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Commit 64f09733 authored by Roland McGrath's avatar Roland McGrath
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x86 ptrace: unify TIF_SINGLESTEP 



This unifies the treatment of TIF_SINGLESTEP on i386 and x86_64.
The bit is now excluded from _TIF_WORK_MASK on i386 as it has been
on x86_64.  This means the do_notify_resume() path using it is never
used, so TIF_SINGLESTEP is not cleared on returning to user mode.

Both now leave TIF_SINGLESTEP set when returning to user, so that
it's already set on an int $0x80 system call entry.  This removes
the need for testing TF on the system_call path.  Doing it this way
fixes the regression for PTRACE_SINGLESTEP into a sigreturn syscall,
introduced by commit 1e2e99f0.

The clear_TF_reenable case that sets TIF_SINGLESTEP can only happen
on a non-exception kernel entry, i.e. sysenter/syscall instruction.
That will always get to the syscall exit tracing path.

Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
parent 6718d0d6

arch/x86/kernel/entry_32.S

+0 −4
Original line number Diff line number Diff line
@@ -383,10 +383,6 @@ syscall_exit: 
					# setting need_resched or sigpending

					# between sampling and the iret

	TRACE_IRQS_OFF

	testl $X86_EFLAGS_TF,PT_EFLAGS(%esp)	# If tracing set singlestep flag on exit

	jz no_singlestep

	orl $_TIF_SINGLESTEP,TI_flags(%ebp)

no_singlestep:

	movl TI_flags(%ebp), %ecx

	testw $_TIF_ALLWORK_MASK, %cx	# current->work

	jne syscall_exit_work

arch/x86/kernel/signal_32.c

+0 −6
Original line number Diff line number Diff line
@@ -657,12 +657,6 @@ static void do_signal(struct pt_regs *regs) 
void

do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)

{

	/* Pending single-step? */

	if (thread_info_flags & _TIF_SINGLESTEP) {

		regs->flags |= X86_EFLAGS_TF;

		clear_thread_flag(TIF_SINGLESTEP);

	}



	/* deal with pending signal delivery */

	if (thread_info_flags & _TIF_SIGPENDING)

		do_signal(regs);

arch/x86/kernel/signal_64.c

+0 −6
Original line number Diff line number Diff line
@@ -487,12 +487,6 @@ static void do_signal(struct pt_regs *regs) 
void do_notify_resume(struct pt_regs *regs, void *unused,

		      __u32 thread_info_flags)

{

	/* Pending single-step? */

	if (thread_info_flags & _TIF_SINGLESTEP) {

		regs->flags |= X86_EFLAGS_TF;

		clear_thread_flag(TIF_SINGLESTEP);

	}



#ifdef CONFIG_X86_MCE

	/* notify userspace of pending MCEs */

	if (thread_info_flags & _TIF_MCE_NOTIFY)

include/asm-x86/thread_info.h

+2 −2
Original line number Diff line number Diff line
@@ -124,7 +124,7 @@ struct thread_info { 
/* work to do on interrupt/exception return */

#define _TIF_WORK_MASK							\

	(0x0000FFFF &							\

	 ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP|	\

	 ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|			\

	 _TIF_SECCOMP|_TIF_SYSCALL_EMU))



/* work to do on any return to user space */
@@ -132,7 +132,7 @@ struct thread_info { 


/* Only used for 64 bit */

#define _TIF_DO_NOTIFY_MASK						\

	(_TIF_SIGPENDING|_TIF_SINGLESTEP|_TIF_MCE_NOTIFY|_TIF_HRTICK_RESCHED)

	(_TIF_SIGPENDING|_TIF_MCE_NOTIFY|_TIF_HRTICK_RESCHED)



/* flags to check in __switch_to() */

#define _TIF_WORK_CTXSW							\