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/
Please note that we can't trace compat system calls here because AArch32 mode does not share the same syscall table with AArch64. Just define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS in order to avoid unexpected results (bogus syscalls reported or even hang-up).
Acked-by: Will Deacon will.deacon@arm.com Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/ftrace.h | 18 ++++++++++++++++++ arch/arm64/include/asm/syscall.h | 1 + arch/arm64/include/asm/unistd.h | 2 ++ arch/arm64/kernel/ptrace.c | 9 +++++++++ 5 files changed, 31 insertions(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 6954959..b1dcdb4 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -43,6 +43,7 @@ config ARM64 select HAVE_MEMBLOCK select HAVE_PATA_PLATFORM 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/ftrace.h b/arch/arm64/include/asm/ftrace.h index c44c4b1..7616255 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -44,6 +44,24 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) #define CALLER_ADDR4 ((unsigned long)return_address(4)) #define CALLER_ADDR5 ((unsigned long)return_address(5)) #define CALLER_ADDR6 ((unsigned long)return_address(6)) + +#include <linux/compat.h> + +/* + * Because AArch32 mode does not share the same syscall table with AArch64, + * tracing compat syscalls may result in reporting bogus syscalls or even + * hang-up, so just do not trace them. + * See kernel/trace/trace_syscalls.c + * + * x86 code says: + * If the user realy wants these, then they should use the + * raw syscall tracepoints with filtering. + */ +#define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS +static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs) +{ + return is_compat_task(); +} #endif /* ifndef __ASSEMBLY__ */
#endif /* __ASM_FTRACE_H */ 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 c47a3ed..3ee76ed 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -42,6 +42,9 @@ #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. @@ -1091,11 +1094,17 @@ asmlinkage int syscall_trace_enter(struct pt_regs *regs) if (test_thread_flag(TIF_SYSCALL_TRACE)) tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
+ if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) + trace_sys_enter(regs, regs->syscallno); + return regs->syscallno; }
asmlinkage void syscall_trace_exit(struct pt_regs *regs) { + if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) + trace_sys_exit(regs, regs_return_value(regs)); + if (test_thread_flag(TIF_SYSCALL_TRACE)) tracehook_report_syscall(regs, PTRACE_SYSCALL_EXIT); }