linux-kernel - [PATCH] arm64: make a single hook to syscall

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Date:	Fri,  7 Feb 2014 19:07:31 +0900
From:	AKASHI Takahiro <takahiro.akashi@...aro.org>
To:	will.deacon@....com
Cc:	viro@...iv.linux.org.uk, eparis@...hat.com, rgb@...hat.com,
	catalin.marinas@....com, arndb@...db.de,
	linux-arm-kernel@...ts.infradead.org,
	linaro-kernel@...ts.linaro.org, linux-kernel@...r.kernel.org,
	linux-audit@...hat.com, patches@...aro.org,
	AKASHI Takahiro <takahiro.akashi@...aro.org>
Subject: [PATCH] arm64: make a single hook to syscall_trace() for all syscall features

Currently syscall_trace() is called only for ptrace.
With additional TIF_xx flags introduced, it is now called in all the cases
of audit, ftrace and seccomp in addition to ptrace.
Those features will be implemented later, but it's safe to include them
now because they can not be turned on anyway.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
---
 arch/arm64/include/asm/thread_info.h |   13 +++++++++++++
 arch/arm64/kernel/entry.S            |    5 +++--
 arch/arm64/kernel/ptrace.c           |   11 +++++------
 3 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index 720e70b..c3df797 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -91,6 +91,9 @@ static inline struct thread_info *current_thread_info(void)
 /*
  * thread information flags:
  *  TIF_SYSCALL_TRACE	- syscall trace active
+ *  TIF_SYSCALL_TRACEPOINT - syscall tracepoint for ftrace
+ *  TIF_SYSCALL_AUDIT	- syscall auditing
+ *  TIF_SECOMP		- syscall secure computing
  *  TIF_SIGPENDING	- signal pending
  *  TIF_NEED_RESCHED	- rescheduling necessary
  *  TIF_NOTIFY_RESUME	- callback before returning to user
@@ -101,6 +104,9 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_NEED_RESCHED	1
 #define TIF_NOTIFY_RESUME	2	/* callback before returning to user */
 #define TIF_SYSCALL_TRACE	8
+#define TIF_SYSCALL_AUDIT	9
+#define TIF_SYSCALL_TRACEPOINT	10
+#define TIF_SECCOMP		11
 #define TIF_POLLING_NRFLAG	16
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
 #define TIF_FREEZE		19
@@ -112,10 +118,17 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
+#define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
+#define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
+#define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
+#define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 #define _TIF_32BIT		(1 << TIF_32BIT)
 
 #define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
 				 _TIF_NOTIFY_RESUME)
 
+#define _TIF_WORK_SYSCALL	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
+				 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP)
+
 #endif /* __KERNEL__ */
 #endif /* __ASM_THREAD_INFO_H */
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 39ac630..c94b2ab 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -631,8 +631,9 @@ el0_svc_naked:					// compat entry point
 	enable_irq
 
 	get_thread_info tsk
-	ldr	x16, [tsk, #TI_FLAGS]		// check for syscall tracing
-	tbnz	x16, #TIF_SYSCALL_TRACE, __sys_trace // are we tracing syscalls?
+	ldr	x16, [tsk, #TI_FLAGS]		// check for syscall hooks
+	tst	x16, #_TIF_WORK_SYSCALL
+	b.ne	__sys_trace
 	adr	lr, ret_fast_syscall		// return address
 	cmp     scno, sc_nr                     // check upper syscall limit
 	b.hs	ni_sys
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 6a8928b..64ce39f 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -1062,9 +1062,6 @@ asmlinkage int syscall_trace(int dir, struct pt_regs *regs)
 {
 	unsigned long saved_reg;
 
-	if (!test_thread_flag(TIF_SYSCALL_TRACE))
-		return regs->syscallno;
-
 	if (is_compat_task()) {
 		/* AArch32 uses ip (r12) for scratch */
 		saved_reg = regs->regs[12];
@@ -1078,10 +1075,12 @@ asmlinkage int syscall_trace(int dir, struct pt_regs *regs)
 		regs->regs[7] = dir;
 	}
 
-	if (dir)
+	if (dir) {
 		tracehook_report_syscall_exit(regs, 0);
-	else if (tracehook_report_syscall_entry(regs))
-		regs->syscallno = ~0UL;
+	} else {
+		if (tracehook_report_syscall_entry(regs))
+			regs->syscallno = ~0UL;
+	}
 
 	if (is_compat_task())
 		regs->regs[12] = saved_reg;
-- 
1.7.9.5

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