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    SubjectRe: [PATCH v3 5/6] arm64: ftrace: Add system call tracepoint
    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@linaro.org>
    >> ---
    >> 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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