Re: [PATCH v3 5/6] arm64: ftrace: Add system call tracepoint

[AKASHI Takahiro]

On 02/18/2014 04:29 AM, Will Deacon wrote:
> On Fri, Feb 07, 2014 at 10:18:55AM +0000, AKASHI Takahiro wrote:
> > This patch allows system call entry or exit to be traced as ftrace events,
> > ie. sys_enter_*/sys_exit_*, if CONFIG_FTRACE_SYSCALLS is enabled.
> > Those events appear and can be controlled under
> >      ${sysfs}/tracing/events/syscalls/
> >
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
> > ---
> >   arch/arm64/Kconfig               |    1 +
> >   arch/arm64/include/asm/syscall.h |    1 +
> >   arch/arm64/include/asm/unistd.h  |    2 ++
> >   arch/arm64/kernel/ptrace.c       |    5 +++++
> >   4 files changed, 9 insertions(+)
> >
> > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > index 43fce76..9bdaf5c 100644
> > --- a/arch/arm64/Kconfig
> > +++ b/arch/arm64/Kconfig
> > @@ -42,6 +42,7 @@ config ARM64
> >   	select HAVE_HW_BREAKPOINT if PERF_EVENTS
> >   	select HAVE_MEMBLOCK
> >   	select HAVE_PERF_EVENTS
> > +	select HAVE_SYSCALL_TRACEPOINTS
> >   	select IRQ_DOMAIN
> >   	select MODULES_USE_ELF_RELA
> >   	select NO_BOOTMEM
> > diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
> > index 70ba9d4..383771e 100644
> > --- a/arch/arm64/include/asm/syscall.h
> > +++ b/arch/arm64/include/asm/syscall.h
> > @@ -18,6 +18,7 @@
> >
> >   #include <linux/err.h>
> >
> > +extern const void *sys_call_table[];
> >
> >   static inline int syscall_get_nr(struct task_struct *task,
> >   				 struct pt_regs *regs)
> > diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
> > index 82ce217..c335479 100644
> > --- a/arch/arm64/include/asm/unistd.h
> > +++ b/arch/arm64/include/asm/unistd.h
> > @@ -28,3 +28,5 @@
> >   #endif
> >   #define __ARCH_WANT_SYS_CLONE
> >   #include <uapi/asm/unistd.h>
> > +
> > +#define NR_syscalls (__NR_syscalls)
> > diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
> > index 64ce39f..f4c3c4e 100644
> > --- a/arch/arm64/kernel/ptrace.c
> > +++ b/arch/arm64/kernel/ptrace.c
> > @@ -41,6 +41,9 @@
> >   #include <asm/traps.h>
> >   #include <asm/system_misc.h>
> >
> > +#define CREATE_TRACE_POINTS
> > +#include <trace/events/syscalls.h>
> > +
> >   /*
> >    * TODO: does not yet catch signals sent when the child dies.
> >    * in exit.c or in signal.c.
> > @@ -1076,10 +1079,12 @@ asmlinkage int syscall_trace(int dir, struct pt_regs *regs)
> >   	}
> >
> >   	if (dir) {
> > +		trace_sys_exit(regs, regs->syscallno);
> >   		tracehook_report_syscall_exit(regs, 0);
> >   	} else {
> >   		if (tracehook_report_syscall_entry(regs))
> >   			regs->syscallno = ~0UL;
> > +		trace_sys_enter(regs, regs->syscallno);
>
> Shouldn't these calls be guarded by a TIF_SYSCALL_TRACEPOINT check?

Yes. I will add the guard.

-Takahiro AKASHI

> Will
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