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).
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/ftrace.h | 20 ++++++++++++++++ arch/arm64/include/asm/syscall.h | 1 + arch/arm64/include/asm/unistd.h | 2 ++ arch/arm64/kernel/ptrace.c | 48 ++++++++++++++++++++++---------------- 5 files changed, 52 insertions(+), 20 deletions(-)
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..4ef06f1 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -44,6 +44,26 @@ 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 <asm/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 1 +static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs) +{ + if (is_compat_task()) + return true; + return false; +} #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 9993a8f..9c52b3e 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. @@ -1062,29 +1065,31 @@ asmlinkage int syscall_trace_enter(struct pt_regs *regs) { unsigned long saved_reg;
- if (!test_thread_flag(TIF_SYSCALL_TRACE)) - return regs->syscallno; + if (test_thread_flag(TIF_SYSCALL_TRACE)) { + /* + * A scrach register (ip(r12) on AArch32, x7 on AArch64) is + * used to denote syscall entry/exit: + * 0 -> entry + */ + if (is_compat_task()) { + saved_reg = regs->regs[12]; + regs->regs[12] = 0; + } else { + saved_reg = regs->regs[7]; + regs->regs[7] = 0; + }
- /* - * A scrach register (ip(r12) on AArch32, x7 on AArch64) is - * used to denote syscall entry/exit: - * 0 -> entry - */ - if (is_compat_task()) { - saved_reg = regs->regs[12]; - regs->regs[12] = 0; - } else { - saved_reg = regs->regs[7]; - regs->regs[7] = 0; - } + if (tracehook_report_syscall_entry(regs)) + regs->syscallno = ~0UL;
- if (tracehook_report_syscall_entry(regs)) - regs->syscallno = ~0UL; + if (is_compat_task()) + regs->regs[12] = saved_reg; + else + regs->regs[7] = saved_reg; + }
- if (is_compat_task()) - regs->regs[12] = saved_reg; - else - regs->regs[7] = saved_reg; + if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) + trace_sys_enter(regs, regs->syscallno);
return regs->syscallno; } @@ -1093,6 +1098,9 @@ asmlinkage void syscall_trace_exit(struct pt_regs *regs) { unsigned long saved_reg;
+ if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) + trace_sys_exit(regs, regs_return_value(regs)); + if (!test_thread_flag(TIF_SYSCALL_TRACE)) return;