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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>
This commit is contained in:
Oleg Nesterov 2013-07-08 16:00:56 -07:00 committed by Linus Torvalds
parent 7c8df28633
commit e6a7d60771
1 changed files with 14 additions and 24 deletions
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38
arch/x86/kernel/ptrace.c
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@ -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];
unsigned len, type;
bool disabled = !decode_dr7(data, i, &len, &type);
struct perf_event *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;
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;
}