parisc: Fix ptrace syscall number modification

[uclinux-h8/linux.git] / arch / parisc / kernel / ptrace.c

diff --git a/arch/parisc/kernel/ptrace.c b/arch/parisc/kernel/ptrace.c
index 2582df1..0964c23 100644 (file)
--- a/arch/parisc/kernel/ptrace.c
+++ b/arch/parisc/kernel/ptrace.c
@@ -308,15 +308,29 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 
 long do_syscall_trace_enter(struct pt_regs *regs)
 {
-       if (test_thread_flag(TIF_SYSCALL_TRACE) &&
-           tracehook_report_syscall_entry(regs)) {
+       if (test_thread_flag(TIF_SYSCALL_TRACE)) {
+               int rc = tracehook_report_syscall_entry(regs);
+
                /*
-                * Tracing decided this syscall should not happen or the
-                * debugger stored an invalid system call number. Skip
-                * the system call and the system call restart handling.
+                * As tracesys_next does not set %r28 to -ENOSYS
+                * when %r20 is set to -1, initialize it here.
                 */
-               regs->gr[20] = -1UL;
-               goto out;
+               regs->gr[28] = -ENOSYS;
+
+               if (rc) {
+                       /*
+                        * A nonzero return code from
+                        * tracehook_report_syscall_entry() tells us
+                        * to prevent the syscall execution.  Skip
+                        * the syscall call and the syscall restart handling.
+                        *
+                        * Note that the tracer may also just change
+                        * regs->gr[20] to an invalid syscall number,
+                        * that is handled by tracesys_next.
+                        */
+                       regs->gr[20] = -1UL;
+                       return -1;
+               }
        }
 
        /* Do the secure computing check after ptrace. */
@@ -340,7 +354,6 @@ long do_syscall_trace_enter(struct pt_regs *regs)
                        regs->gr[24] & 0xffffffff,
                        regs->gr[23] & 0xffffffff);
 
-out:
        /*
         * Sign extend the syscall number to 64bit since it may have been
         * modified by a compat ptrace call