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kernel-fxtec-pro1x/arch/x86/kernel/entry_64.S
Steven Rostedt e49dc19c6a ftrace: function graph return for function entry 
Impact: feature, let entry function decide to trace or not

This patch lets the graph tracer entry function decide if the tracing
should be done at the end as well. This requires all function graph
entry functions return 1 if it should trace, or 0 if the return should
not be traced.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-03 08:56:26 +01:00

1537 lines
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/*
* linux/arch/x86_64/entry.S
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
* Copyright (C) 2000 Pavel Machek <pavel@suse.cz>
*/
/*
* entry.S contains the system-call and fault low-level handling routines.
*
* NOTE: This code handles signal-recognition, which happens every time
* after an interrupt and after each system call.
*
* Normal syscalls and interrupts don't save a full stack frame, this is
* only done for syscall tracing, signals or fork/exec et.al.
*
* A note on terminology:
* - top of stack: Architecture defined interrupt frame from SS to RIP
* at the top of the kernel process stack.
* - partial stack frame: partially saved registers upto R11.
* - full stack frame: Like partial stack frame, but all register saved.
*
* Some macro usage:
* - CFI macros are used to generate dwarf2 unwind information for better
* backtraces. They don't change any code.
* - SAVE_ALL/RESTORE_ALL - Save/restore all registers
* - SAVE_ARGS/RESTORE_ARGS - Save/restore registers that C functions modify.
* There are unfortunately lots of special cases where some registers
* not touched. The macro is a big mess that should be cleaned up.
* - SAVE_REST/RESTORE_REST - Handle the registers not saved by SAVE_ARGS.
* Gives a full stack frame.
* - ENTRY/END Define functions in the symbol table.
* - FIXUP_TOP_OF_STACK/RESTORE_TOP_OF_STACK - Fix up the hardware stack
* frame that is otherwise undefined after a SYSCALL
* - TRACE_IRQ_* - Trace hard interrupt state for lock debugging.
* - errorentry/paranoidentry/zeroentry - Define exception entry points.
*/
#include <linux/linkage.h>
#include <asm/segment.h>
#include <asm/cache.h>
#include <asm/errno.h>
#include <asm/dwarf2.h>
#include <asm/calling.h>
#include <asm/asm-offsets.h>
#include <asm/msr.h>
#include <asm/unistd.h>
#include <asm/thread_info.h>
#include <asm/hw_irq.h>
#include <asm/page.h>
#include <asm/irqflags.h>
#include <asm/paravirt.h>
#include <asm/ftrace.h>
/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */
#include <linux/elf-em.h>
#define AUDIT_ARCH_X86_64 (EM_X86_64|__AUDIT_ARCH_64BIT|__AUDIT_ARCH_LE)
#define __AUDIT_ARCH_64BIT 0x80000000
#define __AUDIT_ARCH_LE 0x40000000
.code64
#ifdef CONFIG_FUNCTION_TRACER
#ifdef CONFIG_DYNAMIC_FTRACE
ENTRY(mcount)
retq
END(mcount)
ENTRY(ftrace_caller)
cmpl $0, function_trace_stop
jne ftrace_stub
/* taken from glibc */
subq $0x38, %rsp
movq %rax, (%rsp)
movq %rcx, 8(%rsp)
movq %rdx, 16(%rsp)
movq %rsi, 24(%rsp)
movq %rdi, 32(%rsp)
movq %r8, 40(%rsp)
movq %r9, 48(%rsp)
movq 0x38(%rsp), %rdi
movq 8(%rbp), %rsi
subq $MCOUNT_INSN_SIZE, %rdi
.globl ftrace_call
ftrace_call:
call ftrace_stub
movq 48(%rsp), %r9
movq 40(%rsp), %r8
movq 32(%rsp), %rdi
movq 24(%rsp), %rsi
movq 16(%rsp), %rdx
movq 8(%rsp), %rcx
movq (%rsp), %rax
addq $0x38, %rsp
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
.globl ftrace_graph_call
ftrace_graph_call:
jmp ftrace_stub
#endif
.globl ftrace_stub
ftrace_stub:
retq
END(ftrace_caller)
#else /* ! CONFIG_DYNAMIC_FTRACE */
ENTRY(mcount)
cmpl $0, function_trace_stop
jne ftrace_stub
cmpq $ftrace_stub, ftrace_trace_function
jnz trace
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
cmpq $ftrace_stub, ftrace_graph_return
jnz ftrace_graph_caller
cmpq $ftrace_graph_entry_stub, ftrace_graph_entry
jnz ftrace_graph_caller
#endif
.globl ftrace_stub
ftrace_stub:
retq
trace:
/* taken from glibc */
subq $0x38, %rsp
movq %rax, (%rsp)
movq %rcx, 8(%rsp)
movq %rdx, 16(%rsp)
movq %rsi, 24(%rsp)
movq %rdi, 32(%rsp)
movq %r8, 40(%rsp)
movq %r9, 48(%rsp)
movq 0x38(%rsp), %rdi
movq 8(%rbp), %rsi
subq $MCOUNT_INSN_SIZE, %rdi
call *ftrace_trace_function
movq 48(%rsp), %r9
movq 40(%rsp), %r8
movq 32(%rsp), %rdi
movq 24(%rsp), %rsi
movq 16(%rsp), %rdx
movq 8(%rsp), %rcx
movq (%rsp), %rax
addq $0x38, %rsp
jmp ftrace_stub
END(mcount)
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_TRACER */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(ftrace_graph_caller)
cmpl $0, function_trace_stop
jne ftrace_stub
subq $0x38, %rsp
movq %rax, (%rsp)
movq %rcx, 8(%rsp)
movq %rdx, 16(%rsp)
movq %rsi, 24(%rsp)
movq %rdi, 32(%rsp)
movq %r8, 40(%rsp)
movq %r9, 48(%rsp)
leaq 8(%rbp), %rdi
movq 0x38(%rsp), %rsi
subq $MCOUNT_INSN_SIZE, %rsi
call prepare_ftrace_return
movq 48(%rsp), %r9
movq 40(%rsp), %r8
movq 32(%rsp), %rdi
movq 24(%rsp), %rsi
movq 16(%rsp), %rdx
movq 8(%rsp), %rcx
movq (%rsp), %rax
addq $0x38, %rsp
retq
END(ftrace_graph_caller)
.globl return_to_handler
return_to_handler:
subq $80, %rsp
movq %rax, (%rsp)
movq %rcx, 8(%rsp)
movq %rdx, 16(%rsp)
movq %rsi, 24(%rsp)
movq %rdi, 32(%rsp)
movq %r8, 40(%rsp)
movq %r9, 48(%rsp)
movq %r10, 56(%rsp)
movq %r11, 64(%rsp)
call ftrace_return_to_handler
movq %rax, 72(%rsp)
movq 64(%rsp), %r11
movq 56(%rsp), %r10
movq 48(%rsp), %r9
movq 40(%rsp), %r8
movq 32(%rsp), %rdi
movq 24(%rsp), %rsi
movq 16(%rsp), %rdx
movq 8(%rsp), %rcx
movq (%rsp), %rax
addq $72, %rsp
retq
#endif
#ifndef CONFIG_PREEMPT
#define retint_kernel retint_restore_args
#endif
#ifdef CONFIG_PARAVIRT
ENTRY(native_usergs_sysret64)
swapgs
sysretq
#endif /* CONFIG_PARAVIRT */
.macro TRACE_IRQS_IRETQ offset=ARGOFFSET
#ifdef CONFIG_TRACE_IRQFLAGS
bt $9,EFLAGS-\offset(%rsp) /* interrupts off? */
jnc 1f
TRACE_IRQS_ON
1:
#endif
.endm
/*
* C code is not supposed to know about undefined top of stack. Every time
* a C function with an pt_regs argument is called from the SYSCALL based
* fast path FIXUP_TOP_OF_STACK is needed.
* RESTORE_TOP_OF_STACK syncs the syscall state after any possible ptregs
* manipulation.
*/
/* %rsp:at FRAMEEND */
.macro FIXUP_TOP_OF_STACK tmp
movq %gs:pda_oldrsp,\tmp
movq \tmp,RSP(%rsp)
movq $__USER_DS,SS(%rsp)
movq $__USER_CS,CS(%rsp)
movq $-1,RCX(%rsp)
movq R11(%rsp),\tmp /* get eflags */
movq \tmp,EFLAGS(%rsp)
.endm
.macro RESTORE_TOP_OF_STACK tmp,offset=0
movq RSP-\offset(%rsp),\tmp
movq \tmp,%gs:pda_oldrsp
movq EFLAGS-\offset(%rsp),\tmp
movq \tmp,R11-\offset(%rsp)
.endm
.macro FAKE_STACK_FRAME child_rip
/* push in order ss, rsp, eflags, cs, rip */
xorl %eax, %eax
pushq $__KERNEL_DS /* ss */
CFI_ADJUST_CFA_OFFSET 8
/*CFI_REL_OFFSET ss,0*/
pushq %rax /* rsp */
CFI_ADJUST_CFA_OFFSET 8
CFI_REL_OFFSET rsp,0
pushq $(1<<9) /* eflags - interrupts on */
CFI_ADJUST_CFA_OFFSET 8
/*CFI_REL_OFFSET rflags,0*/
pushq $__KERNEL_CS /* cs */
CFI_ADJUST_CFA_OFFSET 8
/*CFI_REL_OFFSET cs,0*/
pushq \child_rip /* rip */
CFI_ADJUST_CFA_OFFSET 8
CFI_REL_OFFSET rip,0
pushq %rax /* orig rax */
CFI_ADJUST_CFA_OFFSET 8
.endm
.macro UNFAKE_STACK_FRAME
addq $8*6, %rsp
CFI_ADJUST_CFA_OFFSET -(6*8)
.endm
.macro CFI_DEFAULT_STACK start=1
.if \start
CFI_STARTPROC simple
CFI_SIGNAL_FRAME
CFI_DEF_CFA rsp,SS+8
.else
CFI_DEF_CFA_OFFSET SS+8
.endif
CFI_REL_OFFSET r15,R15
CFI_REL_OFFSET r14,R14
CFI_REL_OFFSET r13,R13
CFI_REL_OFFSET r12,R12
CFI_REL_OFFSET rbp,RBP
CFI_REL_OFFSET rbx,RBX
CFI_REL_OFFSET r11,R11
CFI_REL_OFFSET r10,R10
CFI_REL_OFFSET r9,R9
CFI_REL_OFFSET r8,R8
CFI_REL_OFFSET rax,RAX
CFI_REL_OFFSET rcx,RCX
CFI_REL_OFFSET rdx,RDX
CFI_REL_OFFSET rsi,RSI
CFI_REL_OFFSET rdi,RDI
CFI_REL_OFFSET rip,RIP
/*CFI_REL_OFFSET cs,CS*/
/*CFI_REL_OFFSET rflags,EFLAGS*/
CFI_REL_OFFSET rsp,RSP
/*CFI_REL_OFFSET ss,SS*/
.endm
/*
* A newly forked process directly context switches into this.
*/
/* rdi: prev */
ENTRY(ret_from_fork)
CFI_DEFAULT_STACK
push kernel_eflags(%rip)
CFI_ADJUST_CFA_OFFSET 8
popf # reset kernel eflags
CFI_ADJUST_CFA_OFFSET -8
call schedule_tail
GET_THREAD_INFO(%rcx)
testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT),TI_flags(%rcx)
jnz rff_trace
rff_action:
RESTORE_REST
testl $3,CS-ARGOFFSET(%rsp) # from kernel_thread?
je int_ret_from_sys_call
testl $_TIF_IA32,TI_flags(%rcx)
jnz int_ret_from_sys_call
RESTORE_TOP_OF_STACK %rdi,ARGOFFSET
jmp ret_from_sys_call
rff_trace:
movq %rsp,%rdi
call syscall_trace_leave
GET_THREAD_INFO(%rcx)
jmp rff_action
CFI_ENDPROC
END(ret_from_fork)
/*
* System call entry. Upto 6 arguments in registers are supported.
*
* SYSCALL does not save anything on the stack and does not change the
* stack pointer.
*/
/*
* Register setup:
* rax system call number
* rdi arg0
* rcx return address for syscall/sysret, C arg3
* rsi arg1
* rdx arg2
* r10 arg3 (--> moved to rcx for C)
* r8 arg4
* r9 arg5
* r11 eflags for syscall/sysret, temporary for C
* r12-r15,rbp,rbx saved by C code, not touched.
*
* Interrupts are off on entry.
* Only called from user space.
*
* XXX if we had a free scratch register we could save the RSP into the stack frame
* and report it properly in ps. Unfortunately we haven't.
*
* When user can change the frames always force IRET. That is because
* it deals with uncanonical addresses better. SYSRET has trouble
* with them due to bugs in both AMD and Intel CPUs.
*/
ENTRY(system_call)
CFI_STARTPROC simple
CFI_SIGNAL_FRAME
CFI_DEF_CFA rsp,PDA_STACKOFFSET
CFI_REGISTER rip,rcx
/*CFI_REGISTER rflags,r11*/
SWAPGS_UNSAFE_STACK
/*
* A hypervisor implementation might want to use a label
* after the swapgs, so that it can do the swapgs
* for the guest and jump here on syscall.
*/
ENTRY(system_call_after_swapgs)
movq %rsp,%gs:pda_oldrsp
movq %gs:pda_kernelstack,%rsp
/*
* No need to follow this irqs off/on section - it's straight
* and short:
*/
ENABLE_INTERRUPTS(CLBR_NONE)
SAVE_ARGS 8,1
movq %rax,ORIG_RAX-ARGOFFSET(%rsp)
movq %rcx,RIP-ARGOFFSET(%rsp)
CFI_REL_OFFSET rip,RIP-ARGOFFSET
GET_THREAD_INFO(%rcx)
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%rcx)
jnz tracesys
system_call_fastpath:
cmpq $__NR_syscall_max,%rax
ja badsys
movq %r10,%rcx
call *sys_call_table(,%rax,8) # XXX: rip relative
movq %rax,RAX-ARGOFFSET(%rsp)
/*
* Syscall return path ending with SYSRET (fast path)
* Has incomplete stack frame and undefined top of stack.
*/
ret_from_sys_call:
movl $_TIF_ALLWORK_MASK,%edi
/* edi: flagmask */
sysret_check:
LOCKDEP_SYS_EXIT
GET_THREAD_INFO(%rcx)
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
movl TI_flags(%rcx),%edx
andl %edi,%edx
jnz sysret_careful
CFI_REMEMBER_STATE
/*
* sysretq will re-enable interrupts:
*/
TRACE_IRQS_ON
movq RIP-ARGOFFSET(%rsp),%rcx
CFI_REGISTER rip,rcx
RESTORE_ARGS 0,-ARG_SKIP,1
/*CFI_REGISTER rflags,r11*/
movq %gs:pda_oldrsp, %rsp
USERGS_SYSRET64
CFI_RESTORE_STATE
/* Handle reschedules */
/* edx: work, edi: workmask */
sysret_careful:
bt $TIF_NEED_RESCHED,%edx
jnc sysret_signal
TRACE_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
pushq %rdi
CFI_ADJUST_CFA_OFFSET 8
call schedule
popq %rdi
CFI_ADJUST_CFA_OFFSET -8
jmp sysret_check
/* Handle a signal */
sysret_signal:
TRACE_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
#ifdef CONFIG_AUDITSYSCALL
bt $TIF_SYSCALL_AUDIT,%edx
jc sysret_audit
#endif
/* edx: work flags (arg3) */
leaq do_notify_resume(%rip),%rax
leaq -ARGOFFSET(%rsp),%rdi # &pt_regs -> arg1
xorl %esi,%esi # oldset -> arg2
call ptregscall_common
movl $_TIF_WORK_MASK,%edi
/* Use IRET because user could have changed frame. This
works because ptregscall_common has called FIXUP_TOP_OF_STACK. */
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
jmp int_with_check
badsys:
movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
jmp ret_from_sys_call
#ifdef CONFIG_AUDITSYSCALL
/*
* Fast path for syscall audit without full syscall trace.
* We just call audit_syscall_entry() directly, and then
* jump back to the normal fast path.
*/
auditsys:
movq %r10,%r9 /* 6th arg: 4th syscall arg */
movq %rdx,%r8 /* 5th arg: 3rd syscall arg */
movq %rsi,%rcx /* 4th arg: 2nd syscall arg */
movq %rdi,%rdx /* 3rd arg: 1st syscall arg */
movq %rax,%rsi /* 2nd arg: syscall number */
movl $AUDIT_ARCH_X86_64,%edi /* 1st arg: audit arch */
call audit_syscall_entry
LOAD_ARGS 0 /* reload call-clobbered registers */
jmp system_call_fastpath
/*
* Return fast path for syscall audit. Call audit_syscall_exit()
* directly and then jump back to the fast path with TIF_SYSCALL_AUDIT
* masked off.
*/
sysret_audit:
movq %rax,%rsi /* second arg, syscall return value */
cmpq $0,%rax /* is it < 0? */
setl %al /* 1 if so, 0 if not */
movzbl %al,%edi /* zero-extend that into %edi */
inc %edi /* first arg, 0->1(AUDITSC_SUCCESS), 1->2(AUDITSC_FAILURE) */
call audit_syscall_exit
movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi
jmp sysret_check
#endif /* CONFIG_AUDITSYSCALL */
/* Do syscall tracing */
tracesys:
#ifdef CONFIG_AUDITSYSCALL
testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%rcx)
jz auditsys
#endif
SAVE_REST
movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */
FIXUP_TOP_OF_STACK %rdi
movq %rsp,%rdi
call syscall_trace_enter
/*
* Reload arg registers from stack in case ptrace changed them.
* We don't reload %rax because syscall_trace_enter() returned
* the value it wants us to use in the table lookup.
*/
LOAD_ARGS ARGOFFSET, 1
RESTORE_REST
cmpq $__NR_syscall_max,%rax
ja int_ret_from_sys_call /* RAX(%rsp) set to -ENOSYS above */
movq %r10,%rcx /* fixup for C */
call *sys_call_table(,%rax,8)
movq %rax,RAX-ARGOFFSET(%rsp)
/* Use IRET because user could have changed frame */
/*
* Syscall return path ending with IRET.
* Has correct top of stack, but partial stack frame.
*/
.globl int_ret_from_sys_call
.globl int_with_check
int_ret_from_sys_call:
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
testl $3,CS-ARGOFFSET(%rsp)
je retint_restore_args
movl $_TIF_ALLWORK_MASK,%edi
/* edi: mask to check */
int_with_check:
LOCKDEP_SYS_EXIT_IRQ
GET_THREAD_INFO(%rcx)
movl TI_flags(%rcx),%edx
andl %edi,%edx
jnz int_careful
andl $~TS_COMPAT,TI_status(%rcx)
jmp retint_swapgs
/* Either reschedule or signal or syscall exit tracking needed. */
/* First do a reschedule test. */
/* edx: work, edi: workmask */
int_careful:
bt $TIF_NEED_RESCHED,%edx
jnc int_very_careful
TRACE_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
pushq %rdi
CFI_ADJUST_CFA_OFFSET 8
call schedule
popq %rdi
CFI_ADJUST_CFA_OFFSET -8
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
jmp int_with_check
/* handle signals and tracing -- both require a full stack frame */
int_very_careful:
TRACE_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
SAVE_REST
/* Check for syscall exit trace */
testl $_TIF_WORK_SYSCALL_EXIT,%edx
jz int_signal
pushq %rdi
CFI_ADJUST_CFA_OFFSET 8
leaq 8(%rsp),%rdi # &ptregs -> arg1
call syscall_trace_leave
popq %rdi
CFI_ADJUST_CFA_OFFSET -8
andl $~(_TIF_WORK_SYSCALL_EXIT|_TIF_SYSCALL_EMU),%edi
jmp int_restore_rest
int_signal:
testl $_TIF_DO_NOTIFY_MASK,%edx
jz 1f
movq %rsp,%rdi # &ptregs -> arg1
xorl %esi,%esi # oldset -> arg2
call do_notify_resume
1: movl $_TIF_WORK_MASK,%edi
int_restore_rest:
RESTORE_REST
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
jmp int_with_check
CFI_ENDPROC
END(system_call)
/*
* Certain special system calls that need to save a complete full stack frame.
*/
.macro PTREGSCALL label,func,arg
.globl \label
\label:
leaq \func(%rip),%rax
leaq -ARGOFFSET+8(%rsp),\arg /* 8 for return address */
jmp ptregscall_common
END(\label)
.endm
CFI_STARTPROC
PTREGSCALL stub_clone, sys_clone, %r8
PTREGSCALL stub_fork, sys_fork, %rdi
PTREGSCALL stub_vfork, sys_vfork, %rdi
PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx
PTREGSCALL stub_iopl, sys_iopl, %rsi
ENTRY(ptregscall_common)
popq %r11
CFI_ADJUST_CFA_OFFSET -8
CFI_REGISTER rip, r11
SAVE_REST
movq %r11, %r15
CFI_REGISTER rip, r15
FIXUP_TOP_OF_STACK %r11
call *%rax
RESTORE_TOP_OF_STACK %r11
movq %r15, %r11
CFI_REGISTER rip, r11
RESTORE_REST
pushq %r11
CFI_ADJUST_CFA_OFFSET 8
CFI_REL_OFFSET rip, 0
ret
CFI_ENDPROC
END(ptregscall_common)
ENTRY(stub_execve)
CFI_STARTPROC
popq %r11
CFI_ADJUST_CFA_OFFSET -8
CFI_REGISTER rip, r11
SAVE_REST
FIXUP_TOP_OF_STACK %r11
movq %rsp, %rcx
call sys_execve
RESTORE_TOP_OF_STACK %r11
movq %rax,RAX(%rsp)
RESTORE_REST
jmp int_ret_from_sys_call
CFI_ENDPROC
END(stub_execve)
/*
* sigreturn is special because it needs to restore all registers on return.
* This cannot be done with SYSRET, so use the IRET return path instead.
*/
ENTRY(stub_rt_sigreturn)
CFI_STARTPROC
addq $8, %rsp
CFI_ADJUST_CFA_OFFSET -8
SAVE_REST
movq %rsp,%rdi
FIXUP_TOP_OF_STACK %r11
call sys_rt_sigreturn
movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer
RESTORE_REST
jmp int_ret_from_sys_call
CFI_ENDPROC
END(stub_rt_sigreturn)
/*
* initial frame state for interrupts and exceptions
*/
.macro _frame ref
CFI_STARTPROC simple
CFI_SIGNAL_FRAME
CFI_DEF_CFA rsp,SS+8-\ref
/*CFI_REL_OFFSET ss,SS-\ref*/
CFI_REL_OFFSET rsp,RSP-\ref
/*CFI_REL_OFFSET rflags,EFLAGS-\ref*/
/*CFI_REL_OFFSET cs,CS-\ref*/
CFI_REL_OFFSET rip,RIP-\ref
.endm
/* initial frame state for interrupts (and exceptions without error code) */
#define INTR_FRAME _frame RIP
/* initial frame state for exceptions with error code (and interrupts with
vector already pushed) */
#define XCPT_FRAME _frame ORIG_RAX
/*
* Interrupt entry/exit.
*
* Interrupt entry points save only callee clobbered registers in fast path.
*
* Entry runs with interrupts off.
*/
/* 0(%rsp): interrupt number */
.macro interrupt func
cld
SAVE_ARGS
leaq -ARGOFFSET(%rsp),%rdi # arg1 for handler
pushq %rbp
/*
* Save rbp twice: One is for marking the stack frame, as usual, and the
* other, to fill pt_regs properly. This is because bx comes right
* before the last saved register in that structure, and not bp. If the
* base pointer were in the place bx is today, this would not be needed.
*/
movq %rbp, -8(%rsp)
CFI_ADJUST_CFA_OFFSET 8
CFI_REL_OFFSET rbp, 0
movq %rsp,%rbp
CFI_DEF_CFA_REGISTER rbp
testl $3,CS(%rdi)
je 1f
SWAPGS
/* irqcount is used to check if a CPU is already on an interrupt
stack or not. While this is essentially redundant with preempt_count
it is a little cheaper to use a separate counter in the PDA
(short of moving irq_enter into assembly, which would be too
much work) */
1: incl %gs:pda_irqcount
cmoveq %gs:pda_irqstackptr,%rsp
push %rbp # backlink for old unwinder
/*
* We entered an interrupt context - irqs are off:
*/
TRACE_IRQS_OFF
call \func
.endm
ENTRY(common_interrupt)
XCPT_FRAME
interrupt do_IRQ
/* 0(%rsp): oldrsp-ARGOFFSET */
ret_from_intr:
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
decl %gs:pda_irqcount
leaveq
CFI_DEF_CFA_REGISTER rsp
CFI_ADJUST_CFA_OFFSET -8
exit_intr:
GET_THREAD_INFO(%rcx)
testl $3,CS-ARGOFFSET(%rsp)
je retint_kernel
/* Interrupt came from user space */
/*
* Has a correct top of stack, but a partial stack frame
* %rcx: thread info. Interrupts off.
*/
retint_with_reschedule:
movl $_TIF_WORK_MASK,%edi
retint_check:
LOCKDEP_SYS_EXIT_IRQ
movl TI_flags(%rcx),%edx
andl %edi,%edx
CFI_REMEMBER_STATE
jnz retint_careful
retint_swapgs: /* return to user-space */
/*
* The iretq could re-enable interrupts:
*/
DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_IRETQ
SWAPGS
jmp restore_args
retint_restore_args: /* return to kernel space */
DISABLE_INTERRUPTS(CLBR_ANY)
/*
* The iretq could re-enable interrupts:
*/
TRACE_IRQS_IRETQ
restore_args:
RESTORE_ARGS 0,8,0
irq_return:
INTERRUPT_RETURN
.section __ex_table, "a"
.quad irq_return, bad_iret
.previous
#ifdef CONFIG_PARAVIRT
ENTRY(native_iret)
iretq
.section __ex_table,"a"
.quad native_iret, bad_iret
.previous
#endif
.section .fixup,"ax"
bad_iret:
/*
* The iret traps when the %cs or %ss being restored is bogus.
* We've lost the original trap vector and error code.
* #GPF is the most likely one to get for an invalid selector.
* So pretend we completed the iret and took the #GPF in user mode.
*
* We are now running with the kernel GS after exception recovery.
* But error_entry expects us to have user GS to match the user %cs,
* so swap back.
*/
pushq $0
SWAPGS
jmp general_protection
.previous
/* edi: workmask, edx: work */
retint_careful:
CFI_RESTORE_STATE
bt $TIF_NEED_RESCHED,%edx
jnc retint_signal
TRACE_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
pushq %rdi
CFI_ADJUST_CFA_OFFSET 8
call schedule
popq %rdi
CFI_ADJUST_CFA_OFFSET -8
GET_THREAD_INFO(%rcx)
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
jmp retint_check
retint_signal:
testl $_TIF_DO_NOTIFY_MASK,%edx
jz retint_swapgs
TRACE_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
SAVE_REST
movq $-1,ORIG_RAX(%rsp)
xorl %esi,%esi # oldset
movq %rsp,%rdi # &pt_regs
call do_notify_resume
RESTORE_REST
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
GET_THREAD_INFO(%rcx)
jmp retint_with_reschedule
#ifdef CONFIG_PREEMPT
/* Returning to kernel space. Check if we need preemption */
/* rcx: threadinfo. interrupts off. */
ENTRY(retint_kernel)
cmpl $0,TI_preempt_count(%rcx)
jnz retint_restore_args
bt $TIF_NEED_RESCHED,TI_flags(%rcx)
jnc retint_restore_args
bt $9,EFLAGS-ARGOFFSET(%rsp) /* interrupts off? */
jnc retint_restore_args
call preempt_schedule_irq
jmp exit_intr
#endif
CFI_ENDPROC
END(common_interrupt)
/*
* APIC interrupts.
*/
.macro apicinterrupt num,func
INTR_FRAME
pushq $~(\num)
CFI_ADJUST_CFA_OFFSET 8
interrupt \func
jmp ret_from_intr
CFI_ENDPROC
.endm
ENTRY(thermal_interrupt)
apicinterrupt THERMAL_APIC_VECTOR,smp_thermal_interrupt
END(thermal_interrupt)
ENTRY(threshold_interrupt)
apicinterrupt THRESHOLD_APIC_VECTOR,mce_threshold_interrupt
END(threshold_interrupt)
#ifdef CONFIG_SMP
ENTRY(reschedule_interrupt)
apicinterrupt RESCHEDULE_VECTOR,smp_reschedule_interrupt
END(reschedule_interrupt)
.macro INVALIDATE_ENTRY num
ENTRY(invalidate_interrupt\num)
apicinterrupt INVALIDATE_TLB_VECTOR_START+\num,smp_invalidate_interrupt
END(invalidate_interrupt\num)
.endm
INVALIDATE_ENTRY 0
INVALIDATE_ENTRY 1
INVALIDATE_ENTRY 2
INVALIDATE_ENTRY 3
INVALIDATE_ENTRY 4
INVALIDATE_ENTRY 5
INVALIDATE_ENTRY 6
INVALIDATE_ENTRY 7
ENTRY(call_function_interrupt)
apicinterrupt CALL_FUNCTION_VECTOR,smp_call_function_interrupt
END(call_function_interrupt)
ENTRY(call_function_single_interrupt)
apicinterrupt CALL_FUNCTION_SINGLE_VECTOR,smp_call_function_single_interrupt
END(call_function_single_interrupt)
ENTRY(irq_move_cleanup_interrupt)
apicinterrupt IRQ_MOVE_CLEANUP_VECTOR,smp_irq_move_cleanup_interrupt
END(irq_move_cleanup_interrupt)
#endif
ENTRY(apic_timer_interrupt)
apicinterrupt LOCAL_TIMER_VECTOR,smp_apic_timer_interrupt
END(apic_timer_interrupt)
ENTRY(uv_bau_message_intr1)
apicinterrupt 220,uv_bau_message_interrupt
END(uv_bau_message_intr1)
ENTRY(error_interrupt)
apicinterrupt ERROR_APIC_VECTOR,smp_error_interrupt
END(error_interrupt)
ENTRY(spurious_interrupt)
apicinterrupt SPURIOUS_APIC_VECTOR,smp_spurious_interrupt
END(spurious_interrupt)
/*
* Exception entry points.
*/
.macro zeroentry sym
INTR_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
pushq $0 /* push error code/oldrax */
CFI_ADJUST_CFA_OFFSET 8
pushq %rax /* push real oldrax to the rdi slot */
CFI_ADJUST_CFA_OFFSET 8
CFI_REL_OFFSET rax,0
leaq \sym(%rip),%rax
jmp error_entry
CFI_ENDPROC
.endm
.macro errorentry sym
XCPT_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
pushq %rax
CFI_ADJUST_CFA_OFFSET 8
CFI_REL_OFFSET rax,0
leaq \sym(%rip),%rax
jmp error_entry
CFI_ENDPROC
.endm
/* error code is on the stack already */
/* handle NMI like exceptions that can happen everywhere */
.macro paranoidentry sym, ist=0, irqtrace=1
SAVE_ALL
cld
movl $1,%ebx
movl $MSR_GS_BASE,%ecx
rdmsr
testl %edx,%edx
js 1f
SWAPGS
xorl %ebx,%ebx
1:
.if \ist
movq %gs:pda_data_offset, %rbp
.endif
.if \irqtrace
TRACE_IRQS_OFF
.endif
movq %rsp,%rdi
movq ORIG_RAX(%rsp),%rsi
movq $-1,ORIG_RAX(%rsp)
.if \ist
subq $EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp)
.endif
call \sym
.if \ist
addq $EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp)
.endif
DISABLE_INTERRUPTS(CLBR_NONE)
.if \irqtrace
TRACE_IRQS_OFF
.endif
.endm
/*
* "Paranoid" exit path from exception stack.
* Paranoid because this is used by NMIs and cannot take
* any kernel state for granted.
* We don't do kernel preemption checks here, because only
* NMI should be common and it does not enable IRQs and
* cannot get reschedule ticks.
*
* "trace" is 0 for the NMI handler only, because irq-tracing
* is fundamentally NMI-unsafe. (we cannot change the soft and
* hard flags at once, atomically)
*/
.macro paranoidexit trace=1
/* ebx: no swapgs flag */
paranoid_exit\trace:
testl %ebx,%ebx /* swapgs needed? */
jnz paranoid_restore\trace
testl $3,CS(%rsp)
jnz paranoid_userspace\trace
paranoid_swapgs\trace:
.if \trace
TRACE_IRQS_IRETQ 0
.endif
SWAPGS_UNSAFE_STACK
paranoid_restore\trace:
RESTORE_ALL 8
jmp irq_return
paranoid_userspace\trace:
GET_THREAD_INFO(%rcx)
movl TI_flags(%rcx),%ebx
andl $_TIF_WORK_MASK,%ebx
jz paranoid_swapgs\trace
movq %rsp,%rdi /* &pt_regs */
call sync_regs
movq %rax,%rsp /* switch stack for scheduling */
testl $_TIF_NEED_RESCHED,%ebx
jnz paranoid_schedule\trace
movl %ebx,%edx /* arg3: thread flags */
.if \trace
TRACE_IRQS_ON
.endif
ENABLE_INTERRUPTS(CLBR_NONE)
xorl %esi,%esi /* arg2: oldset */
movq %rsp,%rdi /* arg1: &pt_regs */
call do_notify_resume
DISABLE_INTERRUPTS(CLBR_NONE)
.if \trace
TRACE_IRQS_OFF
.endif
jmp paranoid_userspace\trace
paranoid_schedule\trace:
.if \trace
TRACE_IRQS_ON
.endif
ENABLE_INTERRUPTS(CLBR_ANY)
call schedule
DISABLE_INTERRUPTS(CLBR_ANY)
.if \trace
TRACE_IRQS_OFF
.endif
jmp paranoid_userspace\trace
CFI_ENDPROC
.endm
/*
* Exception entry point. This expects an error code/orig_rax on the stack
* and the exception handler in %rax.
*/
KPROBE_ENTRY(error_entry)
_frame RDI
CFI_REL_OFFSET rax,0
/* rdi slot contains rax, oldrax contains error code */
cld
subq $14*8,%rsp
CFI_ADJUST_CFA_OFFSET (14*8)
movq %rsi,13*8(%rsp)
CFI_REL_OFFSET rsi,RSI
movq 14*8(%rsp),%rsi /* load rax from rdi slot */
CFI_REGISTER rax,rsi
movq %rdx,12*8(%rsp)
CFI_REL_OFFSET rdx,RDX
movq %rcx,11*8(%rsp)
CFI_REL_OFFSET rcx,RCX
movq %rsi,10*8(%rsp) /* store rax */
CFI_REL_OFFSET rax,RAX
movq %r8, 9*8(%rsp)
CFI_REL_OFFSET r8,R8
movq %r9, 8*8(%rsp)
CFI_REL_OFFSET r9,R9
movq %r10,7*8(%rsp)
CFI_REL_OFFSET r10,R10
movq %r11,6*8(%rsp)
CFI_REL_OFFSET r11,R11
movq %rbx,5*8(%rsp)
CFI_REL_OFFSET rbx,RBX
movq %rbp,4*8(%rsp)
CFI_REL_OFFSET rbp,RBP
movq %r12,3*8(%rsp)
CFI_REL_OFFSET r12,R12
movq %r13,2*8(%rsp)
CFI_REL_OFFSET r13,R13
movq %r14,1*8(%rsp)
CFI_REL_OFFSET r14,R14
movq %r15,(%rsp)
CFI_REL_OFFSET r15,R15
xorl %ebx,%ebx
testl $3,CS(%rsp)
je error_kernelspace
error_swapgs:
SWAPGS
error_sti:
TRACE_IRQS_OFF
movq %rdi,RDI(%rsp)
CFI_REL_OFFSET rdi,RDI
movq %rsp,%rdi
movq ORIG_RAX(%rsp),%rsi /* get error code */
movq $-1,ORIG_RAX(%rsp)
call *%rax
/* ebx: no swapgs flag (1: don't need swapgs, 0: need it) */
error_exit:
movl %ebx,%eax
RESTORE_REST
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
GET_THREAD_INFO(%rcx)
testl %eax,%eax
jne retint_kernel
LOCKDEP_SYS_EXIT_IRQ
movl TI_flags(%rcx),%edx
movl $_TIF_WORK_MASK,%edi
andl %edi,%edx
jnz retint_careful
jmp retint_swapgs
CFI_ENDPROC
error_kernelspace:
incl %ebx
/* There are two places in the kernel that can potentially fault with
usergs. Handle them here. The exception handlers after
iret run with kernel gs again, so don't set the user space flag.
B stepping K8s sometimes report an truncated RIP for IRET
exceptions returning to compat mode. Check for these here too. */
leaq irq_return(%rip),%rcx
cmpq %rcx,RIP(%rsp)
je error_swapgs
movl %ecx,%ecx /* zero extend */
cmpq %rcx,RIP(%rsp)
je error_swapgs
cmpq $gs_change,RIP(%rsp)
je error_swapgs
jmp error_sti
KPROBE_END(error_entry)
/* Reload gs selector with exception handling */
/* edi: new selector */
ENTRY(native_load_gs_index)
CFI_STARTPROC
pushf
CFI_ADJUST_CFA_OFFSET 8
DISABLE_INTERRUPTS(CLBR_ANY | ~(CLBR_RDI))
SWAPGS
gs_change:
movl %edi,%gs
2: mfence /* workaround */
SWAPGS
popf
CFI_ADJUST_CFA_OFFSET -8
ret
CFI_ENDPROC
ENDPROC(native_load_gs_index)
.section __ex_table,"a"
.align 8
.quad gs_change,bad_gs
.previous
.section .fixup,"ax"
/* running with kernelgs */
bad_gs:
SWAPGS /* switch back to user gs */
xorl %eax,%eax
movl %eax,%gs
jmp 2b
.previous
/*
* Create a kernel thread.
*
* C extern interface:
* extern long kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
*
* asm input arguments:
* rdi: fn, rsi: arg, rdx: flags
*/
ENTRY(kernel_thread)
CFI_STARTPROC
FAKE_STACK_FRAME $child_rip
SAVE_ALL
# rdi: flags, rsi: usp, rdx: will be &pt_regs
movq %rdx,%rdi
orq kernel_thread_flags(%rip),%rdi
movq $-1, %rsi
movq %rsp, %rdx
xorl %r8d,%r8d
xorl %r9d,%r9d
# clone now
call do_fork
movq %rax,RAX(%rsp)
xorl %edi,%edi
/*
* It isn't worth to check for reschedule here,
* so internally to the x86_64 port you can rely on kernel_thread()
* not to reschedule the child before returning, this avoids the need
* of hacks for example to fork off the per-CPU idle tasks.
* [Hopefully no generic code relies on the reschedule -AK]
*/
RESTORE_ALL
UNFAKE_STACK_FRAME
ret
CFI_ENDPROC
ENDPROC(kernel_thread)
child_rip:
pushq $0 # fake return address
CFI_STARTPROC
/*
* Here we are in the child and the registers are set as they were
* at kernel_thread() invocation in the parent.
*/
movq %rdi, %rax
movq %rsi, %rdi
call *%rax
# exit
mov %eax, %edi
call do_exit
CFI_ENDPROC
ENDPROC(child_rip)
/*
* execve(). This function needs to use IRET, not SYSRET, to set up all state properly.
*
* C extern interface:
* extern long execve(char *name, char **argv, char **envp)
*
* asm input arguments:
* rdi: name, rsi: argv, rdx: envp
*
* We want to fallback into:
* extern long sys_execve(char *name, char **argv,char **envp, struct pt_regs *regs)
*
* do_sys_execve asm fallback arguments:
* rdi: name, rsi: argv, rdx: envp, rcx: fake frame on the stack
*/
ENTRY(kernel_execve)
CFI_STARTPROC
FAKE_STACK_FRAME $0
SAVE_ALL
movq %rsp,%rcx
call sys_execve
movq %rax, RAX(%rsp)
RESTORE_REST
testq %rax,%rax
je int_ret_from_sys_call
RESTORE_ARGS
UNFAKE_STACK_FRAME
ret
CFI_ENDPROC
ENDPROC(kernel_execve)
KPROBE_ENTRY(page_fault)
errorentry do_page_fault
KPROBE_END(page_fault)
ENTRY(coprocessor_error)
zeroentry do_coprocessor_error
END(coprocessor_error)
ENTRY(simd_coprocessor_error)
zeroentry do_simd_coprocessor_error
END(simd_coprocessor_error)
ENTRY(device_not_available)
zeroentry do_device_not_available
END(device_not_available)
/* runs on exception stack */
KPROBE_ENTRY(debug)
INTR_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
pushq $0
CFI_ADJUST_CFA_OFFSET 8
paranoidentry do_debug, DEBUG_STACK
paranoidexit
KPROBE_END(debug)
/* runs on exception stack */
KPROBE_ENTRY(nmi)
INTR_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
pushq $-1
CFI_ADJUST_CFA_OFFSET 8
paranoidentry do_nmi, 0, 0
#ifdef CONFIG_TRACE_IRQFLAGS
paranoidexit 0
#else
jmp paranoid_exit1
CFI_ENDPROC
#endif
KPROBE_END(nmi)
KPROBE_ENTRY(int3)
INTR_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
pushq $0
CFI_ADJUST_CFA_OFFSET 8
paranoidentry do_int3, DEBUG_STACK
jmp paranoid_exit1
CFI_ENDPROC
KPROBE_END(int3)
ENTRY(overflow)
zeroentry do_overflow
END(overflow)
ENTRY(bounds)
zeroentry do_bounds
END(bounds)
ENTRY(invalid_op)
zeroentry do_invalid_op
END(invalid_op)
ENTRY(coprocessor_segment_overrun)
zeroentry do_coprocessor_segment_overrun
END(coprocessor_segment_overrun)
/* runs on exception stack */
ENTRY(double_fault)
XCPT_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
paranoidentry do_double_fault
jmp paranoid_exit1
CFI_ENDPROC
END(double_fault)
ENTRY(invalid_TSS)
errorentry do_invalid_TSS
END(invalid_TSS)
ENTRY(segment_not_present)
errorentry do_segment_not_present
END(segment_not_present)
/* runs on exception stack */
ENTRY(stack_segment)
XCPT_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
paranoidentry do_stack_segment
jmp paranoid_exit1
CFI_ENDPROC
END(stack_segment)
KPROBE_ENTRY(general_protection)
errorentry do_general_protection
KPROBE_END(general_protection)
ENTRY(alignment_check)
errorentry do_alignment_check
END(alignment_check)
ENTRY(divide_error)
zeroentry do_divide_error
END(divide_error)
ENTRY(spurious_interrupt_bug)
zeroentry do_spurious_interrupt_bug
END(spurious_interrupt_bug)
#ifdef CONFIG_X86_MCE
/* runs on exception stack */
ENTRY(machine_check)
INTR_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
pushq $0
CFI_ADJUST_CFA_OFFSET 8
paranoidentry do_machine_check
jmp paranoid_exit1
CFI_ENDPROC
END(machine_check)
#endif
/* Call softirq on interrupt stack. Interrupts are off. */
ENTRY(call_softirq)
CFI_STARTPROC
push %rbp
CFI_ADJUST_CFA_OFFSET 8
CFI_REL_OFFSET rbp,0
mov %rsp,%rbp
CFI_DEF_CFA_REGISTER rbp
incl %gs:pda_irqcount
cmove %gs:pda_irqstackptr,%rsp
push %rbp # backlink for old unwinder
call __do_softirq
leaveq
CFI_DEF_CFA_REGISTER rsp
CFI_ADJUST_CFA_OFFSET -8
decl %gs:pda_irqcount
ret
CFI_ENDPROC
ENDPROC(call_softirq)
KPROBE_ENTRY(ignore_sysret)
CFI_STARTPROC
mov $-ENOSYS,%eax
sysret
CFI_ENDPROC
ENDPROC(ignore_sysret)
#ifdef CONFIG_XEN
ENTRY(xen_hypervisor_callback)
zeroentry xen_do_hypervisor_callback
END(xen_hypervisor_callback)
/*
# A note on the "critical region" in our callback handler.
# We want to avoid stacking callback handlers due to events occurring
# during handling of the last event. To do this, we keep events disabled
# until we've done all processing. HOWEVER, we must enable events before
# popping the stack frame (can't be done atomically) and so it would still
# be possible to get enough handler activations to overflow the stack.
# Although unlikely, bugs of that kind are hard to track down, so we'd
# like to avoid the possibility.
# So, on entry to the handler we detect whether we interrupted an
# existing activation in its critical region -- if so, we pop the current
# activation and restart the handler using the previous one.
*/
ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs)
CFI_STARTPROC
/* Since we don't modify %rdi, evtchn_do_upall(struct *pt_regs) will
see the correct pointer to the pt_regs */
movq %rdi, %rsp # we don't return, adjust the stack frame
CFI_ENDPROC
CFI_DEFAULT_STACK
11: incl %gs:pda_irqcount
movq %rsp,%rbp
CFI_DEF_CFA_REGISTER rbp
cmovzq %gs:pda_irqstackptr,%rsp
pushq %rbp # backlink for old unwinder
call xen_evtchn_do_upcall
popq %rsp
CFI_DEF_CFA_REGISTER rsp
decl %gs:pda_irqcount
jmp error_exit
CFI_ENDPROC
END(do_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 do not need to fix up as Xen has already reloaded all segment
# registers that could be reloaded and zeroed the others.
# Category 2 we fix up by killing the current process. 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 comparing each saved segment register
# with its current contents: any discrepancy means we in category 1.
*/
ENTRY(xen_failsafe_callback)
framesz = (RIP-0x30) /* workaround buggy gas */
_frame framesz
CFI_REL_OFFSET rcx, 0
CFI_REL_OFFSET r11, 8
movw %ds,%cx
cmpw %cx,0x10(%rsp)
CFI_REMEMBER_STATE
jne 1f
movw %es,%cx
cmpw %cx,0x18(%rsp)
jne 1f
movw %fs,%cx
cmpw %cx,0x20(%rsp)
jne 1f
movw %gs,%cx
cmpw %cx,0x28(%rsp)
jne 1f
/* All segments match their saved values => Category 2 (Bad IRET). */
movq (%rsp),%rcx
CFI_RESTORE rcx
movq 8(%rsp),%r11
CFI_RESTORE r11
addq $0x30,%rsp
CFI_ADJUST_CFA_OFFSET -0x30
pushq $0
CFI_ADJUST_CFA_OFFSET 8
pushq %r11
CFI_ADJUST_CFA_OFFSET 8
pushq %rcx
CFI_ADJUST_CFA_OFFSET 8
jmp general_protection
CFI_RESTORE_STATE
1: /* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */
movq (%rsp),%rcx
CFI_RESTORE rcx
movq 8(%rsp),%r11
CFI_RESTORE r11
addq $0x30,%rsp
CFI_ADJUST_CFA_OFFSET -0x30
pushq $0
CFI_ADJUST_CFA_OFFSET 8
SAVE_ALL
jmp error_exit
CFI_ENDPROC
END(xen_failsafe_callback)
#endif /* CONFIG_XEN */
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