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authorOleg Nesterov <oleg@redhat.com>2013-07-09 01:00:56 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-09 19:33:26 +0200
commite6a7d6077106e5c72f0519ec113d986df67ee001 (patch)
tree90ff605d73b95af65700d47af64029b71c98cf5f
parentptrace: revert "Prepare to fix racy accesses on task breakpoints" (diff)
downloadlinux-e6a7d6077106e5c72f0519ec113d986df67ee001.tar.xz
linux-e6a7d6077106e5c72f0519ec113d986df67ee001.zip
ptrace/x86: simplify the "disable" logic in ptrace_write_dr7()
ptrace_write_dr7() looks unnecessarily overcomplicated. We can factor out ptrace_modify_breakpoint() and do not do "continue" twice, just we need to pass the proper "disabled" argument to ptrace_modify_breakpoint(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jan Kratochvil <jan.kratochvil@redhat.com> Cc: Michael Neuling <mikey@neuling.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Prasad <prasad@linux.vnet.ibm.com> Cc: Russell King <linux@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/x86/kernel/ptrace.c40
1 files changed, 15 insertions, 25 deletions
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 7a98b21945aa..0649f166d7c6 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -637,9 +637,7 @@ static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data)
struct thread_struct *thread = &(tsk->thread);
unsigned long old_dr7;
int i, orig_ret = 0, rc = 0;
- int enabled, second_pass = 0;
- unsigned len, type;
- struct perf_event *bp;
+ int second_pass = 0;
data &= ~DR_CONTROL_RESERVED;
old_dr7 = ptrace_get_dr7(thread->ptrace_bps);
@@ -649,30 +647,22 @@ restore:
* appropriate changes to each.
*/
for (i = 0; i < HBP_NUM; i++) {
- enabled = decode_dr7(data, i, &len, &type);
- bp = thread->ptrace_bps[i];
-
- if (!enabled) {
- if (bp) {
- /*
- * Don't unregister the breakpoints right-away,
- * unless all register_user_hw_breakpoint()
- * requests have succeeded. This prevents
- * any window of opportunity for debug
- * register grabbing by other users.
- */
- if (!second_pass)
- continue;
-
- rc = ptrace_modify_breakpoint(bp, len, type,
- tsk, 1);
- if (rc)
- break;
- }
- continue;
+ unsigned len, type;
+ bool disabled = !decode_dr7(data, i, &len, &type);
+ struct perf_event *bp = thread->ptrace_bps[i];
+
+ if (disabled) {
+ /*
+ * Don't unregister the breakpoints right-away, unless
+ * all register_user_hw_breakpoint() requests have
+ * succeeded. This prevents any window of opportunity
+ * for debug register grabbing by other users.
+ */
+ if (!bp || !second_pass)
+ continue;
}
- rc = ptrace_modify_breakpoint(bp, len, type, tsk, 0);
+ rc = ptrace_modify_breakpoint(bp, len, type, tsk, disabled);
if (rc)
break;
}