linux-user: Don't call gdb_handlesig() before queue_signal()

The CPU main-loop routines for linux-user generally
call gdb_handlesig() when they're about to queue a
SIGTRAP signal. This is wrong, because queue_signal()
will cause us to pend a signal, and process_pending_signals()
will then call gdb_handlesig() itself. So the effect is that
we notify gdb of the SIGTRAP, and then if gdb says "OK,
continue with signal X" we will incorrectly notify
gdb of the signal X as well. We don't do this double-notify
for anything else, only SIGTRAP.

Remove this unnecessary and incorrect code from all
the targets except for nios2 (whose main loop is
doing something different and broken, and will be handled
in a separate patch).

This bug only manifests if the user responds to the reported
SIGTRAP using "signal SIGFOO" rather than "continue"; since
the latter is the overwhelmingly common thing to do after a
breakpoint most people won't have hit this.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20181019174958.26616-2-peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

16 files changed, 62 insertions, 151 deletions

diff --git a/linux-user/aarch64/cpu_loop.c b/linux-user/aarch64/cpu_loop.c
index c97a646546..65d815f030 100644
--- a/linux-user/aarch64/cpu_loop.c
+++ b/linux-user/aarch64/cpu_loop.c
@@ -73,7 +73,7 @@
 void cpu_loop(CPUARMState *env)
 {
     CPUState *cs = CPU(arm_env_get_cpu(env));
-    int trapnr, sig;
+    int trapnr;
     abi_long ret;
     target_siginfo_t info;
 
@@ -121,13 +121,10 @@ void cpu_loop(CPUARMState *env)
             break;
         case EXCP_DEBUG:
         case EXCP_BKPT:
-            sig = gdb_handlesig(cs, TARGET_SIGTRAP);
-            if (sig) {
-                info.si_signo = sig;
-                info.si_errno = 0;
-                info.si_code = TARGET_TRAP_BRKPT;
-                queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
-            }
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case EXCP_SEMIHOST:
             env->xregs[0] = do_arm_semihosting(env);
diff --git a/linux-user/alpha/cpu_loop.c b/linux-user/alpha/cpu_loop.c
index c1a98c8cbf..824b6d6658 100644
--- a/linux-user/alpha/cpu_loop.c
+++ b/linux-user/alpha/cpu_loop.c
@@ -179,14 +179,10 @@ void cpu_loop(CPUAlphaState *env)
             }
             break;
         case EXCP_DEBUG:
-            info.si_signo = gdb_handlesig(cs, TARGET_SIGTRAP);
-            if (info.si_signo) {
-                info.si_errno = 0;
-                info.si_code = TARGET_TRAP_BRKPT;
-                queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
-            } else {
-                arch_interrupt = false;
-            }
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case EXCP_INTERRUPT:
             /* Just indicate that signals should be handled asap.  */
diff --git a/linux-user/arm/cpu_loop.c b/linux-user/arm/cpu_loop.c
index 26928fbbb2..ee68aa60bf 100644
--- a/linux-user/arm/cpu_loop.c
+++ b/linux-user/arm/cpu_loop.c
@@ -397,18 +397,10 @@ void cpu_loop(CPUARMState *env)
             break;
         case EXCP_DEBUG:
         excp_debug:
-            {
-                int sig;
-
-                sig = gdb_handlesig(cs, TARGET_SIGTRAP);
-                if (sig)
-                  {
-                    info.si_signo = sig;
-                    info.si_errno = 0;
-                    info.si_code = TARGET_TRAP_BRKPT;
-                    queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
-                  }
-            }
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case EXCP_KERNEL_TRAP:
             if (do_kernel_trap(env))
diff --git a/linux-user/cris/cpu_loop.c b/linux-user/cris/cpu_loop.c
index 37bdcfa8cc..dacf604c7d 100644
--- a/linux-user/cris/cpu_loop.c
+++ b/linux-user/cris/cpu_loop.c
@@ -64,18 +64,10 @@ void cpu_loop(CPUCRISState *env)
             }
             break;
         case EXCP_DEBUG:
-            {
-                int sig;
-
-                sig = gdb_handlesig(cs, TARGET_SIGTRAP);
-                if (sig)
-                  {
-                    info.si_signo = sig;
-                    info.si_errno = 0;
-                    info.si_code = TARGET_TRAP_BRKPT;
-                    queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
-                  }
-            }
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case EXCP_ATOMIC:
             cpu_exec_step_atomic(cs);
diff --git a/linux-user/hppa/cpu_loop.c b/linux-user/hppa/cpu_loop.c
index 0301c766c6..880955fdef 100644
--- a/linux-user/hppa/cpu_loop.c
+++ b/linux-user/hppa/cpu_loop.c
@@ -182,13 +182,10 @@ void cpu_loop(CPUHPPAState *env)
             queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case EXCP_DEBUG:
-            trapnr = gdb_handlesig(cs, TARGET_SIGTRAP);
-            if (trapnr) {
-                info.si_signo = trapnr;
-                info.si_errno = 0;
-                info.si_code = TARGET_TRAP_BRKPT;
-                queue_signal(env, trapnr, QEMU_SI_FAULT, &info);
-            }
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case EXCP_INTERRUPT:
             /* just indicate that signals should be handled asap */
diff --git a/linux-user/i386/cpu_loop.c b/linux-user/i386/cpu_loop.c
index 2374abfd0b..51cfa006c9 100644
--- a/linux-user/i386/cpu_loop.c
+++ b/linux-user/i386/cpu_loop.c
@@ -225,18 +225,10 @@ void cpu_loop(CPUX86State *env)
             /* just indicate that signals should be handled asap */
             break;
         case EXCP_DEBUG:
-            {
-                int sig;
-
-                sig = gdb_handlesig(cs, TARGET_SIGTRAP);
-                if (sig)
-                  {
-                    info.si_signo = sig;
-                    info.si_errno = 0;
-                    info.si_code = TARGET_TRAP_BRKPT;
-                    queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
-                  }
-            }
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case EXCP_ATOMIC:
             cpu_exec_step_atomic(cs);
diff --git a/linux-user/m68k/cpu_loop.c b/linux-user/m68k/cpu_loop.c
index 30c3332af4..bfb41bbcc5 100644
--- a/linux-user/m68k/cpu_loop.c
+++ b/linux-user/m68k/cpu_loop.c
@@ -112,18 +112,10 @@ void cpu_loop(CPUM68KState *env)
             }
             break;
         case EXCP_DEBUG:
-            {
-                int sig;
-
-                sig = gdb_handlesig(cs, TARGET_SIGTRAP);
-                if (sig)
-                  {
-                    info.si_signo = sig;
-                    info.si_errno = 0;
-                    info.si_code = TARGET_TRAP_BRKPT;
-                    queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
-                  }
-            }
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case EXCP_ATOMIC:
             cpu_exec_step_atomic(cs);
diff --git a/linux-user/microblaze/cpu_loop.c b/linux-user/microblaze/cpu_loop.c
index 2af93eb39a..c2190e15fd 100644
--- a/linux-user/microblaze/cpu_loop.c
+++ b/linux-user/microblaze/cpu_loop.c
@@ -113,18 +113,10 @@ void cpu_loop(CPUMBState *env)
             }
             break;
         case EXCP_DEBUG:
-            {
-                int sig;
-
-                sig = gdb_handlesig(cs, TARGET_SIGTRAP);
-                if (sig)
-                  {
-                    info.si_signo = sig;
-                    info.si_errno = 0;
-                    info.si_code = TARGET_TRAP_BRKPT;
-                    queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
-                  }
-            }
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case EXCP_ATOMIC:
             cpu_exec_step_atomic(cs);
diff --git a/linux-user/mips/cpu_loop.c b/linux-user/mips/cpu_loop.c
index 97e495747f..d0f62ec9b6 100644
--- a/linux-user/mips/cpu_loop.c
+++ b/linux-user/mips/cpu_loop.c
@@ -592,18 +592,10 @@ done_syscall:
             /* just indicate that signals should be handled asap */
             break;
         case EXCP_DEBUG:
-            {
-                int sig;
-
-                sig = gdb_handlesig(cs, TARGET_SIGTRAP);
-                if (sig)
-                  {
-                    info.si_signo = sig;
-                    info.si_errno = 0;
-                    info.si_code = TARGET_TRAP_BRKPT;
-                    queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
-                  }
-            }
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case EXCP_SC:
             if (do_store_exclusive(env)) {
diff --git a/linux-user/openrisc/cpu_loop.c b/linux-user/openrisc/cpu_loop.c
index 6c6ea871e1..f496e4b48a 100644
--- a/linux-user/openrisc/cpu_loop.c
+++ b/linux-user/openrisc/cpu_loop.c
@@ -85,13 +85,10 @@ void cpu_loop(CPUOpenRISCState *env)
             /* We processed the pending cpu work above.  */
             break;
         case EXCP_DEBUG:
-            trapnr = gdb_handlesig(cs, TARGET_SIGTRAP);
-            if (trapnr) {
-                info.si_signo = trapnr;
-                info.si_errno = 0;
-                info.si_code = TARGET_TRAP_BRKPT;
-                queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
-            }
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case EXCP_ATOMIC:
             cpu_exec_step_atomic(cs);
diff --git a/linux-user/ppc/cpu_loop.c b/linux-user/ppc/cpu_loop.c
index 133a87f349..801f5ace29 100644
--- a/linux-user/ppc/cpu_loop.c
+++ b/linux-user/ppc/cpu_loop.c
@@ -69,7 +69,7 @@ void cpu_loop(CPUPPCState *env)
 {
     CPUState *cs = CPU(ppc_env_get_cpu(env));
     target_siginfo_t info;
-    int trapnr, sig;
+    int trapnr;
     target_ulong ret;
 
     for(;;) {
@@ -449,15 +449,10 @@ void cpu_loop(CPUPPCState *env)
             env->gpr[3] = ret;
             break;
         case EXCP_DEBUG:
-            sig = gdb_handlesig(cs, TARGET_SIGTRAP);
-            if (sig) {
-                info.si_signo = sig;
-                info.si_errno = 0;
-                info.si_code = TARGET_TRAP_BRKPT;
-                queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
-            } else {
-                arch_interrupt = false;
-            }
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case EXCP_INTERRUPT:
             /* just indicate that signals should be handled asap */
diff --git a/linux-user/riscv/cpu_loop.c b/linux-user/riscv/cpu_loop.c
index f137d39d7e..4cf3e94632 100644
--- a/linux-user/riscv/cpu_loop.c
+++ b/linux-user/riscv/cpu_loop.c
@@ -88,7 +88,7 @@ void cpu_loop(CPURISCVState *env)
             break;
         case EXCP_DEBUG:
         gdbstep:
-            signum = gdb_handlesig(cs, TARGET_SIGTRAP);
+            signum = TARGET_SIGTRAP;
             sigcode = TARGET_TRAP_BRKPT;
             break;
         default:
diff --git a/linux-user/s390x/cpu_loop.c b/linux-user/s390x/cpu_loop.c
index 99f5f1594f..51b5412ea2 100644
--- a/linux-user/s390x/cpu_loop.c
+++ b/linux-user/s390x/cpu_loop.c
@@ -61,12 +61,9 @@ void cpu_loop(CPUS390XState *env)
             break;
 
         case EXCP_DEBUG:
-            sig = gdb_handlesig(cs, TARGET_SIGTRAP);
-            if (sig) {
-                n = TARGET_TRAP_BRKPT;
-                goto do_signal_pc;
-            }
-            break;
+            sig = TARGET_SIGTRAP;
+            n = TARGET_TRAP_BRKPT;
+            goto do_signal_pc;
         case EXCP_PGM:
             n = env->int_pgm_code;
             switch (n) {
diff --git a/linux-user/sh4/cpu_loop.c b/linux-user/sh4/cpu_loop.c
index fdd348170b..47e54b9b61 100644
--- a/linux-user/sh4/cpu_loop.c
+++ b/linux-user/sh4/cpu_loop.c
@@ -57,19 +57,10 @@ void cpu_loop(CPUSH4State *env)
             /* just indicate that signals should be handled asap */
             break;
         case EXCP_DEBUG:
-            {
-                int sig;
-
-                sig = gdb_handlesig(cs, TARGET_SIGTRAP);
-                if (sig) {
-                    info.si_signo = sig;
-                    info.si_errno = 0;
-                    info.si_code = TARGET_TRAP_BRKPT;
-                    queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
-                } else {
-                    arch_interrupt = false;
-                }
-            }
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case 0xa0:
         case 0xc0:
diff --git a/linux-user/sparc/cpu_loop.c b/linux-user/sparc/cpu_loop.c
index 91f714afc6..7d5b337b97 100644
--- a/linux-user/sparc/cpu_loop.c
+++ b/linux-user/sparc/cpu_loop.c
@@ -268,18 +268,10 @@ void cpu_loop (CPUSPARCState *env)
             }
             break;
         case EXCP_DEBUG:
-            {
-                int sig;
-
-                sig = gdb_handlesig(cs, TARGET_SIGTRAP);
-                if (sig)
-                  {
-                    info.si_signo = sig;
-                    info.si_errno = 0;
-                    info.si_code = TARGET_TRAP_BRKPT;
-                    queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
-                  }
-            }
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case EXCP_ATOMIC:
             cpu_exec_step_atomic(cs);
diff --git a/linux-user/xtensa/cpu_loop.c b/linux-user/xtensa/cpu_loop.c
index d142988ebe..bee78edb8a 100644
--- a/linux-user/xtensa/cpu_loop.c
+++ b/linux-user/xtensa/cpu_loop.c
@@ -239,13 +239,10 @@ void cpu_loop(CPUXtensaState *env)
             }
             break;
         case EXCP_DEBUG:
-            trapnr = gdb_handlesig(cs, TARGET_SIGTRAP);
-            if (trapnr) {
-                info.si_signo = trapnr;
-                info.si_errno = 0;
-                info.si_code = TARGET_TRAP_BRKPT;
-                queue_signal(env, trapnr, QEMU_SI_FAULT, &info);
-            }
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
         case EXC_DEBUG:
         default: