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x86 ptrace: unify TIF_SINGLESTEP

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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 1e2e99f0e4.

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: Roland McGrath <roland@redhat.com>
This commit is contained in:
Roland McGrath 2008-07-09 01:33:14 -07:00
parent 6718d0d6da
commit 64f0973319
4 changed files with 2 additions and 18 deletions
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4
arch/x86/kernel/entry_32.S
View File

@ -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

6
arch/x86/kernel/signal_32.c
View File

@ -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);

6
arch/x86/kernel/signal_64.c
View File

@ -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)

4
include/asm-x86/thread_info.h
View File

@ -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 \