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Merge "Clarify which architectures do/don't need sa_restorer." into main am: 3a4a0c73bb

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Original change: https://android-review.googlesource.com/c/platform/bionic/+/2925677

Change-Id: I9d34c5192e489fa24cdc58fbe258916d81d8564f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
This commit is contained in:
Elliott Hughes 2024-01-26 00:16:51 +00:00 committed by Automerger Merge Worker
commit dc7d5ab6a9
3 changed files with 12 additions and 105 deletions
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1
libc/Android.bp
View file

@ -954,7 +954,6 @@ cc_library_static {
"arch-x86/bionic/__bionic_clone.S",
"arch-x86/bionic/_exit_with_stack_teardown.S",
"arch-x86/bionic/libcrt_compat.c",
"arch-x86/bionic/__restore.S",
"arch-x86/bionic/setjmp.S",
"arch-x86/bionic/syscall.S",
"arch-x86/bionic/vfork.S",

91
libc/arch-x86/bionic/__restore.S
View file

@ -1,91 +0,0 @@
/*
* Copyright (C) 2014 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <private/bionic_asm.h>
#include <private/bionic_asm_dwarf_exprs.h>
// Offsets into struct sigcontext.
#define OFFSET_EDI 16
#define OFFSET_ESI 20
#define OFFSET_EBP 24
#define OFFSET_ESP 28
#define OFFSET_EBX 32
#define OFFSET_EDX 36
#define OFFSET_ECX 40
#define OFFSET_EAX 44
#define OFFSET_EIP 56
// Non-standard DWARF constants for the x86 registers.
#define DW_x86_REG_EAX 0
#define DW_x86_REG_ECX 1
#define DW_x86_REG_EDX 2
#define DW_x86_REG_EBX 3
#define DW_x86_REG_ESP 4
#define DW_x86_REG_EBP 5
#define DW_x86_REG_ESI 6
#define DW_x86_REG_EDI 7
#define DW_x86_REG_EIP 8
#define RESTORE_GPR(reg, extra_offset) \
m_cfi_breg_offset DW_x86_REG_ ## reg, \
DW_x86_REG_ESP, \
(OFFSET_ ## reg + (extra_offset));
// Restoring ESP is unnecessary as the unwinder simply uses the CFA value.
#define RESTORE_GPRS(extra_offset) \
m_cfi_def_cfa_deref DW_x86_REG_ESP, (OFFSET_ESP + (extra_offset)); \
RESTORE_GPR(EDI, extra_offset) \
RESTORE_GPR(ESI, extra_offset) \
RESTORE_GPR(EBP, extra_offset) \
RESTORE_GPR(EBX, extra_offset) \
RESTORE_GPR(EDX, extra_offset) \
RESTORE_GPR(ECX, extra_offset) \
RESTORE_GPR(EAX, extra_offset) \
RESTORE_GPR(EIP, extra_offset) \
.text
.cfi_startproc
.cfi_signal_frame
RESTORE_GPRS(4)
nop // See comment in libc/arch-x86_64/bionic/__restore_rt.S about this nop.
ENTRY_NO_DWARF_PRIVATE(__restore)
popl %eax
RESTORE_GPRS(0)
movl $__NR_sigreturn, %eax
int $0x80
END(__restore) // Not END_NO_DWARF because we _manually_ set up CFI.
.cfi_startproc
.cfi_signal_frame
RESTORE_GPRS(160)
nop // See comment in libc/arch-x86_64/bionic/__restore_rt.S about this nop.
ENTRY_NO_DWARF_PRIVATE(__restore_rt)
movl $__NR_rt_sigreturn, %eax
int $0x80
END(__restore_rt) // Not END_NO_DWARF because we _manually_ set up CFI.

25
libc/bionic/sigaction.cpp
View file

@ -39,25 +39,24 @@ extern "C" void __restore(void);
extern "C" int __rt_sigaction(int, const struct __kernel_sigaction*, struct __kernel_sigaction*, size_t);
int sigaction(int signal, const struct sigaction* bionic_new_action, struct sigaction* bionic_old_action) {
__kernel_sigaction kernel_new_action;
__kernel_sigaction kernel_new_action = {};
if (bionic_new_action != nullptr) {
kernel_new_action.sa_flags = bionic_new_action->sa_flags;
kernel_new_action.sa_handler = bionic_new_action->sa_handler;
// Don't filter signals here; if the caller asked for everything to be blocked, we should obey.
kernel_new_action.sa_mask = bionic_new_action->sa_mask;
#if defined(SA_RESTORER)
#if defined(__x86_64__)
// riscv64 doesn't have sa_restorer. For arm64 and 32-bit x86, unwinding
// works best if you just let the kernel supply the default restorer
// from [vdso]. gdb doesn't care, but libgcc needs the nop that the
// kernel includes before the actual code. (We could add that ourselves,
// but why bother?)
// TODO: why do arm32 and x86-64 need this to unwind through signal handlers?
kernel_new_action.sa_restorer = bionic_new_action->sa_restorer;
#if defined(__aarch64__)
// arm64 has sa_restorer, but unwinding works best if you just let the
// kernel supply the default restorer from [vdso]. gdb doesn't care, but
// libgcc needs the nop that the kernel includes before the actual code.
// (We could add that ourselves, but why bother?)
#else
if (!(kernel_new_action.sa_flags & SA_RESTORER)) {
kernel_new_action.sa_flags |= SA_RESTORER;
kernel_new_action.sa_restorer = &__restore_rt;
}
#endif
#endif
}
@ -90,10 +89,11 @@ extern "C" int __rt_sigaction(int, const struct sigaction64*, struct sigaction64
// by extracting the implementation of sigaction64 to a static function.
static int __sigaction64(int signal, const struct sigaction64* bionic_new,
struct sigaction64* bionic_old) {
struct sigaction64 kernel_new;
struct sigaction64 kernel_new = {};
if (bionic_new) {
kernel_new = *bionic_new;
#if defined(SA_RESTORER)
#if defined(__arm__)
// (See sa_restorer comment in sigaction() above.)
if (!(kernel_new.sa_flags & SA_RESTORER)) {
kernel_new.sa_flags |= SA_RESTORER;
kernel_new.sa_restorer = (kernel_new.sa_flags & SA_SIGINFO) ? &__restore_rt : &__restore;
@ -110,9 +110,8 @@ static int __sigaction64(int signal, const struct sigaction64* bionic_new,
int sigaction(int signal, const struct sigaction* bionic_new, struct sigaction* bionic_old) {
// The 32-bit ABI is broken. struct sigaction includes a too-small sigset_t,
// so we have to translate to struct sigaction64 first.
struct sigaction64 kernel_new;
struct sigaction64 kernel_new = {};
if (bionic_new) {
kernel_new = {};
kernel_new.sa_flags = bionic_new->sa_flags;
kernel_new.sa_handler = bionic_new->sa_handler;
#if defined(SA_RESTORER)