linux-user: Split out helpers for sigsuspend

Two new functions: process_sigsuspend_mask and finish_sigsuspend_mask.
Move the size check and copy-from-user code.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20220315084308.433109-3-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

3 files changed, 66 insertions, 23 deletions

diff --git a/linux-user/signal-common.h b/linux-user/signal-common.h
index 2113165a75..6a7e4a93fc 100644
--- a/linux-user/signal-common.h
+++ b/linux-user/signal-common.h
@@ -92,4 +92,30 @@ abi_long do_swapcontext(CPUArchState *env, abi_ulong uold_ctx,
  */
 int block_signals(void); /* Returns non zero if signal pending */
 
+/**
+ * process_sigsuspend_mask: read and apply syscall-local signal mask
+ *
+ * Read the guest signal mask from @sigset, length @sigsize.
+ * Convert that to a host signal mask and save it to sigpending_mask.
+ *
+ * Return value: negative target errno, or zero;
+ *               store &sigpending_mask into *pset on success.
+ */
+int process_sigsuspend_mask(sigset_t **pset, target_ulong sigset,
+                            target_ulong sigsize);
+
+/**
+ * finish_sigsuspend_mask: finish a sigsuspend-like syscall
+ *
+ * Set in_sigsuspend if we need to use the modified sigset
+ * during process_pending_signals.
+ */
+static inline void finish_sigsuspend_mask(int ret)
+{
+    if (ret != -QEMU_ERESTARTSYS) {
+        TaskState *ts = (TaskState *)thread_cpu->opaque;
+        ts->in_sigsuspend = 1;
+    }
+}
+
 #endif
diff --git a/linux-user/signal.c b/linux-user/signal.c
index 2a3f3cc23f..092e70b80c 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -1199,3 +1199,26 @@ void process_pending_signals(CPUArchState *cpu_env)
     }
     ts->in_sigsuspend = 0;
 }
+
+int process_sigsuspend_mask(sigset_t **pset, target_ulong sigset,
+                            target_ulong sigsize)
+{
+    TaskState *ts = (TaskState *)thread_cpu->opaque;
+    sigset_t *host_set = &ts->sigsuspend_mask;
+    target_sigset_t *target_sigset;
+
+    if (sigsize != sizeof(*target_sigset)) {
+        /* Like the kernel, we enforce correct size sigsets */
+        return -TARGET_EINVAL;
+    }
+
+    target_sigset = lock_user(VERIFY_READ, sigset, sigsize, 1);
+    if (!target_sigset) {
+        return -TARGET_EFAULT;
+    }
+    target_to_host_sigset(host_set, target_sigset);
+    unlock_user(target_sigset, sigset, 0);
+
+    *pset = host_set;
+    return 0;
+}
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 77cd88b537..d9b5662ff8 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -9557,41 +9557,35 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
 #ifdef TARGET_NR_sigsuspend
     case TARGET_NR_sigsuspend:
         {
-            TaskState *ts = cpu->opaque;
+            sigset_t *set;
+
 #if defined(TARGET_ALPHA)
+            TaskState *ts = cpu->opaque;
             /* target_to_host_old_sigset will bswap back */
             abi_ulong mask = tswapal(arg1);
-            target_to_host_old_sigset(&ts->sigsuspend_mask, &mask);
+            set = &ts->sigsuspend_mask;
+            target_to_host_old_sigset(set, &mask);
 #else
-            if (!(p = lock_user(VERIFY_READ, arg1, sizeof(target_sigset_t), 1)))
-                return -TARGET_EFAULT;
-            target_to_host_old_sigset(&ts->sigsuspend_mask, p);
-            unlock_user(p, arg1, 0);
-#endif
-            ret = get_errno(safe_rt_sigsuspend(&ts->sigsuspend_mask,
-                                               SIGSET_T_SIZE));
-            if (ret != -QEMU_ERESTARTSYS) {
-                ts->in_sigsuspend = 1;
+            ret = process_sigsuspend_mask(&set, arg1, sizeof(target_sigset_t));
+            if (ret != 0) {
+                return ret;
             }
+#endif
+            ret = get_errno(safe_rt_sigsuspend(set, SIGSET_T_SIZE));
+            finish_sigsuspend_mask(ret);
         }
         return ret;
 #endif
     case TARGET_NR_rt_sigsuspend:
         {
-            TaskState *ts = cpu->opaque;
+            sigset_t *set;
 
-            if (arg2 != sizeof(target_sigset_t)) {
-                return -TARGET_EINVAL;
-            }
-            if (!(p = lock_user(VERIFY_READ, arg1, sizeof(target_sigset_t), 1)))
-                return -TARGET_EFAULT;
-            target_to_host_sigset(&ts->sigsuspend_mask, p);
-            unlock_user(p, arg1, 0);
-            ret = get_errno(safe_rt_sigsuspend(&ts->sigsuspend_mask,
-                                               SIGSET_T_SIZE));
-            if (ret != -QEMU_ERESTARTSYS) {
-                ts->in_sigsuspend = 1;
+            ret = process_sigsuspend_mask(&set, arg1, arg2);
+            if (ret != 0) {
+                return ret;
             }
+            ret = get_errno(safe_rt_sigsuspend(set, SIGSET_T_SIZE));
+            finish_sigsuspend_mask(ret);
         }
         return ret;
 #ifdef TARGET_NR_rt_sigtimedwait