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linux/arch/i386/kernel/entry.S
Jan Beulich adf1423698 [PATCH] i386/x86-64: Work around gcc bug with noreturn functions in unwinder 
Current gcc generates calls not jumps to noreturn functions. When that happens the
return address can point to the next function, which confuses the unwinder.

This patch works around it by marking asynchronous exception
frames in contrast normal call frames in the unwind information.  Then teach
the unwinder to decode this.

For normal call frames the unwinder now subtracts one from the address which avoids
this problem.  The standard libgcc unwinder uses the same trick.

It doesn't include adjustment of the printed address (i.e. for the original
example, it'd still be kernel_math_error+0 that gets displayed, but the
unwinder wouldn't get confused anymore.

This only works with binutils 2.6.17+ and some versions of H.J.Lu's 2.6.16
unfortunately because earlier binutils don't support .cfi_signal_frame

[AK: added automatic detection of the new binutils and wrote description]

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26 10:52:41 +02:00

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/*
* linux/arch/i386/entry.S
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
/*
* entry.S contains the system-call and fault low-level handling routines.
* This also contains the timer-interrupt handler, as well as all interrupts
* and faults that can result in a task-switch.
*
* NOTE: This code handles signal-recognition, which happens every time
* after a timer-interrupt and after each system call.
*
* I changed all the .align's to 4 (16 byte alignment), as that's faster
* on a 486.
*
* Stack layout in 'ret_from_system_call':
* ptrace needs to have all regs 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) - orig_eax
* 28(%esp) - %eip
* 2C(%esp) - %cs
* 30(%esp) - %eflags
* 34(%esp) - %oldesp
* 38(%esp) - %oldss
*
* "current" is in register %ebx during any slow entries.
*/
#include <linux/linkage.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.h>
#include <asm/desc.h>
#include <asm/dwarf2.h>
#include "irq_vectors.h"
#define nr_syscalls ((syscall_table_size)/4)
EBX = 0x00
ECX = 0x04
EDX = 0x08
ESI = 0x0C
EDI = 0x10
EBP = 0x14
EAX = 0x18
DS = 0x1C
ES = 0x20
ORIG_EAX = 0x24
EIP = 0x28
CS = 0x2C
EFLAGS = 0x30
OLDESP = 0x34
OLDSS = 0x38
CF_MASK = 0x00000001
TF_MASK = 0x00000100
IF_MASK = 0x00000200
DF_MASK = 0x00000400
NT_MASK = 0x00004000
VM_MASK = 0x00020000
/* These are replaces for paravirtualization */
#define DISABLE_INTERRUPTS cli
#define ENABLE_INTERRUPTS sti
#define ENABLE_INTERRUPTS_SYSEXIT sti; sysexit
#define INTERRUPT_RETURN iret
#define GET_CR0_INTO_EAX movl %cr0, %eax
#ifdef CONFIG_PREEMPT
#define preempt_stop DISABLE_INTERRUPTS; TRACE_IRQS_OFF
#else
#define preempt_stop
#define resume_kernel restore_nocheck
#endif
.macro TRACE_IRQS_IRET
#ifdef CONFIG_TRACE_IRQFLAGS
testl $IF_MASK,EFLAGS(%esp) # interrupts off?
jz 1f
TRACE_IRQS_ON
1:
#endif
.endm
#ifdef CONFIG_VM86
#define resume_userspace_sig check_userspace
#else
#define resume_userspace_sig resume_userspace
#endif
#define SAVE_ALL \
cld; \
pushl %es; \
CFI_ADJUST_CFA_OFFSET 4;\
/*CFI_REL_OFFSET es, 0;*/\
pushl %ds; \
CFI_ADJUST_CFA_OFFSET 4;\
/*CFI_REL_OFFSET ds, 0;*/\
pushl %eax; \
CFI_ADJUST_CFA_OFFSET 4;\
CFI_REL_OFFSET eax, 0;\
pushl %ebp; \
CFI_ADJUST_CFA_OFFSET 4;\
CFI_REL_OFFSET ebp, 0;\
pushl %edi; \
CFI_ADJUST_CFA_OFFSET 4;\
CFI_REL_OFFSET edi, 0;\
pushl %esi; \
CFI_ADJUST_CFA_OFFSET 4;\
CFI_REL_OFFSET esi, 0;\
pushl %edx; \
CFI_ADJUST_CFA_OFFSET 4;\
CFI_REL_OFFSET edx, 0;\
pushl %ecx; \
CFI_ADJUST_CFA_OFFSET 4;\
CFI_REL_OFFSET ecx, 0;\
pushl %ebx; \
CFI_ADJUST_CFA_OFFSET 4;\
CFI_REL_OFFSET ebx, 0;\
movl $(__USER_DS), %edx; \
movl %edx, %ds; \
movl %edx, %es;
#define RESTORE_INT_REGS \
popl %ebx; \
CFI_ADJUST_CFA_OFFSET -4;\
CFI_RESTORE ebx;\
popl %ecx; \
CFI_ADJUST_CFA_OFFSET -4;\
CFI_RESTORE ecx;\
popl %edx; \
CFI_ADJUST_CFA_OFFSET -4;\
CFI_RESTORE edx;\
popl %esi; \
CFI_ADJUST_CFA_OFFSET -4;\
CFI_RESTORE esi;\
popl %edi; \
CFI_ADJUST_CFA_OFFSET -4;\
CFI_RESTORE edi;\
popl %ebp; \
CFI_ADJUST_CFA_OFFSET -4;\
CFI_RESTORE ebp;\
popl %eax; \
CFI_ADJUST_CFA_OFFSET -4;\
CFI_RESTORE eax
#define RESTORE_REGS \
RESTORE_INT_REGS; \
1: popl %ds; \
CFI_ADJUST_CFA_OFFSET -4;\
/*CFI_RESTORE ds;*/\
2: popl %es; \
CFI_ADJUST_CFA_OFFSET -4;\
/*CFI_RESTORE es;*/\
.section .fixup,"ax"; \
3: movl $0,(%esp); \
jmp 1b; \
4: movl $0,(%esp); \
jmp 2b; \
.previous; \
.section __ex_table,"a";\
.align 4; \
.long 1b,3b; \
.long 2b,4b; \
.previous
#define RING0_INT_FRAME \
CFI_STARTPROC simple;\
CFI_SIGNAL_FRAME;\
CFI_DEF_CFA esp, 3*4;\
/*CFI_OFFSET cs, -2*4;*/\
CFI_OFFSET eip, -3*4
#define RING0_EC_FRAME \
CFI_STARTPROC simple;\
CFI_SIGNAL_FRAME;\
CFI_DEF_CFA esp, 4*4;\
/*CFI_OFFSET cs, -2*4;*/\
CFI_OFFSET eip, -3*4
#define RING0_PTREGS_FRAME \
CFI_STARTPROC simple;\
CFI_SIGNAL_FRAME;\
CFI_DEF_CFA esp, OLDESP-EBX;\
/*CFI_OFFSET cs, CS-OLDESP;*/\
CFI_OFFSET eip, EIP-OLDESP;\
/*CFI_OFFSET es, ES-OLDESP;*/\
/*CFI_OFFSET ds, DS-OLDESP;*/\
CFI_OFFSET eax, EAX-OLDESP;\
CFI_OFFSET ebp, EBP-OLDESP;\
CFI_OFFSET edi, EDI-OLDESP;\
CFI_OFFSET esi, ESI-OLDESP;\
CFI_OFFSET edx, EDX-OLDESP;\
CFI_OFFSET ecx, ECX-OLDESP;\
CFI_OFFSET ebx, EBX-OLDESP
ENTRY(ret_from_fork)
CFI_STARTPROC
pushl %eax
CFI_ADJUST_CFA_OFFSET 4
call schedule_tail
GET_THREAD_INFO(%ebp)
popl %eax
CFI_ADJUST_CFA_OFFSET -4
pushl $0x0202 # Reset kernel eflags
CFI_ADJUST_CFA_OFFSET 4
popfl
CFI_ADJUST_CFA_OFFSET -4
jmp syscall_exit
CFI_ENDPROC
/*
* 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
RING0_PTREGS_FRAME
ret_from_exception:
preempt_stop
ret_from_intr:
GET_THREAD_INFO(%ebp)
check_userspace:
movl EFLAGS(%esp), %eax # mix EFLAGS and CS
movb CS(%esp), %al
andl $(VM_MASK | SEGMENT_RPL_MASK), %eax
cmpl $USER_RPL, %eax
jb resume_kernel # not returning to v8086 or userspace
ENTRY(resume_userspace)
DISABLE_INTERRUPTS # make sure we don't miss an interrupt
# setting need_resched or sigpending
# between sampling and the iret
movl TI_flags(%ebp), %ecx
andl $_TIF_WORK_MASK, %ecx # is there any work to be done on
# int/exception return?
jne work_pending
jmp restore_all
#ifdef CONFIG_PREEMPT
ENTRY(resume_kernel)
DISABLE_INTERRUPTS
cmpl $0,TI_preempt_count(%ebp) # non-zero preempt_count ?
jnz restore_nocheck
need_resched:
movl TI_flags(%ebp), %ecx # need_resched set ?
testb $_TIF_NEED_RESCHED, %cl
jz restore_all
testl $IF_MASK,EFLAGS(%esp) # interrupts off (exception path) ?
jz restore_all
call preempt_schedule_irq
jmp need_resched
#endif
CFI_ENDPROC
/* SYSENTER_RETURN points to after the "sysenter" instruction in
the vsyscall page. See vsyscall-sysentry.S, which defines the symbol. */
# sysenter call handler stub
ENTRY(sysenter_entry)
CFI_STARTPROC simple
CFI_SIGNAL_FRAME
CFI_DEF_CFA esp, 0
CFI_REGISTER esp, ebp
movl TSS_sysenter_esp0(%esp),%esp
sysenter_past_esp:
/*
* No need to follow this irqs on/off section: the syscall
* disabled irqs and here we enable it straight after entry:
*/
ENABLE_INTERRUPTS
pushl $(__USER_DS)
CFI_ADJUST_CFA_OFFSET 4
/*CFI_REL_OFFSET ss, 0*/
pushl %ebp
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET esp, 0
pushfl
CFI_ADJUST_CFA_OFFSET 4
pushl $(__USER_CS)
CFI_ADJUST_CFA_OFFSET 4
/*CFI_REL_OFFSET cs, 0*/
/*
* Push current_thread_info()->sysenter_return to the stack.
* A tiny bit of offset fixup is necessary - 4*4 means the 4 words
* pushed above; +8 corresponds to copy_thread's esp0 setting.
*/
pushl (TI_sysenter_return-THREAD_SIZE+8+4*4)(%esp)
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET eip, 0
/*
* Load the potential sixth argument from user stack.
* Careful about security.
*/
cmpl $__PAGE_OFFSET-3,%ebp
jae syscall_fault
1: movl (%ebp),%ebp
.section __ex_table,"a"
.align 4
.long 1b,syscall_fault
.previous
pushl %eax
CFI_ADJUST_CFA_OFFSET 4
SAVE_ALL
GET_THREAD_INFO(%ebp)
/* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */
testw $(_TIF_SYSCALL_EMU|_TIF_SYSCALL_TRACE|_TIF_SECCOMP|_TIF_SYSCALL_AUDIT),TI_flags(%ebp)
jnz syscall_trace_entry
cmpl $(nr_syscalls), %eax
jae syscall_badsys
call *sys_call_table(,%eax,4)
movl %eax,EAX(%esp)
DISABLE_INTERRUPTS
TRACE_IRQS_OFF
movl TI_flags(%ebp), %ecx
testw $_TIF_ALLWORK_MASK, %cx
jne syscall_exit_work
/* if something modifies registers it must also disable sysexit */
movl EIP(%esp), %edx
movl OLDESP(%esp), %ecx
xorl %ebp,%ebp
TRACE_IRQS_ON
ENABLE_INTERRUPTS_SYSEXIT
CFI_ENDPROC
# system call handler stub
ENTRY(system_call)
RING0_INT_FRAME # can't unwind into user space anyway
pushl %eax # save orig_eax
CFI_ADJUST_CFA_OFFSET 4
SAVE_ALL
GET_THREAD_INFO(%ebp)
testl $TF_MASK,EFLAGS(%esp)
jz no_singlestep
orl $_TIF_SINGLESTEP,TI_flags(%ebp)
no_singlestep:
# system call tracing in operation / emulation
/* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */
testw $(_TIF_SYSCALL_EMU|_TIF_SYSCALL_TRACE|_TIF_SECCOMP|_TIF_SYSCALL_AUDIT),TI_flags(%ebp)
jnz syscall_trace_entry
cmpl $(nr_syscalls), %eax
jae syscall_badsys
syscall_call:
call *sys_call_table(,%eax,4)
movl %eax,EAX(%esp) # store the return value
syscall_exit:
DISABLE_INTERRUPTS # make sure we don't miss an interrupt
# setting need_resched or sigpending
# between sampling and the iret
TRACE_IRQS_OFF
movl TI_flags(%ebp), %ecx
testw $_TIF_ALLWORK_MASK, %cx # current->work
jne syscall_exit_work
restore_all:
movl EFLAGS(%esp), %eax # mix EFLAGS, SS and CS
# Warning: OLDSS(%esp) contains the wrong/random values if we
# are returning to the kernel.
# See comments in process.c:copy_thread() for details.
movb OLDSS(%esp), %ah
movb CS(%esp), %al
andl $(VM_MASK | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax
cmpl $((SEGMENT_LDT << 8) | USER_RPL), %eax
CFI_REMEMBER_STATE
je ldt_ss # returning to user-space with LDT SS
restore_nocheck:
TRACE_IRQS_IRET
restore_nocheck_notrace:
RESTORE_REGS
addl $4, %esp
CFI_ADJUST_CFA_OFFSET -4
1: INTERRUPT_RETURN
.section .fixup,"ax"
iret_exc:
TRACE_IRQS_ON
ENABLE_INTERRUPTS
pushl $0 # no error code
pushl $do_iret_error
jmp error_code
.previous
.section __ex_table,"a"
.align 4
.long 1b,iret_exc
.previous
CFI_RESTORE_STATE
ldt_ss:
larl OLDSS(%esp), %eax
jnz restore_nocheck
testl $0x00400000, %eax # returning to 32bit stack?
jnz restore_nocheck # allright, normal return
/* If returning to userspace with 16bit stack,
* try to fix the higher word of ESP, as the CPU
* won't restore it.
* This is an "official" bug of all the x86-compatible
* CPUs, which we can try to work around to make
* dosemu and wine happy. */
subl $8, %esp # reserve space for switch16 pointer
CFI_ADJUST_CFA_OFFSET 8
DISABLE_INTERRUPTS
TRACE_IRQS_OFF
movl %esp, %eax
/* Set up the 16bit stack frame with switch32 pointer on top,
* and a switch16 pointer on top of the current frame. */
call setup_x86_bogus_stack
CFI_ADJUST_CFA_OFFSET -8 # frame has moved
TRACE_IRQS_IRET
RESTORE_REGS
lss 20+4(%esp), %esp # switch to 16bit stack
1: INTERRUPT_RETURN
.section __ex_table,"a"
.align 4
.long 1b,iret_exc
.previous
CFI_ENDPROC
# perform work that needs to be done immediately before resumption
ALIGN
RING0_PTREGS_FRAME # can't unwind into user space anyway
work_pending:
testb $_TIF_NEED_RESCHED, %cl
jz work_notifysig
work_resched:
call schedule
DISABLE_INTERRUPTS # make sure we don't miss an interrupt
# setting need_resched or sigpending
# between sampling and the iret
TRACE_IRQS_OFF
movl TI_flags(%ebp), %ecx
andl $_TIF_WORK_MASK, %ecx # is there any work to be done other
# than syscall tracing?
jz restore_all
testb $_TIF_NEED_RESCHED, %cl
jnz work_resched
work_notifysig: # deal with pending signals and
# notify-resume requests
testl $VM_MASK, EFLAGS(%esp)
movl %esp, %eax
jne work_notifysig_v86 # returning to kernel-space or
# vm86-space
xorl %edx, %edx
call do_notify_resume
jmp resume_userspace_sig
ALIGN
work_notifysig_v86:
#ifdef CONFIG_VM86
pushl %ecx # save ti_flags for do_notify_resume
CFI_ADJUST_CFA_OFFSET 4
call save_v86_state # %eax contains pt_regs pointer
popl %ecx
CFI_ADJUST_CFA_OFFSET -4
movl %eax, %esp
xorl %edx, %edx
call do_notify_resume
jmp resume_userspace_sig
#endif
# perform syscall exit tracing
ALIGN
syscall_trace_entry:
movl $-ENOSYS,EAX(%esp)
movl %esp, %eax
xorl %edx,%edx
call do_syscall_trace
cmpl $0, %eax
jne resume_userspace # ret != 0 -> running under PTRACE_SYSEMU,
# so must skip actual syscall
movl ORIG_EAX(%esp), %eax
cmpl $(nr_syscalls), %eax
jnae syscall_call
jmp syscall_exit
# perform syscall exit tracing
ALIGN
syscall_exit_work:
testb $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP), %cl
jz work_pending
TRACE_IRQS_ON
ENABLE_INTERRUPTS # could let do_syscall_trace() call
# schedule() instead
movl %esp, %eax
movl $1, %edx
call do_syscall_trace
jmp resume_userspace
CFI_ENDPROC
RING0_INT_FRAME # can't unwind into user space anyway
syscall_fault:
pushl %eax # save orig_eax
CFI_ADJUST_CFA_OFFSET 4
SAVE_ALL
GET_THREAD_INFO(%ebp)
movl $-EFAULT,EAX(%esp)
jmp resume_userspace
syscall_badsys:
movl $-ENOSYS,EAX(%esp)
jmp resume_userspace
CFI_ENDPROC
#define FIXUP_ESPFIX_STACK \
movl %esp, %eax; \
/* switch to 32bit stack using the pointer on top of 16bit stack */ \
lss %ss:CPU_16BIT_STACK_SIZE-8, %esp; \
/* copy data from 16bit stack to 32bit stack */ \
call fixup_x86_bogus_stack; \
/* put ESP to the proper location */ \
movl %eax, %esp;
#define UNWIND_ESPFIX_STACK \
pushl %eax; \
CFI_ADJUST_CFA_OFFSET 4; \
movl %ss, %eax; \
/* see if on 16bit stack */ \
cmpw $__ESPFIX_SS, %ax; \
je 28f; \
27: popl %eax; \
CFI_ADJUST_CFA_OFFSET -4; \
.section .fixup,"ax"; \
28: movl $__KERNEL_DS, %eax; \
movl %eax, %ds; \
movl %eax, %es; \
/* switch to 32bit stack */ \
FIXUP_ESPFIX_STACK; \
jmp 27b; \
.previous
/*
* Build the entry stubs and pointer table with
* some assembler magic.
*/
.data
ENTRY(interrupt)
.text
vector=0
ENTRY(irq_entries_start)
RING0_INT_FRAME
.rept NR_IRQS
ALIGN
.if vector
CFI_ADJUST_CFA_OFFSET -4
.endif
1: pushl $~(vector)
CFI_ADJUST_CFA_OFFSET 4
jmp common_interrupt
.data
.long 1b
.text
vector=vector+1
.endr
/*
* the CPU automatically disables interrupts when executing an IRQ vector,
* so IRQ-flags tracing has to follow that:
*/
ALIGN
common_interrupt:
SAVE_ALL
TRACE_IRQS_OFF
movl %esp,%eax
call do_IRQ
jmp ret_from_intr
CFI_ENDPROC
#define BUILD_INTERRUPT(name, nr) \
ENTRY(name) \
RING0_INT_FRAME; \
pushl $~(nr); \
CFI_ADJUST_CFA_OFFSET 4; \
SAVE_ALL; \
TRACE_IRQS_OFF \
movl %esp,%eax; \
call smp_/**/name; \
jmp ret_from_intr; \
CFI_ENDPROC
/* The include is where all of the SMP etc. interrupts come from */
#include "entry_arch.h"
KPROBE_ENTRY(page_fault)
RING0_EC_FRAME
pushl $do_page_fault
CFI_ADJUST_CFA_OFFSET 4
ALIGN
error_code:
pushl %ds
CFI_ADJUST_CFA_OFFSET 4
/*CFI_REL_OFFSET ds, 0*/
pushl %eax
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET eax, 0
xorl %eax, %eax
pushl %ebp
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET ebp, 0
pushl %edi
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET edi, 0
pushl %esi
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET esi, 0
pushl %edx
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET edx, 0
decl %eax # eax = -1
pushl %ecx
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET ecx, 0
pushl %ebx
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET ebx, 0
cld
pushl %es
CFI_ADJUST_CFA_OFFSET 4
/*CFI_REL_OFFSET es, 0*/
UNWIND_ESPFIX_STACK
popl %ecx
CFI_ADJUST_CFA_OFFSET -4
/*CFI_REGISTER es, ecx*/
movl ES(%esp), %edi # get the function address
movl ORIG_EAX(%esp), %edx # get the error code
movl %eax, ORIG_EAX(%esp)
movl %ecx, ES(%esp)
/*CFI_REL_OFFSET es, ES*/
movl $(__USER_DS), %ecx
movl %ecx, %ds
movl %ecx, %es
movl %esp,%eax # pt_regs pointer
call *%edi
jmp ret_from_exception
CFI_ENDPROC
KPROBE_END(page_fault)
ENTRY(coprocessor_error)
RING0_INT_FRAME
pushl $0
CFI_ADJUST_CFA_OFFSET 4
pushl $do_coprocessor_error
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
ENTRY(simd_coprocessor_error)
RING0_INT_FRAME
pushl $0
CFI_ADJUST_CFA_OFFSET 4
pushl $do_simd_coprocessor_error
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
ENTRY(device_not_available)
RING0_INT_FRAME
pushl $-1 # mark this as an int
CFI_ADJUST_CFA_OFFSET 4
SAVE_ALL
GET_CR0_INTO_EAX
testl $0x4, %eax # EM (math emulation bit)
jne device_not_available_emulate
preempt_stop
call math_state_restore
jmp ret_from_exception
device_not_available_emulate:
pushl $0 # temporary storage for ORIG_EIP
CFI_ADJUST_CFA_OFFSET 4
call math_emulate
addl $4, %esp
CFI_ADJUST_CFA_OFFSET -4
jmp ret_from_exception
CFI_ENDPROC
/*
* Debug traps and NMI can happen at the one SYSENTER instruction
* that sets up the real kernel stack. Check here, since we can't
* allow the wrong stack to be used.
*
* "TSS_sysenter_esp0+12" is because the NMI/debug handler will have
* already pushed 3 words if it hits on the sysenter instruction:
* eflags, cs and eip.
*
* We just load the right stack, and push the three (known) values
* by hand onto the new stack - while updating the return eip past
* the instruction that would have done it for sysenter.
*/
#define FIX_STACK(offset, ok, label) \
cmpw $__KERNEL_CS,4(%esp); \
jne ok; \
label: \
movl TSS_sysenter_esp0+offset(%esp),%esp; \
CFI_DEF_CFA esp, 0; \
CFI_UNDEFINED eip; \
pushfl; \
CFI_ADJUST_CFA_OFFSET 4; \
pushl $__KERNEL_CS; \
CFI_ADJUST_CFA_OFFSET 4; \
pushl $sysenter_past_esp; \
CFI_ADJUST_CFA_OFFSET 4; \
CFI_REL_OFFSET eip, 0
KPROBE_ENTRY(debug)
RING0_INT_FRAME
cmpl $sysenter_entry,(%esp)
jne debug_stack_correct
FIX_STACK(12, debug_stack_correct, debug_esp_fix_insn)
debug_stack_correct:
pushl $-1 # mark this as an int
CFI_ADJUST_CFA_OFFSET 4
SAVE_ALL
xorl %edx,%edx # error code 0
movl %esp,%eax # pt_regs pointer
call do_debug
jmp ret_from_exception
CFI_ENDPROC
KPROBE_END(debug)
/*
* NMI is doubly nasty. It can happen _while_ we're handling
* a debug fault, and the debug fault hasn't yet been able to
* clear up the stack. So we first check whether we got an
* NMI on the sysenter entry path, but after that we need to
* check whether we got an NMI on the debug path where the debug
* fault happened on the sysenter path.
*/
KPROBE_ENTRY(nmi)
RING0_INT_FRAME
pushl %eax
CFI_ADJUST_CFA_OFFSET 4
movl %ss, %eax
cmpw $__ESPFIX_SS, %ax
popl %eax
CFI_ADJUST_CFA_OFFSET -4
je nmi_16bit_stack
cmpl $sysenter_entry,(%esp)
je nmi_stack_fixup
pushl %eax
CFI_ADJUST_CFA_OFFSET 4
movl %esp,%eax
/* Do not access memory above the end of our stack page,
* it might not exist.
*/
andl $(THREAD_SIZE-1),%eax
cmpl $(THREAD_SIZE-20),%eax
popl %eax
CFI_ADJUST_CFA_OFFSET -4
jae nmi_stack_correct
cmpl $sysenter_entry,12(%esp)
je nmi_debug_stack_check
nmi_stack_correct:
/* We have a RING0_INT_FRAME here */
pushl %eax
CFI_ADJUST_CFA_OFFSET 4
SAVE_ALL
xorl %edx,%edx # zero error code
movl %esp,%eax # pt_regs pointer
call do_nmi
jmp restore_nocheck_notrace
CFI_ENDPROC
nmi_stack_fixup:
RING0_INT_FRAME
FIX_STACK(12,nmi_stack_correct, 1)
jmp nmi_stack_correct
nmi_debug_stack_check:
/* We have a RING0_INT_FRAME here */
cmpw $__KERNEL_CS,16(%esp)
jne nmi_stack_correct
cmpl $debug,(%esp)
jb nmi_stack_correct
cmpl $debug_esp_fix_insn,(%esp)
ja nmi_stack_correct
FIX_STACK(24,nmi_stack_correct, 1)
jmp nmi_stack_correct
nmi_16bit_stack:
/* We have a RING0_INT_FRAME here.
*
* create the pointer to lss back
*/
pushl %ss
CFI_ADJUST_CFA_OFFSET 4
pushl %esp
CFI_ADJUST_CFA_OFFSET 4
movzwl %sp, %esp
addw $4, (%esp)
/* copy the iret frame of 12 bytes */
.rept 3
pushl 16(%esp)
CFI_ADJUST_CFA_OFFSET 4
.endr
pushl %eax
CFI_ADJUST_CFA_OFFSET 4
SAVE_ALL
FIXUP_ESPFIX_STACK # %eax == %esp
CFI_ADJUST_CFA_OFFSET -20 # the frame has now moved
xorl %edx,%edx # zero error code
call do_nmi
RESTORE_REGS
lss 12+4(%esp), %esp # back to 16bit stack
1: INTERRUPT_RETURN
CFI_ENDPROC
.section __ex_table,"a"
.align 4
.long 1b,iret_exc
.previous
KPROBE_END(nmi)
KPROBE_ENTRY(int3)
RING0_INT_FRAME
pushl $-1 # mark this as an int
CFI_ADJUST_CFA_OFFSET 4
SAVE_ALL
xorl %edx,%edx # zero error code
movl %esp,%eax # pt_regs pointer
call do_int3
jmp ret_from_exception
CFI_ENDPROC
KPROBE_END(int3)
ENTRY(overflow)
RING0_INT_FRAME
pushl $0
CFI_ADJUST_CFA_OFFSET 4
pushl $do_overflow
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
ENTRY(bounds)
RING0_INT_FRAME
pushl $0
CFI_ADJUST_CFA_OFFSET 4
pushl $do_bounds
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
ENTRY(invalid_op)
RING0_INT_FRAME
pushl $0
CFI_ADJUST_CFA_OFFSET 4
pushl $do_invalid_op
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
ENTRY(coprocessor_segment_overrun)
RING0_INT_FRAME
pushl $0
CFI_ADJUST_CFA_OFFSET 4
pushl $do_coprocessor_segment_overrun
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
ENTRY(invalid_TSS)
RING0_EC_FRAME
pushl $do_invalid_TSS
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
ENTRY(segment_not_present)
RING0_EC_FRAME
pushl $do_segment_not_present
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
ENTRY(stack_segment)
RING0_EC_FRAME
pushl $do_stack_segment
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
KPROBE_ENTRY(general_protection)
RING0_EC_FRAME
pushl $do_general_protection
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
KPROBE_END(general_protection)
ENTRY(alignment_check)
RING0_EC_FRAME
pushl $do_alignment_check
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
ENTRY(divide_error)
RING0_INT_FRAME
pushl $0 # no error code
CFI_ADJUST_CFA_OFFSET 4
pushl $do_divide_error
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
#ifdef CONFIG_X86_MCE
ENTRY(machine_check)
RING0_INT_FRAME
pushl $0
CFI_ADJUST_CFA_OFFSET 4
pushl machine_check_vector
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
#endif
ENTRY(spurious_interrupt_bug)
RING0_INT_FRAME
pushl $0
CFI_ADJUST_CFA_OFFSET 4
pushl $do_spurious_interrupt_bug
CFI_ADJUST_CFA_OFFSET 4
jmp error_code
CFI_ENDPROC
#ifdef CONFIG_STACK_UNWIND
ENTRY(arch_unwind_init_running)
CFI_STARTPROC
movl 4(%esp), %edx
movl (%esp), %ecx
leal 4(%esp), %eax
movl %ebx, EBX(%edx)
xorl %ebx, %ebx
movl %ebx, ECX(%edx)
movl %ebx, EDX(%edx)
movl %esi, ESI(%edx)
movl %edi, EDI(%edx)
movl %ebp, EBP(%edx)
movl %ebx, EAX(%edx)
movl $__USER_DS, DS(%edx)
movl $__USER_DS, ES(%edx)
movl %ebx, ORIG_EAX(%edx)
movl %ecx, EIP(%edx)
movl 12(%esp), %ecx
movl $__KERNEL_CS, CS(%edx)
movl %ebx, EFLAGS(%edx)
movl %eax, OLDESP(%edx)
movl 8(%esp), %eax
movl %ecx, 8(%esp)
movl EBX(%edx), %ebx
movl $__KERNEL_DS, OLDSS(%edx)
jmpl *%eax
CFI_ENDPROC
ENDPROC(arch_unwind_init_running)
#endif
ENTRY(kernel_thread_helper)
pushl $0 # fake return address for unwinder
CFI_STARTPROC
movl %edx,%eax
push %edx
CFI_ADJUST_CFA_OFFSET 4
call *%ebx
push %eax
CFI_ADJUST_CFA_OFFSET 4
call do_exit
CFI_ENDPROC
ENDPROC(kernel_thread_helper)
.section .rodata,"a"
#include "syscall_table.S"
syscall_table_size=(.-sys_call_table)
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