ARM: hw_breakpoint: disallow per-cpu breakpoints without overflow handler
Single-stepping a breakpoint requires us to disable it temporarily so that we don't get stuck in a recursive debug trap. With per-cpu breakpoints this presents a problem where an interrupt can be taken before the single-step has completed and a new task is eventually scheduled. This new task will not hit the breakpoint because it will have been disabled during the previous handling code. This patch disallows per-cpu breakpoints on ARM when an overflow handler is not present. A similar effect can be created by placing breakpoints on a shell and then running applications there. Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
parent
9ebb3cbcc3
commit
3ce70b2e24
|
@ -622,10 +622,12 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
|
|||
* Currently we rely on an overflow handler to take
|
||||
* care of single-stepping the breakpoint when it fires.
|
||||
* In the case of userspace breakpoints on a core with V7 debug,
|
||||
* we can use the mismatch feature as a poor-man's hardware single-step.
|
||||
* we can use the mismatch feature as a poor-man's hardware
|
||||
* single-step, but this only works for per-task breakpoints.
|
||||
*/
|
||||
if (WARN_ONCE(!bp->overflow_handler &&
|
||||
(arch_check_bp_in_kernelspace(bp) || !core_has_mismatch_brps()),
|
||||
(arch_check_bp_in_kernelspace(bp) || !core_has_mismatch_brps()
|
||||
|| !bp->hw.bp_target),
|
||||
"overflow handler required but none found")) {
|
||||
ret = -EINVAL;
|
||||
}
|
||||
|
|
Loading…
Reference in New Issue