Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (9581b7d2) · Commits · 戴 / test

arch/x86/kernel/cpu/perf_event.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -1276,16 +1276,16 @@ void perf_events_lapic_init(void)
		static int __kprobes
		perf_event_nmi_handler(unsigned int cmd, struct pt_regs *regs)
		{
		int ret;
		u64 start_clock;
		u64 finish_clock;
		int ret;

		if (!atomic_read(&active_events))
		return NMI_DONE;

		start_clock = local_clock();
		start_clock = sched_clock();
		ret = x86_pmu.handle_irq(regs);
		finish_clock = local_clock();
		finish_clock = sched_clock();

		perf_sample_event_took(finish_clock - start_clock);

+2 −2

Original line number	Diff line number	Diff line
		@@ -113,10 +113,10 @@ static int __kprobes nmi_handle(unsigned int type, struct pt_regs *regs, bool b2
		u64 before, delta, whole_msecs;
		int remainder_ns, decimal_msecs, thishandled;

		before = local_clock();
		before = sched_clock();
		thishandled = a->handler(type, regs);
		handled += thishandled;
		delta = local_clock() - before;
		delta = sched_clock() - before;
		trace_nmi_handler(a->handler, (int)delta, thishandled);

		if (delta < nmi_longest_ns)

+7 −5

Original line number	Diff line number	Diff line
		@@ -456,13 +456,15 @@ struct perf_event_mmap_page {
		/*
		* Control data for the mmap() data buffer.
		*
		* User-space reading the @data_head value should issue an rmb(), on
		* SMP capable platforms, after reading this value -- see
		* perf_event_wakeup().
		* User-space reading the @data_head value should issue an smp_rmb(),
		* after reading this value.
		*
		* When the mapping is PROT_WRITE the @data_tail value should be
		* written by userspace to reflect the last read data. In this case
		* the kernel will not over-write unread data.
		* written by userspace to reflect the last read data, after issueing
		* an smp_mb() to separate the data read from the ->data_tail store.
		* In this case the kernel will not over-write unread data.
		*
		* See perf_output_put_handle() for the data ordering.
		*/
		__u64 data_head; /* head in the data section */
		__u64 data_tail; /* user-space written tail */

+27 −4

Original line number	Diff line number	Diff line
		@@ -87,10 +87,31 @@ again:
		goto out;

		/*
		* Publish the known good head. Rely on the full barrier implied
		* by atomic_dec_and_test() order the rb->head read and this
		* write.
		* Since the mmap() consumer (userspace) can run on a different CPU:
		*
		* kernel user
		*
		* READ ->data_tail READ ->data_head
		* smp_mb() (A) smp_rmb() (C)
		* WRITE $data READ $data
		* smp_wmb() (B) smp_mb() (D)
		* STORE ->data_head WRITE ->data_tail
		*
		* Where A pairs with D, and B pairs with C.
		*
		* I don't think A needs to be a full barrier because we won't in fact
		* write data until we see the store from userspace. So we simply don't
		* issue the data WRITE until we observe it. Be conservative for now.
		*
		* OTOH, D needs to be a full barrier since it separates the data READ
		* from the tail WRITE.
		*
		* For B a WMB is sufficient since it separates two WRITEs, and for C
		* an RMB is sufficient since it separates two READs.
		*
		* See perf_output_begin().
		*/
		smp_wmb();
		rb->user_page->data_head = head;

		/*
		@@ -154,9 +175,11 @@ int perf_output_begin(struct perf_output_handle *handle,
		* Userspace could choose to issue a mb() before updating the
		* tail pointer. So that all reads will be completed before the
		* write is issued.
		*
		* See perf_output_put_handle().
		*/
		tail = ACCESS_ONCE(rb->user_page->data_tail);
		smp_rmb();
		smp_mb();
		offset = head = local_read(&rb->head);
		head += size;
		if (unlikely(!perf_output_space(rb, tail, offset, head)))