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linux/arch/x86/kernel/entry_64.S
Roland McGrath eca91e7838 x86_64: fix delayed signals 
On three of the several paths in entry_64.S that call
do_notify_resume() on the way back to user mode, we fail to properly
check again for newly-arrived work that requires another call to
do_notify_resume() before going to user mode.  These paths set the
mask to check only _TIF_NEED_RESCHED, but this is wrong.  The other
paths that lead to do_notify_resume() do this correctly already, and
entry_32.S does it correctly in all cases.

All paths back to user mode have to check all the _TIF_WORK_MASK
flags at the last possible stage, with interrupts disabled.
Otherwise, we miss any flags (TIF_SIGPENDING for example) that were
set any time after we entered do_notify_resume().  More work flags
can be set (or left set) synchronously inside do_notify_resume(), as
TIF_SIGPENDING can be, or asynchronously by interrupts or other CPUs
(which then send an asynchronous interrupt).

There are many different scenarios that could hit this bug, most of
them races.  The simplest one to demonstrate does not require any
race: when one signal has done handler setup at the check before
returning from a syscall, and there is another signal pending that
should be handled.  The second signal's handler should interrupt the
first signal handler before it actually starts (so the interrupted PC
is still at the handler's entry point).  Instead, it runs away until
the next kernel entry (next syscall, tick, etc).

This test behaves correctly on 32-bit kernels, and fails on 64-bit
(either 32-bit or 64-bit test binary).  With this fix, it works.

    #define _GNU_SOURCE
    #include <stdio.h>
    #include <signal.h>
    #include <string.h>
    #include <sys/ucontext.h>

    #ifndef REG_RIP
    #define REG_RIP REG_EIP
    #endif

    static sig_atomic_t hit1, hit2;

    static void
    handler (int sig, siginfo_t *info, void *ctx)
    {
      ucontext_t *uc = ctx;

      if ((void *) uc->uc_mcontext.gregs[REG_RIP] == &handler)
        {
          if (sig == SIGUSR1)
            hit1 = 1;
          else
            hit2 = 1;
        }

      printf ("%s at %#lx\n", strsignal (sig),
              uc->uc_mcontext.gregs[REG_RIP]);
    }

    int
    main (void)
    {
      struct sigaction sa;
      sigset_t set;

      sigemptyset (&sa.sa_mask);
      sa.sa_flags = SA_SIGINFO;
      sa.sa_sigaction = &handler;

      if (sigaction (SIGUSR1, &sa, NULL)
          || sigaction (SIGUSR2, &sa, NULL))
        return 2;

      sigemptyset (&set);
      sigaddset (&set, SIGUSR1);
      sigaddset (&set, SIGUSR2);
      if (sigprocmask (SIG_BLOCK, &set, NULL))
        return 3;

      printf ("main at %p, handler at %p\n", &main, &handler);

      raise (SIGUSR1);
      raise (SIGUSR2);

      if (sigprocmask (SIG_UNBLOCK, &set, NULL))
        return 4;

      if (hit1 + hit2 == 1)
        {
          puts ("PASS");
          return 0;
        }

      puts ("FAIL");
      return 1;
    }

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-12 07:11:10 +02:00

1206 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>
.code64
#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 4
popf # reset kernel eflags
CFI_ADJUST_CFA_OFFSET -4
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_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP), \
TI_flags(%rcx)
jnz tracesys
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)
testl $_TIF_DO_NOTIFY_MASK,%edx
jz 1f
/* Really a signal */
/* 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
1: 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
/* Do syscall tracing */
tracesys:
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
LOAD_ARGS ARGOFFSET /* reload args from stack in case ptrace changed it */
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
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_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP),%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_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP),%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
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(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
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:
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 math_state_restore
END(device_not_available)
/* runs on exception stack */
KPROBE_ENTRY(debug)
INTR_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
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
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
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
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
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)
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