[PATCH v2 3/5] gdbstub: Save target's siginfo

[Gustavo Romero <gustavo.romero@linaro.org>]

Save target's siginfo into gdbserver_state so it can be used later, for
example, in any stub that requires the target's si_signo and si_code.

This change affects only linux-user mode.

Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
---
 gdbstub/internals.h    |  3 +++
 gdbstub/user-target.c  |  3 ++-
 gdbstub/user.c         | 14 ++++++++++----
 include/gdbstub/user.h |  6 +++++-
 linux-user/main.c      |  2 +-
 linux-user/signal.c    |  5 ++++-
 6 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/gdbstub/internals.h b/gdbstub/internals.h
index 56b7c13b75..a7cc69dab3 100644
--- a/gdbstub/internals.h
+++ b/gdbstub/internals.h
@@ -58,6 +58,9 @@ typedef struct GDBState {
     int line_csum; /* checksum at the end of the packet */
     GByteArray *last_packet;
     int signal;
+#ifdef CONFIG_USER_ONLY
+    uint8_t siginfo[MAX_SIGINFO_LENGTH];
+#endif
     bool multiprocess;
     GDBProcess *processes;
     int process_num;
diff --git a/gdbstub/user-target.c b/gdbstub/user-target.c
index b7d4c37cd8..215bf33ab3 100644
--- a/gdbstub/user-target.c
+++ b/gdbstub/user-target.c
@@ -10,11 +10,12 @@
 #include "qemu/osdep.h"
 #include "exec/gdbstub.h"
 #include "qemu.h"
-#include "internals.h"
 #ifdef CONFIG_LINUX
 #include "linux-user/loader.h"
 #include "linux-user/qemu.h"
+#include "gdbstub/user.h"
 #endif
+#include "internals.h"
 
 /*
  * Map target signal numbers to GDB protocol signal numbers and vice
diff --git a/gdbstub/user.c b/gdbstub/user.c
index a157e67f95..777fa78ef4 100644
--- a/gdbstub/user.c
+++ b/gdbstub/user.c
@@ -131,7 +131,8 @@ void gdb_qemu_exit(int code)
     exit(code);
 }
 
-int gdb_handlesig(CPUState *cpu, int sig, const char *reason)
+int gdb_handlesig(CPUState *cpu, int sig, const char *reason, void *siginfo,
+                  int siginfo_len)
 {
     char buf[256];
     int n;
@@ -140,6 +141,11 @@ int gdb_handlesig(CPUState *cpu, int sig, const char *reason)
         return sig;
     }
 
+    if (siginfo) {
+        /* Save target-specific siginfo. */
+        memcpy(gdbserver_state.siginfo, siginfo, siginfo_len);
+    }
+
     /* disable single step if it was enabled */
     cpu_single_step(cpu, 0);
     tb_flush(cpu);
@@ -510,7 +516,7 @@ void gdb_breakpoint_remove_all(CPUState *cs)
 void gdb_syscall_handling(const char *syscall_packet)
 {
     gdb_put_packet(syscall_packet);
-    gdb_handlesig(gdbserver_state.c_cpu, 0, NULL);
+    gdb_handlesig(gdbserver_state.c_cpu, 0, NULL, NULL, 0);
 }
 
 static bool should_catch_syscall(int num)
@@ -528,7 +534,7 @@ void gdb_syscall_entry(CPUState *cs, int num)
 {
     if (should_catch_syscall(num)) {
         g_autofree char *reason = g_strdup_printf("syscall_entry:%x;", num);
-        gdb_handlesig(cs, gdb_target_sigtrap(), reason);
+        gdb_handlesig(cs, gdb_target_sigtrap(), reason, NULL, 0);
     }
 }
 
@@ -536,7 +542,7 @@ void gdb_syscall_return(CPUState *cs, int num)
 {
     if (should_catch_syscall(num)) {
         g_autofree char *reason = g_strdup_printf("syscall_return:%x;", num);
-        gdb_handlesig(cs, gdb_target_sigtrap(), reason);
+        gdb_handlesig(cs, gdb_target_sigtrap(), reason, NULL, 0);
     }
 }
 
diff --git a/include/gdbstub/user.h b/include/gdbstub/user.h
index 6647af2123..0ec9a7e596 100644
--- a/include/gdbstub/user.h
+++ b/include/gdbstub/user.h
@@ -9,11 +9,15 @@
 #ifndef GDBSTUB_USER_H
 #define GDBSTUB_USER_H
 
+#define MAX_SIGINFO_LENGTH 128
+
 /**
  * gdb_handlesig() - yield control to gdb
  * @cpu: CPU
  * @sig: if non-zero, the signal number which caused us to stop
  * @reason: stop reason for stop reply packet or NULL
+ * @siginfo: target-specific siginfo struct
+ * @siginfo_len: target-specific siginfo struct length
  *
  * This function yields control to gdb, when a user-mode-only target
  * needs to stop execution. If @sig is non-zero, then we will send a
@@ -25,7 +29,7 @@
  * or 0 if no signal should be delivered, ie the signal that caused
  * us to stop should be ignored.
  */
-int gdb_handlesig(CPUState *, int, const char *);
+int gdb_handlesig(CPUState *, int, const char *, void *, int);
 
 /**
  * gdb_signalled() - inform remote gdb of sig exit
diff --git a/linux-user/main.c b/linux-user/main.c
index 049fd85a2a..3187be48d6 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -1014,7 +1014,7 @@ int main(int argc, char **argv, char **envp)
                     gdbstub);
             exit(EXIT_FAILURE);
         }
-        gdb_handlesig(cpu, 0, NULL);
+        gdb_handlesig(cpu, 0, NULL, NULL, 0);
     }
 
 #ifdef CONFIG_SEMIHOSTING
diff --git a/linux-user/signal.c b/linux-user/signal.c
index 7a4c8e416e..98d1eacffe 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -34,6 +34,9 @@
 #include "user/safe-syscall.h"
 #include "tcg/tcg.h"
 
+/* target_siginfo_t must fit in gdbstub's siginfo save area. */
+QEMU_BUILD_BUG_ON(sizeof(target_siginfo_t) > MAX_SIGINFO_LENGTH);
+
 static struct target_sigaction sigact_table[TARGET_NSIG];
 
 static void host_signal_handler(int host_signum, siginfo_t *info,
@@ -1186,7 +1189,7 @@ static void handle_pending_signal(CPUArchState *cpu_env, int sig,
      */
     tswap_siginfo(&k->info, &k->info);
 
-    sig = gdb_handlesig(cpu, sig, NULL);
+    sig = gdb_handlesig(cpu, sig, NULL, &k->info, sizeof(k->info));
     if (!sig) {
         sa = NULL;
         handler = TARGET_SIG_IGN;
-- 
2.34.1