RE: [patch 2/4] ia64 use trace hook

["Luck, Tony" <tony.luck@xxxxxxxxx>]

>      Note that the calling arch code should handle the return value from
>      tracehook_report_syscall_entry(), which is behavior that was not
>      required for the old ptrace support. This needs to implement some
>      form of safe abort of the syscall. See the kerneldoc comments for the
>      exact details.

I think this patch meets this requirement.  The 2.6.27 version of
tracehook_report_syscall_entry() always returns 0 ... so the error
code paths are untested.

-Tony

---

diff --git a/arch/ia64/ia32/ia32_entry.S b/arch/ia64/ia32/ia32_entry.S
index 1fabfb7..a73ec00 100644
--- a/arch/ia64/ia32/ia32_entry.S
+++ b/arch/ia64/ia32/ia32_entry.S
@@ -108,6 +108,11 @@ GLOBAL_ENTRY(ia32_trace_syscall)
 	;;
 	st8 [r2]=r3				// initialize return code to -ENOSYS
 	br.call.sptk.few rp=syscall_trace_enter	// give parent a chance to catch syscall args
+	cmp.lt p6,p0=r8,r0			// check tracehook
+	adds r2=IA64_PT_REGS_R8_OFFSET+16,sp	// r2 = &pt_regs.r8
+	;;
+(p6)	st8.spill [r2]=r8			// store return value in slot for r8
+(p6)	br.spnt.few .ret4
 .ret2:	// Need to reload arguments (they may be changed by the tracing process)
 	adds r2=IA64_PT_REGS_R1_OFFSET+16,sp	// r2 = &pt_regs.r1
 	adds r3=IA64_PT_REGS_R13_OFFSET+16,sp	// r3 = &pt_regs.r13
diff --git a/arch/ia64/kernel/entry.S b/arch/ia64/kernel/entry.S
index 0dd6c14..7ef0c59 100644
--- a/arch/ia64/kernel/entry.S
+++ b/arch/ia64/kernel/entry.S
@@ -534,6 +534,11 @@ GLOBAL_ENTRY(ia64_trace_syscall)
  	stf.spill [r16]=f10
  	stf.spill [r17]=f11
 	br.call.sptk.many rp=syscall_trace_enter // give parent a chance to catch syscall args
+	cmp.lt p6,p0=r8,r0			// check tracehook
+	adds r2=PT(R8)+16,sp			// r2 = &pt_regs.r8
+	adds r3=PT(R10)+16,sp			// r3 = &pt_regs.r10
+	mov r10=0
+(p6)	br.cond.sptk strace_error		// syscall failed ->
 	adds r16=PT(F6)+16,sp
 	adds r17=PT(F7)+16,sp
 	;;
diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c
index 475bfe1..ba72f15 100644
--- a/arch/ia64/kernel/ptrace.c
+++ b/arch/ia64/kernel/ptrace.c
@@ -1234,13 +1234,14 @@ arch_ptrace (struct task_struct *child, long request, long addr, long data)
 
 /* "asmlinkage" so the input arguments are preserved... */
 
-asmlinkage void
+asmlinkage int
 syscall_trace_enter (long arg0, long arg1, long arg2, long arg3,
 		     long arg4, long arg5, long arg6, long arg7,
 		     struct pt_regs regs)
 {
 	if (test_thread_flag(TIF_SYSCALL_TRACE))
-		tracehook_report_syscall_entry(&regs);
+		if (tracehook_report_syscall_entry(&regs))
+			return -ENOSYS;
 
 	/* copy user rbs to kernel rbs */
 	if (test_thread_flag(TIF_RESTORE_RSE))
@@ -1261,6 +1262,7 @@ syscall_trace_enter (long arg0, long arg1, long arg2, long arg3,
 		audit_syscall_entry(arch, syscall, arg0, arg1, arg2, arg3);
 	}
 
+	return 0;
 }
 
 /* "asmlinkage" so the input arguments are preserved... */
--
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