[PATCH v4 1/4] ptrace: move clearing of TIF_SYSCALL_EMU flag to core

From: Sudeep Holla
Date: Thu May 23 2019 - 05:09:25 EST


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_unlink
which gets executed from ptrace_detach and also keep it along with
or close to clearing of TIF_SYSCALL_TRACE.

Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
---
arch/powerpc/kernel/ptrace.c | 1 -
arch/x86/kernel/ptrace.c | 3 ---
kernel/ptrace.c | 3 +++
3 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 684b0b315c32..8c92febf5f44 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -2521,7 +2521,6 @@ 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 6f357f4fc859..16c7fc1eabcf 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -117,6 +117,9 @@ void __ptrace_unlink(struct task_struct *child)
BUG_ON(!child->ptrace);

clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+#ifdef TIF_SYSCALL_EMU
+ clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+#endif

child->parent = child->real_parent;
list_del_init(&child->ptrace_entry);
--
2.17.1