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/*--------------------------------------------------------------------*/
/*--- Support for doing system calls. syscall-x86-linux.S ---*/
/*--------------------------------------------------------------------*/
/*
This file is part of Valgrind, a dynamic binary instrumentation
framework.
Copyright (C) 2000-2017 Julian Seward
jseward@acm.org
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, see <http://www.gnu.org/licenses/>.
The GNU General Public License is contained in the file COPYING.
*/
#include "pub_core_basics_asm.h"
#if defined(VGP_x86_linux)
#include "pub_core_vkiscnums_asm.h"
#include "libvex_guest_offsets.h"
/*----------------------------------------------------------------*/
/*
Perform a syscall for the client. This will run a syscall
with the client's specific per-thread signal mask.
The structure of this function is such that, if the syscall is
interrupted by a signal, we can determine exactly what
execution state we were in with respect to the execution of
the syscall by examining the value of %eip in the signal
handler. This means that we can always do the appropriate
thing to precisely emulate the kernel's signal/syscall
interactions.
The syscall number is taken from the argument, even though it
should also be in regs->m_eax. The syscall result is written
back to regs->m_eax on completion.
Returns 0 if the syscall was successfully called (even if the
syscall itself failed), or a nonzero error code in the lowest
8 bits if one of the sigprocmasks failed (there's no way to
determine which one failed). And there's no obvious way to
recover from that either, but nevertheless we want to know.
VG_(fixup_guest_state_after_syscall_interrupted) does the
thread state fixup in the case where we were interrupted by a
signal.
Prototype:
UWord ML_(do_syscall_for_client_WRK)(
Int syscallno, // 0
void* guest_state, // 4
const vki_sigset_t *sysmask, // 8
const vki_sigset_t *postmask, // 12
Int sigsetSzB) // 16
*/
/* from vki_arch.h */
#define VKI_SIG_SETMASK 2
.globl ML_(do_syscall_for_client_WRK)
ML_(do_syscall_for_client_WRK):
.cfi_startproc
/* save callee-saved regs */
push %esi
.cfi_adjust_cfa_offset 4
.cfi_offset %esi, -8
push %edi
.cfi_adjust_cfa_offset 4
.cfi_offset %esi, -12
push %ebx
.cfi_adjust_cfa_offset 4
.cfi_offset %esi, -16
push %ebp
.cfi_adjust_cfa_offset 4
.cfi_offset %esi, -20
#define FSZ ((4+1)*4) /* 4 args + ret addr */
1: /* Even though we can't take a signal until the sigprocmask completes,
start the range early.
If eip is in the range [1,2), the syscall hasn't been started yet */
/* Set the signal mask which should be current during the syscall. */
movl $ __NR_rt_sigprocmask, %eax
movl $ VKI_SIG_SETMASK, %ebx
movl 8+FSZ(%esp), %ecx
movl 12+FSZ(%esp), %edx
movl 16+FSZ(%esp), %esi
int $0x80
testl %eax, %eax
js 7f /* sigprocmask failed */
movl 4+FSZ(%esp), %eax /* eax == ThreadState * */
movl OFFSET_x86_EBX(%eax), %ebx
movl OFFSET_x86_ECX(%eax), %ecx
movl OFFSET_x86_EDX(%eax), %edx
movl OFFSET_x86_ESI(%eax), %esi
movl OFFSET_x86_EDI(%eax), %edi
movl OFFSET_x86_EBP(%eax), %ebp
movl 0+FSZ(%esp), %eax /* use syscallno argument rather than thread EAX */
/* If eip==2, then the syscall was either just about to start,
or was interrupted and the kernel was restarting it. */
2: int $0x80
3: /* In the range [3, 4), the syscall result is in %eax, but hasn't been
committed to EAX. */
movl 4+FSZ(%esp), %ebx
movl %eax, OFFSET_x86_EAX(%ebx) /* save back to EAX */
4: /* Re-block signals. If eip is in [4,5), then the syscall is complete and
we needn't worry about it. */
movl $ __NR_rt_sigprocmask, %eax
movl $ VKI_SIG_SETMASK, %ebx
movl 12+FSZ(%esp), %ecx
xorl %edx, %edx
movl 16+FSZ(%esp), %esi
int $0x80
testl %eax, %eax
js 7f /* sigprocmask failed */
5: /* now safe from signals */
movl $0, %eax /* SUCCESS */
popl %ebp
.cfi_adjust_cfa_offset -4
popl %ebx
.cfi_adjust_cfa_offset -4
popl %edi
.cfi_adjust_cfa_offset -4
popl %esi
.cfi_adjust_cfa_offset -4
ret
.cfi_adjust_cfa_offset 4*4
7: /* failure: return 0x8000 | error code */
negl %eax
andl $0x7FFF, %eax
orl $0x8000, %eax
popl %ebp
.cfi_adjust_cfa_offset -4
popl %ebx
.cfi_adjust_cfa_offset -4
popl %edi
.cfi_adjust_cfa_offset -4
popl %esi
.cfi_adjust_cfa_offset -4
ret
.cfi_endproc
#undef FSZ
.section .rodata
/* export the ranges so that
VG_(fixup_guest_state_after_syscall_interrupted) can do the
right thing */
.globl ML_(blksys_setup)
.globl ML_(blksys_restart)
.globl ML_(blksys_complete)
.globl ML_(blksys_committed)
.globl ML_(blksys_finished)
ML_(blksys_setup): .long 1b
ML_(blksys_restart): .long 2b
ML_(blksys_complete): .long 3b
ML_(blksys_committed): .long 4b
ML_(blksys_finished): .long 5b
.previous
#endif // defined(VGP_x86_linux)
/* Let the linker know we don't need an executable stack */
MARK_STACK_NO_EXEC
/*--------------------------------------------------------------------*/
/*--- end ---*/
/*--------------------------------------------------------------------*/
|
