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Subject[PATCH 4/7] add syscall tracepoints

add two tracepoints in syscall exit and entry path, conditioned on
TIF_SYSCALL_FTRACE. Supports the syscall trace event code.


Signed-off-by: Jason Baron <jbaron@redhat.com>

---
arch/x86/kernel/ptrace.c | 6 ++++--
include/trace/syscall.h | 18 ++++++++++++++++++
kernel/tracepoint.c | 38 ++++++++++++++++++++++++++++++++++++++
3 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 09ecbde..1c7301a 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -36,6 +36,8 @@
#include <asm/ds.h>

#include <trace/syscall.h>
+DEFINE_TRACE(syscall_enter);
+DEFINE_TRACE(syscall_exit);

#include "tls.h"

@@ -1498,7 +1500,7 @@ asmregparm long syscall_trace_enter(struct pt_regs *regs)
ret = -1L;

if (unlikely(test_thread_flag(TIF_SYSCALL_FTRACE)))
- ftrace_syscall_enter(regs);
+ trace_syscall_enter(regs, regs->orig_ax);

if (unlikely(current->audit_context)) {
if (IS_IA32)
@@ -1524,7 +1526,7 @@ asmregparm void syscall_trace_leave(struct pt_regs *regs)
audit_syscall_exit(AUDITSC_RESULT(regs->ax), regs->ax);

if (unlikely(test_thread_flag(TIF_SYSCALL_FTRACE)))
- ftrace_syscall_exit(regs);
+ trace_syscall_exit(regs, regs->ax);

if (test_thread_flag(TIF_SYSCALL_TRACE))
tracehook_report_syscall_exit(regs, 0);
diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index 8cfe515..d5d8310 100644
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -2,6 +2,24 @@
#define _TRACE_SYSCALL_H

#include <asm/ptrace.h>
+#include <linux/tracepoint.h>
+
+extern void syscall_regfunc(void);
+extern void syscall_unregfunc(void);
+
+DECLARE_TRACE_REG(syscall_enter,
+ TP_PROTO(struct pt_regs *regs, long id),
+ TP_ARGS(regs, id),
+ syscall_regfunc,
+ syscall_unregfunc
+);
+
+DECLARE_TRACE_REG(syscall_exit,
+ TP_PROTO(struct pt_regs *regs, long ret),
+ TP_ARGS(regs, ret),
+ syscall_regfunc,
+ syscall_unregfunc
+);

/*
* A syscall entry in the ftrace syscalls array.
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 1ef5d3a..5b34ff9 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -24,6 +24,7 @@
#include <linux/tracepoint.h>
#include <linux/err.h>
#include <linux/slab.h>
+#include <linux/sched.h>

extern struct tracepoint __start___tracepoints[];
extern struct tracepoint __stop___tracepoints[];
@@ -577,3 +578,40 @@ static int init_tracepoints(void)
__initcall(init_tracepoints);

#endif /* CONFIG_MODULES */
+
+DEFINE_MUTEX(regfunc_mutex);
+int sys_tracepoint_refcount;
+
+void syscall_regfunc(void)
+{
+ unsigned long flags;
+ struct task_struct *g, *t;
+
+ mutex_lock(&regfunc_mutex);
+ if (!sys_tracepoint_refcount) {
+ read_lock_irqsave(&tasklist_lock, flags);
+ do_each_thread(g, t) {
+ set_tsk_thread_flag(t, TIF_SYSCALL_FTRACE);
+ } while_each_thread(g, t);
+ read_unlock_irqrestore(&tasklist_lock, flags);
+ }
+ sys_tracepoint_refcount++;
+ mutex_unlock(&regfunc_mutex);
+}
+
+void syscall_unregfunc(void)
+{
+ unsigned long flags;
+ struct task_struct *g, *t;
+
+ mutex_lock(&regfunc_mutex);
+ sys_tracepoint_refcount--;
+ if (!sys_tracepoint_refcount) {
+ read_lock_irqsave(&tasklist_lock, flags);
+ do_each_thread(g, t) {
+ clear_tsk_thread_flag(t, TIF_SYSCALL_FTRACE);
+ } while_each_thread(g, t);
+ read_unlock_irqrestore(&tasklist_lock, flags);
+ }
+ mutex_unlock(&regfunc_mutex);
+}
--
1.6.0.6


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