[PATCH 0/3] ARM support for syscall tracing

[PATCH 0/3] ARM support for syscall tracing

[Wade Farnsworth]

This is a rework of Steven Walter's syscall tracing patches first
posted here:

http://lists.infradead.org/pipermail/linux-arm-kernel/2011-November/074454.html

I've rebased the patches against the current mainline master branch, as well
as implemented several changes based on feedback from Will Deacon and
Russel King.

Wade Farnsworth (3):
  ARM: add support for the generic syscall.h interface
  ARM: add TRACEHOOK support
  ARM: support syscall tracing

 arch/arm/Kconfig                   |    2 +
 arch/arm/include/asm/ptrace.h      |    5 ++
 arch/arm/include/asm/syscall.h     |   93 ++++++++++++++++++++++++++++++++++++
 arch/arm/include/asm/thread_info.h |    2 +
 arch/arm/include/asm/unistd.h      |   12 +++++
 arch/arm/kernel/entry-common.S     |   16 +++++-
 arch/arm/kernel/ptrace.c           |   34 +++++++------
 arch/arm/kernel/signal.c           |    2 +
 8 files changed, 149 insertions(+), 17 deletions(-)
 create mode 100644 arch/arm/include/asm/syscall.h

[PATCH 1/3] ARM: add support for the generic syscall.h interface

[Wade Farnsworth]

Supplying the asm-generic/syscall.h interface is a
pre-requisite for HAVE_ARCH_TRACEHOOK

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
---
 arch/arm/include/asm/syscall.h |   93 ++++++++++++++++++++++++++++++++++++++++
 1 files changed, 93 insertions(+), 0 deletions(-)
 create mode 100644 arch/arm/include/asm/syscall.h

diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h
new file mode 100644
index 0000000..d5e30ef
--- /dev/null
+++ b/arch/arm/include/asm/syscall.h
@@ -0,0 +1,93 @@
+/*
+ * Access to user system call parameters and results
+ *
+ * See asm-generic/syscall.h for descriptions of what we must do here.
+ */
+
+#ifndef _ASM_ARM_SYSCALL_H
+#define _ASM_ARM_SYSCALL_H
+
+#include <linux/err.h>
+
+extern const unsigned long sys_call_table[];
+
+static inline int syscall_get_nr(struct task_struct *task,
+				 struct pt_regs *regs)
+{
+	return task_thread_info(task)->syscall;
+}
+
+static inline void syscall_rollback(struct task_struct *task,
+				    struct pt_regs *regs)
+{
+	regs->ARM_r0 = regs->ARM_ORIG_r0;
+}
+
+static inline long syscall_get_error(struct task_struct *task,
+				     struct pt_regs *regs)
+{
+	unsigned long error = regs->ARM_r0;
+	return IS_ERR_VALUE(error) ? error : 0;
+}
+
+static inline long syscall_get_return_value(struct task_struct *task,
+					    struct pt_regs *regs)
+{
+	return regs->ARM_r0;
+}
+
+static inline void syscall_set_return_value(struct task_struct *task,
+					    struct pt_regs *regs,
+					    int error, long val)
+{
+	regs->ARM_r0 = (long) error ?: val;
+}
+
+#define SYSCALL_MAX_ARGS 7
+
+static inline void syscall_get_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 unsigned long *args)
+{
+	if (i + n > SYSCALL_MAX_ARGS) {
+		unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;
+		unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;
+		pr_warning("%s called with max args %d, handling only %d\n",
+			   __func__, i + n, SYSCALL_MAX_ARGS);
+		memset(args_bad, 0, n_bad * sizeof(args[0]));
+		n = SYSCALL_MAX_ARGS - i;
+	}
+
+	if (i == 0) {
+		args[0] = regs->ARM_ORIG_r0;
+		args++;
+		i++;
+		n--;
+	}
+
+	memcpy(args, &regs->ARM_r0 + i, n * sizeof(args[0]));
+}
+
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 const unsigned long *args)
+{
+	if (i + n > SYSCALL_MAX_ARGS) {
+		pr_warning("%s called with max args %d, handling only %d\n",
+			   __func__, i + n, SYSCALL_MAX_ARGS);
+		n = SYSCALL_MAX_ARGS - i;
+	}
+
+	if (i == 0) {
+		regs->ARM_ORIG_r0 = args[0];
+		args++;
+		i++;
+		n--;
+	}
+
+	memcpy(&regs->ARM_r0 + i, args, n * sizeof(args[0]));
+}
+
+#endif /* _ASM_ARM_SYSCALL_H */
-- 
1.7.0.4

[PATCH 1/3] ARM: add support for the generic syscall.h interface

[Will Deacon]

Hi Wade,

On Wed, Feb 22, 2012 at 02:45:36PM +0000, Wade Farnsworth wrote:
> Supplying the asm-generic/syscall.h interface is a
> pre-requisite for HAVE_ARCH_TRACEHOOK
> 
> Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
> Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
> ---
>  arch/arm/include/asm/syscall.h |   93 ++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 93 insertions(+), 0 deletions(-)
>  create mode 100644 arch/arm/include/asm/syscall.h

[...]

> +
> +static inline void syscall_set_return_value(struct task_struct *task,
> +					    struct pt_regs *regs,
> +					    int error, long val)
> +{
> +	regs->ARM_r0 = (long) error ?: val;
> +}

This looks like far too much fun for kernel code, although I see that '?:'
does appear elsewhere in the kernel. Usually in perl regexs though :)

Will

[PATCH 1/3] ARM: add support for the generic syscall.h interface

[Wade Farnsworth]

Will Deacon wrote:
> Hi Wade,
>
> On Wed, Feb 22, 2012 at 02:45:36PM +0000, Wade Farnsworth wrote:
>> Supplying the asm-generic/syscall.h interface is a
>> pre-requisite for HAVE_ARCH_TRACEHOOK
>>
>> Signed-off-by: Steven Walter<stevenrwalter@gmail.com>
>> Signed-off-by: Wade Farnsworth<wade_farnsworth@mentor.com>
>> ---
>>   arch/arm/include/asm/syscall.h |   93 ++++++++++++++++++++++++++++++++++++++++
>>   1 files changed, 93 insertions(+), 0 deletions(-)
>>   create mode 100644 arch/arm/include/asm/syscall.h
>
> [...]
>
>> +
>> +static inline void syscall_set_return_value(struct task_struct *task,
>> +					    struct pt_regs *regs,
>> +					    int error, long val)
>> +{
>> +	regs->ARM_r0 = (long) error ?: val;
>> +}
>
> This looks like far too much fun for kernel code, although I see that '?:'
> does appear elsewhere in the kernel. Usually in perl regexs though :)
>

OK, I'll change this to

regs->ARM_r0 = (long) error ? error : val;

That better? :)

Thanks,

-Wade

[PATCH 2/3] ARM: add TRACEHOOK support

[Wade Farnsworth]

Add calls to tracehook_report_syscall_{entry,exit} and tracehook_signal_handler

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
---
 arch/arm/Kconfig              |    1 +
 arch/arm/include/asm/ptrace.h |    5 +++++
 arch/arm/kernel/ptrace.c      |   21 ++++++---------------
 arch/arm/kernel/signal.c      |    2 ++
 4 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a48aecc..0faad0c 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -10,6 +10,7 @@ config ARM
 	select GENERIC_ATOMIC64 if (CPU_V6 || !CPU_32v6K || !AEABI)
 	select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
 	select HAVE_ARCH_KGDB
+	select HAVE_ARCH_TRACEHOOK
 	select HAVE_KPROBES if !XIP_KERNEL
 	select HAVE_KRETPROBES if (HAVE_KPROBES)
 	select HAVE_FUNCTION_TRACER if (!XIP_KERNEL)
diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h
index 451808b..355ece5 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -249,6 +249,11 @@ static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
 	return regs->ARM_sp;
 }
 
+static inline unsigned long user_stack_pointer(struct pt_regs *regs)
+{
+	return regs->ARM_sp;
+}
+
 #endif /* __KERNEL__ */
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index e33870f..5cc5415 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -23,6 +23,7 @@
 #include <linux/perf_event.h>
 #include <linux/hw_breakpoint.h>
 #include <linux/regset.h>
+#include <linux/tracehook.h>
 
 #include <asm/pgtable.h>
 #include <asm/system.h>
@@ -923,24 +924,14 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
 
 	if (!test_thread_flag(TIF_SYSCALL_TRACE))
 		return scno;
-	if (!(current->ptrace & PT_PTRACED))
-		return scno;
 
 	current_thread_info()->syscall = scno;
 
-	/* the 0x80 provides a way for the tracing parent to distinguish
-	   between a syscall stop and SIGTRAP delivery */
-	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
-				 ? 0x80 : 0));
-	/*
-	 * this isn't the same as continuing with a signal, but it will do
-	 * for normal use.  strace only continues with a signal if the
-	 * stopping signal is not SIGTRAP.  -brl
-	 */
-	if (current->exit_code) {
-		send_sig(current->exit_code, current, 1);
-		current->exit_code = 0;
-	}
+	if (why)
+		tracehook_report_syscall_exit(regs, 0);
+	else if (tracehook_report_syscall_entry(regs))
+		current_thread_info()->syscall = -1;
+
 	regs->ARM_ip = ip;
 
 	return current_thread_info()->syscall;
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 9e617bd..6f084c1 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -644,6 +644,8 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
 	recalc_sigpending();
 	spin_unlock_irq(&tsk->sighand->siglock);
 
+	tracehook_signal_handler(sig, info, ka, regs, 0);
+
 	return 0;
 }
 
-- 
1.7.0.4

[PATCH 3/3] ARM: support syscall tracing

[Wade Farnsworth]

As specified by ftrace-design.txt, TIF_SYSCALL_TRACEPOINT was
added, as well as NR_syscalls in asm/unistd.h.  Additionally,
__sys_trace was modified to call trace_sys_enter and
trace_sys_exit when appropriate.

Tests #2 - #4 of "perf test" now complete successfully.

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
---
 arch/arm/Kconfig                   |    1 +
 arch/arm/include/asm/thread_info.h |    2 ++
 arch/arm/include/asm/unistd.h      |   12 ++++++++++++
 arch/arm/kernel/entry-common.S     |   16 ++++++++++++++--
 arch/arm/kernel/ptrace.c           |   23 ++++++++++++++++++-----
 5 files changed, 47 insertions(+), 7 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 0faad0c..b1d9396 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -11,6 +11,7 @@ config ARM
 	select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_TRACEHOOK
+	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_KPROBES if !XIP_KERNEL
 	select HAVE_KRETPROBES if (HAVE_KPROBES)
 	select HAVE_FUNCTION_TRACER if (!XIP_KERNEL)
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index d4c24d4..f2ff2de 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -146,6 +146,7 @@ extern void vfp_flush_hwstate(struct thread_info *);
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
 #define TIF_RESTORE_SIGMASK	20
 #define TIF_SECCOMP		21
+#define TIF_SYSCALL_TRACEPOINT	22
 
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
@@ -156,6 +157,7 @@ extern void vfp_flush_hwstate(struct thread_info *);
 #define _TIF_USING_IWMMXT	(1 << TIF_USING_IWMMXT)
 #define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
+#define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 
 /* Checks for any syscall work in entry-common.S */
 #define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT)
diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
index 512cd14..e4a2e78 100644
--- a/arch/arm/include/asm/unistd.h
+++ b/arch/arm/include/asm/unistd.h
@@ -405,6 +405,18 @@
 #define __NR_process_vm_readv		(__NR_SYSCALL_BASE+376)
 #define __NR_process_vm_writev		(__NR_SYSCALL_BASE+377)
 
+#ifdef __KERNEL__
+
+/* This may need to be greater than __NR_last_syscall+1 in order to
+ * account for the padding in the syscall table */
+#define __NR_syscalls  (380)
+
+#ifndef __ASSEMBLY__
+#define NR_syscalls (__NR_syscalls)
+#endif /* __ASSEMBLY__ */
+
+#endif /* __KERNEL__ */
+
 /*
  * The following SWIs are ARM private.
  */
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 9fd0ba9..9bed212 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -79,6 +79,11 @@ no_work_pending:
 ENDPROC(ret_to_user_from_irq)
 ENDPROC(ret_to_user)
 
+.macro test_syscall_tracing reg
+       tst     \reg, #_TIF_SYSCALL_WORK
+       tsteq   \reg, #_TIF_SYSCALL_TRACEPOINT
+.endm
+
 /*
  * This is how we return from a fork.
  */
@@ -87,7 +92,7 @@ ENTRY(ret_from_fork)
 	get_thread_info tsk
 	ldr	r1, [tsk, #TI_FLAGS]		@ check for syscall tracing
 	mov	why, #1
-	tst	r1, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
+	test_syscall_tracing r1
 	beq	ret_slow_syscall
 	mov	r1, sp
 	mov	r0, #1				@ trace exit [IP = 1]
@@ -98,6 +103,13 @@ ENDPROC(ret_from_fork)
 	.equ NR_syscalls,0
 #define CALL(x) .equ NR_syscalls,NR_syscalls+1
 #include "calls.S"
+
+/* Ensure that the system call table is not larger than __NR_syscalls,
+ * which is the value the rest of the system sees */
+.ifgt NR_syscalls - __NR_syscalls
+.error "__NR_syscalls is less than the size of the syscall table"
+.endif
+
 #undef CALL
 #define CALL(x) .long x
 
@@ -446,7 +458,7 @@ ENTRY(vector_swi)
 1:
 #endif
 
-	tst	r10, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
+	test_syscall_tracing r10
 	bne	__sys_trace
 
 	cmp	scno, #NR_syscalls		@ check upper syscall limit
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 5cc5415..5e15e67 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -29,6 +29,9 @@
 #include <asm/system.h>
 #include <asm/traps.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/syscalls.h>
+
 #define REG_PC	15
 #define REG_PSR	16
 /*
@@ -922,15 +925,25 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
 		audit_syscall_entry(AUDIT_ARCH_ARMEB, scno, regs->ARM_r0,
 				    regs->ARM_r1, regs->ARM_r2, regs->ARM_r3);
 
-	if (!test_thread_flag(TIF_SYSCALL_TRACE))
+	if (!test_thread_flag(TIF_SYSCALL_TRACE) &&
+	    !test_thread_flag(TIF_SYSCALL_TRACEPOINT))
 		return scno;
 
 	current_thread_info()->syscall = scno;
 
-	if (why)
-		tracehook_report_syscall_exit(regs, 0);
-	else if (tracehook_report_syscall_entry(regs))
-		current_thread_info()->syscall = -1;
+	if (test_thread_flag(TIF_SYSCALL_TRACE)) {
+		if (why)
+			tracehook_report_syscall_exit(regs, 0);
+		else if (tracehook_report_syscall_entry(regs))
+			current_thread_info()->syscall = -1;
+	}
+
+	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) {
+		if (why)
+			trace_sys_exit(regs, scno);
+		else
+			trace_sys_enter(regs, scno);
+	}
 
 	regs->ARM_ip = ip;
 
-- 
1.7.0.4

[PATCH 3/3] ARM: support syscall tracing

[Will Deacon]

On Wed, Feb 22, 2012 at 02:47:00PM +0000, Wade Farnsworth wrote:
> As specified by ftrace-design.txt, TIF_SYSCALL_TRACEPOINT was
> added, as well as NR_syscalls in asm/unistd.h.  Additionally,
> __sys_trace was modified to call trace_sys_enter and
> trace_sys_exit when appropriate.
> 
> Tests #2 - #4 of "perf test" now complete successfully.
> 
> Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
> Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
> ---

[...]

> diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
> index 512cd14..e4a2e78 100644
> --- a/arch/arm/include/asm/unistd.h
> +++ b/arch/arm/include/asm/unistd.h
> @@ -405,6 +405,18 @@
>  #define __NR_process_vm_readv		(__NR_SYSCALL_BASE+376)
>  #define __NR_process_vm_writev		(__NR_SYSCALL_BASE+377)
>  
> +#ifdef __KERNEL__
> +
> +/* This may need to be greater than __NR_last_syscall+1 in order to
> + * account for the padding in the syscall table */
> +#define __NR_syscalls  (380)

Do we actually have padding in the syscall table? It looks like a list of
.long to me. I'd rather put the correct number in if possible.

> +#ifndef __ASSEMBLY__
> +#define NR_syscalls (__NR_syscalls)
> +#endif /* __ASSEMBLY__ */

Hmm, these guards feel like a hack. Would moving the define into syscall.h
help?

> diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
> index 9fd0ba9..9bed212 100644
> --- a/arch/arm/kernel/entry-common.S
> +++ b/arch/arm/kernel/entry-common.S
> @@ -79,6 +79,11 @@ no_work_pending:
>  ENDPROC(ret_to_user_from_irq)
>  ENDPROC(ret_to_user)
>  
> +.macro test_syscall_tracing reg
> +       tst     \reg, #_TIF_SYSCALL_WORK
> +       tsteq   \reg, #_TIF_SYSCALL_TRACEPOINT
> +.endm
> +
>  /*
>   * This is how we return from a fork.
>   */
> @@ -87,7 +92,7 @@ ENTRY(ret_from_fork)
>  	get_thread_info tsk
>  	ldr	r1, [tsk, #TI_FLAGS]		@ check for syscall tracing
>  	mov	why, #1
> -	tst	r1, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
> +	test_syscall_tracing r1
>  	beq	ret_slow_syscall
>  	mov	r1, sp
>  	mov	r0, #1				@ trace exit [IP = 1]
> @@ -98,6 +103,13 @@ ENDPROC(ret_from_fork)
>  	.equ NR_syscalls,0
>  #define CALL(x) .equ NR_syscalls,NR_syscalls+1
>  #include "calls.S"
> +
> +/* Ensure that the system call table is not larger than __NR_syscalls,
> + * which is the value the rest of the system sees */
> +.ifgt NR_syscalls - __NR_syscalls
> +.error "__NR_syscalls is less than the size of the syscall table"
> +.endif

I think it would also be nice to check for equality here if we can.

Rest of the code looks alright, but it should be tested with OABI if it
hasn't been already.

Will

[PATCH 3/3] ARM: support syscall tracing

[Wade Farnsworth]

Will Deacon wrote:
> On Wed, Feb 22, 2012 at 02:47:00PM +0000, Wade Farnsworth wrote:
>> As specified by ftrace-design.txt, TIF_SYSCALL_TRACEPOINT was
>> added, as well as NR_syscalls in asm/unistd.h.  Additionally,
>> __sys_trace was modified to call trace_sys_enter and
>> trace_sys_exit when appropriate.
>>
>> Tests #2 - #4 of "perf test" now complete successfully.
>>
>> Signed-off-by: Steven Walter<stevenrwalter@gmail.com>
>> Signed-off-by: Wade Farnsworth<wade_farnsworth@mentor.com>
>> ---
>
> [...]
>
>> diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
>> index 512cd14..e4a2e78 100644
>> --- a/arch/arm/include/asm/unistd.h
>> +++ b/arch/arm/include/asm/unistd.h
>> @@ -405,6 +405,18 @@
>>   #define __NR_process_vm_readv		(__NR_SYSCALL_BASE+376)
>>   #define __NR_process_vm_writev		(__NR_SYSCALL_BASE+377)
>>
>> +#ifdef __KERNEL__
>> +
>> +/* This may need to be greater than __NR_last_syscall+1 in order to
>> + * account for the padding in the syscall table */
>> +#define __NR_syscalls  (380)
>
> Do we actually have padding in the syscall table? It looks like a list of
> .long to me. I'd rather put the correct number in if possible.

This patch will calculate NR_syscalls by counting the number of entries 
in calls.S.  calls.S may add up to three entries of padding at the end 
of that file that __NR_syscalls needs to account for.

>
>> +#ifndef __ASSEMBLY__
>> +#define NR_syscalls (__NR_syscalls)
>> +#endif /* __ASSEMBLY__ */
>
> Hmm, these guards feel like a hack. Would moving the define into syscall.h
> help?

I'll give this a shot, though I'll also note that adding the guards on 
!__ASSEMBLY__ was suggested by Russel:

http://lists.infradead.org/pipermail/linux-arm-kernel/2011-November/074506.html

>
>> diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
>> index 9fd0ba9..9bed212 100644
>> --- a/arch/arm/kernel/entry-common.S
>> +++ b/arch/arm/kernel/entry-common.S
>> @@ -79,6 +79,11 @@ no_work_pending:
>>   ENDPROC(ret_to_user_from_irq)
>>   ENDPROC(ret_to_user)
>>
>> +.macro test_syscall_tracing reg
>> +       tst     \reg, #_TIF_SYSCALL_WORK
>> +       tsteq   \reg, #_TIF_SYSCALL_TRACEPOINT
>> +.endm
>> +
>>   /*
>>    * This is how we return from a fork.
>>    */
>> @@ -87,7 +92,7 @@ ENTRY(ret_from_fork)
>>   	get_thread_info tsk
>>   	ldr	r1, [tsk, #TI_FLAGS]		@ check for syscall tracing
>>   	mov	why, #1
>> -	tst	r1, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
>> +	test_syscall_tracing r1
>>   	beq	ret_slow_syscall
>>   	mov	r1, sp
>>   	mov	r0, #1				@ trace exit [IP = 1]
>> @@ -98,6 +103,13 @@ ENDPROC(ret_from_fork)
>>   	.equ NR_syscalls,0
>>   #define CALL(x) .equ NR_syscalls,NR_syscalls+1
>>   #include "calls.S"
>> +
>> +/* Ensure that the system call table is not larger than __NR_syscalls,
>> + * which is the value the rest of the system sees */
>> +.ifgt NR_syscalls - __NR_syscalls
>> +.error "__NR_syscalls is less than the size of the syscall table"
>> +.endif
>
> I think it would also be nice to check for equality here if we can.

Should be doable.

>
> Rest of the code looks alright, but it should be tested with OABI if it
> hasn't been already.
>

I might be able to build my userspace against OABI.  I'll see what I can 
dig up.

Thanks for the review!

-Wade

[PATCH v2 0/3] ARM support for syscall tracing

[Wade Farnsworth]

This is a rework of Steven Walter's syscall tracing patches first
posted here:

http://lists.infradead.org/pipermail/linux-arm-kernel/2011-November/074454.html

I've rebased the patches against the current mainline master branch, as well
as implemented several changes based on feedback from Will Deacon and
Russel King.

v2: - Tested on EABI and OABI.
    - Removed an instance of the ?: operator in syscall_set_return_value()
    - Moved #define of NR_syscalls to syscall.h
    - Changed the test of NR_syscalls vs __NR_syscalls in entry-common.S
      to .ifne

Wade Farnsworth (3):
  ARM: add support for the generic syscall.h interface
  ARM: add TRACEHOOK support
  ARM: support syscall tracing

 arch/arm/Kconfig                   |    2 +
 arch/arm/include/asm/ptrace.h      |    5 ++
 arch/arm/include/asm/syscall.h     |   97 ++++++++++++++++++++++++++++++++++++
 arch/arm/include/asm/thread_info.h |    2 +
 arch/arm/include/asm/unistd.h      |    8 +++
 arch/arm/kernel/entry-common.S     |   16 +++++-
 arch/arm/kernel/ptrace.c           |   34 +++++++------
 arch/arm/kernel/signal.c           |    2 +
 8 files changed, 149 insertions(+), 17 deletions(-)
 create mode 100644 arch/arm/include/asm/syscall.h

[PATCH v2 1/3] ARM: add support for the generic syscall.h interface

[Wade Farnsworth]

Supplying the asm-generic/syscall.h interface is a
pre-requisite for HAVE_ARCH_TRACEHOOK

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
---
 arch/arm/include/asm/syscall.h |   93 ++++++++++++++++++++++++++++++++++++++++
 1 files changed, 93 insertions(+), 0 deletions(-)
 create mode 100644 arch/arm/include/asm/syscall.h

diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h
new file mode 100644
index 0000000..c334a23
--- /dev/null
+++ b/arch/arm/include/asm/syscall.h
@@ -0,0 +1,93 @@
+/*
+ * Access to user system call parameters and results
+ *
+ * See asm-generic/syscall.h for descriptions of what we must do here.
+ */
+
+#ifndef _ASM_ARM_SYSCALL_H
+#define _ASM_ARM_SYSCALL_H
+
+#include <linux/err.h>
+
+extern const unsigned long sys_call_table[];
+
+static inline int syscall_get_nr(struct task_struct *task,
+				 struct pt_regs *regs)
+{
+	return task_thread_info(task)->syscall;
+}
+
+static inline void syscall_rollback(struct task_struct *task,
+				    struct pt_regs *regs)
+{
+	regs->ARM_r0 = regs->ARM_ORIG_r0;
+}
+
+static inline long syscall_get_error(struct task_struct *task,
+				     struct pt_regs *regs)
+{
+	unsigned long error = regs->ARM_r0;
+	return IS_ERR_VALUE(error) ? error : 0;
+}
+
+static inline long syscall_get_return_value(struct task_struct *task,
+					    struct pt_regs *regs)
+{
+	return regs->ARM_r0;
+}
+
+static inline void syscall_set_return_value(struct task_struct *task,
+					    struct pt_regs *regs,
+					    int error, long val)
+{
+	regs->ARM_r0 = (long) error ? error : val;
+}
+
+#define SYSCALL_MAX_ARGS 7
+
+static inline void syscall_get_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 unsigned long *args)
+{
+	if (i + n > SYSCALL_MAX_ARGS) {
+		unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;
+		unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;
+		pr_warning("%s called with max args %d, handling only %d\n",
+			   __func__, i + n, SYSCALL_MAX_ARGS);
+		memset(args_bad, 0, n_bad * sizeof(args[0]));
+		n = SYSCALL_MAX_ARGS - i;
+	}
+
+	if (i == 0) {
+		args[0] = regs->ARM_ORIG_r0;
+		args++;
+		i++;
+		n--;
+	}
+
+	memcpy(args, &regs->ARM_r0 + i, n * sizeof(args[0]));
+}
+
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 const unsigned long *args)
+{
+	if (i + n > SYSCALL_MAX_ARGS) {
+		pr_warning("%s called with max args %d, handling only %d\n",
+			   __func__, i + n, SYSCALL_MAX_ARGS);
+		n = SYSCALL_MAX_ARGS - i;
+	}
+
+	if (i == 0) {
+		regs->ARM_ORIG_r0 = args[0];
+		args++;
+		i++;
+		n--;
+	}
+
+	memcpy(&regs->ARM_r0 + i, args, n * sizeof(args[0]));
+}
+
+#endif /* _ASM_ARM_SYSCALL_H */
-- 
1.7.0.4

[PATCH v2 2/3] ARM: add TRACEHOOK support

[Wade Farnsworth]

Add calls to tracehook_report_syscall_{entry,exit} and tracehook_signal_handler

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
---
 arch/arm/Kconfig              |    1 +
 arch/arm/include/asm/ptrace.h |    5 +++++
 arch/arm/kernel/ptrace.c      |   21 ++++++---------------
 arch/arm/kernel/signal.c      |    2 ++
 4 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a48aecc..0faad0c 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -10,6 +10,7 @@ config ARM
 	select GENERIC_ATOMIC64 if (CPU_V6 || !CPU_32v6K || !AEABI)
 	select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
 	select HAVE_ARCH_KGDB
+	select HAVE_ARCH_TRACEHOOK
 	select HAVE_KPROBES if !XIP_KERNEL
 	select HAVE_KRETPROBES if (HAVE_KPROBES)
 	select HAVE_FUNCTION_TRACER if (!XIP_KERNEL)
diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h
index 451808b..355ece5 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -249,6 +249,11 @@ static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
 	return regs->ARM_sp;
 }
 
+static inline unsigned long user_stack_pointer(struct pt_regs *regs)
+{
+	return regs->ARM_sp;
+}
+
 #endif /* __KERNEL__ */
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index ede6443..46f4b41 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -24,6 +24,7 @@
 #include <linux/hw_breakpoint.h>
 #include <linux/regset.h>
 #include <linux/audit.h>
+#include <linux/tracehook.h>
 
 #include <asm/pgtable.h>
 #include <asm/system.h>
@@ -930,24 +931,14 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
 
 	if (!test_thread_flag(TIF_SYSCALL_TRACE))
 		return scno;
-	if (!(current->ptrace & PT_PTRACED))
-		return scno;
 
 	current_thread_info()->syscall = scno;
 
-	/* the 0x80 provides a way for the tracing parent to distinguish
-	   between a syscall stop and SIGTRAP delivery */
-	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
-				 ? 0x80 : 0));
-	/*
-	 * this isn't the same as continuing with a signal, but it will do
-	 * for normal use.  strace only continues with a signal if the
-	 * stopping signal is not SIGTRAP.  -brl
-	 */
-	if (current->exit_code) {
-		send_sig(current->exit_code, current, 1);
-		current->exit_code = 0;
-	}
+	if (why)
+		tracehook_report_syscall_exit(regs, 0);
+	else if (tracehook_report_syscall_entry(regs))
+		current_thread_info()->syscall = -1;
+
 	regs->ARM_ip = ip;
 
 	return current_thread_info()->syscall;
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 9e617bd..6f084c1 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -644,6 +644,8 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
 	recalc_sigpending();
 	spin_unlock_irq(&tsk->sighand->siglock);
 
+	tracehook_signal_handler(sig, info, ka, regs, 0);
+
 	return 0;
 }
 
-- 
1.7.0.4

[PATCH v2 3/3] ARM: support syscall tracing

[Wade Farnsworth]

As specified by ftrace-design.txt, TIF_SYSCALL_TRACEPOINT was
added, as well as NR_syscalls in asm/unistd.h.  Additionally,
__sys_trace was modified to call trace_sys_enter and
trace_sys_exit when appropriate.

Tests #2 - #4 of "perf test" now complete successfully.

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
---
 arch/arm/Kconfig                   |    1 +
 arch/arm/include/asm/syscall.h     |    4 ++++
 arch/arm/include/asm/thread_info.h |    2 ++
 arch/arm/include/asm/unistd.h      |    8 ++++++++
 arch/arm/kernel/entry-common.S     |   16 ++++++++++++++--
 arch/arm/kernel/ptrace.c           |   23 ++++++++++++++++++-----
 6 files changed, 47 insertions(+), 7 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 0faad0c..b1d9396 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -11,6 +11,7 @@ config ARM
 	select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_TRACEHOOK
+	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_KPROBES if !XIP_KERNEL
 	select HAVE_KRETPROBES if (HAVE_KPROBES)
 	select HAVE_FUNCTION_TRACER if (!XIP_KERNEL)
diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h
index c334a23..47486a4 100644
--- a/arch/arm/include/asm/syscall.h
+++ b/arch/arm/include/asm/syscall.h
@@ -9,6 +9,10 @@
 
 #include <linux/err.h>
 
+#include <asm/unistd.h>
+
+#define NR_syscalls (__NR_syscalls)
+
 extern const unsigned long sys_call_table[];
 
 static inline int syscall_get_nr(struct task_struct *task,
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index d4c24d4..f2ff2de 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -146,6 +146,7 @@ extern void vfp_flush_hwstate(struct thread_info *);
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
 #define TIF_RESTORE_SIGMASK	20
 #define TIF_SECCOMP		21
+#define TIF_SYSCALL_TRACEPOINT	22
 
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
@@ -156,6 +157,7 @@ extern void vfp_flush_hwstate(struct thread_info *);
 #define _TIF_USING_IWMMXT	(1 << TIF_USING_IWMMXT)
 #define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
+#define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 
 /* Checks for any syscall work in entry-common.S */
 #define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT)
diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
index 512cd14..d27d7d7 100644
--- a/arch/arm/include/asm/unistd.h
+++ b/arch/arm/include/asm/unistd.h
@@ -406,6 +406,14 @@
 #define __NR_process_vm_writev		(__NR_SYSCALL_BASE+377)
 
 /*
+ * This may need to be greater than __NR_last_syscall+1 in order to
+ * account for the padding in the syscall table
+ */
+#ifdef __KERNEL__
+#define __NR_syscalls  (380)
+#endif /* __KERNEL__ */
+
+/*
  * The following SWIs are ARM private.
  */
 #define __ARM_NR_BASE			(__NR_SYSCALL_BASE+0x0f0000)
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 9fd0ba9..01686b2 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -79,6 +79,11 @@ no_work_pending:
 ENDPROC(ret_to_user_from_irq)
 ENDPROC(ret_to_user)
 
+.macro test_syscall_tracing reg
+       tst     \reg, #_TIF_SYSCALL_WORK
+       tsteq   \reg, #_TIF_SYSCALL_TRACEPOINT
+.endm
+
 /*
  * This is how we return from a fork.
  */
@@ -87,7 +92,7 @@ ENTRY(ret_from_fork)
 	get_thread_info tsk
 	ldr	r1, [tsk, #TI_FLAGS]		@ check for syscall tracing
 	mov	why, #1
-	tst	r1, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
+	test_syscall_tracing r1
 	beq	ret_slow_syscall
 	mov	r1, sp
 	mov	r0, #1				@ trace exit [IP = 1]
@@ -98,6 +103,13 @@ ENDPROC(ret_from_fork)
 	.equ NR_syscalls,0
 #define CALL(x) .equ NR_syscalls,NR_syscalls+1
 #include "calls.S"
+
+/* Ensure that the system call table is not larger than __NR_syscalls,
+ * which is the value the rest of the system sees */
+.ifne NR_syscalls - __NR_syscalls
+.error "__NR_syscalls is less than the size of the syscall table"
+.endif
+
 #undef CALL
 #define CALL(x) .long x
 
@@ -446,7 +458,7 @@ ENTRY(vector_swi)
 1:
 #endif
 
-	tst	r10, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
+	test_syscall_tracing r10
 	bne	__sys_trace
 
 	cmp	scno, #NR_syscalls		@ check upper syscall limit
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 46f4b41..dbbf4ce 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -30,6 +30,9 @@
 #include <asm/system.h>
 #include <asm/traps.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/syscalls.h>
+
 #define REG_PC	15
 #define REG_PSR	16
 /*
@@ -929,15 +932,25 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
 		audit_syscall_entry(AUDIT_ARCH_NR, scno, regs->ARM_r0,
 				    regs->ARM_r1, regs->ARM_r2, regs->ARM_r3);
 
-	if (!test_thread_flag(TIF_SYSCALL_TRACE))
+	if (!test_thread_flag(TIF_SYSCALL_TRACE) &&
+	    !test_thread_flag(TIF_SYSCALL_TRACEPOINT))
 		return scno;
 
 	current_thread_info()->syscall = scno;
 
-	if (why)
-		tracehook_report_syscall_exit(regs, 0);
-	else if (tracehook_report_syscall_entry(regs))
-		current_thread_info()->syscall = -1;
+	if (test_thread_flag(TIF_SYSCALL_TRACE)) {
+		if (why)
+			tracehook_report_syscall_exit(regs, 0);
+		else if (tracehook_report_syscall_entry(regs))
+			current_thread_info()->syscall = -1;
+	}
+
+	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) {
+		if (why)
+			trace_sys_exit(regs, scno);
+		else
+			trace_sys_enter(regs, scno);
+	}
 
 	regs->ARM_ip = ip;
 
-- 
1.7.0.4

[PATCH v2 0/3] ARM support for syscall tracing

[Will Deacon]

Hi Wade,

On Wed, Feb 29, 2012 at 02:34:40PM +0000, Wade Farnsworth wrote:
> This is a rework of Steven Walter's syscall tracing patches first
> posted here:
> 
> http://lists.infradead.org/pipermail/linux-arm-kernel/2011-November/074454.html
> 
> I've rebased the patches against the current mainline master branch, as well
> as implemented several changes based on feedback from Will Deacon and
> Russel King.
> 
> v2: - Tested on EABI and OABI.
>     - Removed an instance of the ?: operator in syscall_set_return_value()
>     - Moved #define of NR_syscalls to syscall.h
>     - Changed the test of NR_syscalls vs __NR_syscalls in entry-common.S
>       to .ifne
> 
> Wade Farnsworth (3):
>   ARM: add support for the generic syscall.h interface
>   ARM: add TRACEHOOK support
>   ARM: support syscall tracing

I'm pretty happy with these three patches now, so feel free to add:

Reviewed-by: Will Deacon <will.deacon@arm.com>

Once Russell is ok with them you can put them in the patch system.

Cheers,

Will

[PATCH v3 0/3] ARM support for syscall tracing

[Wade Farnsworth]

This is a rework of Steven Walter's syscall tracing patches first
posted here:

http://lists.infradead.org/pipermail/linux-arm-kernel/2011-November/074454.html

I've rebased the patches against the current mainline master branch, as well
as implemented several changes based on feedback from Will Deacon and
Russell King.

v2: - Tested on EABI and OABI.
    - Removed an instance of the ?: operator in syscall_set_return_value()
    - Moved #define of NR_syscalls to syscall.h
    - Changed the test of NR_syscalls vs __NR_syscalls in entry-common.S
      to .ifne
v3: - Added Will Deacon's Reviewed-by line.  Code is identical to v2.

Wade Farnsworth (3):
  ARM: add support for the generic syscall.h interface
  ARM: add TRACEHOOK support
  ARM: support syscall tracing

 arch/arm/Kconfig                   |    2 +
 arch/arm/include/asm/ptrace.h      |    5 ++
 arch/arm/include/asm/syscall.h     |   97 ++++++++++++++++++++++++++++++++++++
 arch/arm/include/asm/thread_info.h |    2 +
 arch/arm/include/asm/unistd.h      |    8 +++
 arch/arm/kernel/entry-common.S     |   16 +++++-
 arch/arm/kernel/ptrace.c           |   34 +++++++------
 arch/arm/kernel/signal.c           |    2 +
 8 files changed, 149 insertions(+), 17 deletions(-)
 create mode 100644 arch/arm/include/asm/syscall.h

[PATCH v3 1/3] ARM: add support for the generic syscall.h interface

[Wade Farnsworth]

Supplying the asm-generic/syscall.h interface is a
pre-requisite for HAVE_ARCH_TRACEHOOK

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/include/asm/syscall.h |   93 ++++++++++++++++++++++++++++++++++++++++
 1 files changed, 93 insertions(+), 0 deletions(-)
 create mode 100644 arch/arm/include/asm/syscall.h

diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h
new file mode 100644
index 0000000..c334a23
--- /dev/null
+++ b/arch/arm/include/asm/syscall.h
@@ -0,0 +1,93 @@
+/*
+ * Access to user system call parameters and results
+ *
+ * See asm-generic/syscall.h for descriptions of what we must do here.
+ */
+
+#ifndef _ASM_ARM_SYSCALL_H
+#define _ASM_ARM_SYSCALL_H
+
+#include <linux/err.h>
+
+extern const unsigned long sys_call_table[];
+
+static inline int syscall_get_nr(struct task_struct *task,
+				 struct pt_regs *regs)
+{
+	return task_thread_info(task)->syscall;
+}
+
+static inline void syscall_rollback(struct task_struct *task,
+				    struct pt_regs *regs)
+{
+	regs->ARM_r0 = regs->ARM_ORIG_r0;
+}
+
+static inline long syscall_get_error(struct task_struct *task,
+				     struct pt_regs *regs)
+{
+	unsigned long error = regs->ARM_r0;
+	return IS_ERR_VALUE(error) ? error : 0;
+}
+
+static inline long syscall_get_return_value(struct task_struct *task,
+					    struct pt_regs *regs)
+{
+	return regs->ARM_r0;
+}
+
+static inline void syscall_set_return_value(struct task_struct *task,
+					    struct pt_regs *regs,
+					    int error, long val)
+{
+	regs->ARM_r0 = (long) error ? error : val;
+}
+
+#define SYSCALL_MAX_ARGS 7
+
+static inline void syscall_get_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 unsigned long *args)
+{
+	if (i + n > SYSCALL_MAX_ARGS) {
+		unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;
+		unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;
+		pr_warning("%s called with max args %d, handling only %d\n",
+			   __func__, i + n, SYSCALL_MAX_ARGS);
+		memset(args_bad, 0, n_bad * sizeof(args[0]));
+		n = SYSCALL_MAX_ARGS - i;
+	}
+
+	if (i == 0) {
+		args[0] = regs->ARM_ORIG_r0;
+		args++;
+		i++;
+		n--;
+	}
+
+	memcpy(args, &regs->ARM_r0 + i, n * sizeof(args[0]));
+}
+
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 const unsigned long *args)
+{
+	if (i + n > SYSCALL_MAX_ARGS) {
+		pr_warning("%s called with max args %d, handling only %d\n",
+			   __func__, i + n, SYSCALL_MAX_ARGS);
+		n = SYSCALL_MAX_ARGS - i;
+	}
+
+	if (i == 0) {
+		regs->ARM_ORIG_r0 = args[0];
+		args++;
+		i++;
+		n--;
+	}
+
+	memcpy(&regs->ARM_r0 + i, args, n * sizeof(args[0]));
+}
+
+#endif /* _ASM_ARM_SYSCALL_H */
-- 
1.7.0.4

[PATCH v3 2/3] ARM: add TRACEHOOK support

[Wade Farnsworth]

Add calls to tracehook_report_syscall_{entry,exit} and tracehook_signal_handler

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/Kconfig              |    1 +
 arch/arm/include/asm/ptrace.h |    5 +++++
 arch/arm/kernel/ptrace.c      |   21 ++++++---------------
 arch/arm/kernel/signal.c      |    2 ++
 4 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a48aecc..0faad0c 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -10,6 +10,7 @@ config ARM
 	select GENERIC_ATOMIC64 if (CPU_V6 || !CPU_32v6K || !AEABI)
 	select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
 	select HAVE_ARCH_KGDB
+	select HAVE_ARCH_TRACEHOOK
 	select HAVE_KPROBES if !XIP_KERNEL
 	select HAVE_KRETPROBES if (HAVE_KPROBES)
 	select HAVE_FUNCTION_TRACER if (!XIP_KERNEL)
diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h
index 451808b..355ece5 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -249,6 +249,11 @@ static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
 	return regs->ARM_sp;
 }
 
+static inline unsigned long user_stack_pointer(struct pt_regs *regs)
+{
+	return regs->ARM_sp;
+}
+
 #endif /* __KERNEL__ */
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index ede6443..46f4b41 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -24,6 +24,7 @@
 #include <linux/hw_breakpoint.h>
 #include <linux/regset.h>
 #include <linux/audit.h>
+#include <linux/tracehook.h>
 
 #include <asm/pgtable.h>
 #include <asm/system.h>
@@ -930,24 +931,14 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
 
 	if (!test_thread_flag(TIF_SYSCALL_TRACE))
 		return scno;
-	if (!(current->ptrace & PT_PTRACED))
-		return scno;
 
 	current_thread_info()->syscall = scno;
 
-	/* the 0x80 provides a way for the tracing parent to distinguish
-	   between a syscall stop and SIGTRAP delivery */
-	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
-				 ? 0x80 : 0));
-	/*
-	 * this isn't the same as continuing with a signal, but it will do
-	 * for normal use.  strace only continues with a signal if the
-	 * stopping signal is not SIGTRAP.  -brl
-	 */
-	if (current->exit_code) {
-		send_sig(current->exit_code, current, 1);
-		current->exit_code = 0;
-	}
+	if (why)
+		tracehook_report_syscall_exit(regs, 0);
+	else if (tracehook_report_syscall_entry(regs))
+		current_thread_info()->syscall = -1;
+
 	regs->ARM_ip = ip;
 
 	return current_thread_info()->syscall;
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 9e617bd..6f084c1 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -644,6 +644,8 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
 	recalc_sigpending();
 	spin_unlock_irq(&tsk->sighand->siglock);
 
+	tracehook_signal_handler(sig, info, ka, regs, 0);
+
 	return 0;
 }
 
-- 
1.7.0.4

[PATCH v3 3/3] ARM: support syscall tracing

[Wade Farnsworth]

As specified by ftrace-design.txt, TIF_SYSCALL_TRACEPOINT was
added, as well as NR_syscalls in asm/unistd.h.  Additionally,
__sys_trace was modified to call trace_sys_enter and
trace_sys_exit when appropriate.

Tests #2 - #4 of "perf test" now complete successfully.

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/Kconfig                   |    1 +
 arch/arm/include/asm/syscall.h     |    4 ++++
 arch/arm/include/asm/thread_info.h |    2 ++
 arch/arm/include/asm/unistd.h      |    8 ++++++++
 arch/arm/kernel/entry-common.S     |   16 ++++++++++++++--
 arch/arm/kernel/ptrace.c           |   23 ++++++++++++++++++-----
 6 files changed, 47 insertions(+), 7 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 0faad0c..b1d9396 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -11,6 +11,7 @@ config ARM
 	select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_TRACEHOOK
+	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_KPROBES if !XIP_KERNEL
 	select HAVE_KRETPROBES if (HAVE_KPROBES)
 	select HAVE_FUNCTION_TRACER if (!XIP_KERNEL)
diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h
index c334a23..47486a4 100644
--- a/arch/arm/include/asm/syscall.h
+++ b/arch/arm/include/asm/syscall.h
@@ -9,6 +9,10 @@
 
 #include <linux/err.h>
 
+#include <asm/unistd.h>
+
+#define NR_syscalls (__NR_syscalls)
+
 extern const unsigned long sys_call_table[];
 
 static inline int syscall_get_nr(struct task_struct *task,
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index d4c24d4..f2ff2de 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -146,6 +146,7 @@ extern void vfp_flush_hwstate(struct thread_info *);
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
 #define TIF_RESTORE_SIGMASK	20
 #define TIF_SECCOMP		21
+#define TIF_SYSCALL_TRACEPOINT	22
 
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
@@ -156,6 +157,7 @@ extern void vfp_flush_hwstate(struct thread_info *);
 #define _TIF_USING_IWMMXT	(1 << TIF_USING_IWMMXT)
 #define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
+#define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 
 /* Checks for any syscall work in entry-common.S */
 #define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT)
diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
index 512cd14..d27d7d7 100644
--- a/arch/arm/include/asm/unistd.h
+++ b/arch/arm/include/asm/unistd.h
@@ -406,6 +406,14 @@
 #define __NR_process_vm_writev		(__NR_SYSCALL_BASE+377)
 
 /*
+ * This may need to be greater than __NR_last_syscall+1 in order to
+ * account for the padding in the syscall table
+ */
+#ifdef __KERNEL__
+#define __NR_syscalls  (380)
+#endif /* __KERNEL__ */
+
+/*
  * The following SWIs are ARM private.
  */
 #define __ARM_NR_BASE			(__NR_SYSCALL_BASE+0x0f0000)
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 9fd0ba9..01686b2 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -79,6 +79,11 @@ no_work_pending:
 ENDPROC(ret_to_user_from_irq)
 ENDPROC(ret_to_user)
 
+.macro test_syscall_tracing reg
+       tst     \reg, #_TIF_SYSCALL_WORK
+       tsteq   \reg, #_TIF_SYSCALL_TRACEPOINT
+.endm
+
 /*
  * This is how we return from a fork.
  */
@@ -87,7 +92,7 @@ ENTRY(ret_from_fork)
 	get_thread_info tsk
 	ldr	r1, [tsk, #TI_FLAGS]		@ check for syscall tracing
 	mov	why, #1
-	tst	r1, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
+	test_syscall_tracing r1
 	beq	ret_slow_syscall
 	mov	r1, sp
 	mov	r0, #1				@ trace exit [IP = 1]
@@ -98,6 +103,13 @@ ENDPROC(ret_from_fork)
 	.equ NR_syscalls,0
 #define CALL(x) .equ NR_syscalls,NR_syscalls+1
 #include "calls.S"
+
+/* Ensure that the system call table is not larger than __NR_syscalls,
+ * which is the value the rest of the system sees */
+.ifne NR_syscalls - __NR_syscalls
+.error "__NR_syscalls is less than the size of the syscall table"
+.endif
+
 #undef CALL
 #define CALL(x) .long x
 
@@ -446,7 +458,7 @@ ENTRY(vector_swi)
 1:
 #endif
 
-	tst	r10, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
+	test_syscall_tracing r10
 	bne	__sys_trace
 
 	cmp	scno, #NR_syscalls		@ check upper syscall limit
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 46f4b41..dbbf4ce 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -30,6 +30,9 @@
 #include <asm/system.h>
 #include <asm/traps.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/syscalls.h>
+
 #define REG_PC	15
 #define REG_PSR	16
 /*
@@ -929,15 +932,25 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
 		audit_syscall_entry(AUDIT_ARCH_NR, scno, regs->ARM_r0,
 				    regs->ARM_r1, regs->ARM_r2, regs->ARM_r3);
 
-	if (!test_thread_flag(TIF_SYSCALL_TRACE))
+	if (!test_thread_flag(TIF_SYSCALL_TRACE) &&
+	    !test_thread_flag(TIF_SYSCALL_TRACEPOINT))
 		return scno;
 
 	current_thread_info()->syscall = scno;
 
-	if (why)
-		tracehook_report_syscall_exit(regs, 0);
-	else if (tracehook_report_syscall_entry(regs))
-		current_thread_info()->syscall = -1;
+	if (test_thread_flag(TIF_SYSCALL_TRACE)) {
+		if (why)
+			tracehook_report_syscall_exit(regs, 0);
+		else if (tracehook_report_syscall_entry(regs))
+			current_thread_info()->syscall = -1;
+	}
+
+	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) {
+		if (why)
+			trace_sys_exit(regs, scno);
+		else
+			trace_sys_enter(regs, scno);
+	}
 
 	regs->ARM_ip = ip;
 
-- 
1.7.0.4

[PATCH v4 0/3] ARM support for syscall tracing

[Wade Farnsworth]

This is a rework of Steven Walter's syscall tracing patches first
posted here:

http://lists.infradead.org/pipermail/linux-arm-kernel/2011-November/074454.html

I've rebased the patches against the current mainline master branch, as well
as implemented several changes based on feedback from Will Deacon and
Russel King.

v2: - Tested on EABI and OABI.
    - Removed an instance of the ?: operator in syscall_set_return_value()
    - Moved #define of NR_syscalls to syscall.h
    - Changed the test of NR_syscalls vs __NR_syscalls in entry-common.S
      to .ifne
v3: - Added Will Deacon's Reviewed-by line.  Code is identical to v2.
v4: - Updated comment and error string for the NR_syscalls test to
      reflect that it's now testing for inequality.

Russell, now that this has been reviewed by Will and tested with both
ABIs, is this okay to submit to your patch tracker?

Wade Farnsworth (3):
  ARM: add support for the generic syscall.h interface
  ARM: add TRACEHOOK support
  ARM: support syscall tracing

 arch/arm/Kconfig                   |    2 +
 arch/arm/include/asm/ptrace.h      |    5 ++
 arch/arm/include/asm/syscall.h     |   97 ++++++++++++++++++++++++++++++++++++
 arch/arm/include/asm/thread_info.h |    2 +
 arch/arm/include/asm/unistd.h      |    8 +++
 arch/arm/kernel/entry-common.S     |   18 ++++++-
 arch/arm/kernel/ptrace.c           |   34 +++++++------
 arch/arm/kernel/signal.c           |    2 +
 8 files changed, 151 insertions(+), 17 deletions(-)
 create mode 100644 arch/arm/include/asm/syscall.h

[PATCH v4 1/3] ARM: add support for the generic syscall.h interface

[Wade Farnsworth]

Supplying the asm-generic/syscall.h interface is a
pre-requisite for HAVE_ARCH_TRACEHOOK

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/include/asm/syscall.h |   93 ++++++++++++++++++++++++++++++++++++++++
 1 files changed, 93 insertions(+), 0 deletions(-)
 create mode 100644 arch/arm/include/asm/syscall.h

diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h
new file mode 100644
index 0000000..c334a23
--- /dev/null
+++ b/arch/arm/include/asm/syscall.h
@@ -0,0 +1,93 @@
+/*
+ * Access to user system call parameters and results
+ *
+ * See asm-generic/syscall.h for descriptions of what we must do here.
+ */
+
+#ifndef _ASM_ARM_SYSCALL_H
+#define _ASM_ARM_SYSCALL_H
+
+#include <linux/err.h>
+
+extern const unsigned long sys_call_table[];
+
+static inline int syscall_get_nr(struct task_struct *task,
+				 struct pt_regs *regs)
+{
+	return task_thread_info(task)->syscall;
+}
+
+static inline void syscall_rollback(struct task_struct *task,
+				    struct pt_regs *regs)
+{
+	regs->ARM_r0 = regs->ARM_ORIG_r0;
+}
+
+static inline long syscall_get_error(struct task_struct *task,
+				     struct pt_regs *regs)
+{
+	unsigned long error = regs->ARM_r0;
+	return IS_ERR_VALUE(error) ? error : 0;
+}
+
+static inline long syscall_get_return_value(struct task_struct *task,
+					    struct pt_regs *regs)
+{
+	return regs->ARM_r0;
+}
+
+static inline void syscall_set_return_value(struct task_struct *task,
+					    struct pt_regs *regs,
+					    int error, long val)
+{
+	regs->ARM_r0 = (long) error ? error : val;
+}
+
+#define SYSCALL_MAX_ARGS 7
+
+static inline void syscall_get_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 unsigned long *args)
+{
+	if (i + n > SYSCALL_MAX_ARGS) {
+		unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;
+		unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;
+		pr_warning("%s called with max args %d, handling only %d\n",
+			   __func__, i + n, SYSCALL_MAX_ARGS);
+		memset(args_bad, 0, n_bad * sizeof(args[0]));
+		n = SYSCALL_MAX_ARGS - i;
+	}
+
+	if (i == 0) {
+		args[0] = regs->ARM_ORIG_r0;
+		args++;
+		i++;
+		n--;
+	}
+
+	memcpy(args, &regs->ARM_r0 + i, n * sizeof(args[0]));
+}
+
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 const unsigned long *args)
+{
+	if (i + n > SYSCALL_MAX_ARGS) {
+		pr_warning("%s called with max args %d, handling only %d\n",
+			   __func__, i + n, SYSCALL_MAX_ARGS);
+		n = SYSCALL_MAX_ARGS - i;
+	}
+
+	if (i == 0) {
+		regs->ARM_ORIG_r0 = args[0];
+		args++;
+		i++;
+		n--;
+	}
+
+	memcpy(&regs->ARM_r0 + i, args, n * sizeof(args[0]));
+}
+
+#endif /* _ASM_ARM_SYSCALL_H */
-- 
1.7.0.4

[PATCH v4 2/3] ARM: add TRACEHOOK support

[Wade Farnsworth]

Add calls to tracehook_report_syscall_{entry,exit} and tracehook_signal_handler

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/Kconfig              |    1 +
 arch/arm/include/asm/ptrace.h |    5 +++++
 arch/arm/kernel/ptrace.c      |   21 ++++++---------------
 arch/arm/kernel/signal.c      |    2 ++
 4 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index dfb0312..c87e23f 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -10,6 +10,7 @@ config ARM
 	select GENERIC_ATOMIC64 if (CPU_V6 || !CPU_32v6K || !AEABI)
 	select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
 	select HAVE_ARCH_KGDB
+	select HAVE_ARCH_TRACEHOOK
 	select HAVE_KPROBES if !XIP_KERNEL
 	select HAVE_KRETPROBES if (HAVE_KPROBES)
 	select HAVE_FUNCTION_TRACER if (!XIP_KERNEL)
diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h
index 451808b..355ece5 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -249,6 +249,11 @@ static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
 	return regs->ARM_sp;
 }
 
+static inline unsigned long user_stack_pointer(struct pt_regs *regs)
+{
+	return regs->ARM_sp;
+}
+
 #endif /* __KERNEL__ */
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index ede6443..46f4b41 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -24,6 +24,7 @@
 #include <linux/hw_breakpoint.h>
 #include <linux/regset.h>
 #include <linux/audit.h>
+#include <linux/tracehook.h>
 
 #include <asm/pgtable.h>
 #include <asm/system.h>
@@ -930,24 +931,14 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
 
 	if (!test_thread_flag(TIF_SYSCALL_TRACE))
 		return scno;
-	if (!(current->ptrace & PT_PTRACED))
-		return scno;
 
 	current_thread_info()->syscall = scno;
 
-	/* the 0x80 provides a way for the tracing parent to distinguish
-	   between a syscall stop and SIGTRAP delivery */
-	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
-				 ? 0x80 : 0));
-	/*
-	 * this isn't the same as continuing with a signal, but it will do
-	 * for normal use.  strace only continues with a signal if the
-	 * stopping signal is not SIGTRAP.  -brl
-	 */
-	if (current->exit_code) {
-		send_sig(current->exit_code, current, 1);
-		current->exit_code = 0;
-	}
+	if (why)
+		tracehook_report_syscall_exit(regs, 0);
+	else if (tracehook_report_syscall_entry(regs))
+		current_thread_info()->syscall = -1;
+
 	regs->ARM_ip = ip;
 
 	return current_thread_info()->syscall;
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 9e617bd..6f084c1 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -644,6 +644,8 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
 	recalc_sigpending();
 	spin_unlock_irq(&tsk->sighand->siglock);
 
+	tracehook_signal_handler(sig, info, ka, regs, 0);
+
 	return 0;
 }
 
-- 
1.7.0.4

[PATCH v4 3/3] ARM: support syscall tracing

[Wade Farnsworth]

As specified by ftrace-design.txt, TIF_SYSCALL_TRACEPOINT was
added, as well as NR_syscalls in asm/unistd.h.  Additionally,
__sys_trace was modified to call trace_sys_enter and
trace_sys_exit when appropriate.

Tests #2 - #4 of "perf test" now complete successfully.

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
Signed-off-by: Wade Farnsworth <wade_farnsworth@mentor.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/Kconfig                   |    1 +
 arch/arm/include/asm/syscall.h     |    4 ++++
 arch/arm/include/asm/thread_info.h |    2 ++
 arch/arm/include/asm/unistd.h      |    8 ++++++++
 arch/arm/kernel/entry-common.S     |   18 ++++++++++++++++--
 arch/arm/kernel/ptrace.c           |   23 ++++++++++++++++++-----
 6 files changed, 49 insertions(+), 7 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index c87e23f..5603715 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -11,6 +11,7 @@ config ARM
 	select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_TRACEHOOK
+	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_KPROBES if !XIP_KERNEL
 	select HAVE_KRETPROBES if (HAVE_KPROBES)
 	select HAVE_FUNCTION_TRACER if (!XIP_KERNEL)
diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h
index c334a23..47486a4 100644
--- a/arch/arm/include/asm/syscall.h
+++ b/arch/arm/include/asm/syscall.h
@@ -9,6 +9,10 @@
 
 #include <linux/err.h>
 
+#include <asm/unistd.h>
+
+#define NR_syscalls (__NR_syscalls)
+
 extern const unsigned long sys_call_table[];
 
 static inline int syscall_get_nr(struct task_struct *task,
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index d4c24d4..f2ff2de 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -146,6 +146,7 @@ extern void vfp_flush_hwstate(struct thread_info *);
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
 #define TIF_RESTORE_SIGMASK	20
 #define TIF_SECCOMP		21
+#define TIF_SYSCALL_TRACEPOINT	22
 
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
@@ -156,6 +157,7 @@ extern void vfp_flush_hwstate(struct thread_info *);
 #define _TIF_USING_IWMMXT	(1 << TIF_USING_IWMMXT)
 #define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
+#define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 
 /* Checks for any syscall work in entry-common.S */
 #define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT)
diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
index 512cd14..d27d7d7 100644
--- a/arch/arm/include/asm/unistd.h
+++ b/arch/arm/include/asm/unistd.h
@@ -406,6 +406,14 @@
 #define __NR_process_vm_writev		(__NR_SYSCALL_BASE+377)
 
 /*
+ * This may need to be greater than __NR_last_syscall+1 in order to
+ * account for the padding in the syscall table
+ */
+#ifdef __KERNEL__
+#define __NR_syscalls  (380)
+#endif /* __KERNEL__ */
+
+/*
  * The following SWIs are ARM private.
  */
 #define __ARM_NR_BASE			(__NR_SYSCALL_BASE+0x0f0000)
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 9fd0ba9..3df0ca3 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -79,6 +79,11 @@ no_work_pending:
 ENDPROC(ret_to_user_from_irq)
 ENDPROC(ret_to_user)
 
+.macro test_syscall_tracing reg
+       tst     \reg, #_TIF_SYSCALL_WORK
+       tsteq   \reg, #_TIF_SYSCALL_TRACEPOINT
+.endm
+
 /*
  * This is how we return from a fork.
  */
@@ -87,7 +92,7 @@ ENTRY(ret_from_fork)
 	get_thread_info tsk
 	ldr	r1, [tsk, #TI_FLAGS]		@ check for syscall tracing
 	mov	why, #1
-	tst	r1, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
+	test_syscall_tracing r1
 	beq	ret_slow_syscall
 	mov	r1, sp
 	mov	r0, #1				@ trace exit [IP = 1]
@@ -98,6 +103,15 @@ ENDPROC(ret_from_fork)
 	.equ NR_syscalls,0
 #define CALL(x) .equ NR_syscalls,NR_syscalls+1
 #include "calls.S"
+
+/*
+ * Ensure that the system call table is equal to __NR_syscalls,
+ * which is the value the rest of the system sees
+ */
+.ifne NR_syscalls - __NR_syscalls
+.error "__NR_syscalls is not equal to the size of the syscall table"
+.endif
+
 #undef CALL
 #define CALL(x) .long x
 
@@ -446,7 +460,7 @@ ENTRY(vector_swi)
 1:
 #endif
 
-	tst	r10, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
+	test_syscall_tracing r10
 	bne	__sys_trace
 
 	cmp	scno, #NR_syscalls		@ check upper syscall limit
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 46f4b41..dbbf4ce 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -30,6 +30,9 @@
 #include <asm/system.h>
 #include <asm/traps.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/syscalls.h>
+
 #define REG_PC	15
 #define REG_PSR	16
 /*
@@ -929,15 +932,25 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
 		audit_syscall_entry(AUDIT_ARCH_NR, scno, regs->ARM_r0,
 				    regs->ARM_r1, regs->ARM_r2, regs->ARM_r3);
 
-	if (!test_thread_flag(TIF_SYSCALL_TRACE))
+	if (!test_thread_flag(TIF_SYSCALL_TRACE) &&
+	    !test_thread_flag(TIF_SYSCALL_TRACEPOINT))
 		return scno;
 
 	current_thread_info()->syscall = scno;
 
-	if (why)
-		tracehook_report_syscall_exit(regs, 0);
-	else if (tracehook_report_syscall_entry(regs))
-		current_thread_info()->syscall = -1;
+	if (test_thread_flag(TIF_SYSCALL_TRACE)) {
+		if (why)
+			tracehook_report_syscall_exit(regs, 0);
+		else if (tracehook_report_syscall_entry(regs))
+			current_thread_info()->syscall = -1;
+	}
+
+	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) {
+		if (why)
+			trace_sys_exit(regs, scno);
+		else
+			trace_sys_enter(regs, scno);
+	}
 
 	regs->ARM_ip = ip;
 
-- 
1.7.0.4

[PATCH v4 0/3] ARM support for syscall tracing

[Will Deacon]

Hi Wade,

On Fri, Mar 23, 2012 at 02:50:22PM +0000, Wade Farnsworth wrote:
> Russell, now that this has been reviewed by Will and tested with both
> ABIs, is this okay to submit to your patch tracker?

I'd recommend putting this into the patch system once -rc1 has landed.
Any conflicts after that are fairly unlikely and Russell can decide what
to do with the patches then.

Cheers,

Will

[RFC] ARM support for syscall tracing

[Steven Walter]

I recently noticed that "perf test" fails tests #2 - #4 on ARM.  In
investigating that failure, I noticed that those tests rely on
FTRACE_SYSCALLS, which was not available on ARM.

It didn't look like too much work to enable HAVE_SYSCALL_TRACEPOINTS, so
that's what I did in the patches that follow.  This is a
request-for-comment because I don't entirely understand some of the
changes I made, so it's quite likely that some parts are either
out-and-out wrong, or at least can be done a better way.

That said, the tests in "perf test" pass except for #1 (kallsyms), and
strace still seems to report sensible values for system calls.

Comments?

[PATCH 2/3] ARM: add TRACEHOOK support

[Steven Walter]

Add calls to tracehook_report_syscall_{entry,exit} and tracehook_signal_handler

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
---
 arch/arm/Kconfig              |    1 +
 arch/arm/include/asm/ptrace.h |    5 +++++
 arch/arm/kernel/ptrace.c      |   21 +++++++--------------
 arch/arm/kernel/signal.c      |    2 ++
 4 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index b65b910..0a93d76 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -10,6 +10,7 @@ config ARM
 	select GENERIC_ATOMIC64 if (CPU_V6 || !CPU_32v6K || !AEABI)
 	select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
 	select HAVE_ARCH_KGDB
+	select HAVE_ARCH_TRACEHOOK
 	select HAVE_KPROBES if (!XIP_KERNEL && !THUMB2_KERNEL)
 	select HAVE_KRETPROBES if (HAVE_KPROBES)
 	select HAVE_FUNCTION_TRACER if (!XIP_KERNEL)
diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h
index 312d108..98ea76d 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -235,6 +235,11 @@ static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
 	return regs->ARM_sp;
 }
 
+static inline unsigned long user_stack_pointer(struct pt_regs *regs)
+{
+	return regs->ARM_sp;
+}
+
 #endif /* __KERNEL__ */
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 9726006..1411848 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -22,6 +22,7 @@
 #include <linux/perf_event.h>
 #include <linux/hw_breakpoint.h>
 #include <linux/regset.h>
+#include <linux/tracehook.h>
 
 #include <asm/pgtable.h>
 #include <asm/system.h>
@@ -928,8 +929,6 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
 
 	if (!test_thread_flag(TIF_SYSCALL_TRACE))
 		return scno;
-	if (!(current->ptrace & PT_PTRACED))
-		return scno;
 
 	/*
 	 * Save IP.  IP is used to denote syscall entry/exit:
@@ -940,19 +939,13 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
 
 	current_thread_info()->syscall = scno;
 
-	/* the 0x80 provides a way for the tracing parent to distinguish
-	   between a syscall stop and SIGTRAP delivery */
-	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
-				 ? 0x80 : 0));
-	/*
-	 * this isn't the same as continuing with a signal, but it will do
-	 * for normal use.  strace only continues with a signal if the
-	 * stopping signal is not SIGTRAP.  -brl
-	 */
-	if (current->exit_code) {
-		send_sig(current->exit_code, current, 1);
-		current->exit_code = 0;
+	if (why == 0) {
+		if (tracehook_report_syscall_entry(regs))
+			current_thread_info()->syscall = -1;
+	} else {
+		tracehook_report_syscall_exit(regs, 0);
 	}
+
 	regs->ARM_ip = ip;
 
 	return current_thread_info()->syscall;
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 0340224..26c26f5 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -645,6 +645,8 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
 	recalc_sigpending();
 	spin_unlock_irq(&tsk->sighand->siglock);
 
+	tracehook_signal_handler(sig, info, ka, regs, 0);
+
 	return 0;
 }
 
-- 
1.7.5.4.2.g81f75

[PATCH 2/3] ARM: add TRACEHOOK support

[Will Deacon]

Hi Steven,

On Tue, Nov 29, 2011 at 04:28:14PM +0000, Steven Walter wrote:
> diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
> index 9726006..1411848 100644
> --- a/arch/arm/kernel/ptrace.c
> +++ b/arch/arm/kernel/ptrace.c
> @@ -22,6 +22,7 @@
>  #include <linux/perf_event.h>
>  #include <linux/hw_breakpoint.h>
>  #include <linux/regset.h>
> +#include <linux/tracehook.h>
>  
>  #include <asm/pgtable.h>
>  #include <asm/system.h>
> @@ -928,8 +929,6 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
>  
>  	if (!test_thread_flag(TIF_SYSCALL_TRACE))
>  		return scno;
> -	if (!(current->ptrace & PT_PTRACED))
> -		return scno;

This means that we can potentially corrupt current_thread_info()->syscall
for tasks that aren't being traced. I don't think that matters as it's only
used by ptrace, but worth bearing in mind.

>  	/*
>  	 * Save IP.  IP is used to denote syscall entry/exit:
> @@ -940,19 +939,13 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
>  
>  	current_thread_info()->syscall = scno;
>  
> -	/* the 0x80 provides a way for the tracing parent to distinguish
> -	   between a syscall stop and SIGTRAP delivery */
> -	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
> -				 ? 0x80 : 0));
> -	/*
> -	 * this isn't the same as continuing with a signal, but it will do
> -	 * for normal use.  strace only continues with a signal if the
> -	 * stopping signal is not SIGTRAP.  -brl
> -	 */
> -	if (current->exit_code) {
> -		send_sig(current->exit_code, current, 1);
> -		current->exit_code = 0;
> +	if (why == 0) {
> +		if (tracehook_report_syscall_entry(regs))
> +			current_thread_info()->syscall = -1;

Why do you set syscall to -1 here? It looks like
tracehook_report_syscall_entry always returns 0, but even so, I'm not sure
what this -1 represents. You could also rewrite this a bit more neatly:

if (why)
	tracehook_report_syscall_exit(...);
else
	tracehook_report_syscall_entry(...);


> +	} else {
> +		tracehook_report_syscall_exit(regs, 0);
>  	}
> +
>  	regs->ARM_ip = ip;
>  
>  	return current_thread_info()->syscall;
> diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
> index 0340224..26c26f5 100644
> --- a/arch/arm/kernel/signal.c
> +++ b/arch/arm/kernel/signal.c
> @@ -645,6 +645,8 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
>  	recalc_sigpending();
>  	spin_unlock_irq(&tsk->sighand->siglock);
>  
> +	tracehook_signal_handler(sig, info, ka, regs, 0);
> +

This doesn't appear to do anything but I guess that's where it should live.

Will

[PATCH 2/3] ARM: add TRACEHOOK support

[Steven Walter]

On Tue, Nov 29, 2011 at 12:04 PM, Will Deacon <will.deacon@arm.com> wrote:
> Hi Steven,
>
> On Tue, Nov 29, 2011 at 04:28:14PM +0000, Steven Walter wrote:
>> diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
>> index 9726006..1411848 100644
>> --- a/arch/arm/kernel/ptrace.c
>> +++ b/arch/arm/kernel/ptrace.c
>> @@ -22,6 +22,7 @@
>> ?#include <linux/perf_event.h>
>> ?#include <linux/hw_breakpoint.h>
>> ?#include <linux/regset.h>
>> +#include <linux/tracehook.h>
>>
>> ?#include <asm/pgtable.h>
>> ?#include <asm/system.h>
>> @@ -928,8 +929,6 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
>>
>> ? ? ? if (!test_thread_flag(TIF_SYSCALL_TRACE))
>> ? ? ? ? ? ? ? return scno;
>> - ? ? if (!(current->ptrace & PT_PTRACED))
>> - ? ? ? ? ? ? return scno;
>
> This means that we can potentially corrupt current_thread_info()->syscall
> for tasks that aren't being traced. I don't think that matters as it's only
> used by ptrace, but worth bearing in mind.

Is it valid for a process to have TIF_SYSCALL_TRACE set but not
PT_PTRACED?  Given that they were checking both before, one might
assume so, but I don't really know what that would mean.

>> ? ? ? /*
>> ? ? ? ?* Save IP. ?IP is used to denote syscall entry/exit:
>> @@ -940,19 +939,13 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
>>
>> ? ? ? current_thread_info()->syscall = scno;
>>
>> - ? ? /* the 0x80 provides a way for the tracing parent to distinguish
>> - ? ? ? ?between a syscall stop and SIGTRAP delivery */
>> - ? ? ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
>> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? 0x80 : 0));
>> - ? ? /*
>> - ? ? ?* this isn't the same as continuing with a signal, but it will do
>> - ? ? ?* for normal use. ?strace only continues with a signal if the
>> - ? ? ?* stopping signal is not SIGTRAP. ?-brl
>> - ? ? ?*/
>> - ? ? if (current->exit_code) {
>> - ? ? ? ? ? ? send_sig(current->exit_code, current, 1);
>> - ? ? ? ? ? ? current->exit_code = 0;
>> + ? ? if (why == 0) {
>> + ? ? ? ? ? ? if (tracehook_report_syscall_entry(regs))
>> + ? ? ? ? ? ? ? ? ? ? current_thread_info()->syscall = -1;
>
> Why do you set syscall to -1 here? It looks like
> tracehook_report_syscall_entry always returns 0, but even so, I'm not sure
> what this -1 represents. You could also rewrite this a bit more neatly:

tracehook_report_syscall_entry is marked __must_check, and the comment
says that if it returns non-zero the arch could should abort the
system call.  x86 just returns -1 from its trace function in that
case, so I took the same approach.  In particular, if we treat -1 as
the system call number, the system call should fail with ENOSYS, which
include/linux/tracehook.h says is acceptable.

> if (why)
> ? ? ? ?tracehook_report_syscall_exit(...);
> else
> ? ? ? ?tracehook_report_syscall_entry(...);

Agreed, will fix

>> + ? ? } else {
>> + ? ? ? ? ? ? tracehook_report_syscall_exit(regs, 0);
>> ? ? ? }
>> +
>> ? ? ? regs->ARM_ip = ip;
>>
>> ? ? ? return current_thread_info()->syscall;
>> diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
>> index 0340224..26c26f5 100644
>> --- a/arch/arm/kernel/signal.c
>> +++ b/arch/arm/kernel/signal.c
>> @@ -645,6 +645,8 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
>> ? ? ? recalc_sigpending();
>> ? ? ? spin_unlock_irq(&tsk->sighand->siglock);
>>
>> + ? ? tracehook_signal_handler(sig, info, ka, regs, 0);
>> +
>
> This doesn't appear to do anything but I guess that's where it should live.

Right, I just added it because arch/Kconfig said to :-)
-- 
-Steven Walter <stevenrwalter@gmail.com>