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.

Gabriel Krisman Bertazi committed 5 years ago

Commit 64c19ba1 parent 524666c7 files · +31 −25Browse files

Unified · Split

7 files

include/asm-generic/syscall.h +8 −7
include/linux/entry-common.h +6 −4
include/linux/thread_info.h +2 −0
include/linux/tracehook.h +9 −8
kernel/entry/common.c +2 −2
kernel/fork.c +1 −1
kernel/ptrace.c +3 −3

include/asm-generic/syscall.h+8−7

@@ -43,7 +43,7 @@ int syscall_get_nr(struct task_struct task, struct pt_regs regs); · 42 unmodified lines
43	43	* @regs: task_pt_regs() of @task
44	44	*
45	45	* It's only valid to call this when @task is stopped for system
46		− * call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
	46	+ * call exit tracing (due to %SYSCALL_WORK_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
47	47	* after tracehook_report_syscall_entry() returned nonzero to prevent
48	48	* the system call from taking place.
49	49	*
@@ -63,7 +63,7 @@ void syscall_rollback(struct task_struct task, struct pt_regs regs); · 13 unmodified lines
63	63	* Returns 0 if the system call succeeded, or -ERRORCODE if it failed.
64	64	*
65	65	* It's only valid to call this when @task is stopped for tracing on exit
66		− * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
	66	+ * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
67	67	*/
68	68	long syscall_get_error(struct task_struct task, struct pt_regs regs);
69	69
@@ -76,7 +76,7 @@ long syscall_get_error(struct task_struct task, struct pt_regs regs); · 6 unmodified lines
76	76	* This value is meaningless if syscall_get_error() returned nonzero.
77	77	*
78	78	* It's only valid to call this when @task is stopped for tracing on exit
79		− * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
	79	+ * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
80	80	*/
81	81	long syscall_get_return_value(struct task_struct task, struct pt_regs regs);
82	82
@@ -93,7 +93,7 @@ long syscall_get_return_value(struct task_struct task, struct pt_regs regs); · 10 unmodified lines
93	93	* code; the user sees a failed system call with this errno code.
94	94	*
95	95	* It's only valid to call this when @task is stopped for tracing on exit
96		− * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
	96	+ * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
97	97	*/
98	98	void syscall_set_return_value(struct task_struct task, struct pt_regs regs,
99	99	int error, long val);
@@ -108,7 +108,7 @@ void syscall_set_return_value(struct task_struct task, struct pt_regs regs, · 8 unmodified lines
108	108	* @args[0], and so on.
109	109	*
110	110	* It's only valid to call this when @task is stopped for tracing on
111		− * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
	111	+ * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
112	112	*/
113	113	void syscall_get_arguments(struct task_struct task, struct pt_regs regs,
114	114	unsigned long *args);
@@ -123,7 +123,7 @@ void syscall_get_arguments(struct task_struct task, struct pt_regs regs, · 8 unmodified lines
123	123	* The first argument gets value @args[0], and so on.
124	124	*
125	125	* It's only valid to call this when @task is stopped for tracing on
126		− * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
	126	+ * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
127	127	*/
128	128	void syscall_set_arguments(struct task_struct task, struct pt_regs regs,
129	129	const unsigned long *args);
@@ -135,7 +135,8 @@ void syscall_set_arguments(struct task_struct task, struct pt_regs regs, · 5 unmodified lines
135	135	* Returns the AUDIT_ARCH_* based on the system call convention in use.
136	136	*
137	137	* It's only valid to call this when @task is stopped on entry to a system
138		− * call, due to %TIF_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or %SYSCALL_WORK_SECCOMP.
	138	+ * call, due to %SYSCALL_WORK_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or
	139	+ * %SYSCALL_WORK_SECCOMP.
139	140	*
140	141	* Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must
141	142	* provide an implementation of this.

include/linux/entry-common.h+6−4

@@ -41,7 +41,7 @@ · 40 unmodified lines
41	41	#endif
42	42
43	43	#define SYSCALL_ENTER_WORK \
44		− (_TIF_SYSCALL_TRACE \| _TIF_SYSCALL_AUDIT \| \
	44	+ (_TIF_SYSCALL_AUDIT \| \
45	45	_TIF_SYSCALL_EMU \| \
46	46	ARCH_SYSCALL_ENTER_WORK)
47	47
@@ -53,12 +53,14 @@ · 5 unmodified lines
53	53	#endif
54	54
55	55	#define SYSCALL_EXIT_WORK \
56		− (_TIF_SYSCALL_TRACE \| _TIF_SYSCALL_AUDIT \| \
	56	+ (_TIF_SYSCALL_AUDIT \| \
57	57	ARCH_SYSCALL_EXIT_WORK)
58	58
59	59	#define SYSCALL_WORK_ENTER (SYSCALL_WORK_SECCOMP \| \
60		− SYSCALL_WORK_SYSCALL_TRACEPOINT)
61		−#define SYSCALL_WORK_EXIT (SYSCALL_WORK_SYSCALL_TRACEPOINT)
	60	+ SYSCALL_WORK_SYSCALL_TRACEPOINT \| \
	61	+ SYSCALL_WORK_SYSCALL_TRACE)
	62	+#define SYSCALL_WORK_EXIT (SYSCALL_WORK_SYSCALL_TRACEPOINT \| \
	63	+ SYSCALL_WORK_SYSCALL_TRACE)
62	64
63	65	/*
64	66	* TIF flags handled in exit_to_user_mode_loop()

include/linux/thread_info.h+2−0

@@ -38,10 +38,12 @@ enum { · 37 unmodified lines
38	38	enum syscall_work_bit {
39	39	SYSCALL_WORK_BIT_SECCOMP,
40	40	SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT,
	41	+ SYSCALL_WORK_BIT_SYSCALL_TRACE,
41	42	};
42	43
43	44	#define SYSCALL_WORK_SECCOMP BIT(SYSCALL_WORK_BIT_SECCOMP)
44	45	#define SYSCALL_WORK_SYSCALL_TRACEPOINT BIT(SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT)
	46	+#define SYSCALL_WORK_SYSCALL_TRACE BIT(SYSCALL_WORK_BIT_SYSCALL_TRACE)
45	47
46	48	#include <asm/thread_info.h>
47	49

include/linux/tracehook.h+9−8

@@ -83,11 +83,12 @@ static inline int ptrace_report_syscall(struct pt_regs *regs, · 82 unmodified lines
83	83	* tracehook_report_syscall_entry - task is about to attempt a system call
84	84	* @regs: user register state of current task
85	85	*
86		− * This will be called if %TIF_SYSCALL_TRACE or %TIF_SYSCALL_EMU have been set,
87		− * when the current task has just entered the kernel for a system call.
88		− * Full user register state is available here. Changing the values
89		− * in @regs can affect the system call number and arguments to be tried.
90		− * It is safe to block here, preventing the system call from beginning.
	86	+ * This will be called if %SYSCALL_WORK_SYSCALL_TRACE or
	87	+ * %TIF_SYSCALL_EMU have been set, when the current task has just
	88	+ * entered the kernel for a system call. Full user register state is
	89	+ * available here. Changing the values in @regs can affect the system
	90	+ * call number and arguments to be tried. It is safe to block here,
	91	+ * preventing the system call from beginning.
91	92	*
92	93	* Returns zero normally, or nonzero if the calling arch code should abort
93	94	* 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( · 15 unmodified lines
109	110	* @regs: user register state of current task
110	111	* @step: nonzero if simulating single-step or block-step
111	112	*
112		− * This will be called if %TIF_SYSCALL_TRACE has been set, when the
113		− * current task has just finished an attempted system call. Full
	113	+ * This will be called if %SYSCALL_WORK_SYSCALL_TRACE has been set, when
	114	+ * the current task has just finished an attempted system call. Full
114	115	* user register state is available here. It is safe to block here,
115	116	* preventing signals from being processed.
116	117	*
117	118	* If @step is nonzero, this report is also in lieu of the normal
118	119	* trap that would follow the system call instruction because
119	120	* user_enable_block_step() or user_enable_single_step() was used.
120		− * In this case, %TIF_SYSCALL_TRACE might not be set.
	121	+ * In this case, %SYSCALL_WORK_SYSCALL_TRACE might not be set.
121	122	*
122	123	* Called without locks, just before checking for pending signals.
123	124	*/

kernel/entry/common.c+2−2

@@ -47,7 +47,7 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall, · 46 unmodified lines
47	47	long ret = 0;
48	48
49	49	/* Handle ptrace */
50		− if (ti_work & (_TIF_SYSCALL_TRACE \| _TIF_SYSCALL_EMU)) {
	50	+ if (work & SYSCALL_WORK_SYSCALL_TRACE \|\| ti_work & _TIF_SYSCALL_EMU) {
51	51	ret = arch_syscall_enter_tracehook(regs);
52	52	if (ret \|\| (ti_work & _TIF_SYSCALL_EMU))
53	53	return -1L;
@@ -237,7 +237,7 @@ static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work, · 183 unmodified lines
237	237	trace_sys_exit(regs, syscall_get_return_value(current, regs));
238	238
239	239	step = report_single_step(ti_work);
240		− if (step \|\| ti_work & _TIF_SYSCALL_TRACE)
	240	+ if (step \|\| work & SYSCALL_WORK_SYSCALL_TRACE)
241	241	arch_syscall_exit_tracehook(regs, step);
242	242	}
243	243

kernel/fork.c+1−1

@@ -2158,7 +2158,7 @@ static __latent_entropy struct task_struct *copy_process( · 2157 unmodified lines
2158	2158	* child regardless of CLONE_PTRACE.
2159	2159	*/
2160	2160	user_disable_single_step(p);
2161		− clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
	2161	+ clear_task_syscall_work(p, SYSCALL_TRACE);
2162	2162	#ifdef TIF_SYSCALL_EMU
2163	2163	clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
2164	2164	#endif

kernel/ptrace.c+3−3

@@ -117,7 +117,7 @@ void __ptrace_unlink(struct task_struct *child) · 116 unmodified lines
117	117	const struct cred *old_cred;
118	118	BUG_ON(!child->ptrace);
119	119
120		− clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	120	+ clear_task_syscall_work(child, SYSCALL_TRACE);
121	121	#ifdef TIF_SYSCALL_EMU
122	122	clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
123	123	#endif
@@ -812,9 +812,9 @@ static int ptrace_resume(struct task_struct *child, long request, · 688 unmodified lines
812	812	return -EIO;
813	813
814	814	if (request == PTRACE_SYSCALL)
815		− set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	815	+ set_task_syscall_work(child, SYSCALL_TRACE);
816	816	else
817		− clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	817	+ clear_task_syscall_work(child, SYSCALL_TRACE);
818	818
819	819	#ifdef TIF_SYSCALL_EMU
820	820	if (request == PTRACE_SYSEMU \|\| request == PTRACE_SYSEMU_SINGLESTEP)

ptrace: Migrate to use SYSCALL_TRACE flag

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