[PATCH v4 2/4] x86: simplify _TIF_SYSCALL_EMU handling

From: Sudeep Holla
Date: Thu May 23 2019 - 05:09:28 EST


The usage of emulated/_TIF_SYSCALL_EMU flags in syscall_trace_enter
seems to be bit overcomplicated than required. Let's simplify it.

Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
---
arch/x86/entry/common.c | 17 ++++++-----------
1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index a986b3c8294c..0a61705d62ec 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -72,23 +72,18 @@ static long syscall_trace_enter(struct pt_regs *regs)

struct thread_info *ti = current_thread_info();
unsigned long ret = 0;
- bool emulated = false;
u32 work;

if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
BUG_ON(regs != task_pt_regs(current));

- work = READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY;
+ work = READ_ONCE(ti->flags);

- if (unlikely(work & _TIF_SYSCALL_EMU))
- emulated = true;
-
- if ((emulated || (work & _TIF_SYSCALL_TRACE)) &&
- tracehook_report_syscall_entry(regs))
- return -1L;
-
- if (emulated)
- return -1L;
+ if (work & (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU)) {
+ ret = tracehook_report_syscall_entry(regs);
+ if (ret || (work & _TIF_SYSCALL_EMU))
+ return -1L;
+ }

#ifdef CONFIG_SECCOMP
/*
--
2.17.1