parisc: fix double restarts

Don't bother restoring r28 on syscall restarts; it's clobbered by
syscall anyway.  Reuse (now unused) ->orig_r28 as "no restarts allowed"
flag.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 10 insertions, 10 deletions

diff --git a/arch/parisc/hpux/gate.S b/arch/parisc/hpux/gate.S
index 38a1c1b8d4e8..011468857e98 100644
--- a/arch/parisc/hpux/gate.S
+++ b/arch/parisc/hpux/gate.S
@@ -71,7 +71,7 @@ ENTRY(hpux_gateway_page)
         STREG   %r26, TASK_PT_GR26(%r1)         /* 1st argument */
         STREG   %r27, TASK_PT_GR27(%r1)         /* user dp */
         STREG   %r28, TASK_PT_GR28(%r1)         /* return value 0 */
-        STREG   %r28, TASK_PT_ORIG_R28(%r1)     /* return value 0 (saved for signals) */
+        STREG   %r0, TASK_PT_ORIG_R28(%r1)     /* don't prohibit restarts */
         STREG   %r29, TASK_PT_GR29(%r1)         /* 8th argument */
         STREG   %r31, TASK_PT_GR31(%r1)         /* preserve syscall return ptr */
         
diff --git a/arch/parisc/kernel/signal.c b/arch/parisc/kernel/signal.c
index 594459bde14e..3790a3237172 100644
--- a/arch/parisc/kernel/signal.c
+++ b/arch/parisc/kernel/signal.c
@@ -113,6 +113,8 @@ sys_rt_sigreturn(struct pt_regs *regs, int in_syscall)
                 (usp - sigframe_size);
         DBG(2,"sys_rt_sigreturn: frame is %p\n", frame);
 
+        regs->orig_r28 = 1; /* no restarts for sigreturn */
+
 #ifdef CONFIG_64BIT
         compat_frame = (struct compat_rt_sigframe __user *)frame;
         
@@ -462,6 +464,9 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 static inline void
 syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
 {
+        if (regs->orig_r28)
+                return;
+        regs->orig_r28 = 1; /* no more restarts */
         /* Check the return code */
         switch (regs->gr[28]) {
         case -ERESTART_RESTARTBLOCK:
@@ -482,8 +487,6 @@ syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
                  * we have to do is fiddle the return pointer.
                  */
                 regs->gr[31] -= 8; /* delayed branching */
-                /* Preserve original r28. */
-                regs->gr[28] = regs->orig_r28;
                 break;
         }
 }
@@ -491,6 +494,9 @@ syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
 static inline void
 insert_restart_trampoline(struct pt_regs *regs)
 {
+        if (regs->orig_r28)
+                return;
+        regs->orig_r28 = 1; /* no more restarts */
         switch(regs->gr[28]) {
         case -ERESTART_RESTARTBLOCK: {
                 /* Restart the system call - no handlers present */
@@ -525,9 +531,6 @@ insert_restart_trampoline(struct pt_regs *regs)
                 flush_user_icache_range(regs->gr[30], regs->gr[30] + 4);
 
                 regs->gr[31] = regs->gr[30] + 8;
-                /* Preserve original r28. */
-                regs->gr[28] = regs->orig_r28;
-
                 return;
         }
         case -ERESTARTNOHAND:
@@ -539,9 +542,6 @@ insert_restart_trampoline(struct pt_regs *regs)
                  * slot of the branch external instruction.
                  */
                 regs->gr[31] -= 8;
-                /* Preserve original r28. */
-                regs->gr[28] = regs->orig_r28;
-
                 return;
         }
         default:
diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S
index 82a52b2fb13f..54a9cbfc08ad 100644
--- a/arch/parisc/kernel/syscall.S
+++ b/arch/parisc/kernel/syscall.S
@@ -156,7 +156,7 @@ linux_gateway_entry:
         STREG   %r26, TASK_PT_GR26(%r1)         /* 1st argument */
         STREG   %r27, TASK_PT_GR27(%r1)         /* user dp */
         STREG   %r28, TASK_PT_GR28(%r1)         /* return value 0 */
-        STREG   %r28, TASK_PT_ORIG_R28(%r1)     /* return value 0 (saved for signals) */
+        STREG   %r0, TASK_PT_ORIG_R28(%r1)      /* don't prohibit restarts */
         STREG   %r29, TASK_PT_GR29(%r1)         /* return value 1 */
         STREG   %r31, TASK_PT_GR31(%r1)         /* preserve syscall return ptr */