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

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index fa3cdb1..2a01eee 100644 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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);
        }