 1
|
|
wsr a1, PS
|
|
rsync
|
|
|
|
movi a1, init_task
|
|
movi a0, 0
|
|
addi a1, a1, PT_REGS_OFFSET
|
|
|
|
movi a4, panic
|
|
movi a6, unrecoverable_text
|
|
|
|
callx4 a4
|
|
|
|
1: j 1b
|
|
|
|
|
|
/* -------------------------- FAST EXCEPTION HANDLERS ----------------------- */
|
|
|
|
/*
|
|
* Fast-handler for alloca exceptions
|
|
*
|
|
* The ALLOCA handler is entered when user code executes the MOVSP
|
|
* instruction and the caller's frame is not in the register file.
|
|
* In this case, the caller frame's a0..a3 are on the stack just
|
|
* below sp (a1), and this handler moves them.
|
|
*
|
|
* For "MOVSP <ar>,<as>" without destination register a1, this routine
|
|
* simply moves the value from <as> to <ar> without moving the save area.
|
|
*
|
|
* Entry condition:
|
|
*
|
|
* a0: trashed, original value saved on stack (PT_AREG0)
|
|
* a1: a1
|
|
* a2: new stack pointer, original in DEPC
|
|
* a3: dispatch table
|
|
* depc: a2, original value saved on stack (PT_DEPC)
|
|
* excsave_1: a3
|
|
*
|
|
* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
|
|
* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
|
|
*/
|
|
|
|
#if XCHAL_HAVE_BE
|
|
#define _EXTUI_MOVSP_SRC(ar) extui ar, ar, 4, 4
|
|
#define _EXTUI_MOVSP_DST(ar) extui ar, ar, 0, 4
|
|
#else
|
|
#define _EXTUI_MOVSP_SRC(ar) extui ar, ar, 0, 4
|
|
#define _EXTUI_MOVSP_DST(ar) extui ar, ar, 4, 4
|
|
#endif
|
|
|
|
ENTRY(fast_alloca)
|
|
|
|
/* We shouldn't be in a double exception. */
|
|
|
|
l32i a0, a2, PT_DEPC
|
|
_bgeui a0, VALID_DOUBLE_EXCEPTION_ADDRESS, .Lunhandled_double
|
|
|
|
rsr a0, DEPC # get a2
|
|
s32i a4, a2, PT_AREG4 # save a4 and
|
|
s32i a0, a2, PT_AREG2 # a2 to stack
|
|
|
|
/* Exit critical section. */
|
|
|
|
movi a0, 0
|
|
s32i a0, a3, EXC_TABLE_FIXUP
|
|
|
|
/* Restore a3, excsave_1 */
|
|
|
|
xsr a3, EXCSAVE_1 # make sure excsave_1 is valid for dbl.
|
|
rsr a4, EPC_1 # get exception address
|
|
s32i a3, a2, PT_AREG3 # save a3 to stack
|
|
|
|
#ifdef ALLOCA_EXCEPTION_IN_IRAM
|
|
#error iram not supported
|
|
#else
|
|
/* Note: l8ui not allowed in IRAM/IROM!! */
|
|
l8ui a0, a4, 1 # read as(src) from MOVSP instruction
|
|
#endif
|
|
movi a3, .Lmovsp_src
|
|
_EXTUI_MOVSP_SRC(a0) # extract source register number
|
|
addx8 a3, a0, a3
|
|
jx a3
|
|
|
|
.Lunhandled_double:
|
|
wsr a0, EXCSAVE_1
|
|
movi a0, unrecoverable_exception
|
|
callx0 a0
|
|
|
|
.align 8
|
|
.Lmovsp_src:
|
|
l32i a3, a2, PT_AREG0; _j 1f; .align 8
|
|
mov a3, a1; _j 1f; .align 8
|
|
l32i a3, a2, PT_AREG2; _j 1f; .align 8
|
|
l32i a3, a2, PT_AREG3; _j 1f; .align 8
|
|
l32i a3, a2, PT_AREG4; _j 1f; .align 8
|
|
mov a3, a5; _j 1f; .align 8
|
|
mov a3, a6; _j 1f; .align 8
|
|
mov a3, a7; _j 1f; .align 8
|
|
mov a3, a8; _j 1f; .align 8
|
|
mov a3, a9; _j 1f; .align 8
|
|
mov a3, a10; _j 1f; .align 8
|
|
mov a3, a11; _j 1f; .align 8
|
|
mov a3, a12; _j 1f; .align 8
|
|
mov a3, a13; _j 1f; .align 8
|
|
mov a3, a14; _j 1f; .align 8
|
|
mov a3, a15; _j 1f; .align 8
|
|
|
|
1:
|
|
|
|
#ifdef ALLOCA_EXCEPTION_IN_IRAM
|
|
#error iram not supported
|
|
#else
|
|
l8ui a0, a4, 0 # read ar(dst) from MOVSP instruction
|
|
#endif
|
|
addi a4, a4, 3 # step over movsp
|
|
_EXTUI_MOVSP_DST(a0) # extract destination register
|
|
wsr a4, EPC_1 # save new epc_1
|
|
|
|
_bnei a0, 1, 1f # no 'movsp a1, ax': jump
|
|
|
|
/* Move the save area. This implies the use of the L32E
|
|
* and S32E instructions, because this move must be done with
|
|
* the user's PS.RING privilege levels, not with ring 0
|
|
* (kernel's) privileges currently active with PS.EXCM
|
|
* set. Note that we have stil registered a fixup routine with the
|
|
* double exception vector in case a double exception occurs.
|
|
*/
|
|
|
|
/* a0,a4:avail a1:old user stack a2:exc. stack a3:new user stack. */
|
|
|
|
l32e a0, a1, -16
|
|
l32e a4, a1, -12
|
|
s32e a0, a3, -16
|
|
s32e a4, a3, -12
|
|
l32e a0, a1, -8
|
|
l32e a4, a1, -4
|
|
s32e a0, a3, -8
|
|
s32e a4, a3, -4
|
|
|
|
/* Restore stack-pointer and all the other saved registers. */
|
|
|
|
mov a1, a3
|
|
|
|
l32i a4, a2, PT_AREG4
|
|
l32i a3, a2, PT_AREG3
|
|
l32i a0, a2, PT_AREG0
|
|
l32i a2, a2, PT_AREG2
|
|
rfe
|
|
|
|
/* MOVSP <at>,<as> was invoked with <at> != a1.
|
|
* Because the stack pointer is not being modified,
|
|
* we should be able to just modify the pointer
|
|
* without moving any save area.
|
|
* The processor only traps these occurrences if the
|
|
* caller window isn't live, so unfortunately we can't
|
|
* use this as an alternate trap mechanism.
|
|
* So we just do the move. This requires that we
|
|
* resolve the destination register, not just the source,
|
|
* so there's some extra work.
|
|
* (PERHAPS NOT REALLY NEEDED, BUT CLEANER...)
|
|
*/
|
|
|
|
/* a0 dst-reg, a1 user-stack, a2 stack, a3 value of src reg. */
|
|
|
|
1: movi a4, .Lmovsp_dst
|
|
addx8 a4, a0, a4
|
|
jx a4
|
|
|
|
.align 8
|
|
.Lmovsp_dst:
|
|
s32i a3, a2, PT_AREG0; _j 1f; .align 8
|
|
mov a1, a3; _j 1f; .align 8
|
|
s32i a3, a2, PT_AREG2; _j 1f; .align 8
|
|
s32i a3, a2, PT_AREG3; _j 1f; .align 8
|
|
s32i a3, a2, PT_AREG4; _j 1f; .align 8
|
|
mov a5, a3; _j 1f; .align 8
|
|
mov a6, a3; _j 1f; .align 8
|
|
mov a7, a3; _j 1f; .align 8
|
|
mov a8, a3; _j 1f; .align 8
|
|
mov a9, a3; _j 1f; .align 8
|
|
mov a10, a3; _j 1f; .align 8
|
|
mov a11, a3; _j 1f; .align 8
|
|
mov a12, a3; _j 1f; .align 8
|
|
mov a13, a3; _j 1f; .align 8
|
|
mov a14, a3; _j 1f; .align 8
|
|
mov a15, a3; _j 1f; .align 8
|
|
|
|
1: l32i a4, a2, PT_AREG4
|
|
l32i a3, a2, PT_AREG3
|
|
l32i a0, a2, PT_AREG0
|
|
l32i a2, a2, PT_AREG2
|
|
rfe
|
|
|
|
|
|
/*
|
|
* fast system calls.
|
|
*
|
|
* WARNING: The kernel doesn't save the entire user context before
|
|
* handling a fast system call. These functions are small and short,
|
|
* usually offering some functionality not available to user tasks.
|
|
*
|
|
* BE CAREFUL TO PRESERVE THE USER'S CONTEXT.
|
|
*
|
|
* Entry condition:
|
|
*
|
|
* a0: trashed, original value saved on stack (PT_AREG0)
|
|
* a1: a1
|
|
* a2: new stack pointer, original in DEPC
|
|
* a3: dispatch table
|
|
* depc: a2, original value saved on stack (PT_DEPC)
|
|
* excsave_1: a3
|
|
*/
|
|
|
|
ENTRY(fast_syscall_kernel)
|
|
|
|
/* Skip syscall. */
|
|
|
|
rsr a0, EPC_1
|
|
addi a0, a0, 3
|
|
wsr a0, EPC_1
|
|
|
|
l32i a0, a2, PT_DEPC
|
|
bgeui a0, VALID_DOUBLE_EXCEPTION_ADDRESS, fast_syscall_unrecoverable
|
|
|
|
rsr a0, DEPC # get syscall-nr
|
|
_beqz a0, fast_syscall_spill_registers
|
|
_beqi a0, __NR_xtensa, fast_syscall_xtensa
|
|
|
|
j kernel_exception
|
|
|
|
ENTRY(fast_syscall_user)
|
|
|
|
/* Skip syscall. */
|
|
|
|
rsr a0, EPC_1
|
|
addi a0, a0, 3
|
|
wsr a0, EPC_1
|
|
|
|
l32i a0, a2, PT_DEPC
|
|
bgeui a0, VALID_DOUBLE_EXCEPTION_ADDRESS, fast_syscall_unrecoverable
|
|
|
|
rsr a0, DEPC # get syscall-nr
|
|
_beqz a0, fast_syscall_spill_registers
|
|
_beqi a0, __NR_xtensa, fast_syscall_xtensa
|
|
|
|
j user_exception
|
|
|
|
ENTRY(fast_syscall_unrecoverable)
|
|
|
|
/* Restore all states. */
|
|
|
|
l32i a0, a2, PT_AREG0 # restore a0
|
|
xsr a2, DEPC # restore a2, depc
|
|
rsr a3, EXCSAVE_1
|
|
|
|
wsr a0, EXCSAVE_1
|
|
movi a0, unrecoverable_exception
|
|
callx0 a0
|
|
|
|
|
|
|
|
/*
|
|
* sysxtensa syscall handler
|
|
*
|
|
* int sysxtensa (SYS_XTENSA_ATOMIC_SET, ptr, val, unused);
|
|
* int sysxtensa (SYS_XTENSA_ATOMIC_ADD, ptr, val, unused);
|
|
* int sysxtensa (SYS_XTENSA_ATOMIC_EXG_ADD, ptr, val, unused);
|
|
* int sysxtensa (SYS_XTENSA_ATOMIC_CMP_SWP, ptr, oldval, newval);
|
|
* a2 a6 a3 a4 a5
|
|
*
|
|
* Entry condition:
|
|
*
|
|
* a0: a2 (syscall-nr), original value saved on stack (PT_AREG0)
|
|
* a1: a1
|
|
* a2: new stack pointer, original in a0 and DEPC
|
|
* a3: dispatch table, original in excsave_1
|
|
* a4..a15: unchanged
|
|
* depc: a2, original value saved on stack (PT_DEPC)
|
|
* excsave_1: a3
|
|
*
|
|
* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
|
|
* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
|
|
*
|
|
* Note: we don't have to save a2; a2 holds the return value
|
|
*
|
|
* We use the two macros TRY and CATCH:
|
|
*
|
|
* TRY adds an entry to the __ex_table fixup table for the immediately
|
|
* following instruction.
|
|
*
|
|
* CATCH catches any exception that occurred at one of the preceeding TRY
|
|
* statements and continues from there
|
|
*
|
|
* Usage TRY l32i a0, a1, 0
|
|
* <other code>
|
|
* done: rfe
|
|
* CATCH <set return code>
|
|
* j done
|
|
*/
|
|
|
|
#define TRY \
|
|
.section __ex_table, "a"; \
|
|
.word 66f, 67f; \
|
|
.text; \
|
|
66:
|
|
|
|
#define CATCH \
|
|
67:
|
|
|
|
ENTRY(fast_syscall_xtensa)
|
|
|
|
xsr a3, EXCSAVE_1 # restore a3, excsave1
|
|
|
|
s32i a7, a2, PT_AREG7 # we need an additional register
|
|
movi a7, 4 # sizeof(unsigned int)
|
|
access_ok a3, a7, a0, a2, .Leac # a0: scratch reg, a2: sp
|
|
|
|
addi a6, a6, -1 # assuming SYS_XTENSA_ATOMIC_SET = 1
|
|
_bgeui a6, SYS_XTENSA_COUNT - 1, .Lill
|
|
_bnei a6, SYS_XTENSA_ATOMIC_CMP_SWP - 1, .Lnswp
|
|
|
|
/* Fall through for ATOMIC_CMP_SWP. */
|
|
|
|
.Lswp: /* Atomic compare and swap */
|
|
|
|
TRY l32i a0, a3, 0 # read old value
|
|
bne a0, a4, 1f # same as old value? jump
|
|
TRY s32i a5, a3, 0 # different, modify value
|
|
l32i a7, a2, PT_AREG7 # restore a7
|
|
l32i a0, a2, PT_AREG0 # restore a0
|
|
movi a2, 1 # and return 1
|
|
addi a6, a6, 1 # restore a6 (really necessary?)
|
|
rfe
|
|
|
|
1: l32i a7, a2, PT_AREG7 # restore a7
|
|
l32i a0, a2, PT_AREG0 # restore a0
|
|
movi a2, 0 # return 0 (note that we cannot set
|
|
addi a6, a6, 1 # restore a6 (really necessary?)
|
|
rfe
|
|
|
|
.Lnswp: /* Atomic set, add, and exg_add. */
|
|
|
|
TRY l32i a7, a3, 0 # orig
|
|
add a0, a4, a7 # + arg
|
|
moveqz a0, a4, a6 # set
|
|
TRY s32i a0, a3, 0 # write new value
|
|
|
|
mov a0, a2
|
|
mov a2, a7
|
|
l32i a7, a0, PT_AREG7 # restore a7
|
|
l32i a0, a0, PT_AREG0 # restore a0
|
|
addi a6, a6, 1 # restore a6 (really necessary?)
|
|
rfe
|
|
|
|
CATCH
|
|
.Leac: l32i a7, a2, PT_AREG7 # restore a7
|
|
l32i a0, a2, PT_AREG0 # restore a0
|
|
movi a2, -EFAULT
|
|
rfe
|
|
|
|
.Lill: l32i a7, a2, PT_AREG0 # restore a7
|
|
l32i a0, a2, PT_AREG0 # restore a0
|
|
movi a2, -EINVAL
|
|
rfe
|
|
|
|
|
|
|
|
|
|
/* fast_syscall_spill_registers.
|
|
*
|
|
* Entry condition:
|
|
*
|
|
* a0: trashed, original value saved on stack (PT_AREG0)
|
|
* a1: a1
|
|
* a2: new stack pointer, original in DEPC
|
|
* a3: dispatch table
|
|
* depc: a2, original value saved on stack (PT_DEPC)
|
|
* excsave_1: a3
|
|
*
|
|
* Note: We assume the stack pointer is EXC_TABLE_KSTK in the fixup handler.
|
|
*/
|
|
|
|
ENTRY(fast_syscall_spill_registers)
|
|
|
|
/* Register a FIXUP handler (pass current wb as a parameter) */
|
|
|
|
movi a0, fast_syscall_spill_registers_fixup
|
|
s32i a0, a3, EXC_TABLE_FIXUP
|
|
rsr a0, WINDOWBASE
|
|
s32i a0, a3, EXC_TABLE_PARAM
|
|
|
|
/* Save a3 and SAR on stack. */
|
|
|
|
rsr a0, SAR
|
|
xsr a3, EXCSAVE_1 # restore a3 and excsave_1
|
|
s32i a3, a2, PT_AREG3
|
|
s32i a4, a2, PT_AREG4
|
|
s32i a0, a2, PT_AREG5 # store SAR to PT_AREG5
|
|
|
|
/* The spill routine might clobber a7, a11, and a15. */
|
|
|
|
s32i a7, a2, PT_AREG7
|
|
s32i a11, a2, PT_AREG11
|
|
s32i a15, a2, PT_AREG15
|
|
|
|
call0 _spill_registers # destroys a3, a4, and SAR
|
|
|
|
/* Advance PC, restore registers and SAR, and return from exception. */
|
|
|
|
l32i a3, a2, PT_AREG5
|
|
l32i a4, a2, PT_AREG4
|
|
l32i a0, a2, PT_AREG0
|
|
wsr a3, SAR
|
|
l32i a3, a2, PT_AREG3
|
|
|
|
/* Restore clobbered registers. */
|
|
|
|
l32i a7, a2, PT_AREG7
|
|
l32i a11, a2, PT_AREG11
|
|
l32i a15, a2, PT_AREG15
|
|
|
|
movi a2, 0
|
|
rfe
|
|
|
|
/* Fixup handler.
|
|
*
|
|
* We get here if the spill routine causes an exception, e.g. tlb miss.
|
|
* We basically restore WINDOWBASE and WINDOWSTART to the condition when
|
|
* we entered the spill routine and jump to the user exception handler.
|
|
*
|
|
* a0: value of depc, original value in depc
|
|
* a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE
|
|
* a3: exctable, original value in excsave1
|
|
*/
|
|
|
|
fast_syscall_spill_registers_fixup:
|
|
|
|
rsr a2, WINDOWBASE # get current windowbase (a2 is saved)
|
|
xsr a0, DEPC # restore depc and a0
|
|
ssl a2 # set shift (32 - WB)
|
|
|
|
/* We need to make sure the current registers (a0-a3) are preserved.
|
|
* To do this, we simply set the bit for the current window frame
|
|
* in WS, so that the exception handlers save them to the task stack.
|
|
*/
|
|
|
|
rsr a3, EXCSAVE_1 # get spill-mask
|
|
slli a2, a3, 1 # shift left by one
|
|
|
|
slli a3, a2, 32-WSBITS
|
|
src a2, a2, a3 # a1 = xxwww1yyxxxwww1yy......
|
|
wsr a2, WINDOWSTART # set corrected windowstart
|
|
|
|
movi a3, exc_table
|
|
l32i a2, a3, EXC_TABLE_DOUBLE_SAVE # restore a2
|
|
l32i a3, a3, EXC_TABLE_PARAM # original WB (in user task)
|
|
|
|
/* Return to the original (user task) WINDOWBASE.
|
|
* We leave the following frame behind:
|
|
* a0, a1, a2 same
|
|
* a3: trashed (saved in excsave_1)
|
|
* depc: depc (we have to return to that address)
|
|
* excsave_1: a3
|
|
*/
|
|
|
|
wsr a3, WINDOWBASE
|
|
rsync
|
|
|
|
/* We are now in the original frame when we entered _spill_registers:
|
|
* a0: return address
|
|
* a1: used, stack pointer
|
|
* a2: kernel stack pointer
|
|
* a3: available, saved in EXCSAVE_1
|
|
* depc: exception address
|
|
* excsave: a3
|
|
* Note: This frame might be the same as above.
|
|
*/
|
|
|
|
/* Setup stack pointer. */
|
|
|
|
addi a2, a2, -PT_USER_SIZE
|
|
s32i a0, a2, PT_AREG0
|
|
|
|
/* Make sure we return to this fixup handler. */
|
|
|
|
movi a3, fast_syscall_spill_registers_fixup_return
|
|
s32i a3, a2, PT_DEPC # setup depc
|
|
|
|
/* Jump to the exception handler. */
|
|
|
|
movi a3, exc_table
|
|
rsr a0, EXCCAUSE
|
|
addx4 a0, a0, a3 # find entry in table
|
|
l32i a0, a0, EXC_TABLE_FAST_USER # load handler
|
|
jx a0
|
|
|
|
fast_syscall_spill_registers_fixup_return:
|
|
|
|
/* When we return here, all registers have been restored (a2: DEPC) */
|
|
|
|
wsr a2, DEPC # exception address
|
|
|
|
/* Restore fixup handler. */
|
|
|
|
xsr a3, EXCSAVE_1
|
|
movi a2, fast_syscall_spill_registers_fixup
|
|
s32i a2, a3, EXC_TABLE_FIXUP
|
|
rsr a2, WINDOWBASE
|
|
s32i a2, a3, EXC_TABLE_PARAM
|
|
l32i a2, a3, EXC_TABLE_KSTK
|
|
|
|
/* Load WB at the time the exception occurred. */
|
|
|
|
rsr a3, SAR # WB is still in SAR
|
|
neg a3, a3
|
|
wsr a3, WINDOWBASE
|
|
rsync
|
|
|
|
/* Restore a3 and return. */
|
|
|
|
movi a3, exc_table
|
|
xsr a3, EXCSAVE_1
|
|
|
|
rfde
|
|
|
|
|
|
/*
|
|
* spill all registers.
|
|
*
|
|
* This is not a real function. The following conditions must be met:
|
|
*
|
|
* - must be called with call0.
|
|
* - uses a3, a4 and SAR.
|
|
* - the last 'valid' register of each frame are clobbered.
|
|
* - the caller must have registered a fixup handler
|
|
* (or be inside a critical section)
|
|
* - PS_EXCM must be set (PS_WOE cleared?)
|
|
*/
|
|
|
|
ENTRY(_spill_registers)
|
|
|
|
/*
|
|
* Rotate ws so that the current windowbase is at bit 0.
|
|
* Assume ws = xxxwww1yy (www1 current window frame).
|
|
* Rotate ws right so that a4 = yyxxxwww1.
|
|
*/
|
|
|
|
rsr a4, WINDOWBASE
|
|
rsr a3, WINDOWSTART # a3 = xxxwww1yy
|
|
ssr a4 # holds WB
|
|
slli a4, a3, WSBITS
|
|
or a3, a3, a4 # a3 = xxxwww1yyxxxwww1yy
|
|
srl a3, a3 # a3 = 00xxxwww1yyxxxwww1
|
|
|
|
/* We are done if there are no more than the current register frame. */
|
|
|
|
extui a3, a3, 1, WSBITS-1 # a3 = 0yyxxxwww
|
|
movi a4, (1 << (WSBITS-1))
|
|
_beqz a3, .Lnospill # only one active frame? jump
|
|
|
|
/* We want 1 at the top, so that we return to the current windowbase */
|
|
|
|
or a3, a3, a4 # 1yyxxxwww
|
|
|
|
/* Skip empty frames - get 'oldest' WINDOWSTART-bit. */
|
|
|
|
wsr a3, WINDOWSTART # save shifted windowstart
|
|
neg a4, a3
|
|
and a3, a4, a3 # first bit set from right: 000010000
|
|
|
|
ffs_ws a4, a3 # a4: shifts to skip empty frames
|
|
movi a3, WSBITS
|
|
sub a4, a3, a4 # WSBITS-a4:number of 0-bits from right
|
|
ssr a4 # save in SAR for later.
|
|
|
|
rsr a3, WINDOWBASE
|
|
add a3, a3, a4
|
|
wsr a3, WINDOWBASE
|
|
rsync
|
|
|
|
rsr a3, WINDOWSTART
|
|
srl a3, a3 # shift windowstart
|
|
|
|
/* WB is now just one frame below the oldest frame in the register
|
|
window. WS is shifted so the oldest frame is in bit 0, thus, WB
|
|
and WS differ by one 4-register frame. */
|
|
|
|
/* Save frames. Depending what call was used (call4, call8, call12),
|
|
* we have to save 4,8. or 12 registers.
|
|
*/
|
|
|
|
_bbsi.l a3, 1, .Lc4
|
|
_bbsi.l a3, 2, .Lc8
|
|
|
|
/* Special case: we have a call12-frame starting at a4. */
|
|
|
|
_bbci.l a3, 3, .Lc12 # bit 3 shouldn't be zero! (Jump to Lc12 first)
|
|
|
|
s32e a4, a1, -16 # a1 is valid with an empty spill area
|
|
l32e a4, a5, -12
|
|
s32e a8, a4, -48
|
|
mov a8, a4
|
|
l32e a4, a1, -16
|
|
j .Lc12c
|
|
|
|
.Lnospill:
|
|
ret
|
|
|
|
.Lloop: _bbsi.l a3, 1, .Lc4
|
|
_bbci.l a3, 2, .Lc12
|
|
|
|
.Lc8: s32e a4, a13, -16
|
|
l32e a4, a5, -12
|
|
s32e a8, a4, -32
|
|
s32e a5, a13, -12
|
|
s32e a6, a13, -8
|
|
s32e a7, a13, -4
|
|
s32e a9, a4, -28
|
|
s32e a10, a4, -24
|
|
s32e a11, a4, -20
|
|
|
|
srli a11, a3, 2 # shift windowbase by 2
|
|
rotw 2
|
|
_bnei a3, 1, .Lloop
|
|
|
|
.Lexit: /* Done. Do the final rotation, set WS, and return. */
|
|
|
|
rotw 1
|
|
rsr a3, WINDOWBASE
|
|
ssl a3
|
|
movi a3, 1
|
|
sll a3, a3
|
|
wsr a3, WINDOWSTART
|
|
ret
|
|
|
|
.Lc4: s32e a4, a9, -16
|
|
s32e a5, a9, -12
|
|
s32e a6, a9, -8
|
|
s32e a7, a9, -4
|
|
|
|
srli a7, a3, 1
|
|
rotw 1
|
|
_bnei a3, 1, .Lloop
|
|
j .Lexit
|
|
|
|
.Lc12: _bbci.l a3, 3, .Linvalid_mask # bit 2 shouldn't be zero!
|
|
|
|
/* 12-register frame (call12) */
|
|
|
|
l32e a2, a5, -12
|
|
s32e a8, a2, -48
|
|
mov a8, a2
|
|
|
|
.Lc12c: s32e a9, a8, -44
|
|
s32e a10, a8, -40
|
|
s32e a11, a8, -36
|
|
s32e a12, a8, -32
|
|
s32e a13, a8, -28
|
|
s32e a14, a8, -24
|
|
s32e a15, a8, -20
|
|
srli a15, a3, 3
|
|
|
|
/* The stack pointer for a4..a7 is out of reach, so we rotate the
|
|
* window, grab the stackpointer, and rotate back.
|
|
* Alternatively, we could also use the following approach, but that
|
|
* makes the fixup routine much more complicated:
|
|
* rotw 1
|
|
* s32e a0, a13, -16
|
|
* ...
|
|
* rotw 2
|
|
*/
|
|
|
|
rotw 1
|
|
mov a5, a13
|
|
rotw -1
|
|
|
|
s32e a4, a9, -16
|
|
s32e a5, a9, -12
|
|
s32e a6, a9, -8
|
|
s32e a7, a9, -4
|
|
|
|
rotw 3
|
|
|
|
_beqi a3, 1, .Lexit
|
|
j .Lloop
|
|
|
|
.Linvalid_mask:
|
|
|
|
/* We get here because of an unrecoverable error in the window
|
|
* registers. If we are in user space, we kill the application,
|
|
* however, this condition is unrecoverable in kernel space.
|
|
*/
|
|
|
|
rsr a0, PS
|
|
_bbci.l a0, PS_UM_BIT, 1f
|
|
|
|
/* User space: Setup a dummy frame and kill application.
|
|
* Note: We assume EXC_TABLE_KSTK contains a valid stack pointer.
|
|
*/
|
|
|
|
movi a0, 1
|
|
movi a1, 0
|
|
|
|
wsr a0, WINDOWSTART
|
|
wsr a1, WINDOWBASE
|
|
rsync
|
|
|
|
movi a0, 0
|
|
|
|
movi a3, exc_table
|
|
l32i a1, a3, EXC_TABLE_KSTK
|
|
wsr a3, EXCSAVE_1
|
|
|
|
movi a4, (1 << PS_WOE_BIT) | 1
|
|
wsr a4, PS
|
|
rsync
|
|
|
|
movi a6, SIGSEGV
|
|
movi a4, do_exit
|
|
callx4 a4
|
|
|
|
1: /* Kernel space: PANIC! */
|
|
|
|
wsr a0, EXCSAVE_1
|
|
movi a0, unrecoverable_exception
|
|
callx0 a0 # should not return
|
|
1: j 1b
|
|
|
|
/*
|
|
* We should never get here. Bail out!
|
|
*/
|
|
|
|
ENTRY(fast_second_level_miss_double_kernel)
|
|
|
|
1: movi a0, unrecoverable_exception
|
|
callx0 a0 # should not return
|
|
1: j 1b
|
|
|
|
/* First-level entry handler for user, kernel, and double 2nd-level
|
|
* TLB miss exceptions. Note that for now, user and kernel miss
|
|
* exceptions share the same entry point and are handled identically.
|
|
*
|
|
* An old, less-efficient C version of this function used to exist.
|
|
* We include it below, interleaved as comments, for reference.
|
|
*
|
|
* Entry condition:
|
|
*
|
|
* a0: trashed, original value saved on stack (PT_AREG0)
|
|
* a1: a1
|
|
* a2: new stack pointer, original in DEPC
|
|
* a3: dispatch table
|
|
* depc: a2, original value saved on stack (PT_DEPC)
|
|
* excsave_1: a3
|
|
*
|
|
* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
|
|
* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
|
|
*/
|
|
|
|
ENTRY(fast_second_level_miss)
|
|
|
|
/* Save a1. Note: we don't expect a double exception. */
|
|
|
|
s32i a1, a2, PT_AREG1
|
|
|
|
/* We need to map the page of PTEs for the user task. Find
|
|
* the pointer to that page. Also, it's possible for tsk->mm
|
|
* to be NULL while tsk->active_mm is nonzero if we faulted on
|
|
* a vmalloc address. In that rare case, we must use
|
|
* active_mm instead to avoid a fault in this handler. See
|
|
*
|
|
* http://mail.nl.linux.org/linux-mm/2002-08/msg00258.html
|
|
* (or search Internet on "mm vs. active_mm")
|
|
*
|
|
* if (!mm)
|
|
* mm = tsk->active_mm;
|
|
* pgd = pgd_offset (mm, regs->excvaddr);
|
|
* pmd = pmd_offset (pgd, regs->excvaddr);
|
|
* pmdval = *pmd;
|
|
*/
|
|
|
|
GET_CURRENT(a1,a2)
|
|
l32i a0, a1, TASK_MM # tsk->mm
|
|
beqz a0, 9f
|
|
|
|
|
|
/* We deliberately destroy a3 that holds the exception table. */
|
|
|
|
8: rsr a3, EXCVADDR # fault address
|
|
_PGD_OFFSET(a0, a3, a1)
|
|
l32i a0, a0, 0 # read pmdval
|
|
beqz a0, 2f
|
|
|
|
/* Read ptevaddr and convert to top of page-table page.
|
|
*
|
|
* vpnval = read_ptevaddr_register() & PAGE_MASK;
|
|
* vpnval += DTLB_WAY_PGTABLE;
|
|
* pteval = mk_pte (virt_to_page(pmd_val(pmdval)), PAGE_KERNEL);
|
|
* write_dtlb_entry (pteval, vpnval);
|
|
*
|
|
* The messy computation for 'pteval' above really simplifies
|
|
* into the following:
|
|
*
|
|
* pteval = ((pmdval - PAGE_OFFSET) & PAGE_MASK) | PAGE_DIRECTORY
|
|
*/
|
|
|
|
movi a1, -PAGE_OFFSET
|
|
add a0, a0, a1 # pmdval - PAGE_OFFSET
|
|
extui a1, a0, 0, PAGE_SHIFT # ... & PAGE_MASK
|
|
xor a0, a0, a1
|
|
|
|
movi a1, _PAGE_DIRECTORY
|
|
or a0, a0, a1 # ... | PAGE_DIRECTORY
|
|
|
|
/*
|
|
* We utilize all three wired-ways (7-9) to hold pmd translations.
|
|
* Memory regions are mapped to the DTLBs according to bits 28 and 29.
|
|
* This allows to map the three most common regions to three different
|
|
* DTLBs:
|
|
* 0,1 -> way 7 program (0040.0000) and virtual (c000.0000)
|
|
* 2 -> way 8 shared libaries (2000.0000)
|
|
* 3 -> way 0 stack (3000.0000)
|
|
*/
|
|
|
|
extui a3, a3, 28, 2 # addr. bit 28 and 29 0,1,2,3
|
|
rsr a1, PTEVADDR
|
|
addx2 a3, a3, a3 # -> 0,3,6,9
|
|
srli a1, a1, PAGE_SHIFT
|
|
extui a3, a3, 2, 2 # -> 0,0,1,2
|
|
slli a1, a1, PAGE_SHIFT # ptevaddr & PAGE_MASK
|
|
addi a3, a3, DTLB_WAY_PGD
|
|
add a1, a1, a3 # ... + way_number
|
|
|
|
3: wdtlb a0, a1
|
|
dsync
|
|
|
|
/* Exit critical section. */
|
|
|
|
4: movi a3, exc_table # restore a3
|
|
movi a0, 0
|
|
s32i a0, a3, EXC_TABLE_FIXUP
|
|
|
|
/* Restore the working registers, and return. */
|
|
|
|
l32i a0, a2, PT_AREG0
|
|
l32i a1, a2, PT_AREG1
|
|
l32i a2, a2, PT_DEPC
|
|
xsr a3, EXCSAVE_1
|
|
|
|
bgeui a2, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f
|
|
|
|
/* Restore excsave1 and return. */
|
|
|
|
rsr a2, DEPC
|
|
rfe
|
|
|
|
/* Return from double exception. */
|
|
|
|
1: xsr a2, DEPC
|
|
esync
|
|
rfde
|
|
|
|
9: l32i a0, a1, TASK_ACTIVE_MM # unlikely case mm == 0
|
|
j 8b
|
|
|
|
#if (DCACHE_WAY_SIZE > PAGE_SIZE)
|
|
|
|
2: /* Special case for cache aliasing.
|
|
* We (should) only get here if a clear_user_page, copy_user_page
|
|
* or the aliased cache flush functions got preemptively interrupted
|
|
* by another task. Re-establish temporary mapping to the
|
|
* TLBTEMP_BASE areas.
|
|
*/
|
|
|
|
/* We shouldn't be in a double exception */
|
|
|
|
l32i a0, a2, PT_DEPC
|
|
bgeui a0, VALID_DOUBLE_EXCEPTION_ADDRESS, 2f
|
|
|
|
/* Make sure the exception originated in the special functions */
|
|
|
|
movi a0, __tlbtemp_mapping_start
|
|
rsr a3, EPC_1
|
|
bltu a3, a0, 2f
|
|
movi a0, __tlbtemp_mapping_end
|
|
bgeu a3, a0, 2f
|
|
|
|
/* Check if excvaddr was in one of the TLBTEMP_BASE areas. */
|
|
|
|
movi a3, TLBTEMP_BASE_1
|
|
rsr a0, EXCVADDR
|
|
bltu a0, a3, 2f
|
|
|
|
addi a1, a0, -(2 << (DCACHE_ALIAS_ORDER + PAGE_SHIFT))
|
|
bgeu a1, a3, 2f
|
|
|
|
/* Check if we have to restore an ITLB mapping. */
|
|
|
|
movi a1, __tlbtemp_mapping_itlb
|
|
rsr a3, EPC_1
|
|
sub a3, a3, a1
|
|
|
|
/* Calculate VPN */
|
|
|
|
movi a1, PAGE_MASK
|
|
and a1, a1, a0
|
|
|
|
/* Jump for ITLB entry */
|
|
|
|
bgez a3, 1f
|
|
|
|
/* We can use up to two TLBTEMP areas, one for src and one for dst. */
|
|
|
|
extui a3, a0, PAGE_SHIFT + DCACHE_ALIAS_ORDER, 1
|
|
add a1, a3, a1
|
|
|
|
/* PPN is in a6 for the first TLBTEMP area and in a7 for the second. */
|
|
|
|
mov a0, a6
|
|
movnez a0, a7, a3
|
|
j 3b
|
|
|
|
/* ITLB entry. We only use dst in a6. */
|
|
|
|
1: witlb a6, a1
|
|
isync
|
|
j 4b
|
|
|
|
|
|
#endif // DCACHE_WAY_SIZE > PAGE_SIZE
|
|
|
|
|
|
2: /* Invalid PGD, default exception handling */
|
|
|
|
movi a3, exc_table
|
|
rsr a1, DEPC
|
|
xsr a3, EXCSAVE_1
|
|
s32i a1, a2, PT_AREG2
|
|
s32i a3, a2, PT_AREG3
|
|
mov a1, a2
|
|
|
|
rsr a2, PS
|
|
bbsi.l a2, PS_UM_BIT, 1f
|
|
j _kernel_exception
|
|
1: j _user_exception
|
|
|
|
|
|
/*
|
|
* StoreProhibitedException
|
|
*
|
|
* Update the pte and invalidate the itlb mapping for this pte.
|
|
*
|
|
* Entry condition:
|
|
*
|
|
* a0: trashed, original value saved on stack (PT_AREG0)
|
|
* a1: a1
|
|
* a2: new stack pointer, original in DEPC
|
|
* a3: dispatch table
|
|
* depc: a2, original value saved on stack (PT_DEPC)
|
|
* excsave_1: a3
|
|
*
|
|
* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
|
|
* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
|
|
*/
|
|
|
|
ENTRY(fast_store_prohibited)
|
|
|
|
/* Save a1 and a4. */
|
|
|
|
s32i a1, a2, PT_AREG1
|
|
s32i a4, a2, PT_AREG4
|
|
|
|
GET_CURRENT(a1,a2)
|
|
l32i a0, a1, TASK_MM # tsk->mm
|
|
beqz a0, 9f
|
|
|
|
8: rsr a1, EXCVADDR # fault address
|
|
_PGD_OFFSET(a0, a1, a4)
|
|
l32i a0, a0, 0
|
|
beqz a0, 2f
|
|
|
|
/* Note that we assume _PAGE_WRITABLE_BIT is only set if pte is valid.*/
|
|
|
|
_PTE_OFFSET(a0, a1, a4)
|
|
l32i a4, a0, 0 # read pteval
|
|
bbci.l a4, _PAGE_WRITABLE_BIT, 2f
|
|
|
|
movi a1, _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_HW_WRITE
|
|
or a4, a4, a1
|
|
rsr a1, EXCVADDR
|
|
s32i a4, a0, 0
|
|
|
|
/* We need to flush the cache if we have page coloring. */
|
|
#if (DCACHE_WAY_SIZE > PAGE_SIZE) && XCHAL_DCACHE_IS_WRITEBACK
|
|
dhwb a0, 0
|
|
#endif
|
|
pdtlb a0, a1
|
|
wdtlb a4, a0
|
|
|
|
/* Exit critical section. */
|
|
|
|
movi a0, 0
|
|
s32i a0, a3, EXC_TABLE_FIXUP
|
|
|
|
/* Restore the working registers, and return. */
|
|
|
|
l32i a4, a2, PT_AREG4
|
|
l32i a1, a2, PT_AREG1
|
|
l32i a0, a2, PT_AREG0
|
|
l32i a2, a2, PT_DEPC
|
|
|
|
/* Restore excsave1 and a3. */
|
|
|
|
xsr a3, EXCSAVE_1
|
|
bgeui a2, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f
|
|
|
|
rsr a2, DEPC
|
|
rfe
|
|
|
|
/* Double exception. Restore FIXUP handler and return. */
|
|
|
|
1: xsr a2, DEPC
|
|
esync
|
|
rfde
|
|
|
|
9: l32i a0, a1, TASK_ACTIVE_MM # unlikely case mm == 0
|
|
j 8b
|
|
|
|
2: /* If there was a problem, handle fault in C */
|
|
|
|
rsr a4, DEPC # still holds a2
|
|
xsr a3, EXCSAVE_1
|
|
s32i a4, a2, PT_AREG2
|
|
s32i a3, a2, PT_AREG3
|
|
l32i a4, a2, PT_AREG4
|
|
mov a1, a2
|
|
|
|
rsr a2, PS
|
|
bbsi.l a2, PS_UM_BIT, 1f
|
|
j _kernel_exception
|
|
1: j _user_exception
|
|
|
|
|
|
/*
|
|
* System Calls.
|
|
*
|
|
* void system_call (struct pt_regs* regs, int exccause)
|
|
* a2 a3
|
|
*/
|
|
|
|
ENTRY(system_call)
|
|
entry a1, 32
|
|
|
|
/* regs->syscall = regs->areg[2] */
|
|
|
|
l32i a3, a2, PT_AREG2
|
|
mov a6, a2
|
|
movi a4, do_syscall_trace_enter
|
|
s32i a3, a2, PT_SYSCALL
|
|
callx4 a4
|
|
|
|
/* syscall = sys_call_table[syscall_nr] */
|
|
|
|
movi a4, sys_call_table;
|
|
movi a5, __NR_syscall_count
|
|
movi a6, -ENOSYS
|
|
bgeu a3, a5, 1f
|
|
|
|
addx4 a4, a3, a4
|
|
l32i a4, a4, 0
|
|
movi a5, sys_ni_syscall;
|
|
beq a4, a5, 1f
|
|
|
|
/* Load args: arg0 - arg5 are passed via regs. */
|
|
|
|
l32i a6, a2, PT_AREG6
|
|
l32i a7, a2, PT_AREG3
|
|
l32i a8, a2, PT_AREG4
|
|
l32i a9, a2, PT_AREG5
|
|
l32i a10, a2, PT_AREG8
|
|
l32i a11, a2, PT_AREG9
|
|
|
|
/* Pass one additional argument to the syscall: pt_regs (on stack) */
|
|
s32i a2, a1, 0
|
|
|
|
callx4 a4
|
|
|
|
1: /* regs->areg[2] = return_value */
|
|
|
|
s32i a6, a2, PT_AREG2
|
|
movi a4, do_syscall_trace_leave
|
|
mov a6, a2
|
|
callx4 a4
|
|
retw
|
|
|
|
|
|
/*
|
|
* Create a kernel thread
|
|
*
|
|
* int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
|
|
* a2 a2 a3 a4
|
|
*/
|
|
|
|
ENTRY(kernel_thread)
|
|
entry a1, 16
|
|
|
|
mov a5, a2 # preserve fn over syscall
|
|
mov a7, a3 # preserve args over syscall
|
|
|
|
movi a3, _CLONE_VM | _CLONE_UNTRACED
|
|
movi a2, __NR_clone
|
|
or a6, a4, a3 # arg0: flags
|
|
mov a3, a1 # arg1: sp
|
|
syscall
|
|
|
|
beq a3, a1, 1f # branch if parent
|
|
mov a6, a7 # args
|
|
callx4 a5 # fn(args)
|
|
|
|
movi a2, __NR_exit
|
|
syscall # return value of fn(args) still in a6
|
|
|
|
1: retw
|
|
|
|
/*
|
|
* Do a system call from kernel instead of calling sys_execve, so we end up
|
|
* with proper pt_regs.
|
|
*
|
|
* int kernel_execve(const char *fname, char *const argv[], charg *const envp[])
|
|
* a2 a2 a3 a4
|
|
*/
|
|
|
|
ENTRY(kernel_execve)
|
|
entry a1, 16
|
|
mov a6, a2 # arg0 is in a6
|
|
movi a2, __NR_execve
|
|
syscall
|
|
|
|
retw
|
|
|
|
/*
|
|
* Task switch.
|
|
*
|
|
* struct task* _switch_to (struct task* prev, struct task* next)
|
|
* a2 a2 a3
|
|
*/
|
|
|
|
ENTRY(_switch_to)
|
|
|
|
entry a1, 16
|
|
|
|
mov a12, a2 # preserve 'prev' (a2)
|
|
mov a13, a3 # and 'next' (a3)
|
|
|
|
l32i a4, a2, TASK_THREAD_INFO
|
|
l32i a5, a3, TASK_THREAD_INFO
|
|
|
|
save_xtregs_user a4 a6 a8 a9 a10 a11 THREAD_XTREGS_USER
|
|
|
|
s32i a0, a12, THREAD_RA # save return address
|
|
s32i a1, a12, THREAD_SP # save stack pointer
|
|
|
|
/* Disable ints while we manipulate the stack pointer. */
|
|
|
|
movi a14, (1 << PS_EXCM_BIT) | LOCKLEVEL
|
|
xsr a14, PS
|
|
rsr a3, EXCSAVE_1
|
|
rsync
|
|
s32i a3, a3, EXC_TABLE_FIXUP /* enter critical section */
|
|
|
|
/* Switch CPENABLE */
|
|
|
|
#if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
|
|
l32i a3, a5, THREAD_CPENABLE
|
|
xsr a3, CPENABLE
|
|
s32i a3, a4, THREAD_CPENABLE
|
|
#endif
|
|
|
|
/* Flush register file. */
|
|
|
|
call0 _spill_registers # destroys a3, a4, and SAR
|
|
|
|
/* Set kernel stack (and leave critical section)
|
|
* Note: It's save to set it here. The stack will not be overwritten
|
|
* because the kernel stack will only be loaded again after
|
|
* we return from kernel space.
|
|
*/
|
|
|
|
rsr a3, EXCSAVE_1 # exc_table
|
|
movi a6, 0
|
|
addi a7, a5, PT_REGS_OFFSET
|
|
s32i a6, a3, EXC_TABLE_FIXUP
|
|
s32i a7, a3, EXC_TABLE_KSTK
|
|
|
|
/* restore context of the task that 'next' addresses */
|
|
|
|
l32i a0, a13, THREAD_RA # restore return address
|
|
l32i a1, a13, THREAD_SP # restore stack pointer
|
|
|
|
load_xtregs_user a5 a6 a8 a9 a10 a11 THREAD_XTREGS_USER
|
|
|
|
wsr a14, PS
|
|
mov a2, a12 # return 'prev'
|
|
rsync
|
|
|
|
retw
|
|
|
|
|
|
ENTRY(ret_from_fork)
|
|
|
|
/* void schedule_tail (struct task_struct *prev)
|
|
* Note: prev is still in a6 (return value from fake call4 frame)
|
|
*/
|
|
movi a4, schedule_tail
|
|
callx4 a4
|
|
|
|
movi a4, do_syscall_trace_leave
|
|
mov a6, a1
|
|
callx4 a4
|
|
|
|
j common_exception_return
|
|
|