[PATCH v2 03/10] entry: Wire up syscall_work in common entry code

Gabriel Krisman Bertazi
2020-11-16T17:42:55Z

Prepare the common entry code to use the SYSCALL_WORK flags. They will
be defined in subsequent patches for each type of syscall
work. SYSCALL_WORK_ENTRY/EXIT are defined for the transition, as they
will replace the TIF_ equivalent defines.

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

---
Changes since v2:
- Fix subsystem prefix (tglx)
- Fix verb in commit message (tglx)
- Sort variable declaration (tglx)
---
include/linux/entry-common.h | 3 +++
kernel/entry/common.c | 15 +++++++++------
2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index 1a128baf3628..cbc5c702ee4d 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -64,6 +64,9 @@
(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
_TIF_SYSCALL_TRACEPOINT | ARCH_SYSCALL_EXIT_WORK)

+#define SYSCALL_WORK_ENTER (0)
+#define SYSCALL_WORK_EXIT (0)
+
/*
* TIF flags handled in exit_to_user_mode_loop()
*/
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index bc75c114c1b3..51c25f774791 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 ti_work, unsigned long work)
{
long ret = 0;

@@ -74,11 +74,12 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
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 (ti_work & SYSCALL_ENTER_WORK)
- syscall = syscall_trace_enter(regs, syscall, ti_work);
+ if (work & SYSCALL_WORK_ENTER || ti_work & SYSCALL_ENTER_WORK)
+ syscall = syscall_trace_enter(regs, syscall, ti_work, work);

return syscall;
}
@@ -225,7 +226,8 @@ static inline bool report_single_step(unsigned long ti_work)
}
#endif

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

@@ -245,6 +247,7 @@ 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);

@@ -262,8 +265,8 @@ 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(cached_flags & SYSCALL_EXIT_WORK))
- syscall_exit_work(regs, cached_flags);
+ if (unlikely(work & SYSCALL_WORK_EXIT || cached_flags & SYSCALL_EXIT_WORK))
+ syscall_exit_work(regs, cached_flags, work);
}

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