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authorPeter Maydell <peter.maydell@linaro.org>2016-07-28 16:44:49 +0100
committerRiku Voipio <riku.voipio@linaro.org>2016-09-21 22:01:45 +0300
commitc599d4d6d6e9bfdb64e54c33a22cb26e3496b96d (patch)
tree4f5db178fbb692ad5d8a3819476d0f3c57b51d5a
parent28298c912e2c379f2b7767b351beeb77f001f27f (diff)
downloadqemu-arm-c599d4d6d6e9bfdb64e54c33a22cb26e3496b96d.tar.gz
linux-user: SIGSEGV from sigreturn need not be fatal
If the sigreturn syscall fails to read memory then this causes a SIGSEGV, but this is not necessarily a fatal signal -- the guest process can catch it. We don't implement this correctly because the behaviour of QEMU's force_sig() function has drifted away from the kernel function of the same name -- ours now does "always do a guest core dump and abort execution", whereas the kernel version simply forces the guest to take a signal, which may or may not eventually cause a core dump. Rename our force_sig() to dump_core_and_abort(), and provide a force_sig() which acts more like the kernel version as the sigreturn implementations expect it to. Since force_sig() now returns, we must update all the callsites to return -TARGET_QEMU_ESIGRETURN so that the main loop doesn't change the guest registers before the signal handler is invoked. Reviewed-by: Richard Henderson <rth@twiddle.net> Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
-rw-r--r--linux-user/signal.c81
1 files changed, 54 insertions, 27 deletions
diff --git a/linux-user/signal.c b/linux-user/signal.c
index 43836960c1..60fda18117 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -512,6 +512,27 @@ void signal_init(void)
}
}
+#if !defined(TARGET_OPENRISC) && !defined(TARGET_UNICORE32) && \
+ !defined(TARGET_X86_64)
+/* Force a synchronously taken signal. The kernel force_sig() function
+ * also forces the signal to "not blocked, not ignored", but for QEMU
+ * that work is done in process_pending_signals().
+ */
+static void force_sig(int sig)
+{
+ CPUState *cpu = thread_cpu;
+ CPUArchState *env = cpu->env_ptr;
+ target_siginfo_t info;
+
+ info.si_signo = sig;
+ info.si_errno = 0;
+ info.si_code = TARGET_SI_KERNEL;
+ info._sifields._kill._pid = 0;
+ info._sifields._kill._uid = 0;
+ queue_signal(env, info.si_signo, QEMU_SI_KILL, &info);
+}
+#endif
+
#if !(defined(TARGET_X86_64) || defined(TARGET_UNICORE32))
/* Force a SIGSEGV if we couldn't write to memory trying to set
@@ -526,7 +547,7 @@ static void force_sigsegv(int oldsig)
if (oldsig == SIGSEGV) {
/* Make sure we don't try to deliver the signal again; this will
- * end up with handle_pending_signal() calling force_sig().
+ * end up with handle_pending_signal() calling dump_core_and_abort().
*/
sigact_table[oldsig - 1]._sa_handler = TARGET_SIG_DFL;
}
@@ -540,7 +561,7 @@ static void force_sigsegv(int oldsig)
#endif
/* abort execution with signal */
-static void QEMU_NORETURN force_sig(int target_sig)
+static void QEMU_NORETURN dump_core_and_abort(int target_sig)
{
CPUState *cpu = thread_cpu;
CPUArchState *env = cpu->env_ptr;
@@ -1181,7 +1202,7 @@ long do_sigreturn(CPUX86State *env)
badframe:
unlock_user_struct(frame, frame_addr, 0);
force_sig(TARGET_SIGSEGV);
- return 0;
+ return -TARGET_QEMU_ESIGRETURN;
}
long do_rt_sigreturn(CPUX86State *env)
@@ -1212,7 +1233,7 @@ long do_rt_sigreturn(CPUX86State *env)
badframe:
unlock_user_struct(frame, frame_addr, 0);
force_sig(TARGET_SIGSEGV);
- return 0;
+ return -TARGET_QEMU_ESIGRETURN;
}
#elif defined(TARGET_AARCH64)
@@ -1482,7 +1503,7 @@ long do_rt_sigreturn(CPUARMState *env)
badframe:
unlock_user_struct(frame, frame_addr, 0);
force_sig(TARGET_SIGSEGV);
- return 0;
+ return -TARGET_QEMU_ESIGRETURN;
}
long do_sigreturn(CPUARMState *env)
@@ -2004,8 +2025,8 @@ static long do_sigreturn_v1(CPUARMState *env)
return -TARGET_QEMU_ESIGRETURN;
badframe:
- force_sig(TARGET_SIGSEGV /* , current */);
- return 0;
+ force_sig(TARGET_SIGSEGV);
+ return -TARGET_QEMU_ESIGRETURN;
}
static abi_ulong *restore_sigframe_v2_vfp(CPUARMState *env, abi_ulong *regspace)
@@ -2131,8 +2152,8 @@ static long do_sigreturn_v2(CPUARMState *env)
badframe:
unlock_user_struct(frame, frame_addr, 0);
- force_sig(TARGET_SIGSEGV /* , current */);
- return 0;
+ force_sig(TARGET_SIGSEGV);
+ return -TARGET_QEMU_ESIGRETURN;
}
long do_sigreturn(CPUARMState *env)
@@ -2185,8 +2206,8 @@ static long do_rt_sigreturn_v1(CPUARMState *env)
badframe:
unlock_user_struct(frame, frame_addr, 0);
- force_sig(TARGET_SIGSEGV /* , current */);
- return 0;
+ force_sig(TARGET_SIGSEGV);
+ return -TARGET_QEMU_ESIGRETURN;
}
static long do_rt_sigreturn_v2(CPUARMState *env)
@@ -2218,8 +2239,8 @@ static long do_rt_sigreturn_v2(CPUARMState *env)
badframe:
unlock_user_struct(frame, frame_addr, 0);
- force_sig(TARGET_SIGSEGV /* , current */);
- return 0;
+ force_sig(TARGET_SIGSEGV);
+ return -TARGET_QEMU_ESIGRETURN;
}
long do_rt_sigreturn(CPUARMState *env)
@@ -2553,6 +2574,7 @@ long do_sigreturn(CPUSPARCState *env)
segv_and_exit:
unlock_user_struct(sf, sf_addr, 0);
force_sig(TARGET_SIGSEGV);
+ return -TARGET_QEMU_ESIGRETURN;
}
long do_rt_sigreturn(CPUSPARCState *env)
@@ -3110,8 +3132,8 @@ long do_sigreturn(CPUMIPSState *regs)
return -TARGET_QEMU_ESIGRETURN;
badframe:
- force_sig(TARGET_SIGSEGV/*, current*/);
- return 0;
+ force_sig(TARGET_SIGSEGV);
+ return -TARGET_QEMU_ESIGRETURN;
}
# endif /* O32 */
@@ -3207,8 +3229,8 @@ long do_rt_sigreturn(CPUMIPSState *env)
return -TARGET_QEMU_ESIGRETURN;
badframe:
- force_sig(TARGET_SIGSEGV/*, current*/);
- return 0;
+ force_sig(TARGET_SIGSEGV);
+ return -TARGET_QEMU_ESIGRETURN;
}
#elif defined(TARGET_SH4)
@@ -3474,7 +3496,7 @@ long do_sigreturn(CPUSH4State *regs)
badframe:
unlock_user_struct(frame, frame_addr, 0);
force_sig(TARGET_SIGSEGV);
- return 0;
+ return -TARGET_QEMU_ESIGRETURN;
}
long do_rt_sigreturn(CPUSH4State *regs)
@@ -3506,7 +3528,7 @@ long do_rt_sigreturn(CPUSH4State *regs)
badframe:
unlock_user_struct(frame, frame_addr, 0);
force_sig(TARGET_SIGSEGV);
- return 0;
+ return -TARGET_QEMU_ESIGRETURN;
}
#elif defined(TARGET_MICROBLAZE)
@@ -3725,6 +3747,7 @@ long do_sigreturn(CPUMBState *env)
return -TARGET_QEMU_ESIGRETURN;
badframe:
force_sig(TARGET_SIGSEGV);
+ return -TARGET_QEMU_ESIGRETURN;
}
long do_rt_sigreturn(CPUMBState *env)
@@ -3892,6 +3915,7 @@ long do_sigreturn(CPUCRISState *env)
return -TARGET_QEMU_ESIGRETURN;
badframe:
force_sig(TARGET_SIGSEGV);
+ return -TARGET_QEMU_ESIGRETURN;
}
long do_rt_sigreturn(CPUCRISState *env)
@@ -4383,7 +4407,7 @@ long do_sigreturn(CPUS390XState *env)
badframe:
force_sig(TARGET_SIGSEGV);
- return 0;
+ return -TARGET_QEMU_ESIGRETURN;
}
long do_rt_sigreturn(CPUS390XState *env)
@@ -4414,7 +4438,7 @@ long do_rt_sigreturn(CPUS390XState *env)
badframe:
unlock_user_struct(frame, frame_addr, 0);
force_sig(TARGET_SIGSEGV);
- return 0;
+ return -TARGET_QEMU_ESIGRETURN;
}
#elif defined(TARGET_PPC)
@@ -4973,7 +4997,7 @@ sigsegv:
unlock_user_struct(sr, sr_addr, 1);
unlock_user_struct(sc, sc_addr, 1);
force_sig(TARGET_SIGSEGV);
- return 0;
+ return -TARGET_QEMU_ESIGRETURN;
}
/* See arch/powerpc/kernel/signal_32.c. */
@@ -5028,7 +5052,7 @@ long do_rt_sigreturn(CPUPPCState *env)
sigsegv:
unlock_user_struct(rt_sf, rt_sf_addr, 1);
force_sig(TARGET_SIGSEGV);
- return 0;
+ return -TARGET_QEMU_ESIGRETURN;
}
#elif defined(TARGET_M68K)
@@ -5358,7 +5382,7 @@ long do_sigreturn(CPUM68KState *env)
badframe:
force_sig(TARGET_SIGSEGV);
- return 0;
+ return -TARGET_QEMU_ESIGRETURN;
}
long do_rt_sigreturn(CPUM68KState *env)
@@ -5391,7 +5415,7 @@ long do_rt_sigreturn(CPUM68KState *env)
badframe:
unlock_user_struct(frame, frame_addr, 0);
force_sig(TARGET_SIGSEGV);
- return 0;
+ return -TARGET_QEMU_ESIGRETURN;
}
#elif defined(TARGET_ALPHA)
@@ -5620,6 +5644,7 @@ long do_sigreturn(CPUAlphaState *env)
badframe:
force_sig(TARGET_SIGSEGV);
+ return -TARGET_QEMU_ESIGRETURN;
}
long do_rt_sigreturn(CPUAlphaState *env)
@@ -5649,6 +5674,7 @@ long do_rt_sigreturn(CPUAlphaState *env)
badframe:
unlock_user_struct(frame, frame_addr, 0);
force_sig(TARGET_SIGSEGV);
+ return -TARGET_QEMU_ESIGRETURN;
}
#elif defined(TARGET_TILEGX)
@@ -5813,6 +5839,7 @@ long do_rt_sigreturn(CPUTLGState *env)
badframe:
unlock_user_struct(frame, frame_addr, 0);
force_sig(TARGET_SIGSEGV);
+ return -TARGET_QEMU_ESIGRETURN;
}
#else
@@ -5879,12 +5906,12 @@ static void handle_pending_signal(CPUArchState *cpu_env, int sig,
sig != TARGET_SIGURG &&
sig != TARGET_SIGWINCH &&
sig != TARGET_SIGCONT) {
- force_sig(sig);
+ dump_core_and_abort(sig);
}
} else if (handler == TARGET_SIG_IGN) {
/* ignore sig */
} else if (handler == TARGET_SIG_ERR) {
- force_sig(sig);
+ dump_core_and_abort(sig);
} else {
/* compute the blocked signals during the handler execution */
sigset_t *blocked_set;