[PATCH 1/6] ptrace: move clearing of TIF_SYSCALL_EMU flag to core

Sudeep Holla
2019-02-28T18:32:51Z

While the TIF_SYSCALL_EMU is set in ptrace_resume independent of any
architecture, currently only powerpc and x86 unset the TIF_SYSCALL_EMU
flag in ptrace_disable which gets called from ptrace_detach.

Let's move the clearing of TIF_SYSCALL_EMU flag to ptrace_detach after
we return from ptrace_disable to ensure there's no change in the flow.

Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
arch/powerpc/kernel/ptrace.c | 1 -
arch/x86/kernel/ptrace.c | 3 ---
kernel/ptrace.c | 4 ++++
3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index cdd5d1d3ae41..cb7e1439cafb 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -2508,7 +2508,6 @@ void ptrace_disable(struct task_struct *child)
{
/* make sure the single step bit is not set. */
user_disable_single_step(child);
- clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
}

#ifdef CONFIG_PPC_ADV_DEBUG_REGS
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 4b8ee05dd6ad..45792dbd2443 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -746,9 +746,6 @@ static int ioperm_get(struct task_struct *target,
void ptrace_disable(struct task_struct *child)
{
user_disable_single_step(child);
-#ifdef TIF_SYSCALL_EMU
- clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
-#endif
}

#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 771e93f9c43f..4fa3b7f4c3c7 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -534,6 +534,10 @@ static int ptrace_detach(struct task_struct *child, unsigned int data)
/* Architecture-specific hardware disable .. */
ptrace_disable(child);

+#ifdef TIF_SYSCALL_EMU
+ clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+#endif
+
write_lock_irq(&tasklist_lock);
/*
* We rely on ptrace_freeze_traced(). It can't be killed and
--
2.17.1