From 643ad8388e189dfd14ef76972cf7dc394b3cbebd Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 17 Jun 2011 16:50:35 +0200 Subject: ptrace: introduce ptrace_event_enabled() and simplify ptrace_event() and tracehook_prepare_clone() This patch implements ptrace_event_enabled() which tests whether a given PTRACE_EVENT_* is enabled and use it to simplify ptrace_event() and tracehook_prepare_clone(). PT_EVENT_FLAG() macro is added which calculates PT_TRACE_* flag from PTRACE_EVENT_*. This is used to define PT_TRACE_* flags and by ptrace_event_enabled() to find the matching flag. This is used to make ptrace_event() and tracehook_prepare_clone() simpler. * ptrace_event() callers were responsible for providing mask to test whether the event was enabled. This patch implements ptrace_event_enabled() and make ptrace_event() drop @mask and determine whether the event is enabled from @event. Note that @event is constant and this conversion doesn't add runtime overhead. All conversions except tracehook_report_clone_complete() are trivial. tracehook_report_clone_complete() used to use 0 for @mask (always enabled) but now tests whether the specified event is enabled. This doesn't cause any behavior difference as it's guaranteed that the event specified by @trace is enabled. * tracehook_prepare_clone() now only determines which event is applicable and use ptrace_event_enabled() for enable test. This doesn't introduce any behavior change. Signed-off-by: Tejun Heo Signed-off-by: Oleg Nesterov --- include/linux/ptrace.h | 46 ++++++++++++++++++++++++++++++++-------------- include/linux/tracehook.h | 26 +++++++++++++------------- 2 files changed, 45 insertions(+), 27 deletions(-) (limited to 'include') diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index 3ff20b322598..18feac6f441e 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -90,12 +90,17 @@ #define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */ #define PT_TRACESYSGOOD 0x00000004 #define PT_PTRACE_CAP 0x00000008 /* ptracer can follow suid-exec */ -#define PT_TRACE_FORK 0x00000010 -#define PT_TRACE_VFORK 0x00000020 -#define PT_TRACE_CLONE 0x00000040 -#define PT_TRACE_EXEC 0x00000080 -#define PT_TRACE_VFORK_DONE 0x00000100 -#define PT_TRACE_EXIT 0x00000200 + +/* PT_TRACE_* event enable flags */ +#define PT_EVENT_FLAG_SHIFT 4 +#define PT_EVENT_FLAG(event) (1 << (PT_EVENT_FLAG_SHIFT + (event) - 1)) + +#define PT_TRACE_FORK PT_EVENT_FLAG(PTRACE_EVENT_FORK) +#define PT_TRACE_VFORK PT_EVENT_FLAG(PTRACE_EVENT_VFORK) +#define PT_TRACE_CLONE PT_EVENT_FLAG(PTRACE_EVENT_CLONE) +#define PT_TRACE_EXEC PT_EVENT_FLAG(PTRACE_EVENT_EXEC) +#define PT_TRACE_VFORK_DONE PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE) +#define PT_TRACE_EXIT PT_EVENT_FLAG(PTRACE_EVENT_EXIT) #define PT_TRACE_MASK 0x000003f4 @@ -145,26 +150,39 @@ int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr, int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr, unsigned long data); +/** + * ptrace_event_enabled - test whether a ptrace event is enabled + * @task: ptracee of interest + * @event: %PTRACE_EVENT_* to test + * + * Test whether @event is enabled for ptracee @task. + * + * Returns %true if @event is enabled, %false otherwise. + */ +static inline bool ptrace_event_enabled(struct task_struct *task, int event) +{ + return task->ptrace & PT_EVENT_FLAG(event); +} + /** * ptrace_event - possibly stop for a ptrace event notification - * @mask: %PT_* bit to check in @current->ptrace - * @event: %PTRACE_EVENT_* value to report if @mask is set + * @event: %PTRACE_EVENT_* value to report * @message: value for %PTRACE_GETEVENTMSG to return * - * This checks the @mask bit to see if ptrace wants stops for this event. - * If so we stop, reporting @event and @message to the ptrace parent. + * Check whether @event is enabled and, if so, report @event and @message + * to the ptrace parent. * * Returns nonzero if we did a ptrace notification, zero if not. * * Called without locks. */ -static inline int ptrace_event(int mask, int event, unsigned long message) +static inline int ptrace_event(int event, unsigned long message) { - if (mask && likely(!(current->ptrace & mask))) - return 0; + if (likely(!ptrace_event_enabled(current, event))) + return false; current->ptrace_message = message; ptrace_notify((event << 8) | SIGTRAP); - return 1; + return true; } /** diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h index a3e838784f43..7d38571b0c05 100644 --- a/include/linux/tracehook.h +++ b/include/linux/tracehook.h @@ -201,7 +201,7 @@ static inline void tracehook_report_exec(struct linux_binfmt *fmt, struct linux_binprm *bprm, struct pt_regs *regs) { - if (!ptrace_event(PT_TRACE_EXEC, PTRACE_EVENT_EXEC, 0) && + if (!ptrace_event(PTRACE_EVENT_EXEC, 0) && unlikely(current->ptrace & PT_PTRACED)) send_sig(SIGTRAP, current, 0); } @@ -218,7 +218,7 @@ static inline void tracehook_report_exec(struct linux_binfmt *fmt, */ static inline void tracehook_report_exit(long *exit_code) { - ptrace_event(PT_TRACE_EXIT, PTRACE_EVENT_EXIT, *exit_code); + ptrace_event(PTRACE_EVENT_EXIT, *exit_code); } /** @@ -232,19 +232,19 @@ static inline void tracehook_report_exit(long *exit_code) */ static inline int tracehook_prepare_clone(unsigned clone_flags) { + int event = 0; + if (clone_flags & CLONE_UNTRACED) return 0; - if (clone_flags & CLONE_VFORK) { - if (current->ptrace & PT_TRACE_VFORK) - return PTRACE_EVENT_VFORK; - } else if ((clone_flags & CSIGNAL) != SIGCHLD) { - if (current->ptrace & PT_TRACE_CLONE) - return PTRACE_EVENT_CLONE; - } else if (current->ptrace & PT_TRACE_FORK) - return PTRACE_EVENT_FORK; + if (clone_flags & CLONE_VFORK) + event = PTRACE_EVENT_VFORK; + else if ((clone_flags & CSIGNAL) != SIGCHLD) + event = PTRACE_EVENT_CLONE; + else + event = PTRACE_EVENT_FORK; - return 0; + return ptrace_event_enabled(current, event) ? event : 0; } /** @@ -318,7 +318,7 @@ static inline void tracehook_report_clone_complete(int trace, struct task_struct *child) { if (unlikely(trace)) - ptrace_event(0, trace, pid); + ptrace_event(trace, pid); } /** @@ -336,7 +336,7 @@ static inline void tracehook_report_clone_complete(int trace, static inline void tracehook_report_vfork_done(struct task_struct *child, pid_t pid) { - ptrace_event(PT_TRACE_VFORK_DONE, PTRACE_EVENT_VFORK_DONE, pid); + ptrace_event(PTRACE_EVENT_VFORK_DONE, pid); } /** -- cgit v1.2.3