Commit 64eb35f7 authored by Gabriel Krisman Bertazi's avatar Gabriel Krisman Bertazi Committed by Thomas Gleixner
Browse files

ptrace: Migrate TIF_SYSCALL_EMU 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_EMU, 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/20201116174206.2639648-8-krisman@collabora.com
parent 64c19ba2

include/linux/entry-common.h

+2 −6
Original line number Diff line number Diff line
@@ -13,10 +13,6 @@ 
 * Define dummy _TIF work flags if not defined by the architecture or for

 * disabled functionality.

 */

#ifndef _TIF_SYSCALL_EMU

# define _TIF_SYSCALL_EMU		(0)

#endif



#ifndef _TIF_SYSCALL_AUDIT

# define _TIF_SYSCALL_AUDIT		(0)

#endif
@@ -42,7 +38,6 @@ 


#define SYSCALL_ENTER_WORK						\

	(_TIF_SYSCALL_AUDIT  |						\

	 _TIF_SYSCALL_EMU |						\

	 ARCH_SYSCALL_ENTER_WORK)



/*
@@ -58,7 +53,8 @@ 


#define SYSCALL_WORK_ENTER	(SYSCALL_WORK_SECCOMP |			\

				 SYSCALL_WORK_SYSCALL_TRACEPOINT |	\

				 SYSCALL_WORK_SYSCALL_TRACE)

				 SYSCALL_WORK_SYSCALL_TRACE |		\

				 SYSCALL_WORK_SYSCALL_EMU)

#define SYSCALL_WORK_EXIT	(SYSCALL_WORK_SYSCALL_TRACEPOINT |	\

				 SYSCALL_WORK_SYSCALL_TRACE)

include/linux/thread_info.h

+2 −0
Original line number Diff line number Diff line
@@ -39,11 +39,13 @@ enum syscall_work_bit { 
	SYSCALL_WORK_BIT_SECCOMP,

	SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT,

	SYSCALL_WORK_BIT_SYSCALL_TRACE,

	SYSCALL_WORK_BIT_SYSCALL_EMU,

};



#define SYSCALL_WORK_SECCOMP		BIT(SYSCALL_WORK_BIT_SECCOMP)

#define SYSCALL_WORK_SYSCALL_TRACEPOINT	BIT(SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT)

#define SYSCALL_WORK_SYSCALL_TRACE	BIT(SYSCALL_WORK_BIT_SYSCALL_TRACE)

#define SYSCALL_WORK_SYSCALL_EMU	BIT(SYSCALL_WORK_BIT_SYSCALL_EMU)



#include <asm/thread_info.h>

include/linux/tracehook.h

+1 −1
Original line number Diff line number Diff line
@@ -84,7 +84,7 @@ static inline int ptrace_report_syscall(struct pt_regs *regs, 
 * @regs:		user register state of current task

 *

 * This will be called if %SYSCALL_WORK_SYSCALL_TRACE or

 * %TIF_SYSCALL_EMU have been set, when the current task has just

 * %SYSCALL_WORK_SYSCALL_EMU have been set, when the current task has just

 * entered the kernel for a system call.  Full user register state is

 * available here.  Changing the values in @regs can affect the system

 * call number and arguments to be tried.  It is safe to block here,

kernel/entry/common.c

+10 −9
Original line number Diff line number Diff line
@@ -47,9 +47,9 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall, 
	long ret = 0;



	/* Handle ptrace */

	if (work & SYSCALL_WORK_SYSCALL_TRACE || ti_work & _TIF_SYSCALL_EMU) {

	if (work & (SYSCALL_WORK_SYSCALL_TRACE | SYSCALL_WORK_SYSCALL_EMU)) {

		ret = arch_syscall_enter_tracehook(regs);

		if (ret || (ti_work & _TIF_SYSCALL_EMU))

		if (ret || (work & SYSCALL_WORK_SYSCALL_EMU))

			return -1L;

	}
@@ -208,21 +208,22 @@ static void exit_to_user_mode_prepare(struct pt_regs *regs) 
}



#ifndef _TIF_SINGLESTEP

static inline bool report_single_step(unsigned long ti_work)

static inline bool report_single_step(unsigned long work)

{

	return false;

}

#else

/*

 * If TIF_SYSCALL_EMU is set, then the only reason to report is when

 * If SYSCALL_EMU is set, then the only reason to report is when

 * TIF_SINGLESTEP is set (i.e. PTRACE_SYSEMU_SINGLESTEP).  This syscall

 * instruction has been already reported in syscall_enter_from_user_mode().

 */

#define SYSEMU_STEP	(_TIF_SINGLESTEP | _TIF_SYSCALL_EMU)



static inline bool report_single_step(unsigned long ti_work)

static inline bool report_single_step(unsigned long work)

{

	return (ti_work & SYSEMU_STEP) == _TIF_SINGLESTEP;

	if (!(work & SYSCALL_WORK_SYSCALL_EMU))

		return false;



	return !!(current_thread_info()->flags & _TIF_SINGLESTEP);

}

#endif
@@ -236,7 +237,7 @@ static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work, 
	if (work & SYSCALL_WORK_SYSCALL_TRACEPOINT)

		trace_sys_exit(regs, syscall_get_return_value(current, regs));



	step = report_single_step(ti_work);

	step = report_single_step(work);

	if (step || work & SYSCALL_WORK_SYSCALL_TRACE)

		arch_syscall_exit_tracehook(regs, step);

}

kernel/fork.c

+2 −2
Original line number Diff line number Diff line
@@ -2159,8 +2159,8 @@ static __latent_entropy struct task_struct *copy_process( 
	 */

	user_disable_single_step(p);

	clear_task_syscall_work(p, SYSCALL_TRACE);

#ifdef TIF_SYSCALL_EMU

	clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);

#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)

	clear_task_syscall_work(p, SYSCALL_EMU);

#endif

	clear_tsk_latency_tracing(p);