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linux_dsm_epyc7002/arch/x86/entry/entry_32.S
Andy Lutomirski 2deb4be280 x86/dumpstack: When OOPSing, rewind the stack before do_exit() 
If we call do_exit() with a clean stack, we greatly reduce the risk of
recursive oopses due to stack overflow in do_exit, and we allow
do_exit to work even if we OOPS from an IST stack.  The latter gives
us a much better chance of surviving long enough after we detect a
stack overflow to write out our logs.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/32f73ceb372ec61889598da5e5b145889b9f2e19.1468527351.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-15 10:26:28 +02:00

1167 lines
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/*
* Copyright (C) 1991,1992 Linus Torvalds
*
* entry_32.S contains the system-call and low-level fault and trap handling routines.
*
* Stack layout while running C code:
* ptrace needs to have all registers on the stack.
* If the order here is changed, it needs to be
* updated in fork.c:copy_process(), signal.c:do_signal(),
* ptrace.c and ptrace.h
*
* 0(%esp) - %ebx
* 4(%esp) - %ecx
* 8(%esp) - %edx
* C(%esp) - %esi
* 10(%esp) - %edi
* 14(%esp) - %ebp
* 18(%esp) - %eax
* 1C(%esp) - %ds
* 20(%esp) - %es
* 24(%esp) - %fs
* 28(%esp) - %gs saved iff !CONFIG_X86_32_LAZY_GS
* 2C(%esp) - orig_eax
* 30(%esp) - %eip
* 34(%esp) - %cs
* 38(%esp) - %eflags
* 3C(%esp) - %oldesp
* 40(%esp) - %oldss
*/
#include <linux/linkage.h>
#include <linux/err.h>
#include <asm/thread_info.h>
#include <asm/irqflags.h>
#include <asm/errno.h>
#include <asm/segment.h>
#include <asm/smp.h>
#include <asm/page_types.h>
#include <asm/percpu.h>
#include <asm/processor-flags.h>
#include <asm/ftrace.h>
#include <asm/irq_vectors.h>
#include <asm/cpufeatures.h>
#include <asm/alternative-asm.h>
#include <asm/asm.h>
#include <asm/smap.h>
.section .entry.text, "ax"
/*
* We use macros for low-level operations which need to be overridden
* for paravirtualization. The following will never clobber any registers:
* INTERRUPT_RETURN (aka. "iret")
* GET_CR0_INTO_EAX (aka. "movl %cr0, %eax")
* ENABLE_INTERRUPTS_SYSEXIT (aka "sti; sysexit").
*
* For DISABLE_INTERRUPTS/ENABLE_INTERRUPTS (aka "cli"/"sti"), you must
* specify what registers can be overwritten (CLBR_NONE, CLBR_EAX/EDX/ECX/ANY).
* Allowing a register to be clobbered can shrink the paravirt replacement
* enough to patch inline, increasing performance.
*/
#ifdef CONFIG_PREEMPT
# define preempt_stop(clobbers) DISABLE_INTERRUPTS(clobbers); TRACE_IRQS_OFF
#else
# define preempt_stop(clobbers)
# define resume_kernel restore_all
#endif
.macro TRACE_IRQS_IRET
#ifdef CONFIG_TRACE_IRQFLAGS
testl $X86_EFLAGS_IF, PT_EFLAGS(%esp) # interrupts off?
jz 1f
TRACE_IRQS_ON
1:
#endif
.endm
/*
* User gs save/restore
*
* %gs is used for userland TLS and kernel only uses it for stack
* canary which is required to be at %gs:20 by gcc. Read the comment
* at the top of stackprotector.h for more info.
*
* Local labels 98 and 99 are used.
*/
#ifdef CONFIG_X86_32_LAZY_GS
/* unfortunately push/pop can't be no-op */
.macro PUSH_GS
pushl $0
.endm
.macro POP_GS pop=0
addl $(4 + \pop), %esp
.endm
.macro POP_GS_EX
.endm
/* all the rest are no-op */
.macro PTGS_TO_GS
.endm
.macro PTGS_TO_GS_EX
.endm
.macro GS_TO_REG reg
.endm
.macro REG_TO_PTGS reg
.endm
.macro SET_KERNEL_GS reg
.endm
#else /* CONFIG_X86_32_LAZY_GS */
.macro PUSH_GS
pushl %gs
.endm
.macro POP_GS pop=0
98: popl %gs
.if \pop <> 0
add $\pop, %esp
.endif
.endm
.macro POP_GS_EX
.pushsection .fixup, "ax"
99: movl $0, (%esp)
jmp 98b
.popsection
_ASM_EXTABLE(98b, 99b)
.endm
.macro PTGS_TO_GS
98: mov PT_GS(%esp), %gs
.endm
.macro PTGS_TO_GS_EX
.pushsection .fixup, "ax"
99: movl $0, PT_GS(%esp)
jmp 98b
.popsection
_ASM_EXTABLE(98b, 99b)
.endm
.macro GS_TO_REG reg
movl %gs, \reg
.endm
.macro REG_TO_PTGS reg
movl \reg, PT_GS(%esp)
.endm
.macro SET_KERNEL_GS reg
movl $(__KERNEL_STACK_CANARY), \reg
movl \reg, %gs
.endm
#endif /* CONFIG_X86_32_LAZY_GS */
.macro SAVE_ALL pt_regs_ax=%eax
cld
PUSH_GS
pushl %fs
pushl %es
pushl %ds
pushl \pt_regs_ax
pushl %ebp
pushl %edi
pushl %esi
pushl %edx
pushl %ecx
pushl %ebx
movl $(__USER_DS), %edx
movl %edx, %ds
movl %edx, %es
movl $(__KERNEL_PERCPU), %edx
movl %edx, %fs
SET_KERNEL_GS %edx
.endm
.macro RESTORE_INT_REGS
popl %ebx
popl %ecx
popl %edx
popl %esi
popl %edi
popl %ebp
popl %eax
.endm
.macro RESTORE_REGS pop=0
RESTORE_INT_REGS
1: popl %ds
2: popl %es
3: popl %fs
POP_GS \pop
.pushsection .fixup, "ax"
4: movl $0, (%esp)
jmp 1b
5: movl $0, (%esp)
jmp 2b
6: movl $0, (%esp)
jmp 3b
.popsection
_ASM_EXTABLE(1b, 4b)
_ASM_EXTABLE(2b, 5b)
_ASM_EXTABLE(3b, 6b)
POP_GS_EX
.endm
ENTRY(ret_from_fork)
pushl %eax
call schedule_tail
popl %eax
/* When we fork, we trace the syscall return in the child, too. */
movl %esp, %eax
call syscall_return_slowpath
jmp restore_all
END(ret_from_fork)
ENTRY(ret_from_kernel_thread)
pushl %eax
call schedule_tail
popl %eax
movl PT_EBP(%esp), %eax
call *PT_EBX(%esp)
movl $0, PT_EAX(%esp)
/*
* Kernel threads return to userspace as if returning from a syscall.
* We should check whether anything actually uses this path and, if so,
* consider switching it over to ret_from_fork.
*/
movl %esp, %eax
call syscall_return_slowpath
jmp restore_all
ENDPROC(ret_from_kernel_thread)
/*
* Return to user mode is not as complex as all this looks,
* but we want the default path for a system call return to
* go as quickly as possible which is why some of this is
* less clear than it otherwise should be.
*/
# userspace resumption stub bypassing syscall exit tracing
ALIGN
ret_from_exception:
preempt_stop(CLBR_ANY)
ret_from_intr:
#ifdef CONFIG_VM86
movl PT_EFLAGS(%esp), %eax # mix EFLAGS and CS
movb PT_CS(%esp), %al
andl $(X86_EFLAGS_VM | SEGMENT_RPL_MASK), %eax
#else
/*
* We can be coming here from child spawned by kernel_thread().
*/
movl PT_CS(%esp), %eax
andl $SEGMENT_RPL_MASK, %eax
#endif
cmpl $USER_RPL, %eax
jb resume_kernel # not returning to v8086 or userspace
ENTRY(resume_userspace)
DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_OFF
movl %esp, %eax
call prepare_exit_to_usermode
jmp restore_all
END(ret_from_exception)
#ifdef CONFIG_PREEMPT
ENTRY(resume_kernel)
DISABLE_INTERRUPTS(CLBR_ANY)
need_resched:
cmpl $0, PER_CPU_VAR(__preempt_count)
jnz restore_all
testl $X86_EFLAGS_IF, PT_EFLAGS(%esp) # interrupts off (exception path) ?
jz restore_all
call preempt_schedule_irq
jmp need_resched
END(resume_kernel)
#endif
GLOBAL(__begin_SYSENTER_singlestep_region)
/*
* All code from here through __end_SYSENTER_singlestep_region is subject
* to being single-stepped if a user program sets TF and executes SYSENTER.
* There is absolutely nothing that we can do to prevent this from happening
* (thanks Intel!). To keep our handling of this situation as simple as
* possible, we handle TF just like AC and NT, except that our #DB handler
* will ignore all of the single-step traps generated in this range.
*/
#ifdef CONFIG_XEN
/*
* Xen doesn't set %esp to be precisely what the normal SYSENTER
* entry point expects, so fix it up before using the normal path.
*/
ENTRY(xen_sysenter_target)
addl $5*4, %esp /* remove xen-provided frame */
jmp sysenter_past_esp
#endif
/*
* 32-bit SYSENTER entry.
*
* 32-bit system calls through the vDSO's __kernel_vsyscall enter here
* if X86_FEATURE_SEP is available. This is the preferred system call
* entry on 32-bit systems.
*
* The SYSENTER instruction, in principle, should *only* occur in the
* vDSO. In practice, a small number of Android devices were shipped
* with a copy of Bionic that inlined a SYSENTER instruction. This
* never happened in any of Google's Bionic versions -- it only happened
* in a narrow range of Intel-provided versions.
*
* SYSENTER loads SS, ESP, CS, and EIP from previously programmed MSRs.
* IF and VM in RFLAGS are cleared (IOW: interrupts are off).
* SYSENTER does not save anything on the stack,
* and does not save old EIP (!!!), ESP, or EFLAGS.
*
* To avoid losing track of EFLAGS.VM (and thus potentially corrupting
* user and/or vm86 state), we explicitly disable the SYSENTER
* instruction in vm86 mode by reprogramming the MSRs.
*
* Arguments:
* eax system call number
* ebx arg1
* ecx arg2
* edx arg3
* esi arg4
* edi arg5
* ebp user stack
* 0(%ebp) arg6
*/
ENTRY(entry_SYSENTER_32)
movl TSS_sysenter_sp0(%esp), %esp
sysenter_past_esp:
pushl $__USER_DS /* pt_regs->ss */
pushl %ebp /* pt_regs->sp (stashed in bp) */
pushfl /* pt_regs->flags (except IF = 0) */
orl $X86_EFLAGS_IF, (%esp) /* Fix IF */
pushl $__USER_CS /* pt_regs->cs */
pushl $0 /* pt_regs->ip = 0 (placeholder) */
pushl %eax /* pt_regs->orig_ax */
SAVE_ALL pt_regs_ax=$-ENOSYS /* save rest */
/*
* SYSENTER doesn't filter flags, so we need to clear NT, AC
* and TF ourselves. To save a few cycles, we can check whether
* either was set instead of doing an unconditional popfq.
* This needs to happen before enabling interrupts so that
* we don't get preempted with NT set.
*
* If TF is set, we will single-step all the way to here -- do_debug
* will ignore all the traps. (Yes, this is slow, but so is
* single-stepping in general. This allows us to avoid having
* a more complicated code to handle the case where a user program
* forces us to single-step through the SYSENTER entry code.)
*
* NB.: .Lsysenter_fix_flags is a label with the code under it moved
* out-of-line as an optimization: NT is unlikely to be set in the
* majority of the cases and instead of polluting the I$ unnecessarily,
* we're keeping that code behind a branch which will predict as
* not-taken and therefore its instructions won't be fetched.
*/
testl $X86_EFLAGS_NT|X86_EFLAGS_AC|X86_EFLAGS_TF, PT_EFLAGS(%esp)
jnz .Lsysenter_fix_flags
.Lsysenter_flags_fixed:
/*
* User mode is traced as though IRQs are on, and SYSENTER
* turned them off.
*/
TRACE_IRQS_OFF
movl %esp, %eax
call do_fast_syscall_32
/* XEN PV guests always use IRET path */
ALTERNATIVE "testl %eax, %eax; jz .Lsyscall_32_done", \
"jmp .Lsyscall_32_done", X86_FEATURE_XENPV
/* Opportunistic SYSEXIT */
TRACE_IRQS_ON /* User mode traces as IRQs on. */
movl PT_EIP(%esp), %edx /* pt_regs->ip */
movl PT_OLDESP(%esp), %ecx /* pt_regs->sp */
1: mov PT_FS(%esp), %fs
PTGS_TO_GS
popl %ebx /* pt_regs->bx */
addl $2*4, %esp /* skip pt_regs->cx and pt_regs->dx */
popl %esi /* pt_regs->si */
popl %edi /* pt_regs->di */
popl %ebp /* pt_regs->bp */
popl %eax /* pt_regs->ax */
/*
* Restore all flags except IF. (We restore IF separately because
* STI gives a one-instruction window in which we won't be interrupted,
* whereas POPF does not.)
*/
addl $PT_EFLAGS-PT_DS, %esp /* point esp at pt_regs->flags */
btr $X86_EFLAGS_IF_BIT, (%esp)
popfl
/*
* Return back to the vDSO, which will pop ecx and edx.
* Don't bother with DS and ES (they already contain __USER_DS).
*/
sti
sysexit
.pushsection .fixup, "ax"
2: movl $0, PT_FS(%esp)
jmp 1b
.popsection
_ASM_EXTABLE(1b, 2b)
PTGS_TO_GS_EX
.Lsysenter_fix_flags:
pushl $X86_EFLAGS_FIXED
popfl
jmp .Lsysenter_flags_fixed
GLOBAL(__end_SYSENTER_singlestep_region)
ENDPROC(entry_SYSENTER_32)
/*
* 32-bit legacy system call entry.
*
* 32-bit x86 Linux system calls traditionally used the INT $0x80
* instruction. INT $0x80 lands here.
*
* This entry point can be used by any 32-bit perform system calls.
* Instances of INT $0x80 can be found inline in various programs and
* libraries. It is also used by the vDSO's __kernel_vsyscall
* fallback for hardware that doesn't support a faster entry method.
* Restarted 32-bit system calls also fall back to INT $0x80
* regardless of what instruction was originally used to do the system
* call. (64-bit programs can use INT $0x80 as well, but they can
* only run on 64-bit kernels and therefore land in
* entry_INT80_compat.)
*
* This is considered a slow path. It is not used by most libc
* implementations on modern hardware except during process startup.
*
* Arguments:
* eax system call number
* ebx arg1
* ecx arg2
* edx arg3
* esi arg4
* edi arg5
* ebp arg6
*/
ENTRY(entry_INT80_32)
ASM_CLAC
pushl %eax /* pt_regs->orig_ax */
SAVE_ALL pt_regs_ax=$-ENOSYS /* save rest */
/*
* User mode is traced as though IRQs are on, and the interrupt gate
* turned them off.
*/
TRACE_IRQS_OFF
movl %esp, %eax
call do_int80_syscall_32
.Lsyscall_32_done:
restore_all:
TRACE_IRQS_IRET
restore_all_notrace:
#ifdef CONFIG_X86_ESPFIX32
ALTERNATIVE "jmp restore_nocheck", "", X86_BUG_ESPFIX
movl PT_EFLAGS(%esp), %eax # mix EFLAGS, SS and CS
/*
* Warning: PT_OLDSS(%esp) contains the wrong/random values if we
* are returning to the kernel.
* See comments in process.c:copy_thread() for details.
*/
movb PT_OLDSS(%esp), %ah
movb PT_CS(%esp), %al
andl $(X86_EFLAGS_VM | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax
cmpl $((SEGMENT_LDT << 8) | USER_RPL), %eax
je ldt_ss # returning to user-space with LDT SS
#endif
restore_nocheck:
RESTORE_REGS 4 # skip orig_eax/error_code
irq_return:
INTERRUPT_RETURN
.section .fixup, "ax"
ENTRY(iret_exc )
pushl $0 # no error code
pushl $do_iret_error
jmp error_code
.previous
_ASM_EXTABLE(irq_return, iret_exc)
#ifdef CONFIG_X86_ESPFIX32
ldt_ss:
/*
* Setup and switch to ESPFIX stack
*
* We're returning to userspace with a 16 bit stack. The CPU will not
* restore the high word of ESP for us on executing iret... This is an
* "official" bug of all the x86-compatible CPUs, which we can work
* around to make dosemu and wine happy. We do this by preloading the
* high word of ESP with the high word of the userspace ESP while
* compensating for the offset by changing to the ESPFIX segment with
* a base address that matches for the difference.
*/
#define GDT_ESPFIX_SS PER_CPU_VAR(gdt_page) + (GDT_ENTRY_ESPFIX_SS * 8)
mov %esp, %edx /* load kernel esp */
mov PT_OLDESP(%esp), %eax /* load userspace esp */
mov %dx, %ax /* eax: new kernel esp */
sub %eax, %edx /* offset (low word is 0) */
shr $16, %edx
mov %dl, GDT_ESPFIX_SS + 4 /* bits 16..23 */
mov %dh, GDT_ESPFIX_SS + 7 /* bits 24..31 */
pushl $__ESPFIX_SS
pushl %eax /* new kernel esp */
/*
* Disable interrupts, but do not irqtrace this section: we
* will soon execute iret and the tracer was already set to
* the irqstate after the IRET:
*/
DISABLE_INTERRUPTS(CLBR_EAX)
lss (%esp), %esp /* switch to espfix segment */
jmp restore_nocheck
#endif
ENDPROC(entry_INT80_32)
.macro FIXUP_ESPFIX_STACK
/*
* Switch back for ESPFIX stack to the normal zerobased stack
*
* We can't call C functions using the ESPFIX stack. This code reads
* the high word of the segment base from the GDT and swiches to the
* normal stack and adjusts ESP with the matching offset.
*/
#ifdef CONFIG_X86_ESPFIX32
/* fixup the stack */
mov GDT_ESPFIX_SS + 4, %al /* bits 16..23 */
mov GDT_ESPFIX_SS + 7, %ah /* bits 24..31 */
shl $16, %eax
addl %esp, %eax /* the adjusted stack pointer */
pushl $__KERNEL_DS
pushl %eax
lss (%esp), %esp /* switch to the normal stack segment */
#endif
.endm
.macro UNWIND_ESPFIX_STACK
#ifdef CONFIG_X86_ESPFIX32
movl %ss, %eax
/* see if on espfix stack */
cmpw $__ESPFIX_SS, %ax
jne 27f
movl $__KERNEL_DS, %eax
movl %eax, %ds
movl %eax, %es
/* switch to normal stack */
FIXUP_ESPFIX_STACK
27:
#endif
.endm
/*
* Build the entry stubs with some assembler magic.
* We pack 1 stub into every 8-byte block.
*/
.align 8
ENTRY(irq_entries_start)
vector=FIRST_EXTERNAL_VECTOR
.rept (FIRST_SYSTEM_VECTOR - FIRST_EXTERNAL_VECTOR)
pushl $(~vector+0x80) /* Note: always in signed byte range */
vector=vector+1
jmp common_interrupt
.align 8
.endr
END(irq_entries_start)
/*
* the CPU automatically disables interrupts when executing an IRQ vector,
* so IRQ-flags tracing has to follow that:
*/
.p2align CONFIG_X86_L1_CACHE_SHIFT
common_interrupt:
ASM_CLAC
addl $-0x80, (%esp) /* Adjust vector into the [-256, -1] range */
SAVE_ALL
TRACE_IRQS_OFF
movl %esp, %eax
call do_IRQ
jmp ret_from_intr
ENDPROC(common_interrupt)
#define BUILD_INTERRUPT3(name, nr, fn) \
ENTRY(name) \
ASM_CLAC; \
pushl $~(nr); \
SAVE_ALL; \
TRACE_IRQS_OFF \
movl %esp, %eax; \
call fn; \
jmp ret_from_intr; \
ENDPROC(name)
#ifdef CONFIG_TRACING
# define TRACE_BUILD_INTERRUPT(name, nr) BUILD_INTERRUPT3(trace_##name, nr, smp_trace_##name)
#else
# define TRACE_BUILD_INTERRUPT(name, nr)
#endif
#define BUILD_INTERRUPT(name, nr) \
BUILD_INTERRUPT3(name, nr, smp_##name); \
TRACE_BUILD_INTERRUPT(name, nr)
/* The include is where all of the SMP etc. interrupts come from */
#include <asm/entry_arch.h>
ENTRY(coprocessor_error)
ASM_CLAC
pushl $0
pushl $do_coprocessor_error
jmp error_code
END(coprocessor_error)
ENTRY(simd_coprocessor_error)
ASM_CLAC
pushl $0
#ifdef CONFIG_X86_INVD_BUG
/* AMD 486 bug: invd from userspace calls exception 19 instead of #GP */
ALTERNATIVE "pushl $do_general_protection", \
"pushl $do_simd_coprocessor_error", \
X86_FEATURE_XMM
#else
pushl $do_simd_coprocessor_error
#endif
jmp error_code
END(simd_coprocessor_error)
ENTRY(device_not_available)
ASM_CLAC
pushl $-1 # mark this as an int
pushl $do_device_not_available
jmp error_code
END(device_not_available)
#ifdef CONFIG_PARAVIRT
ENTRY(native_iret)
iret
_ASM_EXTABLE(native_iret, iret_exc)
END(native_iret)
#endif
ENTRY(overflow)
ASM_CLAC
pushl $0
pushl $do_overflow
jmp error_code
END(overflow)
ENTRY(bounds)
ASM_CLAC
pushl $0
pushl $do_bounds
jmp error_code
END(bounds)
ENTRY(invalid_op)
ASM_CLAC
pushl $0
pushl $do_invalid_op
jmp error_code
END(invalid_op)
ENTRY(coprocessor_segment_overrun)
ASM_CLAC
pushl $0
pushl $do_coprocessor_segment_overrun
jmp error_code
END(coprocessor_segment_overrun)
ENTRY(invalid_TSS)
ASM_CLAC
pushl $do_invalid_TSS
jmp error_code
END(invalid_TSS)
ENTRY(segment_not_present)
ASM_CLAC
pushl $do_segment_not_present
jmp error_code
END(segment_not_present)
ENTRY(stack_segment)
ASM_CLAC
pushl $do_stack_segment
jmp error_code
END(stack_segment)
ENTRY(alignment_check)
ASM_CLAC
pushl $do_alignment_check
jmp error_code
END(alignment_check)
ENTRY(divide_error)
ASM_CLAC
pushl $0 # no error code
pushl $do_divide_error
jmp error_code
END(divide_error)
#ifdef CONFIG_X86_MCE
ENTRY(machine_check)
ASM_CLAC
pushl $0
pushl machine_check_vector
jmp error_code
END(machine_check)
#endif
ENTRY(spurious_interrupt_bug)
ASM_CLAC
pushl $0
pushl $do_spurious_interrupt_bug
jmp error_code
END(spurious_interrupt_bug)
#ifdef CONFIG_XEN
ENTRY(xen_hypervisor_callback)
pushl $-1 /* orig_ax = -1 => not a system call */
SAVE_ALL
TRACE_IRQS_OFF
/*
* Check to see if we got the event in the critical
* region in xen_iret_direct, after we've reenabled
* events and checked for pending events. This simulates
* iret instruction's behaviour where it delivers a
* pending interrupt when enabling interrupts:
*/
movl PT_EIP(%esp), %eax
cmpl $xen_iret_start_crit, %eax
jb 1f
cmpl $xen_iret_end_crit, %eax
jae 1f
jmp xen_iret_crit_fixup
ENTRY(xen_do_upcall)
1: mov %esp, %eax
call xen_evtchn_do_upcall
#ifndef CONFIG_PREEMPT
call xen_maybe_preempt_hcall
#endif
jmp ret_from_intr
ENDPROC(xen_hypervisor_callback)
/*
* Hypervisor uses this for application faults while it executes.
* We get here for two reasons:
* 1. Fault while reloading DS, ES, FS or GS
* 2. Fault while executing IRET
* Category 1 we fix up by reattempting the load, and zeroing the segment
* register if the load fails.
* Category 2 we fix up by jumping to do_iret_error. We cannot use the
* normal Linux return path in this case because if we use the IRET hypercall
* to pop the stack frame we end up in an infinite loop of failsafe callbacks.
* We distinguish between categories by maintaining a status value in EAX.
*/
ENTRY(xen_failsafe_callback)
pushl %eax
movl $1, %eax
1: mov 4(%esp), %ds
2: mov 8(%esp), %es
3: mov 12(%esp), %fs
4: mov 16(%esp), %gs
/* EAX == 0 => Category 1 (Bad segment)
EAX != 0 => Category 2 (Bad IRET) */
testl %eax, %eax
popl %eax
lea 16(%esp), %esp
jz 5f
jmp iret_exc
5: pushl $-1 /* orig_ax = -1 => not a system call */
SAVE_ALL
jmp ret_from_exception
.section .fixup, "ax"
6: xorl %eax, %eax
movl %eax, 4(%esp)
jmp 1b
7: xorl %eax, %eax
movl %eax, 8(%esp)
jmp 2b
8: xorl %eax, %eax
movl %eax, 12(%esp)
jmp 3b
9: xorl %eax, %eax
movl %eax, 16(%esp)
jmp 4b
.previous
_ASM_EXTABLE(1b, 6b)
_ASM_EXTABLE(2b, 7b)
_ASM_EXTABLE(3b, 8b)
_ASM_EXTABLE(4b, 9b)
ENDPROC(xen_failsafe_callback)
BUILD_INTERRUPT3(xen_hvm_callback_vector, HYPERVISOR_CALLBACK_VECTOR,
xen_evtchn_do_upcall)
#endif /* CONFIG_XEN */
#if IS_ENABLED(CONFIG_HYPERV)
BUILD_INTERRUPT3(hyperv_callback_vector, HYPERVISOR_CALLBACK_VECTOR,
hyperv_vector_handler)
#endif /* CONFIG_HYPERV */
#ifdef CONFIG_FUNCTION_TRACER
#ifdef CONFIG_DYNAMIC_FTRACE
ENTRY(mcount)
ret
END(mcount)
ENTRY(ftrace_caller)
pushl %eax
pushl %ecx
pushl %edx
pushl $0 /* Pass NULL as regs pointer */
movl 4*4(%esp), %eax
movl 0x4(%ebp), %edx
movl function_trace_op, %ecx
subl $MCOUNT_INSN_SIZE, %eax
.globl ftrace_call
ftrace_call:
call ftrace_stub
addl $4, %esp /* skip NULL pointer */
popl %edx
popl %ecx
popl %eax
ftrace_ret:
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
.globl ftrace_graph_call
ftrace_graph_call:
jmp ftrace_stub
#endif
.globl ftrace_stub
ftrace_stub:
ret
END(ftrace_caller)
ENTRY(ftrace_regs_caller)
pushf /* push flags before compare (in cs location) */
/*
* i386 does not save SS and ESP when coming from kernel.
* Instead, to get sp, &regs->sp is used (see ptrace.h).
* Unfortunately, that means eflags must be at the same location
* as the current return ip is. We move the return ip into the
* ip location, and move flags into the return ip location.
*/
pushl 4(%esp) /* save return ip into ip slot */
pushl $0 /* Load 0 into orig_ax */
pushl %gs
pushl %fs
pushl %es
pushl %ds
pushl %eax
pushl %ebp
pushl %edi
pushl %esi
pushl %edx
pushl %ecx
pushl %ebx
movl 13*4(%esp), %eax /* Get the saved flags */
movl %eax, 14*4(%esp) /* Move saved flags into regs->flags location */
/* clobbering return ip */
movl $__KERNEL_CS, 13*4(%esp)
movl 12*4(%esp), %eax /* Load ip (1st parameter) */
subl $MCOUNT_INSN_SIZE, %eax /* Adjust ip */
movl 0x4(%ebp), %edx /* Load parent ip (2nd parameter) */
movl function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */
pushl %esp /* Save pt_regs as 4th parameter */
GLOBAL(ftrace_regs_call)
call ftrace_stub
addl $4, %esp /* Skip pt_regs */
movl 14*4(%esp), %eax /* Move flags back into cs */
movl %eax, 13*4(%esp) /* Needed to keep addl from modifying flags */
movl 12*4(%esp), %eax /* Get return ip from regs->ip */
movl %eax, 14*4(%esp) /* Put return ip back for ret */
popl %ebx
popl %ecx
popl %edx
popl %esi
popl %edi
popl %ebp
popl %eax
popl %ds
popl %es
popl %fs
popl %gs
addl $8, %esp /* Skip orig_ax and ip */
popf /* Pop flags at end (no addl to corrupt flags) */
jmp ftrace_ret
popf
jmp ftrace_stub
#else /* ! CONFIG_DYNAMIC_FTRACE */
ENTRY(mcount)
cmpl $__PAGE_OFFSET, %esp
jb ftrace_stub /* Paging not enabled yet? */
cmpl $ftrace_stub, ftrace_trace_function
jnz trace
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
cmpl $ftrace_stub, ftrace_graph_return
jnz ftrace_graph_caller
cmpl $ftrace_graph_entry_stub, ftrace_graph_entry
jnz ftrace_graph_caller
#endif
.globl ftrace_stub
ftrace_stub:
ret
/* taken from glibc */
trace:
pushl %eax
pushl %ecx
pushl %edx
movl 0xc(%esp), %eax
movl 0x4(%ebp), %edx
subl $MCOUNT_INSN_SIZE, %eax
call *ftrace_trace_function
popl %edx
popl %ecx
popl %eax
jmp ftrace_stub
END(mcount)
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_TRACER */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(ftrace_graph_caller)
pushl %eax
pushl %ecx
pushl %edx
movl 0xc(%esp), %eax
lea 0x4(%ebp), %edx
movl (%ebp), %ecx
subl $MCOUNT_INSN_SIZE, %eax
call prepare_ftrace_return
popl %edx
popl %ecx
popl %eax
ret
END(ftrace_graph_caller)
.globl return_to_handler
return_to_handler:
pushl %eax
pushl %edx
movl %ebp, %eax
call ftrace_return_to_handler
movl %eax, %ecx
popl %edx
popl %eax
jmp *%ecx
#endif
#ifdef CONFIG_TRACING
ENTRY(trace_page_fault)
ASM_CLAC
pushl $trace_do_page_fault
jmp error_code
END(trace_page_fault)
#endif
ENTRY(page_fault)
ASM_CLAC
pushl $do_page_fault
ALIGN
error_code:
/* the function address is in %gs's slot on the stack */
pushl %fs
pushl %es
pushl %ds
pushl %eax
pushl %ebp
pushl %edi
pushl %esi
pushl %edx
pushl %ecx
pushl %ebx
cld
movl $(__KERNEL_PERCPU), %ecx
movl %ecx, %fs
UNWIND_ESPFIX_STACK
GS_TO_REG %ecx
movl PT_GS(%esp), %edi # get the function address
movl PT_ORIG_EAX(%esp), %edx # get the error code
movl $-1, PT_ORIG_EAX(%esp) # no syscall to restart
REG_TO_PTGS %ecx
SET_KERNEL_GS %ecx
movl $(__USER_DS), %ecx
movl %ecx, %ds
movl %ecx, %es
TRACE_IRQS_OFF
movl %esp, %eax # pt_regs pointer
call *%edi
jmp ret_from_exception
END(page_fault)
ENTRY(debug)
/*
* #DB can happen at the first instruction of
* entry_SYSENTER_32 or in Xen's SYSENTER prologue. If this
* happens, then we will be running on a very small stack. We
* need to detect this condition and switch to the thread
* stack before calling any C code at all.
*
* If you edit this code, keep in mind that NMIs can happen in here.
*/
ASM_CLAC
pushl $-1 # mark this as an int
SAVE_ALL
xorl %edx, %edx # error code 0
movl %esp, %eax # pt_regs pointer
/* Are we currently on the SYSENTER stack? */
PER_CPU(cpu_tss + CPU_TSS_SYSENTER_stack + SIZEOF_SYSENTER_stack, %ecx)
subl %eax, %ecx /* ecx = (end of SYSENTER_stack) - esp */
cmpl $SIZEOF_SYSENTER_stack, %ecx
jb .Ldebug_from_sysenter_stack
TRACE_IRQS_OFF
call do_debug
jmp ret_from_exception
.Ldebug_from_sysenter_stack:
/* We're on the SYSENTER stack. Switch off. */
movl %esp, %ebp
movl PER_CPU_VAR(cpu_current_top_of_stack), %esp
TRACE_IRQS_OFF
call do_debug
movl %ebp, %esp
jmp ret_from_exception
END(debug)
/*
* NMI is doubly nasty. It can happen on the first instruction of
* entry_SYSENTER_32 (just like #DB), but it can also interrupt the beginning
* of the #DB handler even if that #DB in turn hit before entry_SYSENTER_32
* switched stacks. We handle both conditions by simply checking whether we
* interrupted kernel code running on the SYSENTER stack.
*/
ENTRY(nmi)
ASM_CLAC
#ifdef CONFIG_X86_ESPFIX32
pushl %eax
movl %ss, %eax
cmpw $__ESPFIX_SS, %ax
popl %eax
je nmi_espfix_stack
#endif
pushl %eax # pt_regs->orig_ax
SAVE_ALL
xorl %edx, %edx # zero error code
movl %esp, %eax # pt_regs pointer
/* Are we currently on the SYSENTER stack? */
PER_CPU(cpu_tss + CPU_TSS_SYSENTER_stack + SIZEOF_SYSENTER_stack, %ecx)
subl %eax, %ecx /* ecx = (end of SYSENTER_stack) - esp */
cmpl $SIZEOF_SYSENTER_stack, %ecx
jb .Lnmi_from_sysenter_stack
/* Not on SYSENTER stack. */
call do_nmi
jmp restore_all_notrace
.Lnmi_from_sysenter_stack:
/*
* We're on the SYSENTER stack. Switch off. No one (not even debug)
* is using the thread stack right now, so it's safe for us to use it.
*/
movl %esp, %ebp
movl PER_CPU_VAR(cpu_current_top_of_stack), %esp
call do_nmi
movl %ebp, %esp
jmp restore_all_notrace
#ifdef CONFIG_X86_ESPFIX32
nmi_espfix_stack:
/*
* create the pointer to lss back
*/
pushl %ss
pushl %esp
addl $4, (%esp)
/* copy the iret frame of 12 bytes */
.rept 3
pushl 16(%esp)
.endr
pushl %eax
SAVE_ALL
FIXUP_ESPFIX_STACK # %eax == %esp
xorl %edx, %edx # zero error code
call do_nmi
RESTORE_REGS
lss 12+4(%esp), %esp # back to espfix stack
jmp irq_return
#endif
END(nmi)
ENTRY(int3)
ASM_CLAC
pushl $-1 # mark this as an int
SAVE_ALL
TRACE_IRQS_OFF
xorl %edx, %edx # zero error code
movl %esp, %eax # pt_regs pointer
call do_int3
jmp ret_from_exception
END(int3)
ENTRY(general_protection)
pushl $do_general_protection
jmp error_code
END(general_protection)
#ifdef CONFIG_KVM_GUEST
ENTRY(async_page_fault)
ASM_CLAC
pushl $do_async_page_fault
jmp error_code
END(async_page_fault)
#endif
ENTRY(rewind_stack_do_exit)
/* Prevent any naive code from trying to unwind to our caller. */
xorl %ebp, %ebp
movl PER_CPU_VAR(cpu_current_top_of_stack), %esi
leal -TOP_OF_KERNEL_STACK_PADDING-PTREGS_SIZE(%esi), %esp
call do_exit
1: jmp 1b
END(rewind_stack_do_exit)
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