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| author | Roland McGrath <roland@redhat.com> | 2008-03-16 21:59:11 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-04-17 17:41:13 +0200 |
| commit | a31f8dd7ee3b2f5645c220406b1e21f82971f32b (patch) | |
| tree | bb8904f23fbb9db5d34558cbe3b61bc3511ea249 | |
| parent | 8ab32bb89b5b9bf06147c31947eba65f0f21c3c0 (diff) | |
| download | linux-a31f8dd7ee3b2f5645c220406b1e21f82971f32b.tar.gz | |
x86: ptrace vs -ENOSYS
When we're stopped at syscall entry tracing, ptrace can change the %rax value from -ENOSYS to something else. If no system call is actually made because the syscall number (now in orig_rax) is bad, then we now always reset %rax to -ENOSYS again. This changes it to leave the return value alone after entry tracing. That way, the %rax value set by ptrace is there to be seen in user mode (or in syscall exit tracing). This is consistent with what the 32-bit kernel does. Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | arch/x86/kernel/entry_64.S | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index c20c9e7e08dd..556a8df522a7 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -319,19 +319,17 @@ badsys: /* Do syscall tracing */ tracesys: SAVE_REST - movq $-ENOSYS,RAX(%rsp) + movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */ FIXUP_TOP_OF_STACK %rdi movq %rsp,%rdi call syscall_trace_enter LOAD_ARGS ARGOFFSET /* reload args from stack in case ptrace changed it */ RESTORE_REST cmpq $__NR_syscall_max,%rax - movq $-ENOSYS,%rcx - cmova %rcx,%rax - ja 1f + ja int_ret_from_sys_call /* RAX(%rsp) set to -ENOSYS above */ movq %r10,%rcx /* fixup for C */ call *sys_call_table(,%rax,8) -1: movq %rax,RAX-ARGOFFSET(%rsp) + movq %rax,RAX-ARGOFFSET(%rsp) /* Use IRET because user could have changed frame */ /* |