lkml.org 
[lkml]   [2014]   [Mar]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v6 7/7] arm64: ftrace: Add system call tracepoint
Date
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;

--
1.7.9.5


\
 
 \ /
  Last update: 2014-03-14 09:01    [W:0.385 / U:0.284 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site