Commit 524666cb authored by Gabriel Krisman Bertazi's avatar Gabriel Krisman Bertazi Committed by Thomas Gleixner
Browse files

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: default avatarGabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarAndy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20201116174206.2639648-6-krisman@collabora.com
parent 23d67a54

include/linux/entry-common.h

+5 −8
Original line number Diff line number Diff line
@@ -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()

include/linux/thread_info.h

+2 −0
Original line number Diff line number Diff line
@@ -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>

include/trace/syscall.h

+3 −3
Original line number Diff line number Diff line
@@ -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)

kernel/entry/common.c

+2 −2
Original line number Diff line number Diff line
@@ -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);

kernel/trace/trace_events.c

+4 −4
Original line number Diff line number Diff line
@@ -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)

{