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Set SA_RESTORER in sigaction()

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GDB looks for specific opcode sequences when trying to recognize a stack
frame as a signal trampoline.  The sequences it looks for happen to be those
created when SA_RESTORER is set, since glibc always sets a restorer.  This
patch does the same here, so that the trampolines can be correctly identified.

Change-Id: I0ac574a68818cb24d939c3527f3aaeb04b853d04
This commit is contained in:
Matt Fischer 2010-01-11 10:02:06 +08:00 committed by Garmin Android technology group
parent c3581dc78a
commit e4fa46e75c
8 changed files with 50 additions and 6 deletions
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2
libc/Android.mk
View file

@ -295,6 +295,8 @@ libc_common_src_files += \
arch-arm/bionic/sigsetjmp.S \
arch-arm/bionic/strlen.c.arm \
arch-arm/bionic/syscall.S \
arch-arm/bionic/sigaction.c \
arch-arm/bionic/__sig_restorer.S \
string/memmove.c.arm \
string/bcopy.c \
string/strcmp.c \

5
libc/SYSCALLS.TXT
View file

@ -167,7 +167,7 @@ int __timer_delete:timer_delete(timer_t)
int utimes(const char*, const struct timeval tvp[2]) 269, 271
# signals
int sigaction(int, const struct sigaction *, struct sigaction *) 67
int sigaction(int, const struct sigaction *, struct sigaction *) -1,67,67
int sigprocmask(int, const sigset_t *, sigset_t *) 126
int __sigsuspend:sigsuspend(int unused1, int unused2, unsigned mask) 72
int __rt_sigaction:rt_sigaction (int sig, const struct sigaction *act, struct sigaction *oact, size_t sigsetsize) 174
@ -175,6 +175,9 @@ int __rt_sigprocmask:rt_sigprocmask (int how, const sigset_t *set, sigset_t
int __rt_sigtimedwait:rt_sigtimedwait(const sigset_t *set, struct siginfo_t *info, struct timespec_t *timeout, size_t sigset_size) 177
int sigpending(sigset_t *) 73
# special stub for ARM, see arch-arm/bionic/sigaction.c
int __sigaction:sigaction(int, const struct sigaction *, struct sigaction *) 67,-1,-1
# sockets
int socket(int, int, int) 281,-1
int socketpair(int, int, int, int*) 288,-1

7
libc/arch-arm/bionic/__sig_restorer.S Normal file
View file

@ -0,0 +1,7 @@
.global __sig_restorer
/* This is the opcode sequence GDB looks for in order to recognize
this stack frame as a signal trampoline (see sigaction.c) */
__sig_restorer:
mov r7, #119 /* __NR_sigreturn */
swi #0

29
libc/arch-arm/bionic/sigaction.c Normal file
View file

@ -0,0 +1,29 @@
#include <signal.h>
extern int __sigaction(int signum, const struct sigaction *act, struct sigaction *oldact);
extern void __sig_restorer();
int sigaction(int signum, const struct sigaction *act, struct sigaction *oldact)
{
struct sigaction real_act;
/* If the caller has not set a custom restorer, then set up a default one.
* The code will function properly without this, however GDB will not be
* able to recognize the stack frame as a signal trampoline, because it
* is hardcoded to look for the instruction sequence that glibc uses in
* its custom restorer. By creating our own restorer with the same
* sequence, we ensure that GDB correctly identifies this as a signal
* trampoline frame.
*
* See http://sourceware.org/ml/gdb/2010-01/msg00143.html for more
* information on this.*/
if(act && !(act->sa_flags & SA_RESTORER)) {
real_act = *act;
real_act.sa_flags |= SA_RESTORER;
real_act.sa_restorer = __sig_restorer;
act = &real_act;
}
return __sigaction(signum, act, oldact);
}

2
libc/arch-arm/syscalls.mk
View file

@ -120,13 +120,13 @@ syscall_src += arch-arm/syscalls/__timer_gettime.S
syscall_src += arch-arm/syscalls/__timer_getoverrun.S
syscall_src += arch-arm/syscalls/__timer_delete.S
syscall_src += arch-arm/syscalls/utimes.S
syscall_src += arch-arm/syscalls/sigaction.S
syscall_src += arch-arm/syscalls/sigprocmask.S
syscall_src += arch-arm/syscalls/__sigsuspend.S
syscall_src += arch-arm/syscalls/__rt_sigaction.S
syscall_src += arch-arm/syscalls/__rt_sigprocmask.S
syscall_src += arch-arm/syscalls/__rt_sigtimedwait.S
syscall_src += arch-arm/syscalls/sigpending.S
syscall_src += arch-arm/syscalls/__sigaction.S
syscall_src += arch-arm/syscalls/socket.S
syscall_src += arch-arm/syscalls/socketpair.S
syscall_src += arch-arm/syscalls/bind.S

6
libc/arch-arm/syscalls/sigaction.S → libc/arch-arm/syscalls/__sigaction.S
View file

@ -2,12 +2,12 @@
#include <sys/linux-syscalls.h>
.text
.type sigaction, #function
.globl sigaction
.type __sigaction, #function
.globl __sigaction
.align 4
.fnstart
sigaction:
__sigaction:
.save {r4, r7}
stmfd sp!, {r4, r7}
ldr r7, =__NR_sigaction

4
libc/include/sys/linux-syscalls.h
View file

@ -103,7 +103,6 @@
#define __NR_nanosleep (__NR_SYSCALL_BASE + 162)
#define __NR_getitimer (__NR_SYSCALL_BASE + 105)
#define __NR_setitimer (__NR_SYSCALL_BASE + 104)
#define __NR_sigaction (__NR_SYSCALL_BASE + 67)
#define __NR_sigprocmask (__NR_SYSCALL_BASE + 126)
#define __NR_sigsuspend (__NR_SYSCALL_BASE + 72)
#define __NR_rt_sigaction (__NR_SYSCALL_BASE + 174)
@ -155,6 +154,7 @@
#define __NR_timer_getoverrun (__NR_SYSCALL_BASE + 260)
#define __NR_timer_delete (__NR_SYSCALL_BASE + 261)
#define __NR_utimes (__NR_SYSCALL_BASE + 269)
#define __NR_sigaction (__NR_SYSCALL_BASE + 67)
#define __NR_socket (__NR_SYSCALL_BASE + 281)
#define __NR_socketpair (__NR_SYSCALL_BASE + 288)
#define __NR_bind (__NR_SYSCALL_BASE + 282)
@ -209,6 +209,7 @@
#define __NR_timer_getoverrun (__NR_SYSCALL_BASE + 262)
#define __NR_timer_delete (__NR_SYSCALL_BASE + 263)
#define __NR_utimes (__NR_SYSCALL_BASE + 271)
#define __NR_sigaction (__NR_SYSCALL_BASE + 67)
#define __NR_socketcall (__NR_SYSCALL_BASE + 102)
#define __NR_epoll_create (__NR_SYSCALL_BASE + 254)
#define __NR_epoll_ctl (__NR_SYSCALL_BASE + 255)
@ -248,6 +249,7 @@
#define __NR_timer_getoverrun (__NR_SYSCALL_BASE + 262)
#define __NR_timer_delete (__NR_SYSCALL_BASE + 263)
#define __NR_utimes (__NR_SYSCALL_BASE + 271)
#define __NR_sigaction (__NR_SYSCALL_BASE + 67)
#define __NR_socketcall (__NR_SYSCALL_BASE + 102)
#define __NR_socketcall (__NR_SYSCALL_BASE + 102)
#define __NR_socketcall (__NR_SYSCALL_BASE + 102)

1
libc/include/sys/linux-unistd.h
View file

@ -141,6 +141,7 @@ int __rt_sigaction (int sig, const struct sigaction *act, struct si
int __rt_sigprocmask (int how, const sigset_t *set, sigset_t *oset, size_t sigsetsize);
int __rt_sigtimedwait (const sigset_t *set, struct siginfo_t *info, struct timespec_t *timeout, size_t sigset_size);
int sigpending (sigset_t *);
int __sigaction (int, const struct sigaction *, struct sigaction *);
int socket (int, int, int);
int socketpair (int, int, int, int*);
int bind (int, struct sockaddr *, int);