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Subject[PATCH 4.9 002/167] ptrace/xtensa: Replace PT_SINGLESTEP with TIF_SINGLESTEP
Date
From: Eric W. Biederman <ebiederm@xmission.com>

commit 4a3d2717d140401df7501a95e454180831a0c5af upstream.

xtensa is the last user of the PT_SINGLESTEP flag. Changing tsk->ptrace in
user_enable_single_step and user_disable_single_step without locking could
potentiallly cause problems.

So use a thread info flag instead of a flag in tsk->ptrace. Use TIF_SINGLESTEP
that xtensa already had defined but unused.

Remove the definitions of PT_SINGLESTEP and PT_BLOCKSTEP as they have no more users.

Cc: stable@vger.kernel.org
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lkml.kernel.org/r/20220505182645.497868-4-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/xtensa/kernel/ptrace.c | 4 ++--
arch/xtensa/kernel/signal.c | 4 ++--
include/linux/ptrace.h | 6 ------
3 files changed, 4 insertions(+), 10 deletions(-)

--- a/arch/xtensa/kernel/ptrace.c
+++ b/arch/xtensa/kernel/ptrace.c
@@ -34,12 +34,12 @@

void user_enable_single_step(struct task_struct *child)
{
- child->ptrace |= PT_SINGLESTEP;
+ set_tsk_thread_flag(child, TIF_SINGLESTEP);
}

void user_disable_single_step(struct task_struct *child)
{
- child->ptrace &= ~PT_SINGLESTEP;
+ clear_tsk_thread_flag(child, TIF_SINGLESTEP);
}

/*
--- a/arch/xtensa/kernel/signal.c
+++ b/arch/xtensa/kernel/signal.c
@@ -458,7 +458,7 @@ static void do_signal(struct pt_regs *re
/* Set up the stack frame */
ret = setup_frame(&ksig, sigmask_to_save(), regs);
signal_setup_done(ret, &ksig, 0);
- if (current->ptrace & PT_SINGLESTEP)
+ if (test_thread_flag(TIF_SINGLESTEP))
task_pt_regs(current)->icountlevel = 1;

return;
@@ -484,7 +484,7 @@ static void do_signal(struct pt_regs *re
/* If there's no signal to deliver, we just restore the saved mask. */
restore_saved_sigmask();

- if (current->ptrace & PT_SINGLESTEP)
+ if (test_thread_flag(TIF_SINGLESTEP))
task_pt_regs(current)->icountlevel = 1;
return;
}
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -38,12 +38,6 @@ extern int ptrace_access_vm(struct task_
#define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
#define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)

-/* single stepping state bits (used on ARM and PA-RISC) */
-#define PT_SINGLESTEP_BIT 31
-#define PT_SINGLESTEP (1<<PT_SINGLESTEP_BIT)
-#define PT_BLOCKSTEP_BIT 30
-#define PT_BLOCKSTEP (1<<PT_BLOCKSTEP_BIT)
-
extern long arch_ptrace(struct task_struct *child, long request,
unsigned long addr, unsigned long data);
extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);

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