Messages in this thread | | | Date | Fri, 19 Jun 2009 04:12:37 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 4/7] add syscall tracepoints |
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On Fri, Jun 12, 2009 at 05:24:54PM -0400, Jason Baron wrote: > > 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
At a first glance I wasn't sure tracepoint.c is the right place for these. But indeed putting those two callbacks here avoids any dependency to the syscall tracer when someone else needs the syscall tracepoints.
Well, I guess we can keep them there.
> @@ -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;
Looks like regfunc_mutex is only there to protect sys_tracepoint_refcount. May be you can just make it atomic_t?
Thanks, Frederic.
> + > +void syscall_regfunc(void) > +{ > + unsigned long flags; > + struct task_struct *g, *t; > + > + mutex_lock(®func_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(®func_mutex); > +} > + > +void syscall_unregfunc(void) > +{ > + unsigned long flags; > + struct task_struct *g, *t; > + > + mutex_lock(®func_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(®func_mutex); > +} > -- > 1.6.0.6 >
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