Create and record the two signal trampolines.
Use them when the guest does not use SA_RESTORER.
Note that x86_64 does not use this code.
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
linux-user/i386/target_signal.h | 2 ++
linux-user/x86_64/target_signal.h | 3 ++
linux-user/i386/signal.c | 56 +++++++++++++++++++++----------
3 files changed, 43 insertions(+), 18 deletions(-)
diff --git a/linux-user/i386/target_signal.h b/linux-user/i386/target_signal.h
index 50361af874..64d09f2e75 100644
--- a/linux-user/i386/target_signal.h
+++ b/linux-user/i386/target_signal.h
@@ -22,4 +22,6 @@ typedef struct target_sigaltstack {
#include "../generic/signal.h"
#define TARGET_ARCH_HAS_SETUP_FRAME
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1
+
#endif /* I386_TARGET_SIGNAL_H */
diff --git a/linux-user/x86_64/target_signal.h
b/linux-user/x86_64/target_signal.h
index 4ea74f20dd..4673c5a886 100644
--- a/linux-user/x86_64/target_signal.h
+++ b/linux-user/x86_64/target_signal.h
@@ -21,4 +21,7 @@ typedef struct target_sigaltstack {
#include "../generic/signal.h"
+/* For x86_64, use of SA_RESTORER is mandatory. */
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 0
+
#endif /* X86_64_TARGET_SIGNAL_H */
diff --git a/linux-user/i386/signal.c b/linux-user/i386/signal.c
index 3b4b55fc0a..b38b5f108e 100644
--- a/linux-user/i386/signal.c
+++ b/linux-user/i386/signal.c
@@ -310,6 +310,22 @@ get_sigframe(struct target_sigaction *ka, CPUX86State
*env, size_t frame_size)
}
#ifndef TARGET_X86_64
+static void install_sigtramp(void *tramp)
+{
+ /* This is popl %eax ; movl $syscall,%eax ; int $0x80 */
+ __put_user(0xb858, (uint16_t *)(tramp + 0));
+ __put_user(TARGET_NR_sigreturn, (int32_t *)(tramp + 2));
+ __put_user(0x80cd, (uint16_t *)(tramp + 6));
+}
+
+static void install_rt_sigtramp(void *tramp)
+{
+ /* This is movl $syscall,%eax ; int $0x80 */
+ __put_user(0xb8, (uint8_t *)(tramp + 0));
+ __put_user(TARGET_NR_rt_sigreturn, (int32_t *)(tramp + 1));
+ __put_user(0x80cd, (uint16_t *)(tramp + 5));
+}
+
/* compare linux/arch/i386/kernel/signal.c:setup_frame() */
void setup_frame(int sig, struct target_sigaction *ka,
target_sigset_t *set, CPUX86State *env)
@@ -338,16 +354,9 @@ void setup_frame(int sig, struct target_sigaction *ka,
if (ka->sa_flags & TARGET_SA_RESTORER) {
__put_user(ka->sa_restorer, &frame->pretcode);
} else {
- uint16_t val16;
- abi_ulong retcode_addr;
- retcode_addr = frame_addr + offsetof(struct sigframe, retcode);
- __put_user(retcode_addr, &frame->pretcode);
- /* This is popl %eax ; movl $,%eax ; int $0x80 */
- val16 = 0xb858;
- __put_user(val16, (uint16_t *)(frame->retcode+0));
- __put_user(TARGET_NR_sigreturn, (int *)(frame->retcode+2));
- val16 = 0x80cd;
- __put_user(val16, (uint16_t *)(frame->retcode+6));
+ /* This is no longer used, but is retained for ABI compatibility. */
+ install_sigtramp(frame->retcode);
+ __put_user(default_sigreturn, &frame->pretcode);
}
/* Set up registers for signal handler */
@@ -416,14 +425,9 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
if (ka->sa_flags & TARGET_SA_RESTORER) {
__put_user(ka->sa_restorer, &frame->pretcode);
} else {
- uint16_t val16;
- addr = frame_addr + offsetof(struct rt_sigframe, retcode);
- __put_user(addr, &frame->pretcode);
- /* This is movl $,%eax ; int $0x80 */
- __put_user(0xb8, (char *)(frame->retcode+0));
- __put_user(TARGET_NR_rt_sigreturn, (int *)(frame->retcode+1));
- val16 = 0x80cd;
- __put_user(val16, (uint16_t *)(frame->retcode+5));
+ /* This is no longer used, but is retained for ABI compatibility. */
+ install_rt_sigtramp(frame->retcode);
+ __put_user(default_rt_sigreturn, &frame->pretcode);
}
#else
/* XXX: Would be slightly better to return -EFAULT here if test fails
@@ -592,3 +596,19 @@ badframe:
force_sig(TARGET_SIGSEGV);
return -TARGET_QEMU_ESIGRETURN;
}
+
+#ifndef TARGET_X86_64
+void setup_sigtramp(abi_ulong sigtramp_page)
+{
+ uint16_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 2 * 8, 0);
+ assert(tramp != NULL);
+
+ default_sigreturn = sigtramp_page;
+ install_sigtramp(tramp);
+
+ default_rt_sigreturn = sigtramp_page + 8;
+ install_rt_sigtramp(tramp + 8);
+
+ unlock_user(tramp, sigtramp_page, 2 * 8);
+}
+#endif
--
2.25.1
