Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
unwind: Fix unwind_deferred_request() vs NMI
task_work_add(RWA_RESUME) isn't NMI-safe, use TWA_NMI_CURRENT when
used from NMI context.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://patch.msgid.link/20250924080119.005422353@infradead.org
+7
-3
+7
-3
kernel/unwind/deferred.c
+7
-3
kernel/unwind/deferred.c
···
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int unwind_deferred_request(struct unwind_work *work, u64 *cookie)
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{
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struct unwind_task_info *info = ¤t->unwind_info;
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+
int twa_mode = TWA_RESUME;
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unsigned long old, bits;
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unsigned long bit;
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int ret;
···
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* Trigger a warning to make it obvious that an architecture
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* is using this in NMI when it should not be.
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*/
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-
if (WARN_ON_ONCE(!CAN_USE_IN_NMI && in_nmi()))
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-
return -EINVAL;
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+
if (in_nmi()) {
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if (WARN_ON_ONCE(!CAN_USE_IN_NMI))
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return -EINVAL;
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twa_mode = TWA_NMI_CURRENT;
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}
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/* Do not allow cancelled works to request again */
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bit = READ_ONCE(work->bit);
···
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}
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/* The work has been claimed, now schedule it. */
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-
ret = task_work_add(current, &info->work, TWA_RESUME);
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ret = task_work_add(current, &info->work, twa_mode);
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if (WARN_ON_ONCE(ret))
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WRITE_ONCE(info->unwind_mask, 0);