parisc: tracehook_report_syscall

This makes parisc use the standard tracehook_report_syscall_entry
and tracehook_report_syscall_exit hooks in <linux/tracehook.h>.

To do this, we need to access current->thread.regs, and to know
whether we're entering or exiting the syscall, so add this to
syscall_trace.
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

arch/parisc/kernel/ptrace.c

@@ -13,6 +13,7 @@
 #include <linux/smp.h>
 #include <linux/errno.h>
 #include <linux/ptrace.h>
+#include <linux/tracehook.h>
 #include <linux/user.h>
 #include <linux/personality.h>
 #include <linux/security.h>
@@ -264,21 +265,19 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 #endif
 
 
-void syscall_trace(void)
+void syscall_trace(int why)
 {
+	struct pt_regs *regs = &current->thread.regs;
+
 	if (!test_thread_flag(TIF_SYSCALL_TRACE))
 		return;
-	if (!(current->ptrace & PT_PTRACED))
-		return;
-	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
-				 ? 0x80 : 0));
 	/*
-	 * this isn't the same as continuing with a signal, but it will do
-	 * for normal use.  strace only continues with a signal if the
-	 * stopping signal is not SIGTRAP.  -brl
+	 * 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 (current->exit_code) {
-		send_sig(current->exit_code, current, 1);
-		current->exit_code = 0;
-	}
+	if (why)
+		tracehook_report_syscall_exit(regs, 0);
+	else if (tracehook_report_syscall_entry(regs))
+		regs->gr[20] = -1;	/* force ENOSYS */
 }

arch/parisc/kernel/syscall.S

@@ -288,6 +288,7 @@ tracesys:
 	STREG	%r18,PT_GR18(%r2)
 	/* Finished saving things for the debugger */
 
+	ldi	0,%r26				/* syscall entry */
 	ldil	L%syscall_trace,%r1
 	ldil	L%tracesys_next,%r2
 	be	R%syscall_trace(%sr7,%r1)
@@ -336,6 +337,7 @@ tracesys_exit:
 #ifdef CONFIG_64BIT
 	ldo	-16(%r30),%r29			/* Reference param save area */
 #endif
+	ldi	1,%r26				/* syscall exit */
 	bl	syscall_trace, %r2
 	STREG   %r28,TASK_PT_GR28(%r1)          /* save return value now */
 	ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */
@@ -358,7 +360,7 @@ tracesys_sigexit:
 	ldo	-16(%r30),%r29			/* Reference param save area */
 #endif
 	bl	syscall_trace, %r2
-	nop
+	ldi	1,%r26				/* syscall exit */
 
 	ldil	L%syscall_exit_rfi,%r1
 	be,n	R%syscall_exit_rfi(%sr7,%r1)