[PATCH v2 00/10] Migrate syscall entry/exit work to SYSCALL_WORK flagset

[PATCH v2 00/10] Migrate syscall entry/exit work to SYSCALL_WORK flagset

[Gabriel Krisman Bertazi]

Hi,

This is the v2 of the SYSCALL_WORK flagset.  It addresses the issues
raised by hch and tglx in the previous iteration (thank you!)  regarding
casts, styling, and naming of the variable fields.  It also fixes
comments that were missing on the previous version.

This was tested by running the modified syscall features on a x86 box.
I just compile tested for architectures that are !CONFIG_GENERIC_ENTRY.

This patchset can be found at the following repo/tag

  https://gitlab.collabora.com/krisman/linux.git -b x86-tif-cleanup-v2

Below, is the original cover letter, with reasoning and design.

Original cover letter
====================

Thomas,

This a refactor work moving the work done by features like seccomp,
ptrace, audit and tracepoints out of the TI flags.  The reasons are:

   1) Scarcity of TI flags in x86 32-bit.

   2) TI flags are defined by the architecture, while these features are
   arch-independent.

   3) Community resistance in merging new architecture-independent
   features as TI flags.

The design exposes a new field in struct thread_info that is read at
syscall_trace_enter and syscall_work_exit in place of the ti flags.
No functional changes is expected from this patchset.  The design and
organization of this patchset achieves the following goals:

  1) SYSCALL_WORK flags are architecture-independent

  2) Architectures that are not using the generic entry code can
  continue to use TI flags transparently and be converted later.

  3) Architectures that migrate to the generic entry code are forced to
  use the new design.

  4) x86, since it supports the generic code, is migrated in this
  patchset.

The transparent usage of TIF or SYSCALL_WORK flags is achieved through
some macros.  Any code outside of the generic entry code is converted to
use the flags only through the accessors.

The patchset has some transition helpers, in an attempt to simplify the
patches converting each of the subsystems separately.  I believe this
simplifies the review while making the tree bisectable.

I tested this by running each of the features in x86.  Other
architectures were compile tested only.

This is based on top of tip/master.

A tree with the patches applies can be pulled from

  https://gitlab.collabora.com/krisman/linux.git -b x86/tif-cleanup-v1

Please, if possible, consider queueing this for the 5.11 merge window,
as this is blocking the Syscall User Dispatch work that has been on the
list for a while.

Gabriel Krisman Bertazi (10):
  x86: Expose syscall_work field in thread_info
  entry: Expose helpers to migrate TIF to SYSCALL_WORK flags
  entry: Wire up syscall_work in common entry code
  seccomp: Migrate to use SYSCALL_WORK flag
  tracepoints: Migrate to use SYSCALL_WORK flag
  ptrace: Migrate to use SYSCALL_TRACE flag
  ptrace: Migrate TIF_SYSCALL_EMU to use SYSCALL_WORK flag
  audit: Migrate to use SYSCALL_WORK flag
  entry: Drop usage of TIF flags in the generic syscall code
  x86: Reclaim unused x86 TI flags

 arch/x86/include/asm/thread_info.h | 11 +-------
 include/asm-generic/syscall.h      | 24 ++++++++++------
 include/linux/entry-common.h       | 44 ++++++++++-------------------
 include/linux/seccomp.h            |  2 +-
 include/linux/thread_info.h        | 44 +++++++++++++++++++++++++++++
 include/linux/tracehook.h          | 17 +++++------
 include/trace/syscall.h            |  6 ++--
 kernel/auditsc.c                   |  4 +--
 kernel/entry/common.c              | 45 +++++++++++++++---------------
 kernel/fork.c                      |  8 +++---
 kernel/ptrace.c                    | 16 +++++------
 kernel/seccomp.c                   |  6 ++--
 kernel/trace/trace_events.c        |  8 +++---
 kernel/tracepoint.c                |  4 +--
 14 files changed, 134 insertions(+), 105 deletions(-)

-- 
2.29.2

[PATCH v2 01/10] x86: Expose syscall_work field in thread_info

[Gabriel Krisman Bertazi]

This field will be used by SYSCALL_WORK flags, migrated from TI flags.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
---
 arch/x86/include/asm/thread_info.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 93277a8d2ef0..b217f63e73b7 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -55,6 +55,7 @@ struct task_struct;
 
 struct thread_info {
 	unsigned long		flags;		/* low level flags */
+	unsigned long		syscall_work;	/* SYSCALL_WORK_ flags */
 	u32			status;		/* thread synchronous flags */
 };
 
-- 
2.29.2

[PATCH v2 02/10] entry: Expose helpers to migrate TIF to SYSCALL_WORK flags

[Gabriel Krisman Bertazi]

With the goal to split the syscall work related flags into a separate
field that is architecture independent, expose transitional helpers that
resolve to either the TIF flags or to the corresponding SYSCALL_WORK
flags.  This will allow architectures to migrate only when they port to
the generic syscall entry code.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v2:
  - Drop bogus cast to ulong (hch)
  - Fix subsystem prefix (tglx)
---
 include/linux/thread_info.h | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index e93e249a4e9b..f2d78de55840 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -97,6 +97,36 @@ static inline int test_ti_thread_flag(struct thread_info *ti, int flag)
 #define test_thread_flag(flag) \
 	test_ti_thread_flag(current_thread_info(), flag)
 
+#ifdef CONFIG_GENERIC_ENTRY
+#define set_syscall_work(fl) \
+	set_bit(SYSCALL_WORK_BIT_##fl, &current_thread_info()->syscall_work)
+#define test_syscall_work(fl) \
+	test_bit(SYSCALL_WORK_BIT_##fl, &current_thread_info()->syscall_work)
+#define clear_syscall_work(fl) \
+	clear_bit(SYSCALL_WORK_BIT_##fl, &current_thread_info()->syscall_work)
+
+#define set_task_syscall_work(t, fl) \
+	set_bit(SYSCALL_WORK_BIT_##fl, &task_thread_info(t)->syscall_work)
+#define test_task_syscall_work(t, fl) \
+	test_bit(SYSCALL_WORK_BIT_##fl, &task_thread_info(t)->syscall_work)
+#define clear_task_syscall_work(t, fl) \
+	clear_bit(SYSCALL_WORK_BIT_##fl, &task_thread_info(t)->syscall_work)
+#else
+#define set_syscall_work(fl) \
+	set_ti_thread_flag(current_thread_info(), SYSCALL_WORK_##fl)
+#define test_syscall_work(fl) \
+	test_ti_thread_flag(current_thread_info(), SYSCALL_WORK_##fl)
+#define clear_syscall_work(fl) \
+	clear_ti_thread_flag(current_thread_info(), SYSCALL_WORK_##fl)
+
+#define set_task_syscall_work(t, fl) \
+	set_ti_thread_flag(task_thread_info(t), TIF_##fl)
+#define test_task_syscall_work(t, fl) \
+	test_ti_thread_flag(task_thread_info(t), TIF_##fl)
+#define clear_task_syscall_work(t, fl) \
+	clear_ti_thread_flag(task_thread_info(t), TIF_##fl)
+#endif /* CONFIG_GENERIC_ENTRY */
+
 #define tif_need_resched() test_thread_flag(TIF_NEED_RESCHED)
 
 #ifndef CONFIG_HAVE_ARCH_WITHIN_STACK_FRAMES
-- 
2.29.2

[PATCH v2 03/10] entry: Wire up syscall_work in common entry code

[Gabriel Krisman Bertazi]

Prepare the common entry code to use the SYSCALL_WORK flags. They will
be defined in subsequent patches for each type of syscall
work. SYSCALL_WORK_ENTRY/EXIT are defined for the transition, as they
will replace the TIF_ equivalent defines.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v2:
  - Fix subsystem prefix (tglx)
  - Fix verb in commit message (tglx)
  - Sort variable declaration (tglx)
---
 include/linux/entry-common.h |  3 +++
 kernel/entry/common.c        | 15 +++++++++------
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index 1a128baf3628..cbc5c702ee4d 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -64,6 +64,9 @@
 	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT |			\
 	 _TIF_SYSCALL_TRACEPOINT | ARCH_SYSCALL_EXIT_WORK)
 
+#define SYSCALL_WORK_ENTER	(0)
+#define SYSCALL_WORK_EXIT	(0)
+
 /*
  * TIF flags handled in exit_to_user_mode_loop()
  */
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index bc75c114c1b3..51c25f774791 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -42,7 +42,7 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
 }
 
 static long syscall_trace_enter(struct pt_regs *regs, long syscall,
-				unsigned long ti_work)
+				unsigned long ti_work, unsigned long work)
 {
 	long ret = 0;
 
@@ -74,11 +74,12 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
 static __always_inline long
 __syscall_enter_from_user_work(struct pt_regs *regs, long syscall)
 {
+	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
 	unsigned long ti_work;
 
 	ti_work = READ_ONCE(current_thread_info()->flags);
-	if (ti_work & SYSCALL_ENTER_WORK)
-		syscall = syscall_trace_enter(regs, syscall, ti_work);
+	if (work & SYSCALL_WORK_ENTER || ti_work & SYSCALL_ENTER_WORK)
+		syscall = syscall_trace_enter(regs, syscall, ti_work, work);
 
 	return syscall;
 }
@@ -225,7 +226,8 @@ static inline bool report_single_step(unsigned long ti_work)
 }
 #endif
 
-static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work)
+static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work,
+			      unsigned long work)
 {
 	bool step;
 
@@ -245,6 +247,7 @@ static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work)
  */
 static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
 {
+	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
 	u32 cached_flags = READ_ONCE(current_thread_info()->flags);
 	unsigned long nr = syscall_get_nr(current, regs);
 
@@ -262,8 +265,8 @@ static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
 	 * enabled, we want to run them exactly once per syscall exit with
 	 * interrupts enabled.
 	 */
-	if (unlikely(cached_flags & SYSCALL_EXIT_WORK))
-		syscall_exit_work(regs, cached_flags);
+	if (unlikely(work & SYSCALL_WORK_EXIT || cached_flags & SYSCALL_EXIT_WORK))
+		syscall_exit_work(regs, cached_flags, work);
 }
 
 __visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs)
-- 
2.29.2

[PATCH v2 04/10] seccomp: Migrate to use SYSCALL_WORK flag

[Gabriel Krisman Bertazi]

When one the generic syscall entry code, use the syscall_work field in
struct thread_info and specific SYSCALL_WORK flags to setup this syscall
work.  This flag has the advantage of being architecture independent.

Users of the flag outside of the generic entry code should rely on the
accessor macros, such that the flag is still correctly resolved for
architectures that don't use the generic entry code and still rely on
TIF flags for system call work.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v2:
  - Drop explicit value assignment in enum (tglx)
  - Avoid FLAG/_FLAG defines (tglx)
  - Fix comment to refer to SYSCALL_WORK_SECCOMP (me)
---
 include/asm-generic/syscall.h | 2 +-
 include/linux/entry-common.h  | 8 ++------
 include/linux/seccomp.h       | 2 +-
 include/linux/thread_info.h   | 6 ++++++
 kernel/entry/common.c         | 2 +-
 kernel/fork.c                 | 2 +-
 kernel/seccomp.c              | 6 +++---
 7 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
index f3135e734387..524d8e68ff5e 100644
--- a/include/asm-generic/syscall.h
+++ b/include/asm-generic/syscall.h
@@ -135,7 +135,7 @@ 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 %TIF_SECCOMP.
+ * call, due to %TIF_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or %SYSCALL_WORK_SECCOMP.
  *
  * Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must
  * provide an implementation of this.
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index cbc5c702ee4d..f3fc4457f63f 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -21,10 +21,6 @@
 # define _TIF_SYSCALL_TRACEPOINT	(0)
 #endif
 
-#ifndef _TIF_SECCOMP
-# define _TIF_SECCOMP			(0)
-#endif
-
 #ifndef _TIF_SYSCALL_AUDIT
 # define _TIF_SYSCALL_AUDIT		(0)
 #endif
@@ -49,7 +45,7 @@
 #endif
 
 #define SYSCALL_ENTER_WORK						\
-	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP |	\
+	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT  |			\
 	 _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_EMU |			\
 	 ARCH_SYSCALL_ENTER_WORK)
 
@@ -64,7 +60,7 @@
 	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT |			\
 	 _TIF_SYSCALL_TRACEPOINT | ARCH_SYSCALL_EXIT_WORK)
 
-#define SYSCALL_WORK_ENTER	(0)
+#define SYSCALL_WORK_ENTER	(SYSCALL_WORK_SECCOMP)
 #define SYSCALL_WORK_EXIT	(0)
 
 /*
diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
index 02aef2844c38..47763f3999f7 100644
--- a/include/linux/seccomp.h
+++ b/include/linux/seccomp.h
@@ -42,7 +42,7 @@ struct seccomp {
 extern int __secure_computing(const struct seccomp_data *sd);
 static inline int secure_computing(void)
 {
-	if (unlikely(test_thread_flag(TIF_SECCOMP)))
+	if (unlikely(test_syscall_work(SECCOMP)))
 		return  __secure_computing(NULL);
 	return 0;
 }
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index f2d78de55840..1d6488130b5c 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -35,6 +35,12 @@ enum {
 	GOOD_STACK,
 };
 
+enum syscall_work_bit {
+	SYSCALL_WORK_BIT_SECCOMP,
+};
+
+#define SYSCALL_WORK_SECCOMP		BIT(SYSCALL_WORK_BIT_SECCOMP)
+
 #include <asm/thread_info.h>
 
 #ifdef __KERNEL__
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 51c25f774791..c321056c73d7 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -54,7 +54,7 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
 	}
 
 	/* Do seccomp after ptrace, to catch any tracer changes. */
-	if (ti_work & _TIF_SECCOMP) {
+	if (work & SYSCALL_WORK_SECCOMP) {
 		ret = __secure_computing(NULL);
 		if (ret == -1L)
 			return ret;
diff --git a/kernel/fork.c b/kernel/fork.c
index 7199d359690c..4433c9c60100 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1625,7 +1625,7 @@ static void copy_seccomp(struct task_struct *p)
 	 * to manually enable the seccomp thread flag here.
 	 */
 	if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
-		set_tsk_thread_flag(p, TIF_SECCOMP);
+		set_task_syscall_work(p, SECCOMP);
 #endif
 }
 
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 8ad7a293255a..f67e92d11ad7 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -356,14 +356,14 @@ static inline void seccomp_assign_mode(struct task_struct *task,
 
 	task->seccomp.mode = seccomp_mode;
 	/*
-	 * Make sure TIF_SECCOMP cannot be set before the mode (and
+	 * Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and
 	 * filter) is set.
 	 */
 	smp_mb__before_atomic();
 	/* Assume default seccomp processes want spec flaw mitigation. */
 	if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
 		arch_seccomp_spec_mitigate(task);
-	set_tsk_thread_flag(task, TIF_SECCOMP);
+	set_task_syscall_work(task, SECCOMP);
 }
 
 #ifdef CONFIG_SECCOMP_FILTER
@@ -929,7 +929,7 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
 
 	/*
 	 * Make sure that any changes to mode from another thread have
-	 * been seen after TIF_SECCOMP was seen.
+	 * been seen after SYSCALL_WORK_SECCOMP was seen.
 	 */
 	rmb();
 
-- 
2.29.2

[PATCH v2 05/10] tracepoints: Migrate to use SYSCALL_WORK flag

[Gabriel Krisman Bertazi]

For architectures that rely on the generic syscall entry code, use the
syscall_work field in struct thread_info and the specific SYSCALL_WORK
flag.  This set of flags has the advantage of being architecture
independent.

Users of the flag outside of the generic entry code should rely on the
accessor macros, such that the flag is still correctly resolved for
architectures that don't use the generic entry code and still rely on
TIF flags for system call work.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v2:
  - Drop explicit value assignment in enum (tglx)
  - Avoid FLAG/_FLAG defines (tglx)
  - Fix comment to refer to SYSCALL_WORK_SECCOMP (me)
---
 include/linux/entry-common.h | 13 +++++--------
 include/linux/thread_info.h  |  2 ++
 include/trace/syscall.h      |  6 +++---
 kernel/entry/common.c        |  4 ++--
 kernel/trace/trace_events.c  |  8 ++++----
 kernel/tracepoint.c          |  4 ++--
 6 files changed, 18 insertions(+), 19 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index f3fc4457f63f..8aba367e5c79 100644
--- 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 1d6488130b5c..ff0ac2ebb4ff 100644
--- 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 dc8ac27d27c1..8e193f3a33b3 100644
--- 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 c321056c73d7..4e2b3c08d939 100644
--- 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 47a71f96e5bc..adf65b502453 100644
--- 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 3f659f855074..7261fa0f5e3c 100644
--- 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);
 	}
-- 
2.29.2

[PATCH v2 06/10] ptrace: Migrate to use SYSCALL_TRACE flag

[Gabriel Krisman Bertazi]

For architectures that rely on the generic syscall entry code, use the
syscall_work field in struct thread_info and the specific SYSCALL_WORK
flag.  This set of flags has the advantage of being architecture
independent.

Users of the flag outside of the generic entry code should rely on the
accessor macros, such that the flag is still correctly resolved for
architectures that don't use the generic entry code and still rely on
TIF flags for system call work.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v2:
  - Drop explicit value assignment in enum (tglx)
  - Avoid FLAG/_FLAG defines (tglx)
  - Fix comment to refer to SYSCALL_WORK (me)
---
 include/asm-generic/syscall.h | 15 ++++++++-------
 include/linux/entry-common.h  | 10 ++++++----
 include/linux/thread_info.h   |  2 ++
 include/linux/tracehook.h     | 17 +++++++++--------
 kernel/entry/common.c         |  4 ++--
 kernel/fork.c                 |  2 +-
 kernel/ptrace.c               |  6 +++---
 7 files changed, 31 insertions(+), 25 deletions(-)

diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
index 524d8e68ff5e..ed94e5658d0c 100644
--- a/include/asm-generic/syscall.h
+++ b/include/asm-generic/syscall.h
@@ -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.
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index 8aba367e5c79..dc864edb7950 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -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()
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index ff0ac2ebb4ff..8fe85cdca822 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -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>
 
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index f7d82e4fafd6..3f20368afe9e 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -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.
  */
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 4e2b3c08d939..2682eba47c33 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -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);
 }
 
diff --git a/kernel/fork.c b/kernel/fork.c
index 4433c9c60100..6f934a930015 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2158,7 +2158,7 @@ static __latent_entropy struct task_struct *copy_process(
 	 * child regardless of CLONE_PTRACE.
 	 */
 	user_disable_single_step(p);
-	clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
+	clear_task_syscall_work(p, SYSCALL_TRACE);
 #ifdef TIF_SYSCALL_EMU
 	clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
 #endif
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 43d6179508d6..55a2bc3186a7 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -117,7 +117,7 @@ void __ptrace_unlink(struct task_struct *child)
 	const struct cred *old_cred;
 	BUG_ON(!child->ptrace);
 
-	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+	clear_task_syscall_work(child, SYSCALL_TRACE);
 #ifdef TIF_SYSCALL_EMU
 	clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 #endif
@@ -812,9 +812,9 @@ static int ptrace_resume(struct task_struct *child, long request,
 		return -EIO;
 
 	if (request == PTRACE_SYSCALL)
-		set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+		set_task_syscall_work(child, SYSCALL_TRACE);
 	else
-		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+		clear_task_syscall_work(child, SYSCALL_TRACE);
 
 #ifdef TIF_SYSCALL_EMU
 	if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
-- 
2.29.2

[PATCH v2 07/10] ptrace: Migrate TIF_SYSCALL_EMU to use SYSCALL_WORK flag

[Gabriel Krisman Bertazi]

For architectures that rely on the generic syscall entry code, use the
syscall_work field in struct thread_info and the specific SYSCALL_WORK
flag.  This set of flags has the advantage of being architecture
independent.

Users of the flag outside of the generic entry code should rely on the
accessor macros, such that the flag is still correctly resolved for
architectures that don't use the generic entry code and still rely on
TIF flags for system call work.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v2:
  - Drop explicit value assignment in enum (tglx)
  - Avoid FLAG/_FLAG defines (tglx)
  - Fix comment to refer to SYSCALL_WORK (me)
---
 include/linux/entry-common.h |  8 ++------
 include/linux/thread_info.h  |  2 ++
 include/linux/tracehook.h    |  2 +-
 kernel/entry/common.c        | 19 ++++++++++---------
 kernel/fork.c                |  4 ++--
 kernel/ptrace.c              | 10 +++++-----
 6 files changed, 22 insertions(+), 23 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index dc864edb7950..39d56558818d 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -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)
 
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index 8fe85cdca822..844c9a102317 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -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>
 
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index 3f20368afe9e..54b925224a13 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -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,
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 2682eba47c33..a7233cca01ba 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -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);
 }
diff --git a/kernel/fork.c b/kernel/fork.c
index 6f934a930015..4f131cb0192a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -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);
 
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 55a2bc3186a7..237bcd6d255c 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -118,8 +118,8 @@ void __ptrace_unlink(struct task_struct *child)
 	BUG_ON(!child->ptrace);
 
 	clear_task_syscall_work(child, SYSCALL_TRACE);
-#ifdef TIF_SYSCALL_EMU
-	clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
+	clear_task_syscall_work(child, SYSCALL_EMU);
 #endif
 
 	child->parent = child->real_parent;
@@ -816,11 +816,11 @@ static int ptrace_resume(struct task_struct *child, long request,
 	else
 		clear_task_syscall_work(child, SYSCALL_TRACE);
 
-#ifdef TIF_SYSCALL_EMU
+#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
 	if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
-		set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+		set_task_syscall_work(child, SYSCALL_EMU);
 	else
-		clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+		clear_task_syscall_work(child, SYSCALL_EMU);
 #endif
 
 	if (is_singleblock(request)) {
-- 
2.29.2

[PATCH v2 08/10] audit: Migrate to use SYSCALL_WORK flag

[Gabriel Krisman Bertazi]

For architectures that rely on the generic syscall entry code, use the
syscall_work field in struct thread_info and the specific SYSCALL_WORK
flag.  This set of flags has the advantage of being architecture
independent.

Users of the flag outside of the generic entry code should rely on the
accessor macros, such that the flag is still correctly resolved for
architectures that don't use the generic entry code and still rely on
TIF flags for system call work.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v2:
  - Drop explicit value assignment in enum (tglx)
  - Avoid FLAG/_FLAG defines (tglx)
  - Fix comment to refer to SYSCALL_WORK (me)
---
 include/asm-generic/syscall.h | 23 ++++++++++++++---------
 include/linux/entry-common.h  | 18 ++++++------------
 include/linux/thread_info.h   |  2 ++
 kernel/auditsc.c              |  4 ++--
 4 files changed, 24 insertions(+), 23 deletions(-)

diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
index ed94e5658d0c..524218ae3825 100644
--- a/include/asm-generic/syscall.h
+++ b/include/asm-generic/syscall.h
@@ -43,9 +43,9 @@ 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 %SYSCALL_WORK_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
- * after tracehook_report_syscall_entry() returned nonzero to prevent
- * the system call from taking place.
+ * call exit tracing (due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT), after tracehook_report_syscall_entry()
+ * returned nonzero to prevent the system call from taking place.
  *
  * This rolls back the register state in @regs so it's as if the
  * system call instruction was a no-op.  The registers containing
@@ -63,7 +63,8 @@ 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 %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT.
  */
 long syscall_get_error(struct task_struct *task, struct pt_regs *regs);
 
@@ -76,7 +77,8 @@ 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 %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT.
  */
 long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs);
 
@@ -93,7 +95,8 @@ 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 %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT.
  */
 void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
 			      int error, long val);
@@ -108,7 +111,8 @@ 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 %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT.
  */
 void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
 			   unsigned long *args);
@@ -123,7 +127,8 @@ 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 %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT.
  */
 void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
 			   const unsigned long *args);
@@ -135,7 +140,7 @@ 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 %SYSCALL_WORK_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or
+ * call, due to %SYSCALL_WORK_SYSCALL_TRACE, %SYSCALL_WORK_SYSCALL_AUDIT, or
  * %SYSCALL_WORK_SECCOMP.
  *
  * Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index 39d56558818d..afeb927e8545 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -13,10 +13,6 @@
  * Define dummy _TIF work flags if not defined by the architecture or for
  * disabled functionality.
  */
-#ifndef _TIF_SYSCALL_AUDIT
-# define _TIF_SYSCALL_AUDIT		(0)
-#endif
-
 #ifndef _TIF_PATCH_PENDING
 # define _TIF_PATCH_PENDING		(0)
 #endif
@@ -36,9 +32,7 @@
 # define ARCH_SYSCALL_ENTER_WORK	(0)
 #endif
 
-#define SYSCALL_ENTER_WORK						\
-	(_TIF_SYSCALL_AUDIT  |						\
-	 ARCH_SYSCALL_ENTER_WORK)
+#define SYSCALL_ENTER_WORK ARCH_SYSCALL_ENTER_WORK
 
 /*
  * TIF flags handled in syscall_exit_to_user_mode()
@@ -47,16 +41,16 @@
 # define ARCH_SYSCALL_EXIT_WORK		(0)
 #endif
 
-#define SYSCALL_EXIT_WORK						\
-	(_TIF_SYSCALL_AUDIT |						\
-	 ARCH_SYSCALL_EXIT_WORK)
+#define SYSCALL_EXIT_WORK ARCH_SYSCALL_EXIT_WORK
 
 #define SYSCALL_WORK_ENTER	(SYSCALL_WORK_SECCOMP |			\
 				 SYSCALL_WORK_SYSCALL_TRACEPOINT |	\
 				 SYSCALL_WORK_SYSCALL_TRACE |		\
-				 SYSCALL_WORK_SYSCALL_EMU)
+				 SYSCALL_WORK_SYSCALL_EMU |		\
+				 SYSCALL_WORK_SYSCALL_AUDIT)
 #define SYSCALL_WORK_EXIT	(SYSCALL_WORK_SYSCALL_TRACEPOINT |	\
-				 SYSCALL_WORK_SYSCALL_TRACE)
+				 SYSCALL_WORK_SYSCALL_TRACE |		\
+				 SYSCALL_WORK_SYSCALL_AUDIT)
 
 /*
  * TIF flags handled in exit_to_user_mode_loop()
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index 844c9a102317..6a597fd5d351 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -40,12 +40,14 @@ enum syscall_work_bit {
 	SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT,
 	SYSCALL_WORK_BIT_SYSCALL_TRACE,
 	SYSCALL_WORK_BIT_SYSCALL_EMU,
+	SYSCALL_WORK_BIT_SYSCALL_AUDIT,
 };
 
 #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)
+#define SYSCALL_WORK_SYSCALL_AUDIT	BIT(SYSCALL_WORK_BIT_SYSCALL_AUDIT)
 
 #include <asm/thread_info.h>
 
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 8dba8f0983b5..c00aa5837965 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -952,7 +952,7 @@ int audit_alloc(struct task_struct *tsk)
 
 	state = audit_filter_task(tsk, &key);
 	if (state == AUDIT_DISABLED) {
-		clear_tsk_thread_flag(tsk, TIF_SYSCALL_AUDIT);
+		clear_task_syscall_work(tsk, SYSCALL_AUDIT);
 		return 0;
 	}
 
@@ -964,7 +964,7 @@ int audit_alloc(struct task_struct *tsk)
 	context->filterkey = key;
 
 	audit_set_context(tsk, context);
-	set_tsk_thread_flag(tsk, TIF_SYSCALL_AUDIT);
+	set_task_syscall_work(tsk, SYSCALL_AUDIT);
 	return 0;
 }
 
-- 
2.29.2

[PATCH v2 09/10] entry: Drop usage of TIF flags in the generic syscall code

[Gabriel Krisman Bertazi]

Now that the flags migration in the common syscall entry is complete and
the code relies exclusively on syscall_work, clean up the
accesses to TI flags in that path.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v2:
  - Fix subsystem prefix (tglx)
---
 include/linux/entry-common.h | 20 +++++++++-----------
 kernel/entry/common.c        | 17 +++++++----------
 2 files changed, 16 insertions(+), 21 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index afeb927e8545..cffd8bf1e085 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -26,31 +26,29 @@
 #endif
 
 /*
- * TIF flags handled in syscall_enter_from_user_mode()
+ * SYSCALL_WORK flags handled in syscall_enter_from_user_mode()
  */
-#ifndef ARCH_SYSCALL_ENTER_WORK
-# define ARCH_SYSCALL_ENTER_WORK	(0)
+#ifndef ARCH_SYSCALL_WORK_ENTER
+# define ARCH_SYSCALL_WORK_ENTER	(0)
 #endif
 
-#define SYSCALL_ENTER_WORK ARCH_SYSCALL_ENTER_WORK
-
 /*
  * TIF flags handled in syscall_exit_to_user_mode()
  */
-#ifndef ARCH_SYSCALL_EXIT_WORK
-# define ARCH_SYSCALL_EXIT_WORK		(0)
+#ifndef ARCH_SYSCALL_WORK_EXIT
+# define ARCH_SYSCALL_WORK_EXIT		(0)
 #endif
 
-#define SYSCALL_EXIT_WORK ARCH_SYSCALL_EXIT_WORK
-
 #define SYSCALL_WORK_ENTER	(SYSCALL_WORK_SECCOMP |			\
 				 SYSCALL_WORK_SYSCALL_TRACEPOINT |	\
 				 SYSCALL_WORK_SYSCALL_TRACE |		\
 				 SYSCALL_WORK_SYSCALL_EMU |		\
-				 SYSCALL_WORK_SYSCALL_AUDIT)
+				 SYSCALL_WORK_SYSCALL_AUDIT |		\
+				 ARCH_SYSCALL_WORK_ENTER)
 #define SYSCALL_WORK_EXIT	(SYSCALL_WORK_SYSCALL_TRACEPOINT |	\
 				 SYSCALL_WORK_SYSCALL_TRACE |		\
-				 SYSCALL_WORK_SYSCALL_AUDIT)
+				 SYSCALL_WORK_SYSCALL_AUDIT |		\
+				 ARCH_SYSCALL_WORK_EXIT)
 
 /*
  * TIF flags handled in exit_to_user_mode_loop()
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index a7233cca01ba..61b6936a0623 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -42,7 +42,7 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
 }
 
 static long syscall_trace_enter(struct pt_regs *regs, long syscall,
-				unsigned long ti_work, unsigned long work)
+				unsigned long work)
 {
 	long ret = 0;
 
@@ -75,11 +75,9 @@ static __always_inline long
 __syscall_enter_from_user_work(struct pt_regs *regs, long syscall)
 {
 	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
-	unsigned long ti_work;
 
-	ti_work = READ_ONCE(current_thread_info()->flags);
-	if (work & SYSCALL_WORK_ENTER || ti_work & SYSCALL_ENTER_WORK)
-		syscall = syscall_trace_enter(regs, syscall, ti_work, work);
+	if (work & SYSCALL_WORK_ENTER)
+		syscall = syscall_trace_enter(regs, syscall, work);
 
 	return syscall;
 }
@@ -227,8 +225,8 @@ static inline bool report_single_step(unsigned long work)
 }
 #endif
 
-static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work,
-			      unsigned long work)
+
+static void syscall_exit_work(struct pt_regs *regs, unsigned long work)
 {
 	bool step;
 
@@ -249,7 +247,6 @@ static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work,
 static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
 {
 	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
-	u32 cached_flags = READ_ONCE(current_thread_info()->flags);
 	unsigned long nr = syscall_get_nr(current, regs);
 
 	CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
@@ -266,8 +263,8 @@ static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
 	 * enabled, we want to run them exactly once per syscall exit with
 	 * interrupts enabled.
 	 */
-	if (unlikely(work & SYSCALL_WORK_EXIT || cached_flags & SYSCALL_EXIT_WORK))
-		syscall_exit_work(regs, cached_flags, work);
+	if (unlikely(work & SYSCALL_WORK_EXIT))
+		syscall_exit_work(regs, work);
 }
 
 __visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs)
-- 
2.29.2

[PATCH v2 10/10] x86: Reclaim unused x86 TI flags

[Gabriel Krisman Bertazi]

Reclaim TI flags that were migrated to syscall_work flags.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
---
 arch/x86/include/asm/thread_info.h | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index b217f63e73b7..33b637442b9e 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -75,15 +75,11 @@ struct thread_info {
  * - these are process state flags that various assembly files
  *   may need to access
  */
-#define TIF_SYSCALL_TRACE	0	/* syscall trace active */
 #define TIF_NOTIFY_RESUME	1	/* callback before returning to user */
 #define TIF_SIGPENDING		2	/* signal pending */
 #define TIF_NEED_RESCHED	3	/* rescheduling necessary */
 #define TIF_SINGLESTEP		4	/* reenable singlestep on user return*/
 #define TIF_SSBD		5	/* Speculative store bypass disable */
-#define TIF_SYSCALL_EMU		6	/* syscall emulation active */
-#define TIF_SYSCALL_AUDIT	7	/* syscall auditing active */
-#define TIF_SECCOMP		8	/* secure computing */
 #define TIF_SPEC_IB		9	/* Indirect branch speculation mitigation */
 #define TIF_SPEC_L1D_FLUSH	10	/* Flush L1D on mm switches (processes) */
 #define TIF_USER_RETURN_NOTIFY	11	/* notify kernel of userspace return */
@@ -101,18 +97,13 @@ struct thread_info {
 #define TIF_FORCED_TF		24	/* true if TF in eflags artificially */
 #define TIF_BLOCKSTEP		25	/* set when we want DEBUGCTLMSR_BTF */
 #define TIF_LAZY_MMU_UPDATES	27	/* task is updating the mmu lazily */
-#define TIF_SYSCALL_TRACEPOINT	28	/* syscall tracepoint instrumentation */
 #define TIF_ADDR32		29	/* 32-bit address space on 64 bits */
 
-#define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
 #define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #define _TIF_SSBD		(1 << TIF_SSBD)
-#define _TIF_SYSCALL_EMU	(1 << TIF_SYSCALL_EMU)
-#define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
-#define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 #define _TIF_SPEC_IB		(1 << TIF_SPEC_IB)
 #define _TIF_SPEC_L1D_FLUSH	(1 << TIF_SPEC_L1D_FLUSH)
 #define _TIF_USER_RETURN_NOTIFY	(1 << TIF_USER_RETURN_NOTIFY)
@@ -129,7 +120,6 @@ struct thread_info {
 #define _TIF_FORCED_TF		(1 << TIF_FORCED_TF)
 #define _TIF_BLOCKSTEP		(1 << TIF_BLOCKSTEP)
 #define _TIF_LAZY_MMU_UPDATES	(1 << TIF_LAZY_MMU_UPDATES)
-#define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 #define _TIF_ADDR32		(1 << TIF_ADDR32)
 
 /* flags to check in __switch_to() */
-- 
2.29.2

[tip: core/entry] x86: Reclaim unused x86 TI flags

[tip-bot2 for Gabriel Krisman Bertazi]

The following commit has been merged into the core/entry branch of tip:

Commit-ID:     51af3f23063946344330a77a7d1dece6fc6bb5d8
Gitweb:        https://git.kernel.org/tip/51af3f23063946344330a77a7d1dece6fc6bb5d8
Author:        Gabriel Krisman Bertazi <krisman@collabora.com>
AuthorDate:    Mon, 16 Nov 2020 12:42:06 -05:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 16 Nov 2020 21:53:16 +01:00

x86: Reclaim unused x86 TI flags

Reclaim TI flags that were migrated to syscall_work flags.

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/20201116174206.2639648-11-krisman@collabora.com

---
 arch/x86/include/asm/thread_info.h | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 0da5d58..0d751d5 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -75,15 +75,11 @@ struct thread_info {
  * - these are process state flags that various assembly files
  *   may need to access
  */
-#define TIF_SYSCALL_TRACE	0	/* syscall trace active */
 #define TIF_NOTIFY_RESUME	1	/* callback before returning to user */
 #define TIF_SIGPENDING		2	/* signal pending */
 #define TIF_NEED_RESCHED	3	/* rescheduling necessary */
 #define TIF_SINGLESTEP		4	/* reenable singlestep on user return*/
 #define TIF_SSBD		5	/* Speculative store bypass disable */
-#define TIF_SYSCALL_EMU		6	/* syscall emulation active */
-#define TIF_SYSCALL_AUDIT	7	/* syscall auditing active */
-#define TIF_SECCOMP		8	/* secure computing */
 #define TIF_SPEC_IB		9	/* Indirect branch speculation mitigation */
 #define TIF_SPEC_FORCE_UPDATE	10	/* Force speculation MSR update in context switch */
 #define TIF_USER_RETURN_NOTIFY	11	/* notify kernel of userspace return */
@@ -100,18 +96,13 @@ struct thread_info {
 #define TIF_FORCED_TF		24	/* true if TF in eflags artificially */
 #define TIF_BLOCKSTEP		25	/* set when we want DEBUGCTLMSR_BTF */
 #define TIF_LAZY_MMU_UPDATES	27	/* task is updating the mmu lazily */
-#define TIF_SYSCALL_TRACEPOINT	28	/* syscall tracepoint instrumentation */
 #define TIF_ADDR32		29	/* 32-bit address space on 64 bits */
 
-#define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
 #define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #define _TIF_SSBD		(1 << TIF_SSBD)
-#define _TIF_SYSCALL_EMU	(1 << TIF_SYSCALL_EMU)
-#define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
-#define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 #define _TIF_SPEC_IB		(1 << TIF_SPEC_IB)
 #define _TIF_SPEC_FORCE_UPDATE	(1 << TIF_SPEC_FORCE_UPDATE)
 #define _TIF_USER_RETURN_NOTIFY	(1 << TIF_USER_RETURN_NOTIFY)
@@ -127,7 +118,6 @@ struct thread_info {
 #define _TIF_FORCED_TF		(1 << TIF_FORCED_TF)
 #define _TIF_BLOCKSTEP		(1 << TIF_BLOCKSTEP)
 #define _TIF_LAZY_MMU_UPDATES	(1 << TIF_LAZY_MMU_UPDATES)
-#define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 #define _TIF_ADDR32		(1 << TIF_ADDR32)
 
 /* flags to check in __switch_to() */

[tip: core/entry] entry: Drop usage of TIF flags in the generic syscall code

[tip-bot2 for Gabriel Krisman Bertazi]

The following commit has been merged into the core/entry branch of tip:

Commit-ID:     2991552447707d791d9d81a5dc161f9e9e90b163
Gitweb:        https://git.kernel.org/tip/2991552447707d791d9d81a5dc161f9e9e90b163
Author:        Gabriel Krisman Bertazi <krisman@collabora.com>
AuthorDate:    Mon, 16 Nov 2020 12:42:05 -05:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 16 Nov 2020 21:53:16 +01:00

entry: Drop usage of TIF flags in the generic syscall code

Now that the flags migration in the common syscall entry code is complete
and the code relies exclusively on thread_info::syscall_work, clean up the
accesses to TI flags in that path.

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/20201116174206.2639648-10-krisman@collabora.com
---
 include/linux/entry-common.h | 26 ++++++++++++--------------
 kernel/entry/common.c        | 17 +++++++----------
 2 files changed, 19 insertions(+), 24 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index d7b96f4..49b26b2 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -26,31 +26,29 @@
 #endif
 
 /*
- * TIF flags handled in syscall_enter_from_user_mode()
+ * SYSCALL_WORK flags handled in syscall_enter_from_user_mode()
  */
-#ifndef ARCH_SYSCALL_ENTER_WORK
-# define ARCH_SYSCALL_ENTER_WORK	(0)
+#ifndef ARCH_SYSCALL_WORK_ENTER
+# define ARCH_SYSCALL_WORK_ENTER	(0)
 #endif
 
-#define SYSCALL_ENTER_WORK ARCH_SYSCALL_ENTER_WORK
-
 /*
- * TIF flags handled in syscall_exit_to_user_mode()
+ * SYSCALL_WORK flags handled in syscall_exit_to_user_mode()
  */
-#ifndef ARCH_SYSCALL_EXIT_WORK
-# define ARCH_SYSCALL_EXIT_WORK		(0)
+#ifndef ARCH_SYSCALL_WORK_EXIT
+# define ARCH_SYSCALL_WORK_EXIT		(0)
 #endif
 
-#define SYSCALL_EXIT_WORK ARCH_SYSCALL_EXIT_WORK
-
 #define SYSCALL_WORK_ENTER	(SYSCALL_WORK_SECCOMP |			\
 				 SYSCALL_WORK_SYSCALL_TRACEPOINT |	\
 				 SYSCALL_WORK_SYSCALL_TRACE |		\
 				 SYSCALL_WORK_SYSCALL_EMU |		\
-				 SYSCALL_WORK_SYSCALL_AUDIT)
+				 SYSCALL_WORK_SYSCALL_AUDIT |		\
+				 ARCH_SYSCALL_WORK_ENTER)
 #define SYSCALL_WORK_EXIT	(SYSCALL_WORK_SYSCALL_TRACEPOINT |	\
 				 SYSCALL_WORK_SYSCALL_TRACE |		\
-				 SYSCALL_WORK_SYSCALL_AUDIT)
+				 SYSCALL_WORK_SYSCALL_AUDIT |		\
+				 ARCH_SYSCALL_WORK_EXIT)
 
 /*
  * TIF flags handled in exit_to_user_mode_loop()
@@ -136,8 +134,8 @@ void syscall_enter_from_user_mode_prepare(struct pt_regs *regs);
  *
  * It handles the following work items:
  *
- *  1) TIF flag dependent invocations of arch_syscall_enter_tracehook(),
- *     __secure_computing(), trace_sys_enter()
+ *  1) syscall_work flag dependent invocations of
+ *     arch_syscall_enter_tracehook(), __secure_computing(), trace_sys_enter()
  *  2) Invocation of audit_syscall_entry()
  */
 long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall);
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 90533f3..91e8fd5 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -42,7 +42,7 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
 }
 
 static long syscall_trace_enter(struct pt_regs *regs, long syscall,
-				unsigned long ti_work, unsigned long work)
+				unsigned long work)
 {
 	long ret = 0;
 
@@ -75,11 +75,9 @@ static __always_inline long
 __syscall_enter_from_user_work(struct pt_regs *regs, long syscall)
 {
 	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
-	unsigned long ti_work;
 
-	ti_work = READ_ONCE(current_thread_info()->flags);
-	if (work & SYSCALL_WORK_ENTER || ti_work & SYSCALL_ENTER_WORK)
-		syscall = syscall_trace_enter(regs, syscall, ti_work, work);
+	if (work & SYSCALL_WORK_ENTER)
+		syscall = syscall_trace_enter(regs, syscall, work);
 
 	return syscall;
 }
@@ -227,8 +225,8 @@ static inline bool report_single_step(unsigned long work)
 }
 #endif
 
-static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work,
-			      unsigned long work)
+
+static void syscall_exit_work(struct pt_regs *regs, unsigned long work)
 {
 	bool step;
 
@@ -249,7 +247,6 @@ static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work,
 static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
 {
 	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
-	u32 cached_flags = READ_ONCE(current_thread_info()->flags);
 	unsigned long nr = syscall_get_nr(current, regs);
 
 	CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
@@ -266,8 +263,8 @@ static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
 	 * enabled, we want to run them exactly once per syscall exit with
 	 * interrupts enabled.
 	 */
-	if (unlikely(work & SYSCALL_WORK_EXIT || cached_flags & SYSCALL_EXIT_WORK))
-		syscall_exit_work(regs, cached_flags, work);
+	if (unlikely(work & SYSCALL_WORK_EXIT))
+		syscall_exit_work(regs, work);
 }
 
 __visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs)

[tip: core/entry] ptrace: Migrate TIF_SYSCALL_EMU to use SYSCALL_WORK flag

[tip-bot2 for Gabriel Krisman Bertazi]

The following commit has been merged into the core/entry branch of tip:

Commit-ID:     64eb35f701f04b30706e21d1b02636b5d31a37d2
Gitweb:        https://git.kernel.org/tip/64eb35f701f04b30706e21d1b02636b5d31a37d2
Author:        Gabriel Krisman Bertazi <krisman@collabora.com>
AuthorDate:    Mon, 16 Nov 2020 12:42:03 -05:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 16 Nov 2020 21:53:16 +01:00

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: 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/20201116174206.2639648-8-krisman@collabora.com
---
 include/linux/entry-common.h |  8 ++------
 include/linux/thread_info.h  |  2 ++
 include/linux/tracehook.h    |  2 +-
 kernel/entry/common.c        | 19 ++++++++++---------
 kernel/fork.c                |  4 ++--
 kernel/ptrace.c              | 10 +++++-----
 6 files changed, 22 insertions(+), 23 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index ae426ab..b30f82b 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -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)
 
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index 761a459..85b8a42 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -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>
 
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index 3f20368..54b9252 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -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,
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 917328a..90533f3 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -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);
 }
diff --git a/kernel/fork.c b/kernel/fork.c
index 99f68c2..02b689a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -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);
 
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 55a2bc3..237bcd6 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -118,8 +118,8 @@ void __ptrace_unlink(struct task_struct *child)
 	BUG_ON(!child->ptrace);
 
 	clear_task_syscall_work(child, SYSCALL_TRACE);
-#ifdef TIF_SYSCALL_EMU
-	clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
+	clear_task_syscall_work(child, SYSCALL_EMU);
 #endif
 
 	child->parent = child->real_parent;
@@ -816,11 +816,11 @@ static int ptrace_resume(struct task_struct *child, long request,
 	else
 		clear_task_syscall_work(child, SYSCALL_TRACE);
 
-#ifdef TIF_SYSCALL_EMU
+#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
 	if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
-		set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+		set_task_syscall_work(child, SYSCALL_EMU);
 	else
-		clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+		clear_task_syscall_work(child, SYSCALL_EMU);
 #endif
 
 	if (is_singleblock(request)) {

[tip: core/entry] audit: Migrate to use SYSCALL_WORK flag

[tip-bot2 for Gabriel Krisman Bertazi]

The following commit has been merged into the core/entry branch of tip:

Commit-ID:     785dc4eb7fd74e3b7f4eac468457b633117e1aea
Gitweb:        https://git.kernel.org/tip/785dc4eb7fd74e3b7f4eac468457b633117e1aea
Author:        Gabriel Krisman Bertazi <krisman@collabora.com>
AuthorDate:    Mon, 16 Nov 2020 12:42:04 -05:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 16 Nov 2020 21:53:16 +01:00

audit: 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_AUDIT, 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/20201116174206.2639648-9-krisman@collabora.com
---
 include/asm-generic/syscall.h | 23 ++++++++++++++---------
 include/linux/entry-common.h  | 18 ++++++------------
 include/linux/thread_info.h   |  2 ++
 kernel/auditsc.c              |  4 ++--
 4 files changed, 24 insertions(+), 23 deletions(-)

diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
index ed94e56..524218a 100644
--- a/include/asm-generic/syscall.h
+++ b/include/asm-generic/syscall.h
@@ -43,9 +43,9 @@ 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 %SYSCALL_WORK_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
- * after tracehook_report_syscall_entry() returned nonzero to prevent
- * the system call from taking place.
+ * call exit tracing (due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT), after tracehook_report_syscall_entry()
+ * returned nonzero to prevent the system call from taking place.
  *
  * This rolls back the register state in @regs so it's as if the
  * system call instruction was a no-op.  The registers containing
@@ -63,7 +63,8 @@ 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 %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT.
  */
 long syscall_get_error(struct task_struct *task, struct pt_regs *regs);
 
@@ -76,7 +77,8 @@ 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 %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT.
  */
 long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs);
 
@@ -93,7 +95,8 @@ 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 %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ * from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT.
  */
 void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
 			      int error, long val);
@@ -108,7 +111,8 @@ 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 %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT.
  */
 void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
 			   unsigned long *args);
@@ -123,7 +127,8 @@ 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 %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
+ * entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or
+ * %SYSCALL_WORK_SYSCALL_AUDIT.
  */
 void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
 			   const unsigned long *args);
@@ -135,7 +140,7 @@ 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 %SYSCALL_WORK_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or
+ * call, due to %SYSCALL_WORK_SYSCALL_TRACE, %SYSCALL_WORK_SYSCALL_AUDIT, or
  * %SYSCALL_WORK_SECCOMP.
  *
  * Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index b30f82b..d7b96f4 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -13,10 +13,6 @@
  * Define dummy _TIF work flags if not defined by the architecture or for
  * disabled functionality.
  */
-#ifndef _TIF_SYSCALL_AUDIT
-# define _TIF_SYSCALL_AUDIT		(0)
-#endif
-
 #ifndef _TIF_PATCH_PENDING
 # define _TIF_PATCH_PENDING		(0)
 #endif
@@ -36,9 +32,7 @@
 # define ARCH_SYSCALL_ENTER_WORK	(0)
 #endif
 
-#define SYSCALL_ENTER_WORK						\
-	(_TIF_SYSCALL_AUDIT  |						\
-	 ARCH_SYSCALL_ENTER_WORK)
+#define SYSCALL_ENTER_WORK ARCH_SYSCALL_ENTER_WORK
 
 /*
  * TIF flags handled in syscall_exit_to_user_mode()
@@ -47,16 +41,16 @@
 # define ARCH_SYSCALL_EXIT_WORK		(0)
 #endif
 
-#define SYSCALL_EXIT_WORK						\
-	(_TIF_SYSCALL_AUDIT |						\
-	 ARCH_SYSCALL_EXIT_WORK)
+#define SYSCALL_EXIT_WORK ARCH_SYSCALL_EXIT_WORK
 
 #define SYSCALL_WORK_ENTER	(SYSCALL_WORK_SECCOMP |			\
 				 SYSCALL_WORK_SYSCALL_TRACEPOINT |	\
 				 SYSCALL_WORK_SYSCALL_TRACE |		\
-				 SYSCALL_WORK_SYSCALL_EMU)
+				 SYSCALL_WORK_SYSCALL_EMU |		\
+				 SYSCALL_WORK_SYSCALL_AUDIT)
 #define SYSCALL_WORK_EXIT	(SYSCALL_WORK_SYSCALL_TRACEPOINT |	\
-				 SYSCALL_WORK_SYSCALL_TRACE)
+				 SYSCALL_WORK_SYSCALL_TRACE |		\
+				 SYSCALL_WORK_SYSCALL_AUDIT)
 
 /*
  * TIF flags handled in exit_to_user_mode_loop()
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index 85b8a42..3173632 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -40,12 +40,14 @@ enum syscall_work_bit {
 	SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT,
 	SYSCALL_WORK_BIT_SYSCALL_TRACE,
 	SYSCALL_WORK_BIT_SYSCALL_EMU,
+	SYSCALL_WORK_BIT_SYSCALL_AUDIT,
 };
 
 #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)
+#define SYSCALL_WORK_SYSCALL_AUDIT	BIT(SYSCALL_WORK_BIT_SYSCALL_AUDIT)
 
 #include <asm/thread_info.h>
 
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 8dba8f0..c00aa58 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -952,7 +952,7 @@ int audit_alloc(struct task_struct *tsk)
 
 	state = audit_filter_task(tsk, &key);
 	if (state == AUDIT_DISABLED) {
-		clear_tsk_thread_flag(tsk, TIF_SYSCALL_AUDIT);
+		clear_task_syscall_work(tsk, SYSCALL_AUDIT);
 		return 0;
 	}
 
@@ -964,7 +964,7 @@ int audit_alloc(struct task_struct *tsk)
 	context->filterkey = key;
 
 	audit_set_context(tsk, context);
-	set_tsk_thread_flag(tsk, TIF_SYSCALL_AUDIT);
+	set_task_syscall_work(tsk, SYSCALL_AUDIT);
 	return 0;
 }
 

[tip: core/entry] tracepoints: Migrate to use SYSCALL_WORK flag

[tip-bot2 for Gabriel Krisman Bertazi]

The following commit has been merged into the core/entry branch of tip:

Commit-ID:     524666cb5de7c38a1925e7401a6e59d68682dd8c
Gitweb:        https://git.kernel.org/tip/524666cb5de7c38a1925e7401a6e59d68682dd8c
Author:        Gabriel Krisman Bertazi <krisman@collabora.com>
AuthorDate:    Mon, 16 Nov 2020 12:42:01 -05:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 16 Nov 2020 21:53:15 +01:00

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
---
 include/linux/entry-common.h | 13 +++++--------
 include/linux/thread_info.h  |  2 ++
 include/trace/syscall.h      |  6 +++---
 kernel/entry/common.c        |  4 ++--
 kernel/trace/trace_events.c  |  8 ++++----
 kernel/tracepoint.c          |  4 ++--
 6 files changed, 18 insertions(+), 19 deletions(-)

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

[tip: core/entry] ptrace: Migrate to use SYSCALL_TRACE flag

[tip-bot2 for Gabriel Krisman Bertazi]

The following commit has been merged into the core/entry branch of tip:

Commit-ID:     64c19ba29b66e98af9306b4a7525fb22c895d252
Gitweb:        https://git.kernel.org/tip/64c19ba29b66e98af9306b4a7525fb22c895d252
Author:        Gabriel Krisman Bertazi <krisman@collabora.com>
AuthorDate:    Mon, 16 Nov 2020 12:42:02 -05:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 16 Nov 2020 21:53:16 +01:00

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: 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/20201116174206.2639648-7-krisman@collabora.com


---
 include/asm-generic/syscall.h | 15 ++++++++-------
 include/linux/entry-common.h  | 10 ++++++----
 include/linux/thread_info.h   |  2 ++
 include/linux/tracehook.h     | 17 +++++++++--------
 kernel/entry/common.c         |  4 ++--
 kernel/fork.c                 |  2 +-
 kernel/ptrace.c               |  6 +++---
 7 files changed, 31 insertions(+), 25 deletions(-)

diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
index 524d8e6..ed94e56 100644
--- a/include/asm-generic/syscall.h
+++ b/include/asm-generic/syscall.h
@@ -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.
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index 2a01eee..ae426ab 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -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()
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index c232043..761a459 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -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>
 
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index f7d82e4..3f20368 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -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.
  */
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index f651967..917328a 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -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);
 }
 
diff --git a/kernel/fork.c b/kernel/fork.c
index bc5b109..99f68c2 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2158,7 +2158,7 @@ static __latent_entropy struct task_struct *copy_process(
 	 * child regardless of CLONE_PTRACE.
 	 */
 	user_disable_single_step(p);
-	clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
+	clear_task_syscall_work(p, SYSCALL_TRACE);
 #ifdef TIF_SYSCALL_EMU
 	clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
 #endif
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 43d6179..55a2bc3 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -117,7 +117,7 @@ void __ptrace_unlink(struct task_struct *child)
 	const struct cred *old_cred;
 	BUG_ON(!child->ptrace);
 
-	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+	clear_task_syscall_work(child, SYSCALL_TRACE);
 #ifdef TIF_SYSCALL_EMU
 	clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 #endif
@@ -812,9 +812,9 @@ static int ptrace_resume(struct task_struct *child, long request,
 		return -EIO;
 
 	if (request == PTRACE_SYSCALL)
-		set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+		set_task_syscall_work(child, SYSCALL_TRACE);
 	else
-		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+		clear_task_syscall_work(child, SYSCALL_TRACE);
 
 #ifdef TIF_SYSCALL_EMU
 	if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)

[tip: core/entry] seccomp: Migrate to use SYSCALL_WORK flag

[tip-bot2 for Gabriel Krisman Bertazi]

The following commit has been merged into the core/entry branch of tip:

Commit-ID:     23d67a54857a768acdb0804cdd6037c324a50ecd
Gitweb:        https://git.kernel.org/tip/23d67a54857a768acdb0804cdd6037c324a50ecd
Author:        Gabriel Krisman Bertazi <krisman@collabora.com>
AuthorDate:    Mon, 16 Nov 2020 12:42:00 -05:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 16 Nov 2020 21:53:15 +01:00

seccomp: 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_SECCOMP, 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/20201116174206.2639648-5-krisman@collabora.com
---
 include/asm-generic/syscall.h | 2 +-
 include/linux/entry-common.h  | 8 ++------
 include/linux/seccomp.h       | 2 +-
 include/linux/thread_info.h   | 6 ++++++
 kernel/entry/common.c         | 2 +-
 kernel/fork.c                 | 2 +-
 kernel/seccomp.c              | 6 +++---
 7 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
index f3135e7..524d8e6 100644
--- a/include/asm-generic/syscall.h
+++ b/include/asm-generic/syscall.h
@@ -135,7 +135,7 @@ 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 %TIF_SECCOMP.
+ * call, due to %TIF_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or %SYSCALL_WORK_SECCOMP.
  *
  * Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must
  * provide an implementation of this.
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index 3fe8f86..fa3cdb1 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -21,10 +21,6 @@
 # define _TIF_SYSCALL_TRACEPOINT	(0)
 #endif
 
-#ifndef _TIF_SECCOMP
-# define _TIF_SECCOMP			(0)
-#endif
-
 #ifndef _TIF_SYSCALL_AUDIT
 # define _TIF_SYSCALL_AUDIT		(0)
 #endif
@@ -49,7 +45,7 @@
 #endif
 
 #define SYSCALL_ENTER_WORK						\
-	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP |	\
+	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT  |			\
 	 _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_EMU |			\
 	 ARCH_SYSCALL_ENTER_WORK)
 
@@ -64,7 +60,7 @@
 	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT |			\
 	 _TIF_SYSCALL_TRACEPOINT | ARCH_SYSCALL_EXIT_WORK)
 
-#define SYSCALL_WORK_ENTER	(0)
+#define SYSCALL_WORK_ENTER	(SYSCALL_WORK_SECCOMP)
 #define SYSCALL_WORK_EXIT	(0)
 
 /*
diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
index 02aef28..47763f3 100644
--- a/include/linux/seccomp.h
+++ b/include/linux/seccomp.h
@@ -42,7 +42,7 @@ struct seccomp {
 extern int __secure_computing(const struct seccomp_data *sd);
 static inline int secure_computing(void)
 {
-	if (unlikely(test_thread_flag(TIF_SECCOMP)))
+	if (unlikely(test_syscall_work(SECCOMP)))
 		return  __secure_computing(NULL);
 	return 0;
 }
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index 0e9fb15..a308ba4 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -35,6 +35,12 @@ enum {
 	GOOD_STACK,
 };
 
+enum syscall_work_bit {
+	SYSCALL_WORK_BIT_SECCOMP,
+};
+
+#define SYSCALL_WORK_SECCOMP		BIT(SYSCALL_WORK_BIT_SECCOMP)
+
 #include <asm/thread_info.h>
 
 #ifdef __KERNEL__
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index e7a11e3..5747a6e 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -54,7 +54,7 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
 	}
 
 	/* Do seccomp after ptrace, to catch any tracer changes. */
-	if (ti_work & _TIF_SECCOMP) {
+	if (work & SYSCALL_WORK_SECCOMP) {
 		ret = __secure_computing(NULL);
 		if (ret == -1L)
 			return ret;
diff --git a/kernel/fork.c b/kernel/fork.c
index 32083db..bc5b109 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1625,7 +1625,7 @@ static void copy_seccomp(struct task_struct *p)
 	 * to manually enable the seccomp thread flag here.
 	 */
 	if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
-		set_tsk_thread_flag(p, TIF_SECCOMP);
+		set_task_syscall_work(p, SECCOMP);
 #endif
 }
 
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 8ad7a29..f67e92d 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -356,14 +356,14 @@ static inline void seccomp_assign_mode(struct task_struct *task,
 
 	task->seccomp.mode = seccomp_mode;
 	/*
-	 * Make sure TIF_SECCOMP cannot be set before the mode (and
+	 * Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and
 	 * filter) is set.
 	 */
 	smp_mb__before_atomic();
 	/* Assume default seccomp processes want spec flaw mitigation. */
 	if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
 		arch_seccomp_spec_mitigate(task);
-	set_tsk_thread_flag(task, TIF_SECCOMP);
+	set_task_syscall_work(task, SECCOMP);
 }
 
 #ifdef CONFIG_SECCOMP_FILTER
@@ -929,7 +929,7 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
 
 	/*
 	 * Make sure that any changes to mode from another thread have
-	 * been seen after TIF_SECCOMP was seen.
+	 * been seen after SYSCALL_WORK_SECCOMP was seen.
 	 */
 	rmb();
 

[tip: core/entry] entry: Expose helpers to migrate TIF to SYSCALL_WORK flags

[tip-bot2 for Gabriel Krisman Bertazi]

The following commit has been merged into the core/entry branch of tip:

Commit-ID:     3136b93c3fb2b7c19e853e049203ff8f2b9dd2cd
Gitweb:        https://git.kernel.org/tip/3136b93c3fb2b7c19e853e049203ff8f2b9dd2cd
Author:        Gabriel Krisman Bertazi <krisman@collabora.com>
AuthorDate:    Mon, 16 Nov 2020 12:41:58 -05:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 16 Nov 2020 21:53:15 +01:00

entry: Expose helpers to migrate TIF to SYSCALL_WORK flags

With the goal to split the syscall work related flags into a separate
field that is architecture independent, expose transitional helpers that
resolve to either the TIF flags or to the corresponding SYSCALL_WORK
flags.  This will allow architectures to migrate only when they port to
the generic syscall entry code.

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/20201116174206.2639648-3-krisman@collabora.com


---
 include/linux/thread_info.h | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index e93e249..0e9fb15 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -97,6 +97,38 @@ static inline int test_ti_thread_flag(struct thread_info *ti, int flag)
 #define test_thread_flag(flag) \
 	test_ti_thread_flag(current_thread_info(), flag)
 
+#ifdef CONFIG_GENERIC_ENTRY
+#define set_syscall_work(fl) \
+	set_bit(SYSCALL_WORK_BIT_##fl, &current_thread_info()->syscall_work)
+#define test_syscall_work(fl) \
+	test_bit(SYSCALL_WORK_BIT_##fl, &current_thread_info()->syscall_work)
+#define clear_syscall_work(fl) \
+	clear_bit(SYSCALL_WORK_BIT_##fl, &current_thread_info()->syscall_work)
+
+#define set_task_syscall_work(t, fl) \
+	set_bit(SYSCALL_WORK_BIT_##fl, &task_thread_info(t)->syscall_work)
+#define test_task_syscall_work(t, fl) \
+	test_bit(SYSCALL_WORK_BIT_##fl, &task_thread_info(t)->syscall_work)
+#define clear_task_syscall_work(t, fl) \
+	clear_bit(SYSCALL_WORK_BIT_##fl, &task_thread_info(t)->syscall_work)
+
+#else /* CONFIG_GENERIC_ENTRY */
+
+#define set_syscall_work(fl)						\
+	set_ti_thread_flag(current_thread_info(), SYSCALL_WORK_##fl)
+#define test_syscall_work(fl) \
+	test_ti_thread_flag(current_thread_info(), SYSCALL_WORK_##fl)
+#define clear_syscall_work(fl) \
+	clear_ti_thread_flag(current_thread_info(), SYSCALL_WORK_##fl)
+
+#define set_task_syscall_work(t, fl) \
+	set_ti_thread_flag(task_thread_info(t), TIF_##fl)
+#define test_task_syscall_work(t, fl) \
+	test_ti_thread_flag(task_thread_info(t), TIF_##fl)
+#define clear_task_syscall_work(t, fl) \
+	clear_ti_thread_flag(task_thread_info(t), TIF_##fl)
+#endif /* !CONFIG_GENERIC_ENTRY */
+
 #define tif_need_resched() test_thread_flag(TIF_NEED_RESCHED)
 
 #ifndef CONFIG_HAVE_ARCH_WITHIN_STACK_FRAMES

[tip: core/entry] entry: Wire up syscall_work in common entry code

[tip-bot2 for Gabriel Krisman Bertazi]

The following commit has been merged into the core/entry branch of tip:

Commit-ID:     b86678cf0f1d76062aa964c5f0c6c89fe5a6dcfd
Gitweb:        https://git.kernel.org/tip/b86678cf0f1d76062aa964c5f0c6c89fe5a6dcfd
Author:        Gabriel Krisman Bertazi <krisman@collabora.com>
AuthorDate:    Mon, 16 Nov 2020 12:41:59 -05:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 16 Nov 2020 21:53:15 +01:00

entry: Wire up syscall_work in common entry code

Prepare the common entry code to use the SYSCALL_WORK flags. They will
be defined in subsequent patches for each type of syscall
work. SYSCALL_WORK_ENTRY/EXIT are defined for the transition, as they
will replace the TIF_ equivalent defines.

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/20201116174206.2639648-4-krisman@collabora.com


---
 include/linux/entry-common.h |  3 +++
 kernel/entry/common.c        | 15 +++++++++------
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index aab5490..3fe8f86 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -64,6 +64,9 @@
 	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT |			\
 	 _TIF_SYSCALL_TRACEPOINT | ARCH_SYSCALL_EXIT_WORK)
 
+#define SYSCALL_WORK_ENTER	(0)
+#define SYSCALL_WORK_EXIT	(0)
+
 /*
  * TIF flags handled in exit_to_user_mode_loop()
  */
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index fa17baa..e7a11e3 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -42,7 +42,7 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
 }
 
 static long syscall_trace_enter(struct pt_regs *regs, long syscall,
-				unsigned long ti_work)
+				unsigned long ti_work, unsigned long work)
 {
 	long ret = 0;
 
@@ -74,11 +74,12 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
 static __always_inline long
 __syscall_enter_from_user_work(struct pt_regs *regs, long syscall)
 {
+	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
 	unsigned long ti_work;
 
 	ti_work = READ_ONCE(current_thread_info()->flags);
-	if (ti_work & SYSCALL_ENTER_WORK)
-		syscall = syscall_trace_enter(regs, syscall, ti_work);
+	if (work & SYSCALL_WORK_ENTER || ti_work & SYSCALL_ENTER_WORK)
+		syscall = syscall_trace_enter(regs, syscall, ti_work, work);
 
 	return syscall;
 }
@@ -225,7 +226,8 @@ static inline bool report_single_step(unsigned long ti_work)
 }
 #endif
 
-static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work)
+static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work,
+			      unsigned long work)
 {
 	bool step;
 
@@ -245,6 +247,7 @@ static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work)
  */
 static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
 {
+	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
 	u32 cached_flags = READ_ONCE(current_thread_info()->flags);
 	unsigned long nr = syscall_get_nr(current, regs);
 
@@ -262,8 +265,8 @@ static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
 	 * enabled, we want to run them exactly once per syscall exit with
 	 * interrupts enabled.
 	 */
-	if (unlikely(cached_flags & SYSCALL_EXIT_WORK))
-		syscall_exit_work(regs, cached_flags);
+	if (unlikely(work & SYSCALL_WORK_EXIT || cached_flags & SYSCALL_EXIT_WORK))
+		syscall_exit_work(regs, cached_flags, work);
 }
 
 __visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs)

[tip: core/entry] x86: Expose syscall_work field in thread_info

[tip-bot2 for Gabriel Krisman Bertazi]

The following commit has been merged into the core/entry branch of tip:

Commit-ID:     b4581a52caff79eab1ea6caaaa4e08526ce2782b
Gitweb:        https://git.kernel.org/tip/b4581a52caff79eab1ea6caaaa4e08526ce2782b
Author:        Gabriel Krisman Bertazi <krisman@collabora.com>
AuthorDate:    Mon, 16 Nov 2020 12:41:57 -05:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Mon, 16 Nov 2020 21:53:15 +01:00

x86: Expose syscall_work field in thread_info

This field will be used by SYSCALL_WORK flags, migrated from TI flags.

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/20201116174206.2639648-2-krisman@collabora.com

---
 arch/x86/include/asm/thread_info.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 06a1710..0da5d58 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -55,6 +55,7 @@ struct task_struct;
 
 struct thread_info {
 	unsigned long		flags;		/* low level flags */
+	unsigned long		syscall_work;	/* SYSCALL_WORK_ flags */
 	u32			status;		/* thread synchronous flags */
 };
 

Re: [PATCH v2 05/10] tracepoints: Migrate to use SYSCALL_WORK flag

[Steven Rostedt]

On Mon, 16 Nov 2020 12:42:01 -0500
Gabriel Krisman Bertazi <krisman@collabora.com> wrote:

> For architectures that rely on the generic syscall entry code, use the
> syscall_work field in struct thread_info and the specific SYSCALL_WORK
> flag.  This set of flags has the advantage of being architecture
> independent.
> 
> Users of the flag outside of the generic entry code should rely on the
> accessor macros, such that the flag is still correctly resolved for
> architectures that don't use the generic entry code and still rely on
> TIF flags for system call work.
> 
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Also added Mathieu to Cc.

-- Steve

> 
> ---
> Changes since v2:
>   - Drop explicit value assignment in enum (tglx)
>   - Avoid FLAG/_FLAG defines (tglx)
>   - Fix comment to refer to SYSCALL_WORK_SECCOMP (me)
> ---
>  include/linux/entry-common.h | 13 +++++--------
>  include/linux/thread_info.h  |  2 ++
>  include/trace/syscall.h      |  6 +++---
>  kernel/entry/common.c        |  4 ++--
>  kernel/trace/trace_events.c  |  8 ++++----
>  kernel/tracepoint.c          |  4 ++--
>  6 files changed, 18 insertions(+), 19 deletions(-)
> 
> diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
> index f3fc4457f63f..8aba367e5c79 100644
> --- 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 1d6488130b5c..ff0ac2ebb4ff 100644
> --- 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 dc8ac27d27c1..8e193f3a33b3 100644
> --- 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 c321056c73d7..4e2b3c08d939 100644
> --- 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 47a71f96e5bc..adf65b502453 100644
> --- 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 3f659f855074..7261fa0f5e3c 100644
> --- 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);
>  	}

Re: [PATCH v2 04/10] seccomp: Migrate to use SYSCALL_WORK flag

[Dmitry Osipenko]

16.11.2020 20:42, Gabriel Krisman Bertazi пишет:
> When one the generic syscall entry code, use the syscall_work field in
> struct thread_info and specific SYSCALL_WORK flags to setup this syscall
> work.  This flag has the advantage of being architecture independent.
> 
> Users of the flag outside of the generic entry code should rely on the
> accessor macros, such that the flag is still correctly resolved for
> architectures that don't use the generic entry code and still rely on
> TIF flags for system call work.
> 
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
> 
> ---
> Changes since v2:
>   - Drop explicit value assignment in enum (tglx)
>   - Avoid FLAG/_FLAG defines (tglx)
>   - Fix comment to refer to SYSCALL_WORK_SECCOMP (me)
> ---
>  include/asm-generic/syscall.h | 2 +-
>  include/linux/entry-common.h  | 8 ++------
>  include/linux/seccomp.h       | 2 +-
>  include/linux/thread_info.h   | 6 ++++++
>  kernel/entry/common.c         | 2 +-
>  kernel/fork.c                 | 2 +-
>  kernel/seccomp.c              | 6 +++---
>  7 files changed, 15 insertions(+), 13 deletions(-)
> 
> diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
> index f3135e734387..524d8e68ff5e 100644
> --- a/include/asm-generic/syscall.h
> +++ b/include/asm-generic/syscall.h
> @@ -135,7 +135,7 @@ 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 %TIF_SECCOMP.
> + * call, due to %TIF_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or %SYSCALL_WORK_SECCOMP.
>   *
>   * Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must
>   * provide an implementation of this.
> diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
> index cbc5c702ee4d..f3fc4457f63f 100644
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
> @@ -21,10 +21,6 @@
>  # define _TIF_SYSCALL_TRACEPOINT	(0)
>  #endif
>  
> -#ifndef _TIF_SECCOMP
> -# define _TIF_SECCOMP			(0)
> -#endif
> -
>  #ifndef _TIF_SYSCALL_AUDIT
>  # define _TIF_SYSCALL_AUDIT		(0)
>  #endif
> @@ -49,7 +45,7 @@
>  #endif
>  
>  #define SYSCALL_ENTER_WORK						\
> -	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP |	\
> +	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT  |			\
>  	 _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_EMU |			\
>  	 ARCH_SYSCALL_ENTER_WORK)
>  
> @@ -64,7 +60,7 @@
>  	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT |			\
>  	 _TIF_SYSCALL_TRACEPOINT | ARCH_SYSCALL_EXIT_WORK)
>  
> -#define SYSCALL_WORK_ENTER	(0)
> +#define SYSCALL_WORK_ENTER	(SYSCALL_WORK_SECCOMP)
>  #define SYSCALL_WORK_EXIT	(0)
>  
>  /*
> diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
> index 02aef2844c38..47763f3999f7 100644
> --- a/include/linux/seccomp.h
> +++ b/include/linux/seccomp.h
> @@ -42,7 +42,7 @@ struct seccomp {
>  extern int __secure_computing(const struct seccomp_data *sd);
>  static inline int secure_computing(void)
>  {
> -	if (unlikely(test_thread_flag(TIF_SECCOMP)))
> +	if (unlikely(test_syscall_work(SECCOMP)))
>  		return  __secure_computing(NULL);
>  	return 0;
>  }
> diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
> index f2d78de55840..1d6488130b5c 100644
> --- a/include/linux/thread_info.h
> +++ b/include/linux/thread_info.h
> @@ -35,6 +35,12 @@ enum {
>  	GOOD_STACK,
>  };
>  
> +enum syscall_work_bit {
> +	SYSCALL_WORK_BIT_SECCOMP,
> +};
> +
> +#define SYSCALL_WORK_SECCOMP		BIT(SYSCALL_WORK_BIT_SECCOMP)
> +
>  #include <asm/thread_info.h>
>  
>  #ifdef __KERNEL__
> diff --git a/kernel/entry/common.c b/kernel/entry/common.c
> index 51c25f774791..c321056c73d7 100644
> --- a/kernel/entry/common.c
> +++ b/kernel/entry/common.c
> @@ -54,7 +54,7 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
>  	}
>  
>  	/* Do seccomp after ptrace, to catch any tracer changes. */
> -	if (ti_work & _TIF_SECCOMP) {
> +	if (work & SYSCALL_WORK_SECCOMP) {
>  		ret = __secure_computing(NULL);
>  		if (ret == -1L)
>  			return ret;
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 7199d359690c..4433c9c60100 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -1625,7 +1625,7 @@ static void copy_seccomp(struct task_struct *p)
>  	 * to manually enable the seccomp thread flag here.
>  	 */
>  	if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
> -		set_tsk_thread_flag(p, TIF_SECCOMP);
> +		set_task_syscall_work(p, SECCOMP);
>  #endif
>  }
>  
> diff --git a/kernel/seccomp.c b/kernel/seccomp.c
> index 8ad7a293255a..f67e92d11ad7 100644
> --- a/kernel/seccomp.c
> +++ b/kernel/seccomp.c
> @@ -356,14 +356,14 @@ static inline void seccomp_assign_mode(struct task_struct *task,
>  
>  	task->seccomp.mode = seccomp_mode;
>  	/*
> -	 * Make sure TIF_SECCOMP cannot be set before the mode (and
> +	 * Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and
>  	 * filter) is set.
>  	 */
>  	smp_mb__before_atomic();
>  	/* Assume default seccomp processes want spec flaw mitigation. */
>  	if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
>  		arch_seccomp_spec_mitigate(task);
> -	set_tsk_thread_flag(task, TIF_SECCOMP);
> +	set_task_syscall_work(task, SECCOMP);
>  }
>  
>  #ifdef CONFIG_SECCOMP_FILTER
> @@ -929,7 +929,7 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
>  
>  	/*
>  	 * Make sure that any changes to mode from another thread have
> -	 * been seen after TIF_SECCOMP was seen.
> +	 * been seen after SYSCALL_WORK_SECCOMP was seen.
>  	 */
>  	rmb();
>  
> 

Hi,

This patch broke seccomp on arm32 using linux-next, chromium browser
doesn't work anymore and there are these errors in KMSG:

Unhandled prefetch abort: breakpoint debug exception (0x002) at ...

Note that arm doesn't use CONFIG_GENERIC_ENTRY. Please fix, thanks in
advance.

Re: [PATCH v2 04/10] seccomp: Migrate to use SYSCALL_WORK flag

[Gabriel Krisman Bertazi]

Dmitry Osipenko <digetx@gmail.com> writes:

> Hi,
>
> This patch broke seccomp on arm32 using linux-next, chromium browser
> doesn't work anymore and there are these errors in KMSG:
>
> Unhandled prefetch abort: breakpoint debug exception (0x002) at ...
>
> Note that arm doesn't use CONFIG_GENERIC_ENTRY. Please fix, thanks in
> advance.

Hi Dmitry,

I believe this is the same problem reported yesterday on this thread

  https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg2390444.html

can you please try the patch I shared on that thread?

  https://lore.kernel.org/patchwork/patch/1344098/

Thanks,

-- 
Gabriel Krisman Bertazi

Re: [PATCH v2 04/10] seccomp: Migrate to use SYSCALL_WORK flag

[Dmitry Osipenko]

24.11.2020 20:55, Gabriel Krisman Bertazi пишет:
> Dmitry Osipenko <digetx@gmail.com> writes:
> 
>> Hi,
>>
>> This patch broke seccomp on arm32 using linux-next, chromium browser
>> doesn't work anymore and there are these errors in KMSG:
>>
>> Unhandled prefetch abort: breakpoint debug exception (0x002) at ...
>>
>> Note that arm doesn't use CONFIG_GENERIC_ENTRY. Please fix, thanks in
>> advance.
> 
> Hi Dmitry,
> 
> I believe this is the same problem reported yesterday on this thread
> 
>   https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg2390444.html
> 
> can you please try the patch I shared on that thread?
> 
>   https://lore.kernel.org/patchwork/patch/1344098/

It works, thank you.

Tested-by: Dmitry Osipenko <digetx@gmail.com>