Commit 64c19ba2 authored by Gabriel Krisman Bertazi's avatar Gabriel Krisman Bertazi Committed by Thomas Gleixner
Browse files

ptrace: Migrate to use SYSCALL_TRACE 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_TRACE, 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/20201116174206.2639648-7-krisman@collabora.com
parent 524666cb

include/asm-generic/syscall.h

+8 −7
Original line number Diff line number Diff line
@@ -43,7 +43,7 @@ int syscall_get_nr(struct task_struct *task, struct pt_regs *regs); 
 * @regs:	task_pt_regs() of @task

 *

 * It's only valid to call this when @task is stopped for system

 * call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),

 * call exit tracing (due to %SYSCALL_WORK_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),

 * after tracehook_report_syscall_entry() returned nonzero to prevent

 * the system call from taking place.

 *
@@ -63,7 +63,7 @@ void syscall_rollback(struct task_struct *task, struct pt_regs *regs); 
 * Returns 0 if the system call succeeded, or -ERRORCODE if it failed.

 *

 * It's only valid to call this when @task is stopped for tracing on exit

 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.

 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.

 */

long syscall_get_error(struct task_struct *task, struct pt_regs *regs);
@@ -76,7 +76,7 @@ long syscall_get_error(struct task_struct *task, struct pt_regs *regs); 
 * This value is meaningless if syscall_get_error() returned nonzero.

 *

 * It's only valid to call this when @task is stopped for tracing on exit

 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.

 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.

 */

long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs);
@@ -93,7 +93,7 @@ long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs); 
 * code; the user sees a failed system call with this errno code.

 *

 * It's only valid to call this when @task is stopped for tracing on exit

 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.

 * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.

 */

void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,

			      int error, long val);
@@ -108,7 +108,7 @@ void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs, 
*  @args[0], and so on.

 *

 * It's only valid to call this when @task is stopped for tracing on

 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.

 * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.

 */

void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,

			   unsigned long *args);
@@ -123,7 +123,7 @@ void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs, 
 * The first argument gets value @args[0], and so on.

 *

 * It's only valid to call this when @task is stopped for tracing on

 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.

 * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.

 */

void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,

			   const unsigned long *args);
@@ -135,7 +135,8 @@ void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs, 
 * Returns the AUDIT_ARCH_* based on the system call convention in use.

 *

 * It's only valid to call this when @task is stopped on entry to a system

 * call, due to %TIF_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or %SYSCALL_WORK_SECCOMP.

 * call, due to %SYSCALL_WORK_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or

 * %SYSCALL_WORK_SECCOMP.

 *

 * Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must

 * provide an implementation of this.

include/linux/entry-common.h

+6 −4
Original line number Diff line number Diff line
@@ -41,7 +41,7 @@ 
#endif



#define SYSCALL_ENTER_WORK						\

	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT  |			\

	(_TIF_SYSCALL_AUDIT  |						\

	 _TIF_SYSCALL_EMU |						\

	 ARCH_SYSCALL_ENTER_WORK)
@@ -53,12 +53,14 @@ 
#endif



#define SYSCALL_EXIT_WORK						\

	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT |			\

	(_TIF_SYSCALL_AUDIT |						\

	 ARCH_SYSCALL_EXIT_WORK)



#define SYSCALL_WORK_ENTER	(SYSCALL_WORK_SECCOMP |			\

				 SYSCALL_WORK_SYSCALL_TRACEPOINT)

#define SYSCALL_WORK_EXIT	(SYSCALL_WORK_SYSCALL_TRACEPOINT)

				 SYSCALL_WORK_SYSCALL_TRACEPOINT |	\

				 SYSCALL_WORK_SYSCALL_TRACE)

#define SYSCALL_WORK_EXIT	(SYSCALL_WORK_SYSCALL_TRACEPOINT |	\

				 SYSCALL_WORK_SYSCALL_TRACE)



/*

 * TIF flags handled in exit_to_user_mode_loop()

include/linux/thread_info.h

+2 −0
Original line number Diff line number Diff line
@@ -38,10 +38,12 @@ enum { 
enum syscall_work_bit {

	SYSCALL_WORK_BIT_SECCOMP,

	SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT,

	SYSCALL_WORK_BIT_SYSCALL_TRACE,

};



#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)



#include <asm/thread_info.h>

include/linux/tracehook.h

+9 −8
Original line number Diff line number Diff line
@@ -83,11 +83,12 @@ static inline int ptrace_report_syscall(struct pt_regs *regs, 
 * tracehook_report_syscall_entry - task is about to attempt a system call

 * @regs:		user register state of current task

 *

 * This will be called if %TIF_SYSCALL_TRACE or %TIF_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, preventing the system call from beginning.

 * This will be called if %SYSCALL_WORK_SYSCALL_TRACE or

 * %TIF_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,

 * preventing the system call from beginning.

 *

 * Returns zero normally, or nonzero if the calling arch code should abort

 * the system call.  That must prevent normal entry so no system call is
@@ -109,15 +110,15 @@ static inline __must_check int tracehook_report_syscall_entry( 
 * @regs:		user register state of current task

 * @step:		nonzero if simulating single-step or block-step

 *

 * This will be called if %TIF_SYSCALL_TRACE has been set, when the

 * current task has just finished an attempted system call.  Full

 * This will be called if %SYSCALL_WORK_SYSCALL_TRACE has been set, when

 * the current task has just finished an attempted system call.  Full

 * user register state is available here.  It is safe to block here,

 * preventing signals from being processed.

 *

 * If @step is nonzero, this report is also in lieu of the normal

 * trap that would follow the system call instruction because

 * user_enable_block_step() or user_enable_single_step() was used.

 * In this case, %TIF_SYSCALL_TRACE might not be set.

 * In this case, %SYSCALL_WORK_SYSCALL_TRACE might not be set.

 *

 * Called without locks, just before checking for pending signals.

 */

kernel/entry/common.c

+2 −2
Original line number Diff line number Diff line
@@ -47,7 +47,7 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall, 
	long ret = 0;



	/* Handle ptrace */

	if (ti_work & (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU)) {

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

		ret = arch_syscall_enter_tracehook(regs);

		if (ret || (ti_work & _TIF_SYSCALL_EMU))

			return -1L;
@@ -237,7 +237,7 @@ static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work, 
		trace_sys_exit(regs, syscall_get_return_value(current, regs));



	step = report_single_step(ti_work);

	if (step || ti_work & _TIF_SYSCALL_TRACE)

	if (step || work & SYSCALL_WORK_SYSCALL_TRACE)

		arch_syscall_exit_tracehook(regs, step);

}