3 files changed, 34 insertions, 27 deletions

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index da52269aec1e..e6fca6a9014d 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -343,7 +343,12 @@ syscall_dotrace:
         stw     r0,_TRAP(r1)
         addi    r3,r1,STACK_FRAME_OVERHEAD
         bl      do_syscall_trace_enter
-        lwz     r0,GPR0(r1)     /* Restore original registers */
+        /*
+         * Restore argument registers possibly just changed.
+         * We use the return value of do_syscall_trace_enter
+         * for call number to look up in the table (r0).
+         */
+        mr      r0,r3
         lwz     r3,GPR3(r1)
         lwz     r4,GPR4(r1)
         lwz     r5,GPR5(r1)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index d7369243ae44..79c089e97ce4 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -214,7 +214,12 @@ syscall_dotrace:
         bl      .save_nvgprs
         addi    r3,r1,STACK_FRAME_OVERHEAD
         bl      .do_syscall_trace_enter
-        ld      r0,GPR0(r1)     /* Restore original registers */
+        /*
+         * Restore argument registers possibly just changed.
+         * We use the return value of do_syscall_trace_enter
+         * for the call number to look up in the table (r0).
+         */
+        mr      r0,r3
         ld      r3,GPR3(r1)
         ld      r4,GPR4(r1)
         ld      r5,GPR5(r1)
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 66204cb51a1a..6b66cd85b433 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -22,6 +22,7 @@
 #include <linux/errno.h>
 #include <linux/ptrace.h>
 #include <linux/regset.h>
+#include <linux/tracehook.h>
 #include <linux/elf.h>
 #include <linux/user.h>
 #include <linux/security.h>
@@ -1014,31 +1015,24 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
         return ret;
 }
 
-static void do_syscall_trace(void)
+/*
+ * We must return the syscall number to actually look up in the table.
+ * This can be -1L to skip running any syscall at all.
+ */
+long do_syscall_trace_enter(struct pt_regs *regs)
 {
-        /* the 0x80 provides a way for the tracing parent to distinguish
-           between a syscall stop and SIGTRAP delivery */
-        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
-         */
-        if (current->exit_code) {
-                send_sig(current->exit_code, current, 1);
-                current->exit_code = 0;
-        }
-}
+        long ret = 0;
 
-void do_syscall_trace_enter(struct pt_regs *regs)
-{
         secure_computing(regs->gpr[0]);
 
-        if (test_thread_flag(TIF_SYSCALL_TRACE)
-            && (current->ptrace & PT_PTRACED))
-                do_syscall_trace();
+        if (test_thread_flag(TIF_SYSCALL_TRACE) &&
+            tracehook_report_syscall_entry(regs))
+                /*
+                 * Tracing decided this syscall should not happen.
+                 * We'll return a bogus call number to get an ENOSYS
+                 * error, but leave the original number in regs->gpr[0].
+                 */
+                ret = -1L;
 
         if (unlikely(current->audit_context)) {
 #ifdef CONFIG_PPC64
@@ -1056,16 +1050,19 @@ void do_syscall_trace_enter(struct pt_regs *regs)
                                             regs->gpr[5] & 0xffffffff,
                                             regs->gpr[6] & 0xffffffff);
         }
+
+        return ret ?: regs->gpr[0];
 }
 
 void do_syscall_trace_leave(struct pt_regs *regs)
 {
+        int step;
+
         if (unlikely(current->audit_context))
                 audit_syscall_exit((regs->ccr&0x10000000)?AUDITSC_FAILURE:AUDITSC_SUCCESS,
                                    regs->result);
 
-        if ((test_thread_flag(TIF_SYSCALL_TRACE)
-             || test_thread_flag(TIF_SINGLESTEP))
-            && (current->ptrace & PT_PTRACED))
-                do_syscall_trace();
+        step = test_thread_flag(TIF_SINGLESTEP);
+        if (step || test_thread_flag(TIF_SYSCALL_TRACE))
+                tracehook_report_syscall_exit(regs, step);
 }