parisc: split syscall_trace into two halves

Instead of fiddling with gr[20], restructure code to return whether
or not to -ENOSYS. (Also do a bit of fiddling to let them take
pt_regs directly instead of re-computing it.)

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

2 files changed, 25 insertions, 22 deletions

diff --git a/arch/parisc/kernel/ptrace.c b/arch/parisc/kernel/ptrace.c
index 2118ed02e886..08f6d2cbf0e0 100644
--- a/arch/parisc/kernel/ptrace.c
+++ b/arch/parisc/kernel/ptrace.c
@@ -264,20 +264,19 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 }
 #endif
 
+long do_syscall_trace_enter(struct pt_regs *regs)
+{
+        if (test_thread_flag(TIF_SYSCALL_TRACE) &&
+            tracehook_report_syscall_entry(regs))
+                return -1L;
+
+        return regs->gr[20];
+}
 
-void syscall_trace(int why)
+void do_syscall_trace_exit(struct pt_regs *regs)
 {
-        struct pt_regs *regs = &current->thread.regs;
+        int stepping = !!(current->ptrace & (PT_SINGLESTEP|PT_BLOCKSTEP));
 
-        if (!test_thread_flag(TIF_SYSCALL_TRACE))
-                return;
-        /*
-         * Report the system call for tracing.  Entry tracing can
-         * decide to abort the call.  We handle that by setting an
-         * invalid syscall number (-1) to force an ENOSYS error.
-         */
-        if (why)
-                tracehook_report_syscall_exit(regs, 0);
-        else if (tracehook_report_syscall_entry(regs))
-                regs->gr[20] = -1;      /* force ENOSYS */
+        if (stepping || test_thread_flag(TIF_SYSCALL_TRACE))
+                tracehook_report_syscall_exit(regs, stepping);
 }
diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S
index 07de1bbb69a5..f5f96021caa0 100644
--- a/arch/parisc/kernel/syscall.S
+++ b/arch/parisc/kernel/syscall.S
@@ -288,19 +288,23 @@ tracesys:
         STREG   %r18,PT_GR18(%r2)
         /* Finished saving things for the debugger */
 
-        ldi     0,%r26                          /* syscall entry */
-        ldil    L%syscall_trace,%r1
+        copy    %r2,%r26
+        ldil    L%do_syscall_trace_enter,%r1
         ldil    L%tracesys_next,%r2
-        be      R%syscall_trace(%sr7,%r1)
+        be      R%do_syscall_trace_enter(%sr7,%r1)
         ldo     R%tracesys_next(%r2),%r2
         
-tracesys_next:  
+tracesys_next:
+        /* do_syscall_trace_enter either returned the syscallno, or -1L,
+         *  so we skip restoring the PT_GR20 below, since we pulled it from
+         *  task->thread.regs.gr[20] above.
+         */
+        copy    %ret0,%r20
         ldil    L%sys_call_table,%r1
         ldo     R%sys_call_table(%r1), %r19
 
         ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */
         LDREG   TI_TASK(%r1), %r1
-        LDREG   TASK_PT_GR20(%r1), %r20
         LDREG   TASK_PT_GR26(%r1), %r26         /* Restore the users args */
         LDREG   TASK_PT_GR25(%r1), %r25
         LDREG   TASK_PT_GR24(%r1), %r24
@@ -337,8 +341,8 @@ tracesys_exit:
 #ifdef CONFIG_64BIT
         ldo     -16(%r30),%r29                  /* Reference param save area */
 #endif
-        ldi     1,%r26                          /* syscall exit */
-        bl      syscall_trace, %r2
+        ldo     TASK_REGS(%r1),%r26
+        bl      do_syscall_trace_exit,%r2
         STREG   %r28,TASK_PT_GR28(%r1)          /* save return value now */
         ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */
         LDREG   TI_TASK(%r1), %r1
@@ -359,8 +363,8 @@ tracesys_sigexit:
 #ifdef CONFIG_64BIT
         ldo     -16(%r30),%r29                  /* Reference param save area */
 #endif
-        bl      syscall_trace, %r2
-        ldi     1,%r26                          /* syscall exit */
+        bl      do_syscall_trace_exit,%r2
+        ldo     TASK_REGS(%r1),%r26
 
         ldil    L%syscall_exit_rfi,%r1
         be,n    R%syscall_exit_rfi(%sr7,%r1)