[PATCH v2 09/10] entry: Drop usage of TIF flags in the generic syscall code

Gabriel Krisman Bertazi
2020-11-16T17:42:57Z

Now that the flags migration in the common syscall entry is complete and
the code relies exclusively on syscall_work, clean up the
accesses to TI flags in that path.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v2:
- Fix subsystem prefix (tglx)
---
include/linux/entry-common.h | 20 +++++++++-----------
kernel/entry/common.c | 17 +++++++----------
2 files changed, 16 insertions(+), 21 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index afeb927e8545..cffd8bf1e085 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -26,31 +26,29 @@
#endif

/*
- * TIF flags handled in syscall_enter_from_user_mode()
+ * SYSCALL_WORK flags handled in syscall_enter_from_user_mode()
*/
-#ifndef ARCH_SYSCALL_ENTER_WORK
-# define ARCH_SYSCALL_ENTER_WORK (0)
+#ifndef ARCH_SYSCALL_WORK_ENTER
+# define ARCH_SYSCALL_WORK_ENTER (0)
#endif

-#define SYSCALL_ENTER_WORK ARCH_SYSCALL_ENTER_WORK
-
/*
* TIF flags handled in syscall_exit_to_user_mode()
*/
-#ifndef ARCH_SYSCALL_EXIT_WORK
-# define ARCH_SYSCALL_EXIT_WORK (0)
+#ifndef ARCH_SYSCALL_WORK_EXIT
+# define ARCH_SYSCALL_WORK_EXIT (0)
#endif

-#define SYSCALL_EXIT_WORK ARCH_SYSCALL_EXIT_WORK
-
#define SYSCALL_WORK_ENTER (SYSCALL_WORK_SECCOMP | \
SYSCALL_WORK_SYSCALL_TRACEPOINT | \
SYSCALL_WORK_SYSCALL_TRACE | \
SYSCALL_WORK_SYSCALL_EMU | \
- SYSCALL_WORK_SYSCALL_AUDIT)
+ SYSCALL_WORK_SYSCALL_AUDIT | \
+ ARCH_SYSCALL_WORK_ENTER)
#define SYSCALL_WORK_EXIT (SYSCALL_WORK_SYSCALL_TRACEPOINT | \
SYSCALL_WORK_SYSCALL_TRACE | \
- SYSCALL_WORK_SYSCALL_AUDIT)
+ SYSCALL_WORK_SYSCALL_AUDIT | \
+ ARCH_SYSCALL_WORK_EXIT)

/*
* TIF flags handled in exit_to_user_mode_loop()
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index a7233cca01ba..61b6936a0623 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -42,7 +42,7 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
}

static long syscall_trace_enter(struct pt_regs *regs, long syscall,
- unsigned long ti_work, unsigned long work)
+ unsigned long work)
{
long ret = 0;

@@ -75,11 +75,9 @@ static __always_inline long
__syscall_enter_from_user_work(struct pt_regs *regs, long syscall)
{
unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
- unsigned long ti_work;

- ti_work = READ_ONCE(current_thread_info()->flags);
- if (work & SYSCALL_WORK_ENTER || ti_work & SYSCALL_ENTER_WORK)
- syscall = syscall_trace_enter(regs, syscall, ti_work, work);
+ if (work & SYSCALL_WORK_ENTER)
+ syscall = syscall_trace_enter(regs, syscall, work);

return syscall;
}
@@ -227,8 +225,8 @@ static inline bool report_single_step(unsigned long work)
}
#endif

-static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work,
- unsigned long work)
+
+static void syscall_exit_work(struct pt_regs *regs, unsigned long work)
{
bool step;

@@ -249,7 +247,6 @@ static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work,
static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
{
unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
- u32 cached_flags = READ_ONCE(current_thread_info()->flags);
unsigned long nr = syscall_get_nr(current, regs);

CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
@@ -266,8 +263,8 @@ static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
* enabled, we want to run them exactly once per syscall exit with
* interrupts enabled.
*/
- if (unlikely(work & SYSCALL_WORK_EXIT || cached_flags & SYSCALL_EXIT_WORK))
- syscall_exit_work(regs, cached_flags, work);
+ if (unlikely(work & SYSCALL_WORK_EXIT))
+ syscall_exit_work(regs, work);
}

__visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs)
--
2.29.2