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x86: ia32 ptrace vs -ENOSYS 

When we're stopped at syscall entry tracing, ptrace can change the %eax
value from -ENOSYS to something else.  If no system call is actually made
because the syscall number (now in orig_eax) is bad, then the %eax value
set by ptrace should be returned to the user.  But, instead it gets reset
to -ENOSYS again.  This is a regression from the native 32-bit kernel.

This change fixes it by leaving the return value alone after entry tracing.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Roland McGrath 2008-03-16 21:57:41 -07:00 committed by Ingo Molnar
parent ede1389f8a
commit 8ab32bb89b
1 changed files with 2 additions and 2 deletions
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4
arch/x86/ia32/ia32entry.S
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@ -325,7 +325,7 @@ ENTRY(ia32_syscall)
jnz ia32_tracesys
ia32_do_syscall:
cmpl $(IA32_NR_syscalls-1),%eax
ja ia32_badsys
ja int_ret_from_sys_call /* ia32_tracesys has set RAX(%rsp) */
IA32_ARG_FIXUP
call *ia32_sys_call_table(,%rax,8) # xxx: rip relative
ia32_sysret:
@ -335,7 +335,7 @@ ia32_sysret:
ia32_tracesys:
SAVE_REST
CLEAR_RREGS
movq $-ENOSYS,RAX(%rsp) /* really needed? */
movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */
movq %rsp,%rdi /* &pt_regs -> arg1 */
call syscall_trace_enter
LOAD_ARGS32 ARGOFFSET /* reload args from stack in case ptrace changed it */