[tip: core/entry] tracepoints: Migrate to use SYSCALL_WORK flag

tip-bot2 for Gabriel Krisman Bertazi
2020-11-16T21:11:59Z

The following commit has been merged into the core/entry branch of tip:

Commit-ID: 524666cb5de7c38a1925e7401a6e59d68682dd8c
Gitweb: https://git.kernel.org/tip/524666cb5de7c38a1925e7401a6e59d68682dd8c
Author: Gabriel Krisman Bertazi <krisman@collabora.com>
AuthorDate: Mon, 16 Nov 2020 12:42:01 -05:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 16 Nov 2020 21:53:15 +01:00

tracepoints: Migrate to use SYSCALL_WORK flag

On architectures using the generic syscall entry code the architecture
independent syscall work is moved to flags in thread_info::syscall_work.
This removes architecture dependencies and frees up TIF bits.

Define SYSCALL_WORK_SYSCALL_TRACEPOINT, use it in the generic entry code
and convert the code which uses the TIF specific helper functions to use
the new *_syscall_work() helpers which either resolve to the new mode for
users of the generic entry code or to the TIF based functions for the other
architectures.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20201116174206.2639648-6-krisman@collabora.com
---
include/linux/entry-common.h | 13 +++++--------
include/linux/thread_info.h | 2 ++
include/trace/syscall.h | 6 +++---
kernel/entry/common.c | 4 ++--
kernel/trace/trace_events.c | 8 ++++----
kernel/tracepoint.c | 4 ++--
6 files changed, 18 insertions(+), 19 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index fa3cdb1..2a01eee 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -17,10 +17,6 @@
# define _TIF_SYSCALL_EMU (0)
#endif

-#ifndef _TIF_SYSCALL_TRACEPOINT
-# define _TIF_SYSCALL_TRACEPOINT (0)
-#endif
-
#ifndef _TIF_SYSCALL_AUDIT
# define _TIF_SYSCALL_AUDIT (0)
#endif
@@ -46,7 +42,7 @@

#define SYSCALL_ENTER_WORK \
(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
- _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_EMU | \
+ _TIF_SYSCALL_EMU | \
ARCH_SYSCALL_ENTER_WORK)

/*
@@ -58,10 +54,11 @@

#define SYSCALL_EXIT_WORK \
(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
- _TIF_SYSCALL_TRACEPOINT | ARCH_SYSCALL_EXIT_WORK)
+ ARCH_SYSCALL_EXIT_WORK)

-#define SYSCALL_WORK_ENTER (SYSCALL_WORK_SECCOMP)
-#define SYSCALL_WORK_EXIT (0)
+#define SYSCALL_WORK_ENTER (SYSCALL_WORK_SECCOMP | \
+ SYSCALL_WORK_SYSCALL_TRACEPOINT)
+#define SYSCALL_WORK_EXIT (SYSCALL_WORK_SYSCALL_TRACEPOINT)

/*
* TIF flags handled in exit_to_user_mode_loop()
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index a308ba4..c232043 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -37,9 +37,11 @@ enum {

enum syscall_work_bit {
SYSCALL_WORK_BIT_SECCOMP,
+ SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT,
};

#define SYSCALL_WORK_SECCOMP BIT(SYSCALL_WORK_BIT_SECCOMP)
+#define SYSCALL_WORK_SYSCALL_TRACEPOINT BIT(SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT)

#include <asm/thread_info.h>

diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index dc8ac27..8e193f3 100644
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -37,10 +37,10 @@ struct syscall_metadata {
#if defined(CONFIG_TRACEPOINTS) && defined(CONFIG_HAVE_SYSCALL_TRACEPOINTS)
static inline void syscall_tracepoint_update(struct task_struct *p)
{
- if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
- set_tsk_thread_flag(p, TIF_SYSCALL_TRACEPOINT);
+ if (test_syscall_work(SYSCALL_TRACEPOINT))
+ set_task_syscall_work(p, SYSCALL_TRACEPOINT);
else
- clear_tsk_thread_flag(p, TIF_SYSCALL_TRACEPOINT);
+ clear_task_syscall_work(p, SYSCALL_TRACEPOINT);
}
#else
static inline void syscall_tracepoint_update(struct task_struct *p)
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 5747a6e..f651967 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -63,7 +63,7 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
/* Either of the above might have changed the syscall number */
syscall = syscall_get_nr(current, regs);

- if (unlikely(ti_work & _TIF_SYSCALL_TRACEPOINT))
+ if (unlikely(work & SYSCALL_WORK_SYSCALL_TRACEPOINT))
trace_sys_enter(regs, syscall);

syscall_enter_audit(regs, syscall);
@@ -233,7 +233,7 @@ static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work,

audit_syscall_exit(regs);

- if (ti_work & _TIF_SYSCALL_TRACEPOINT)
+ if (work & SYSCALL_WORK_SYSCALL_TRACEPOINT)
trace_sys_exit(regs, syscall_get_return_value(current, regs));

step = report_single_step(ti_work);
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 47a71f9..adf65b5 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -3428,10 +3428,10 @@ static __init int event_trace_enable(void)
* initialize events and perhaps start any events that are on the
* command line. Unfortunately, there are some events that will not
* start this early, like the system call tracepoints that need
- * to set the TIF_SYSCALL_TRACEPOINT flag of pid 1. But event_trace_enable()
- * is called before pid 1 starts, and this flag is never set, making
- * the syscall tracepoint never get reached, but the event is enabled
- * regardless (and not doing anything).
+ * to set the %SYSCALL_WORK_SYSCALL_TRACEPOINT flag of pid 1. But
+ * event_trace_enable() is called before pid 1 starts, and this flag
+ * is never set, making the syscall tracepoint never get reached, but
+ * the event is enabled regardless (and not doing anything).
*/
static __init int event_trace_enable_again(void)
{
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 3f659f8..7261fa0 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -594,7 +594,7 @@ int syscall_regfunc(void)
if (!sys_tracepoint_refcount) {
read_lock(&tasklist_lock);
for_each_process_thread(p, t) {
- set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
+ set_task_syscall_work(t, SYSCALL_TRACEPOINT);
}
read_unlock(&tasklist_lock);
}
@@ -611,7 +611,7 @@ void syscall_unregfunc(void)
if (!sys_tracepoint_refcount) {
read_lock(&tasklist_lock);
for_each_process_thread(p, t) {
- clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
+ clear_task_syscall_work(t, SYSCALL_TRACEPOINT);
}
read_unlock(&tasklist_lock);
}