linux-user: Introduce host_signal_mask

Do not directly access the uc_sigmask member.
This is preparation for a sparc64 fix.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

linux-user/include/host/aarch64/host-signal.h

@@ -40,6 +40,11 @@ static inline void host_signal_set_pc(ucontext_t *uc, uintptr_t pc)
     uc->uc_mcontext.pc = pc;
 }
 
+static inline void *host_signal_mask(ucontext_t *uc)
+{
+    return &uc->uc_sigmask;
+}
+
 static inline bool host_signal_write(siginfo_t *info, ucontext_t *uc)
 {
     struct _aarch64_ctx *hdr;

linux-user/include/host/alpha/host-signal.h

@@ -21,6 +21,11 @@ static inline void host_signal_set_pc(ucontext_t *uc, uintptr_t pc)
     uc->uc_mcontext.sc_pc = pc;
 }
 
+static inline void *host_signal_mask(ucontext_t *uc)
+{
+    return &uc->uc_sigmask;
+}
+
 static inline bool host_signal_write(siginfo_t *info, ucontext_t *uc)
 {
     uint32_t *pc = (uint32_t *)host_signal_pc(uc);

linux-user/include/host/arm/host-signal.h

@@ -21,6 +21,11 @@ static inline void host_signal_set_pc(ucontext_t *uc, uintptr_t pc)
     uc->uc_mcontext.arm_pc = pc;
 }
 
+static inline void *host_signal_mask(ucontext_t *uc)
+{
+    return &uc->uc_sigmask;
+}
+
 static inline bool host_signal_write(siginfo_t *info, ucontext_t *uc)
 {
     /*

linux-user/include/host/i386/host-signal.h

@@ -21,6 +21,11 @@ static inline void host_signal_set_pc(ucontext_t *uc, uintptr_t pc)
     uc->uc_mcontext.gregs[REG_EIP] = pc;
 }
 
+static inline void *host_signal_mask(ucontext_t *uc)
+{
+    return &uc->uc_sigmask;
+}
+
 static inline bool host_signal_write(siginfo_t *info, ucontext_t *uc)
 {
     return uc->uc_mcontext.gregs[REG_TRAPNO] == 0xe

linux-user/include/host/loongarch64/host-signal.h

@@ -21,6 +21,11 @@ static inline void host_signal_set_pc(ucontext_t *uc, uintptr_t pc)
     uc->uc_mcontext.__pc = pc;
 }
 
+static inline void *host_signal_mask(ucontext_t *uc)
+{
+    return &uc->uc_sigmask;
+}
+
 static inline bool host_signal_write(siginfo_t *info, ucontext_t *uc)
 {
     const uint32_t *pinsn = (const uint32_t *)host_signal_pc(uc);

linux-user/include/host/mips/host-signal.h

@@ -21,6 +21,11 @@ static inline void host_signal_set_pc(ucontext_t *uc, uintptr_t pc)
     uc->uc_mcontext.pc = pc;
 }
 
+static inline void *host_signal_mask(ucontext_t *uc)
+{
+    return &uc->uc_sigmask;
+}
+
 #if defined(__misp16) || defined(__mips_micromips)
 #error "Unsupported encoding"
 #endif

linux-user/include/host/ppc/host-signal.h

@@ -21,6 +21,11 @@ static inline void host_signal_set_pc(ucontext_t *uc, uintptr_t pc)
     uc->uc_mcontext.regs->nip = pc;
 }
 
+static inline void *host_signal_mask(ucontext_t *uc)
+{
+    return &uc->uc_sigmask;
+}
+
 static inline bool host_signal_write(siginfo_t *info, ucontext_t *uc)
 {
     return uc->uc_mcontext.regs->trap != 0x400

linux-user/include/host/riscv/host-signal.h

@@ -21,6 +21,11 @@ static inline void host_signal_set_pc(ucontext_t *uc, uintptr_t pc)
     uc->uc_mcontext.__gregs[REG_PC] = pc;
 }
 
+static inline void *host_signal_mask(ucontext_t *uc)
+{
+    return &uc->uc_sigmask;
+}
+
 static inline bool host_signal_write(siginfo_t *info, ucontext_t *uc)
 {
     /*

linux-user/include/host/s390/host-signal.h

@@ -21,6 +21,11 @@ static inline void host_signal_set_pc(ucontext_t *uc, uintptr_t pc)
     uc->uc_mcontext.psw.addr = pc;
 }
 
+static inline void *host_signal_mask(ucontext_t *uc)
+{
+    return &uc->uc_sigmask;
+}
+
 static inline bool host_signal_write(siginfo_t *info, ucontext_t *uc)
 {
     uint16_t *pinsn = (uint16_t *)host_signal_pc(uc);

linux-user/include/host/sparc/host-signal.h

@@ -29,6 +29,11 @@ static inline void host_signal_set_pc(ucontext_t *uc, uintptr_t pc)
 #endif
 }
 
+static inline void *host_signal_mask(ucontext_t *uc)
+{
+    return &uc->uc_sigmask;
+}
+
 static inline bool host_signal_write(siginfo_t *info, ucontext_t *uc)
 {
     uint32_t insn = *(uint32_t *)host_signal_pc(uc);

linux-user/include/host/x86_64/host-signal.h

@@ -20,6 +20,11 @@ static inline void host_signal_set_pc(ucontext_t *uc, uintptr_t pc)
     uc->uc_mcontext.gregs[REG_RIP] = pc;
 }
 
+static inline void *host_signal_mask(ucontext_t *uc)
+{
+    return &uc->uc_sigmask;
+}
+
 static inline bool host_signal_write(siginfo_t *info, ucontext_t *uc)
 {
     return uc->uc_mcontext.gregs[REG_TRAPNO] == 0xe

linux-user/signal.c

@@ -820,6 +820,7 @@ static void host_signal_handler(int host_sig, siginfo_t *info, void *puc)
     int guest_sig;
     uintptr_t pc = 0;
     bool sync_sig = false;
+    void *sigmask = host_signal_mask(uc);
 
     /*
      * Non-spoofed SIGSEGV and SIGBUS are synchronous, and need special
@@ -849,8 +850,7 @@ static void host_signal_handler(int host_sig, siginfo_t *info, void *puc)
             if (info->si_code == SEGV_ACCERR && h2g_valid(host_addr)) {
                 /* If this was a write to a TB protected page, restart. */
                 if (is_write &&
-                    handle_sigsegv_accerr_write(cpu, &uc->uc_sigmask,
+                    handle_sigsegv_accerr_write(cpu, sigmask, pc, guest_addr)) {
-                                                pc, guest_addr)) {
                     return;
                 }
 
@@ -865,10 +865,10 @@ static void host_signal_handler(int host_sig, siginfo_t *info, void *puc)
                 }
             }
 
-            sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL);
+            sigprocmask(SIG_SETMASK, sigmask, NULL);
             cpu_loop_exit_sigsegv(cpu, guest_addr, access_type, maperr, pc);
         } else {
-            sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL);
+            sigprocmask(SIG_SETMASK, sigmask, NULL);
             if (info->si_code == BUS_ADRALN) {
                 cpu_loop_exit_sigbus(cpu, guest_addr, access_type, pc);
             }
@@ -909,17 +909,15 @@ static void host_signal_handler(int host_sig, siginfo_t *info, void *puc)
      * now and it getting out to the main loop. Signals will be
      * unblocked again in process_pending_signals().
      *
-     * WARNING: we cannot use sigfillset() here because the uc_sigmask
+     * WARNING: we cannot use sigfillset() here because the sigmask
      * field is a kernel sigset_t, which is much smaller than the
      * libc sigset_t which sigfillset() operates on. Using sigfillset()
      * would write 0xff bytes off the end of the structure and trash
      * data on the struct.
-     * We can't use sizeof(uc->uc_sigmask) either, because the libc
-     * headers define the struct field with the wrong (too large) type.
      */
-    memset(&uc->uc_sigmask, 0xff, SIGSET_T_SIZE);
+    memset(sigmask, 0xff, SIGSET_T_SIZE);
-    sigdelset(&uc->uc_sigmask, SIGSEGV);
+    sigdelset(sigmask, SIGSEGV);
-    sigdelset(&uc->uc_sigmask, SIGBUS);
+    sigdelset(sigmask, SIGBUS);
 
     /* interrupt the virtual CPU as soon as possible */
     cpu_exit(thread_cpu);