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ptrace: introduce ptrace_event_enabled() and simplify ptrace_event() and tracehook_prepare_clone()

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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 <tj@kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
This commit is contained in:
Tejun Heo 2011-06-17 16:50:35 +02:00 • committed by Oleg Nesterov
parent d21142ece4
commit 643ad8388e
2 changed files with 45 additions and 27 deletions
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46
include/linux/ptrace.h
View file

@ -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;
}
/**