[Stable-8.2.1 60/71] linux-user: Fixed cpu restore with pc 0 on SIGBUS

[Michael Tokarev]

From: Robbin Ehn <rehn@rivosinc.com>

Commit f4e1168198 (linux-user: Split out host_sig{segv,bus}_handler)
introduced a bug, when returning from host_sigbus_handler the PC is
never set. Thus cpu_loop_exit_restore is called with a zero PC and
we immediate get a SIGSEGV.

Signed-off-by: Robbin Ehn <rehn@rivosinc.com>
Fixes: f4e1168198 ("linux-user: Split out host_sig{segv,bus}_handler")
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Message-Id: <33f27425878fb529b9e39ef22c303f6e0d90525f.camel@rivosinc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
(cherry picked from commit 6d913158b5023ac948b8fd649d77fc86e28072f6)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/linux-user/signal.c b/linux-user/signal.c
index b35d1e512f..c9527adfa3 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -925,7 +925,7 @@ static void host_sigsegv_handler(CPUState *cpu, siginfo_t 
*info,
     cpu_loop_exit_sigsegv(cpu, guest_addr, access_type, maperr, pc);
 }
 
-static void host_sigbus_handler(CPUState *cpu, siginfo_t *info,
+static uintptr_t host_sigbus_handler(CPUState *cpu, siginfo_t *info,
                                 host_sigcontext *uc)
 {
     uintptr_t pc = host_signal_pc(uc);
@@ -947,6 +947,7 @@ static void host_sigbus_handler(CPUState *cpu, siginfo_t 
*info,
         sigprocmask(SIG_SETMASK, host_signal_mask(uc), NULL);
         cpu_loop_exit_sigbus(cpu, guest_addr, access_type, pc);
     }
+    return pc;
 }
 
 static void host_signal_handler(int host_sig, siginfo_t *info, void *puc)
@@ -974,7 +975,7 @@ static void host_signal_handler(int host_sig, siginfo_t 
*info, void *puc)
             host_sigsegv_handler(cpu, info, uc);
             return;
         case SIGBUS:
-            host_sigbus_handler(cpu, info, uc);
+            pc = host_sigbus_handler(cpu, info, uc);
             sync_sig = true;
             break;
         case SIGILL:
-- 
2.39.2