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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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407 lines
12 KiB
ArmAsm
407 lines
12 KiB
ArmAsm
/*
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* Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARCompact ISA
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*
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* Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com)
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* vineetg: May 2011
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* -Userspace unaligned access emulation
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*
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* vineetg: Feb 2011 (ptrace low level code fixes)
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* -traced syscall return code (r0) was not saved into pt_regs for restoring
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* into user reg-file when traded task rets to user space.
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* -syscalls needing arch-wrappers (mainly for passing sp as pt_regs)
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* were not invoking post-syscall trace hook (jumping directly into
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* ret_from_system_call)
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*
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* vineetg: Nov 2010:
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* -Vector table jumps (@8 bytes) converted into branches (@4 bytes)
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* -To maintain the slot size of 8 bytes/vector, added nop, which is
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* not executed at runtime.
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*
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* vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK)
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* -do_signal()invoked upon TIF_RESTORE_SIGMASK as well
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* -Wrappers for sys_{,rt_}sigsuspend() nolonger needed as they don't
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* need ptregs anymore
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*
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* Vineetg: Oct 2009
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* -In a rare scenario, Process gets a Priv-V exception and gets scheduled
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* out. Since we don't do FAKE RTIE for Priv-V, CPU excpetion state remains
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* active (AE bit enabled). This causes a double fault for a subseq valid
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* exception. Thus FAKE RTIE needed in low level Priv-Violation handler.
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* Instr Error could also cause similar scenario, so same there as well.
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*
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* Vineetg: March 2009 (Supporting 2 levels of Interrupts)
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*
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* Vineetg: Aug 28th 2008: Bug #94984
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* -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap
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* Normally CPU does this automatically, however when doing FAKE rtie,
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* we need to explicitly do this. The problem in macros
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* FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit
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* was being "CLEARED" rather then "SET". Since it is Loop INHIBIT Bit,
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* setting it and not clearing it clears ZOL context
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*
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* Vineetg: May 16th, 2008
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* - r25 now contains the Current Task when in kernel
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*
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* Vineetg: Dec 22, 2007
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* Minor Surgery of Low Level ISR to make it SMP safe
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* - MMU_SCRATCH0 Reg used for freeing up r9 in Level 1 ISR
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* - _current_task is made an array of NR_CPUS
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* - Access of _current_task wrapped inside a macro so that if hardware
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* team agrees for a dedicated reg, no other code is touched
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*
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* Amit Bhor, Rahul Trivedi, Kanika Nema, Sameer Dhavale : Codito Tech 2004
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*/
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#include <linux/errno.h>
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#include <linux/linkage.h> /* {EXTRY,EXIT} */
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#include <asm/entry.h>
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#include <asm/irqflags.h>
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.cpu A7
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;############################ Vector Table #################################
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.macro VECTOR lbl
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#if 1 /* Just in case, build breaks */
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j \lbl
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#else
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b \lbl
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nop
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#endif
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.endm
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.section .vector, "ax",@progbits
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.align 4
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/* Each entry in the vector table must occupy 2 words. Since it is a jump
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* across sections (.vector to .text) we are gauranteed that 'j somewhere'
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* will use the 'j limm' form of the intrsuction as long as somewhere is in
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* a section other than .vector.
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*/
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; ********* Critical System Events **********************
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VECTOR res_service ; 0x0, Reset Vector (0x0)
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VECTOR mem_service ; 0x8, Mem exception (0x1)
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VECTOR instr_service ; 0x10, Instrn Error (0x2)
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; ******************** Device ISRs **********************
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#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
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VECTOR handle_interrupt_level2
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#else
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VECTOR handle_interrupt_level1
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#endif
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.rept 28
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VECTOR handle_interrupt_level1 ; Other devices
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.endr
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/* FOR ARC600: timer = 0x3, uart = 0x8, emac = 0x10 */
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; ******************** Exceptions **********************
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VECTOR EV_MachineCheck ; 0x100, Fatal Machine check (0x20)
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VECTOR EV_TLBMissI ; 0x108, Intruction TLB miss (0x21)
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VECTOR EV_TLBMissD ; 0x110, Data TLB miss (0x22)
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VECTOR EV_TLBProtV ; 0x118, Protection Violation (0x23)
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; or Misaligned Access
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VECTOR EV_PrivilegeV ; 0x120, Privilege Violation (0x24)
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VECTOR EV_Trap ; 0x128, Trap exception (0x25)
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VECTOR EV_Extension ; 0x130, Extn Intruction Excp (0x26)
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.rept 24
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VECTOR reserved ; Reserved Exceptions
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.endr
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;##################### Scratch Mem for IRQ stack switching #############
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ARCFP_DATA int1_saved_reg
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.align 32
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.type int1_saved_reg, @object
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.size int1_saved_reg, 4
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int1_saved_reg:
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.zero 4
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/* Each Interrupt level needs its own scratch */
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ARCFP_DATA int2_saved_reg
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.type int2_saved_reg, @object
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.size int2_saved_reg, 4
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int2_saved_reg:
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.zero 4
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; ---------------------------------------------
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.section .text, "ax",@progbits
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reserved:
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flag 1 ; Unexpected event, halt
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;##################### Interrupt Handling ##############################
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#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
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; ---------------------------------------------
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; Level 2 ISR: Can interrupt a Level 1 ISR
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; ---------------------------------------------
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ENTRY(handle_interrupt_level2)
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INTERRUPT_PROLOGUE 2
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;------------------------------------------------------
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; if L2 IRQ interrupted a L1 ISR, disable preemption
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;
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; This is to avoid a potential L1-L2-L1 scenario
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; -L1 IRQ taken
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; -L2 interrupts L1 (before L1 ISR could run)
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; -preemption off IRQ, user task in syscall picked to run
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; -RTIE to userspace
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; Returns from L2 context fine
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; But both L1 and L2 re-enabled, so another L1 can be taken
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; while prev L1 is still unserviced
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;
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;------------------------------------------------------
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; L2 interrupting L1 implies both L2 and L1 active
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; However both A2 and A1 are NOT set in STATUS32, thus
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; need to check STATUS32_L2 to determine if L1 was active
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ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs)
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bbit0 r9, STATUS_A1_BIT, 1f ; L1 not active when L2 IRQ, so normal
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; bump thread_info->preempt_count (Disable preemption)
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GET_CURR_THR_INFO_FROM_SP r10
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ld r9, [r10, THREAD_INFO_PREEMPT_COUNT]
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add r9, r9, 1
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st r9, [r10, THREAD_INFO_PREEMPT_COUNT]
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1:
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;------------------------------------------------------
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; setup params for Linux common ISR and invoke it
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;------------------------------------------------------
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lr r0, [icause2]
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and r0, r0, 0x1f
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bl.d @arch_do_IRQ
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mov r1, sp
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mov r8,0x2
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sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg
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b ret_from_exception
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END(handle_interrupt_level2)
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#endif
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; ---------------------------------------------
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; User Mode Memory Bus Error Interrupt Handler
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; (Kernel mode memory errors handled via seperate exception vectors)
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; ---------------------------------------------
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ENTRY(mem_service)
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INTERRUPT_PROLOGUE 2
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mov r0, ilink2
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mov r1, sp
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; User process needs to be killed with SIGBUS, but first need to get
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; out of the L2 interrupt context (drop to pure kernel mode) and jump
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; off to "C" code where SIGBUS in enqueued
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lr r3, [status32]
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bclr r3, r3, STATUS_A2_BIT
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or r3, r3, (STATUS_E1_MASK|STATUS_E2_MASK)
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sr r3, [status32_l2]
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mov ilink2, 1f
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rtie
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1:
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bl do_memory_error
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b ret_from_exception
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END(mem_service)
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; ---------------------------------------------
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; Level 1 ISR
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; ---------------------------------------------
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ENTRY(handle_interrupt_level1)
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INTERRUPT_PROLOGUE 1
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lr r0, [icause1]
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and r0, r0, 0x1f
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#ifdef CONFIG_TRACE_IRQFLAGS
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; icause1 needs to be read early, before calling tracing, which
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; can clobber scratch regs, hence use of stack to stash it
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push r0
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TRACE_ASM_IRQ_DISABLE
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pop r0
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#endif
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bl.d @arch_do_IRQ
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mov r1, sp
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mov r8,0x1
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sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg
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b ret_from_exception
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END(handle_interrupt_level1)
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;################### Non TLB Exception Handling #############################
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; ---------------------------------------------
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; Protection Violation Exception Handler
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; ---------------------------------------------
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ENTRY(EV_TLBProtV)
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EXCEPTION_PROLOGUE
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mov r2, r9 ; ECR set into r9 already
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lr r0, [efa] ; Faulting Data address (not part of pt_regs saved above)
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; Exception auto-disables further Intr/exceptions.
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; Re-enable them by pretending to return from exception
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; (so rest of handler executes in pure K mode)
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FAKE_RET_FROM_EXCPN
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mov r1, sp ; Handle to pt_regs
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;------ (5) Type of Protection Violation? ----------
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;
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; ProtV Hardware Exception is triggered for Access Faults of 2 types
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; -Access Violaton : 00_23_(00|01|02|03)_00
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; x r w r+w
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; -Unaligned Access : 00_23_04_00
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;
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bbit1 r2, ECR_C_BIT_PROTV_MISALIG_DATA, 4f
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;========= (6a) Access Violation Processing ========
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bl do_page_fault
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b ret_from_exception
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;========== (6b) Non aligned access ============
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4:
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SAVE_CALLEE_SAVED_USER
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mov r2, sp ; callee_regs
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bl do_misaligned_access
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; TBD: optimize - do this only if a callee reg was involved
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; either a dst of emulated LD/ST or src with address-writeback
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RESTORE_CALLEE_SAVED_USER
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b ret_from_exception
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END(EV_TLBProtV)
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; Wrapper for Linux page fault handler called from EV_TLBMiss*
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; Very similar to ProtV handler case (6a) above, but avoids the extra checks
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; for Misaligned access
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;
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ENTRY(call_do_page_fault)
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EXCEPTION_PROLOGUE
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lr r0, [efa] ; Faulting Data address
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mov r1, sp
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FAKE_RET_FROM_EXCPN
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mov blink, ret_from_exception
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b do_page_fault
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END(call_do_page_fault)
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;############# Common Handlers for ARCompact and ARCv2 ##############
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#include "entry.S"
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;############# Return from Intr/Excp/Trap (ARC Specifics) ##############
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;
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; Restore the saved sys context (common exit-path for EXCPN/IRQ/Trap)
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; IRQ shd definitely not happen between now and rtie
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; All 2 entry points to here already disable interrupts
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.Lrestore_regs:
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# Interrpts are actually disabled from this point on, but will get
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# reenabled after we return from interrupt/exception.
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# But irq tracer needs to be told now...
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TRACE_ASM_IRQ_ENABLE
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lr r10, [status32]
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; Restore REG File. In case multiple Events outstanding,
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; use the same priorty as rtie: EXCPN, L2 IRQ, L1 IRQ, None
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; Note that we use realtime STATUS32 (not pt_regs->status32) to
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; decide that.
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and.f 0, r10, (STATUS_A1_MASK|STATUS_A2_MASK)
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bz .Lexcep_or_pure_K_ret
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; Returning from Interrupts (Level 1 or 2)
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#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
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; Level 2 interrupt return Path - from hardware standpoint
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bbit0 r10, STATUS_A2_BIT, not_level2_interrupt
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;------------------------------------------------------------------
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; However the context returning might not have taken L2 intr itself
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; e.g. Task'A' user-code -> L2 intr -> schedule -> 'B' user-code ret
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; Special considerations needed for the context which took L2 intr
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ld r9, [sp, PT_event] ; Ensure this is L2 intr context
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brne r9, event_IRQ2, 149f
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;------------------------------------------------------------------
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; if L2 IRQ interrupted an L1 ISR, we'd disabled preemption earlier
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; so that sched doesn't move to new task, causing L1 to be delayed
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; undeterministically. Now that we've achieved that, let's reset
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; things to what they were, before returning from L2 context
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;----------------------------------------------------------------
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ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs)
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bbit0 r9, STATUS_A1_BIT, 149f ; L1 not active when L2 IRQ, so normal
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; decrement thread_info->preempt_count (re-enable preemption)
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GET_CURR_THR_INFO_FROM_SP r10
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ld r9, [r10, THREAD_INFO_PREEMPT_COUNT]
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; paranoid check, given A1 was active when A2 happened, preempt count
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; must not be 0 because we would have incremented it.
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; If this does happen we simply HALT as it means a BUG !!!
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cmp r9, 0
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bnz 2f
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flag 1
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2:
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sub r9, r9, 1
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st r9, [r10, THREAD_INFO_PREEMPT_COUNT]
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149:
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INTERRUPT_EPILOGUE 2 ; return from level 2 interrupt
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debug_marker_l2:
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rtie
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not_level2_interrupt:
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#endif
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INTERRUPT_EPILOGUE 1 ; return from level 1 interrupt
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debug_marker_l1:
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rtie
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.Lexcep_or_pure_K_ret:
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;this case is for syscalls or Exceptions or pure kernel mode
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EXCEPTION_EPILOGUE
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debug_marker_syscall:
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rtie
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END(ret_from_exception)
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