From: Jinoh Kang jinoh.kang.kr@gmail.com
A few months after commit 1b1ea639cd6 (ntdll: Use a custom signal restorer for Android., 2014-07-17) has been introduced, bionic rolled its own signal restorer. The patch is at:
https://android-review.googlesource.com/c/platform/bionic/+/107692
In general, rolling our own signal restorer is not a good idea since it interferes with unwinding. GDB seems especially unhappy when the signal restorer's name isn't exactly "__restore_rt".
Fix this by using the custom signal restorer only if the vDSO has disappeared and libc doesn't supply its own signal restorer. This also removes Android-specific code, although there aren't many libcs out there that lack a backup signal restorer.
Signed-off-by: Jinoh Kang jinoh.kang.kr@gmail.com --- dlls/ntdll/unix/signal_i386.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-)
diff --git a/dlls/ntdll/unix/signal_i386.c b/dlls/ntdll/unix/signal_i386.c index e2a6148d609..7a66a7e7c47 100644 --- a/dlls/ntdll/unix/signal_i386.c +++ b/dlls/ntdll/unix/signal_i386.c @@ -50,6 +50,9 @@ #ifdef HAVE_SYS_UCONTEXT_H # include <sys/ucontext.h> #endif +#ifdef HAVE_SYS_AUXV_H +# include <sys/auxv.h> +#endif
#include "ntstatus.h" #define WIN32_NO_STATUS @@ -150,9 +153,9 @@ typedef struct ucontext #define FPUX_sig(context) (FPU_sig(context) && !((context)->uc_mcontext.fpregs->status >> 16) ? (XSAVE_FORMAT *)(FPU_sig(context) + 1) : NULL) #define XState_sig(fpu) (((unsigned int *)fpu->Reserved4)[12] == FP_XSTATE_MAGIC1 ? (XSTATE *)(fpu + 1) : NULL)
-#ifdef __ANDROID__ -/* custom signal restorer since we may have unmapped the one in vdso, and bionic doesn't check for that */ -void rt_sigreturn(void); +#if defined(__linux__) && defined(SA_RESTORER) +/* backup signal restorer if we have unmapped the one in vDSO, and libc doesn't supply its own restorer */ +extern void rt_sigreturn(void) DECLSPEC_HIDDEN; __ASM_GLOBAL_FUNC( rt_sigreturn, "movl $173,%eax\n\t" /* NR_rt_sigreturn */ "int $0x80" ); @@ -2344,9 +2347,18 @@ void signal_init_process(void)
sig_act.sa_mask = server_block_set; sig_act.sa_flags = SA_SIGINFO | SA_RESTART | SA_ONSTACK; -#ifdef __ANDROID__ - sig_act.sa_flags |= SA_RESTORER; - sig_act.sa_restorer = rt_sigreturn; +#if defined(__linux__) && defined(SA_RESTORER) + if (!getauxval(AT_SYSINFO_EHDR)) { + struct sigaction real_sig_act; + + sig_act.sa_sigaction = int_handler; + if (sigaction( SIGINT, &sig_act, NULL ) == -1) goto error; + if (sigaction( SIGINT, NULL, &real_sig_act ) == -1) goto error; + if (!(real_sig_act.sa_flags & SA_RESTORER)) { + sig_act.sa_flags |= SA_RESTORER; + sig_act.sa_restorer = rt_sigreturn; + } + } #endif sig_act.sa_sigaction = int_handler; if (sigaction( SIGINT, &sig_act, NULL ) == -1) goto error;