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Commit 8ab32bb8 authored by Roland McGrath's avatar Roland McGrath Committed by Ingo Molnar
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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: default avatarRoland McGrath <roland@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ede1389f

arch/x86/ia32/ia32entry.S

+2 −2
Original line number Diff line number Diff line
@@ -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 */