powerpc: Make syscall tracing use tracehook.h helpers

This changes powerpc syscall tracing to use the new tracehook.h entry
points.  There is no change, only cleanup.

In addition, the assembly changes allow do_syscall_trace_enter() to
abort the syscall without losing the information about the original
r0 value.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index da52269aec1e86fc05a2e1fb79d46dcc0b846a88..e6fca6a9014d172864b4d6b393132ca4f0369a55 100644 (file)
--- 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 d7369243ae44ab3aa0e12fcec3db30ae717677c2..79c089e97ce4a595ed60e7131e3e39fe366966e9 100644 (file)
--- 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 66204cb51a1aaae8ca95fb7d01e2a9de144dd123..6b66cd85b433ce8c296848f42e77ae5e18bcca87 100644 (file)
--- 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);
 }