ftmemsim-valgrind/coregrind/m_syswrap/syscall-x86-darwin.S
Paul Floyd 6cc2d94d93 Use a different way to tell where the syscall handler was interrupted on FreeBSD and macOS
I was using a global variable. This would be set to '1' just before
calling the function to save cflags and cleared just after, then
using the variable to fill in the 'outside_rnage_ condition
in VG_(fixup_guest_state_after_syscall_interrupted)

Even though I haven't experienced any isseus with that, the comments just before
do_syscall_for_client made me want to try an alternative.

This code is very ugly and won't please the language lawyers.
Functions aren't guaranteed to have an address and there is no
guarantee that the binary layout will reflect the source layout.
Sadly C doesn't have something like "sizeof(*function)" to give
the size of a function in bytes. The next best that I could
manage was to use dummy 'marker' functions just after the
ones I want the end address of and then use the address of
'marker - 1'

I did think of one other way to do this. That would be to
generate a C file containing the function sizes. This would
require

1. "put_flag_size.c" would depend on the VEX guest_(x86|amd64)_helpers
   object files
2. Extract the sizes, for instance

echo -n "const size_t x86_put_eflag_c_size = 0x" > put_flag_size.c
nm -F sysv libvex_x86_freebsd_a-guest_x86_helpers.o | awk -F\| '/LibVEX_GuestX86_put_eflag_c/{print $5}' >> put_flag_size.c
echo ";" >> put_flag_size.c

That seems fairly difficult to do in automake and I'm not sure if
it would be robust.
2022-06-06 15:18:29 +02:00

257 lines
8.1 KiB
ArmAsm

/*--------------------------------------------------------------------*/
/*--- Support for doing system calls. syscall-x86-darwin.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_darwin)
#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 -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, // ebp+8
void* guest_state, // ebp+12
const vki_sigset_t *sysmask, // ebp+16
const vki_sigset_t *postmask, // ebp+20
Int sigsetSzB) // ebp+24
Note that sigsetSzB is totally ignored (and irrelevant).
*/
/* from vki-darwin.h, checked at startup by m_vki.c */
#define VKI_SIG_SETMASK 3
/* DO_SYSCALL MACH|MDEP|UNIX */
#define MACH 1
#define MDEP 2
#define UNIX 3
.macro DO_SYSCALL
/* establish stack frame */
push %ebp
mov %esp, %ebp
subl $$8, %esp /* 16-byte align stack */
L_$0_1: /* Even though we can't take a signal until the
__pthread_sigmask completes, start the range early.
If eip is in the range [1,2), the syscall hasn't been started yet */
/* Set the signal mask which should be current during the syscall. */
/* Set up for __pthread_sigmask(SIG_SETMASK, sysmask, postmask) */
pushl 20(%ebp)
pushl 16(%ebp)
pushl $$VKI_SIG_SETMASK
pushl $$0xcafebabe /* totally fake return address */
movl $$__NR___pthread_sigmask, %eax
int $$0x80 /* should be sysenter? */
jc L_$0_7 /* __pthread_sigmask failed */
addl $$16,%esp
/* Copy syscall parameters to the stack - assume no more than 8
* plus the return address */
/* do_syscall8 */
/* stack is currently aligned assuming 8 parameters */
movl 12(%ebp), %edx
movl OFFSET_x86_ESP(%edx), %edx /* edx = simulated ESP */
movl 28+4(%edx), %eax
pushl %eax
movl 24+4(%edx), %eax
pushl %eax
movl 20+4(%edx), %eax
pushl %eax
movl 16+4(%edx), %eax
pushl %eax
movl 12+4(%edx), %eax
pushl %eax
movl 8+4(%edx), %eax
pushl %eax
movl 4+4(%edx), %eax
pushl %eax
movl 0+4(%edx), %eax
pushl %eax
/* return address */
movl 0(%edx), %eax
pushl %eax
/* Put syscall number in eax */
movl 8(%ebp), %eax
/* If eip==2, then the syscall was either just about to start,
or was interrupted and the kernel was restarting it. */
L_$0_2:
.if $0 == UNIX
int $$0x80 /* UNIX (GrP fixme should be sysenter?) */
.elseif $0 == MACH
int $$0x81
.elseif $0 == MDEP
int $$0x82
.else
error$0 x
.endif
L_$0_3: /* In the range [3, 4), the syscall result is in %eax and %edx and C,
but hasn't been committed to the thread state. */
setc 0(%esp) /* stash returned carry flag */
movl 12(%ebp), %ecx
movl %eax, OFFSET_x86_EAX(%ecx) /* save EAX to vex */
movl %edx, OFFSET_x86_EDX(%ecx) /* save EDX to vex */
.if $0 == UNIX
/* UNIX: save carry flag to vex */
subl $$12, %esp
movl %ecx, 4(%esp)
movl $$0, 0(%esp)
movb 12(%esp), %al
movb %al, 0(%esp)
call _LibVEX_GuestX86_put_eflag_c
addl $$12, %esp
.endif
L_$0_4: /* Re-block signals. If eip is in [4,5), then the syscall is
complete and we needn't worry about it. */
/* Set up for __pthread_sigmask(SIG_SETMASK, postmask, NULL) */
pushl $$0
pushl 20(%ebp)
pushl $$VKI_SIG_SETMASK
pushl $$0xcafef00d /* totally fake return address */
movl $$__NR___pthread_sigmask, %eax
int $$0x80 /* should be sysenter? */
jc L_$0_7 /* __pthread_sigmask failed */
addl $$16,%esp
L_$0_5: /* now safe from signals */
movl $$0, %eax /* SUCCESS */
movl %ebp, %esp
popl %ebp
ret
L_$0_7: /* failure: return 0x8000 | error code */
/* Note that we enter here with %esp being 16 too low
(4 extra words on the stack). But because we're nuking
the stack frame now, that doesn't matter. */
andl $$0x7FFF, %eax
orl $$0x8000, %eax
movl %ebp, %esp
popl %ebp
ret
.endmacro
.globl ML_(do_syscall_for_client_unix_WRK)
ML_(do_syscall_for_client_unix_WRK):
DO_SYSCALL UNIX
.globl ML_(do_syscall_for_client_mach_WRK)
ML_(do_syscall_for_client_mach_WRK):
DO_SYSCALL MACH
.globl ML_(do_syscall_for_client_mdep_WRK)
ML_(do_syscall_for_client_mdep_WRK):
DO_SYSCALL MDEP
.data
/* export the ranges so that
VG_(fixup_guest_state_after_syscall_interrupted) can do the
right thing */
/* eg MK_L_SCLASS_N(UNIX,99) produces L_3_99
since UNIX is #defined to 3 at the top of this file */
#define FOO(scclass,labelno) L_##scclass##_##labelno
#define MK_L_SCCLASS_N(scclass,labelno) FOO(scclass,labelno)
.globl ML_(blksys_setup_MACH)
.globl ML_(blksys_restart_MACH)
.globl ML_(blksys_complete_MACH)
.globl ML_(blksys_committed_MACH)
.globl ML_(blksys_finished_MACH)
ML_(blksys_setup_MACH): .long MK_L_SCCLASS_N(MACH,1)
ML_(blksys_restart_MACH): .long MK_L_SCCLASS_N(MACH,2)
ML_(blksys_complete_MACH): .long MK_L_SCCLASS_N(MACH,3)
ML_(blksys_committed_MACH): .long MK_L_SCCLASS_N(MACH,4)
ML_(blksys_finished_MACH): .long MK_L_SCCLASS_N(MACH,5)
.globl ML_(blksys_setup_MDEP)
.globl ML_(blksys_restart_MDEP)
.globl ML_(blksys_complete_MDEP)
.globl ML_(blksys_committed_MDEP)
.globl ML_(blksys_finished_MDEP)
ML_(blksys_setup_MDEP): .long MK_L_SCCLASS_N(MDEP,1)
ML_(blksys_restart_MDEP): .long MK_L_SCCLASS_N(MDEP,2)
ML_(blksys_complete_MDEP): .long MK_L_SCCLASS_N(MDEP,3)
ML_(blksys_committed_MDEP): .long MK_L_SCCLASS_N(MDEP,4)
ML_(blksys_finished_MDEP): .long MK_L_SCCLASS_N(MDEP,5)
.globl ML_(blksys_setup_UNIX)
.globl ML_(blksys_restart_UNIX)
.globl ML_(blksys_complete_UNIX)
.globl ML_(blksys_committed_UNIX)
.globl ML_(blksys_finished_UNIX)
ML_(blksys_setup_UNIX): .long MK_L_SCCLASS_N(UNIX,1)
ML_(blksys_restart_UNIX): .long MK_L_SCCLASS_N(UNIX,2)
ML_(blksys_complete_UNIX): .long MK_L_SCCLASS_N(UNIX,3)
ML_(blksys_committed_UNIX): .long MK_L_SCCLASS_N(UNIX,4)
ML_(blksys_finished_UNIX): .long MK_L_SCCLASS_N(UNIX,5)
#endif // defined(VGP_x86_darwin)
/* Let the linker know we don't need an executable stack */
MARK_STACK_NO_EXEC
/*--------------------------------------------------------------------*/
/*--- end ---*/
/*--------------------------------------------------------------------*/