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/*--------------------------------------------------------------------*/
/*--- Support for doing system calls. syscall-amd64-freebsd.S ---*/
/*--------------------------------------------------------------------*/
/*
This file is part of Valgrind, a dynamic binary instrumentation
framework.
Copyright (C) 2000-2008 Julian Seward
jseward@acm.org
Copyright (C) 2018-2021 Paul Floyd
pjfloyd@wanadoo.fr
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_amd64_freebsd)
#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 guest_state->guest_RAX. The syscall result
is written back to guest_state->guest_RAX on completion.
Returns 0 if the syscall was successfully called (even if the
syscall itself failed), or a -ve error code if one of the
sigprocmasks failed (there's no way to determine which one
failed).
VG_(fixup_guest_state_after_syscall_interrupted) does the
thread state fixup in the case where we were interrupted by a
signal.
Prototype:
Int ML_(do_syscall_for_client_WRK(
Int syscallno, // rdi
void* guest_state, // rsi
const vki_sigset_t *sysmask, // rdx
const vki_sigset_t *postmask, // rcx
Int sigsetSzB) // r8
*/
/* from vki_arch.h */
#define VKI_SIG_SETMASK 3
.globl ML_(do_syscall_for_client_WRK)
ML_(do_syscall_for_client_WRK):
/* save callee-saved regs */
pushq %rbp
movq %rsp, %rbp
pushq %rdi // -8(%rbp) syscallno
pushq %rsi // -16(%rbp) guest_state
pushq %rdx // -24(%rbp) sysmask
pushq %rcx // -32(%rbp) postmask
pushq %r8 // -40(%rbp) sigsetSzB
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. */
/* Save and restore all 5 arg regs round the call. This is easier
than figuring out the minimal set to save/restore. */
movq $__NR_sigprocmask, %rax // syscall #
movq $VKI_SIG_SETMASK, %rdi // how
movq %rdx, %rsi // sysmask
movq %rcx, %rdx // postmask
syscall
jb 7f /* sigprocmask failed */
/* OK, that worked. Now do the syscall proper. */
/* 6 register parameters */
movq -16(%rbp), %r11 /* r11 = VexGuestAMD64State * */
movq OFFSET_amd64_RDI(%r11), %rdi
movq OFFSET_amd64_RSI(%r11), %rsi
movq OFFSET_amd64_RDX(%r11), %rdx
movq OFFSET_amd64_R10(%r11), %r10
movq OFFSET_amd64_R8(%r11), %r8
movq OFFSET_amd64_R9(%r11), %r9
/* 2 stack parameters plus return address (ignored by syscall) */
/* @todo PJF there is a potential bug here
* syscall can take up to 8 arguments
* but when syscall0 or syscall198 is being used
* one argument is used for the syscall0/198 id
* and one for the actual id and in this case
* there could be 3 stack parameters.
* However, only mmap takes 8 arguments
* and only on x86. It would be an unlikely combination,
* but this might break one day. */
movq OFFSET_amd64_RSP(%r11), %r11 /* r11 = simulated RSP */
movq 16(%r11), %rax
pushq %rax
movq 8(%r11), %rax
pushq %rax
/* (fake) return address. */
movq 0(%r11), %rax
pushq %rax
/* syscallno */
movq -8(%rbp), %rax
/* If rip==2, then the syscall was either just about
to start, or was interrupted and the kernel was
restarting it. */
2: syscall
3: /* In the range [3, 4), the syscall result is in %rax,
but hasn't been committed to RAX. */
/* stack contents: 3 words for syscall above, plus our prologue */
setc 0(%rsp) /* stash returned carry flag */
movq -16(%rbp), %r11 /* r11 = VexGuestAMD64State * */
movq %rax, OFFSET_amd64_RAX(%r11) /* save back to RAX */
movq %rdx, OFFSET_amd64_RDX(%r11) /* save back to RDX */
/* save carry flag to VEX */
xorq %rax, %rax
movb 0(%rsp), %al
movq %rax, %rdi /* arg1 = new flag */
movq %r11, %rsi /* arg2 = vex state */
addq $24, %rsp /* remove syscall parameters */
movl $1, OFFSET_amd64_SETC(%r11)
call LibVEX_GuestAMD64_put_rflag_c
movq -16(%rbp), %r11 /* r11 = VexGuestAMD64State * */
movl $0, OFFSET_amd64_SETC(%r11)
4: /* Re-block signals. If eip is in [4,5), then the syscall
is complete and we needn't worry about it. */
movq $__NR_sigprocmask, %rax // syscall #
movq $VKI_SIG_SETMASK, %rdi // how
movq -32(%rbp), %rsi // postmask
xorq %rdx, %rdx // NULL
syscall
jb 7f /* sigprocmask failed */
5: /* now safe from signals */
xorq %rax,%rax
movq -8(%rbp), %rdi
movq -16(%rbp), %rsi
movq -24(%rbp), %rdx
movq -32(%rbp), %rcx
movq -40(%rbp), %r8
movq %rbp, %rsp
popq %rbp
ret
7: /* failure: return 0x8000 | error code */
orq $0x8000, %rax
movq -8(%rbp), %rdi
movq -16(%rbp), %rsi
movq -24(%rbp), %rdx
movq -32(%rbp), %rcx
movq -40(%rbp), %r8
movq %rbp, %rsp
popq %rbp
ret
.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): .quad 1b
ML_(blksys_restart): .quad 2b
ML_(blksys_complete): .quad 3b
ML_(blksys_committed): .quad 4b
ML_(blksys_finished): .quad 5b
.previous
#endif /* defined(VGP_amd64_freebsd) */
/* Let the linker know we don't need an executable stack */
MARK_STACK_NO_EXEC
/*--------------------------------------------------------------------*/
/*--- end ---*/
/*--------------------------------------------------------------------*/
|
