Merge tag 'trace-ringbuffer-v7.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull ring-buffer fixes from Steven Rostedt:

 - Fix reporting MISSED EVENTS in trace iterator

   When the "trace" file is read with tracing enabled, if the writer
   were to pass the iterator reader, it resets, sets a "missed_events"
   flag and continues. The tracing output checks for missed events and
   if there are some, it prints out "[LOST EVENTS]" to let the user know
   events were dropped.

   But the clearing of the missed_events happened when the tracing
   system queried the ring buffer iterator about missed events. This was
   premature as the ring buffer is per CPU, and the tracing code reads
   all the CPU buffers and checks for missed events when it is read. If
   the CPU iterator that had missed events isn't printed next, the
   output for the LOST EVENTS is lost.

   Clear the missed_events flag when the iterator moves to the next
   event and not when the missed_events flag is queried. Also clear it
   on reset.

 - Flush and stop the persistent ring buffer on panic

   On panic the persistent ring buffer is used to debug what caused the
   panic. But on some architectures, it requires flushing the memory
   from cache, otherwise, the ring buffer persistent memory may not have
   the last events and this could also cause the ring buffer to be
   corrupted on the next boot.

 - Fix nr_subbufs initialization in simple_ring_buffer_init_mm

   The remote simple ring buffer meta data nr_subbufs is initialized too
   early and gets cleared later on, making it zero and not reflect the
   actual number of sub-buffers.

 - Fix unload_page for simple_ring_buffer init rollback

   On error, the pages loaded need to be unloaded. To unload a page it
   is expected that: page = load_page(va); -> unload_page(page). But the
   code was doing: unload_page(va) and not unload_page(page).

 - Create output file from cmd_check_undefined

   The check for undefined symbols checks if the file *.o.checked exists
   and if so it skips doing the work. But the *.o.checked file never was
   created making every build do the work even when it was already done
   previously.

* tag 'trace-ringbuffer-v7.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: Create output file from cmd_check_undefined
  tracing: Fix unload_page for simple_ring_buffer init rollback
  tracing: Fix nr_subbufs initialization in simple_ring_buffer_init_mm()
  ring-buffer: Flush and stop persistent ring buffer on panic
  ring-buffer: Fix reporting of missed events in iterator

25 files changed, 72 insertions, 8 deletions

diff --git a/arch/alpha/include/asm/Kbuild b/arch/alpha/include/asm/Kbuild
index 483965c5a4de..b154b4e3dfa8 100644
--- a/arch/alpha/include/asm/Kbuild
+++ b/arch/alpha/include/asm/Kbuild
@@ -5,4 +5,5 @@ generic-y += agp.h
 generic-y += asm-offsets.h
 generic-y += kvm_para.h
 generic-y += mcs_spinlock.h
+generic-y += ring_buffer.h
 generic-y += text-patching.h
diff --git a/arch/arc/include/asm/Kbuild b/arch/arc/include/asm/Kbuild
index 4c69522e0328..483caacc6988 100644
--- a/arch/arc/include/asm/Kbuild
+++ b/arch/arc/include/asm/Kbuild
@@ -5,5 +5,6 @@ generic-y += extable.h
 generic-y += kvm_para.h
 generic-y += mcs_spinlock.h
 generic-y += parport.h
+generic-y += ring_buffer.h
 generic-y += user.h
 generic-y += text-patching.h
diff --git a/arch/arm/include/asm/Kbuild b/arch/arm/include/asm/Kbuild
index 03657ff8fbe3..decad5f2c826 100644
--- a/arch/arm/include/asm/Kbuild
+++ b/arch/arm/include/asm/Kbuild
@@ -3,6 +3,7 @@ generic-y += early_ioremap.h
 generic-y += extable.h
 generic-y += flat.h
 generic-y += parport.h
+generic-y += ring_buffer.h
 
 generated-y += mach-types.h
 generated-y += unistd-nr.h
diff --git a/arch/arm64/include/asm/ring_buffer.h b/arch/arm64/include/asm/ring_buffer.h
new file mode 100644
index 000000000000..62316c406888
--- /dev/null
+++ b/arch/arm64/include/asm/ring_buffer.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _ASM_ARM64_RING_BUFFER_H
+#define _ASM_ARM64_RING_BUFFER_H
+
+#include <asm/cacheflush.h>
+
+/* Flush D-cache on persistent ring buffer */
+#define arch_ring_buffer_flush_range(start, end)	dcache_clean_pop(start, end)
+
+#endif /* _ASM_ARM64_RING_BUFFER_H */
diff --git a/arch/csky/include/asm/Kbuild b/arch/csky/include/asm/Kbuild
index 3a5c7f6e5aac..7dca0c6cdc84 100644
--- a/arch/csky/include/asm/Kbuild
+++ b/arch/csky/include/asm/Kbuild
@@ -9,6 +9,7 @@ generic-y += qrwlock.h
 generic-y += qrwlock_types.h
 generic-y += qspinlock.h
 generic-y += parport.h
+generic-y += ring_buffer.h
 generic-y += user.h
 generic-y += vmlinux.lds.h
 generic-y += text-patching.h
diff --git a/arch/hexagon/include/asm/Kbuild b/arch/hexagon/include/asm/Kbuild
index 1efa1e993d4b..0f887d4238ed 100644
--- a/arch/hexagon/include/asm/Kbuild
+++ b/arch/hexagon/include/asm/Kbuild
@@ -5,4 +5,5 @@ generic-y += extable.h
 generic-y += iomap.h
 generic-y += kvm_para.h
 generic-y += mcs_spinlock.h
+generic-y += ring_buffer.h
 generic-y += text-patching.h
diff --git a/arch/loongarch/include/asm/Kbuild b/arch/loongarch/include/asm/Kbuild
index 9034b583a88a..7e92957baf6a 100644
--- a/arch/loongarch/include/asm/Kbuild
+++ b/arch/loongarch/include/asm/Kbuild
@@ -10,5 +10,6 @@ generic-y += qrwlock.h
 generic-y += user.h
 generic-y += ioctl.h
 generic-y += mmzone.h
+generic-y += ring_buffer.h
 generic-y += statfs.h
 generic-y += text-patching.h
diff --git a/arch/m68k/include/asm/Kbuild b/arch/m68k/include/asm/Kbuild
index b282e0dd8dc1..62543bf305ff 100644
--- a/arch/m68k/include/asm/Kbuild
+++ b/arch/m68k/include/asm/Kbuild
@@ -3,5 +3,6 @@ generated-y += syscall_table.h
 generic-y += extable.h
 generic-y += kvm_para.h
 generic-y += mcs_spinlock.h
+generic-y += ring_buffer.h
 generic-y += spinlock.h
 generic-y += text-patching.h
diff --git a/arch/microblaze/include/asm/Kbuild b/arch/microblaze/include/asm/Kbuild
index 7178f990e8b3..0030309b47ad 100644
--- a/arch/microblaze/include/asm/Kbuild
+++ b/arch/microblaze/include/asm/Kbuild
@@ -5,6 +5,7 @@ generic-y += extable.h
 generic-y += kvm_para.h
 generic-y += mcs_spinlock.h
 generic-y += parport.h
+generic-y += ring_buffer.h
 generic-y += syscalls.h
 generic-y += tlb.h
 generic-y += user.h
diff --git a/arch/mips/include/asm/Kbuild b/arch/mips/include/asm/Kbuild
index 684569b2ecd6..9771c3d85074 100644
--- a/arch/mips/include/asm/Kbuild
+++ b/arch/mips/include/asm/Kbuild
@@ -12,5 +12,6 @@ generic-y += mcs_spinlock.h
 generic-y += parport.h
 generic-y += qrwlock.h
 generic-y += qspinlock.h
+generic-y += ring_buffer.h
 generic-y += user.h
 generic-y += text-patching.h
diff --git a/arch/nios2/include/asm/Kbuild b/arch/nios2/include/asm/Kbuild
index 28004301c236..0a2530964413 100644
--- a/arch/nios2/include/asm/Kbuild
+++ b/arch/nios2/include/asm/Kbuild
@@ -5,6 +5,7 @@ generic-y += cmpxchg.h
 generic-y += extable.h
 generic-y += kvm_para.h
 generic-y += mcs_spinlock.h
+generic-y += ring_buffer.h
 generic-y += spinlock.h
 generic-y += user.h
 generic-y += text-patching.h
diff --git a/arch/openrisc/include/asm/Kbuild b/arch/openrisc/include/asm/Kbuild
index cef49d60d74c..8aa34621702d 100644
--- a/arch/openrisc/include/asm/Kbuild
+++ b/arch/openrisc/include/asm/Kbuild
@@ -8,4 +8,5 @@ generic-y += spinlock_types.h
 generic-y += spinlock.h
 generic-y += qrwlock_types.h
 generic-y += qrwlock.h
+generic-y += ring_buffer.h
 generic-y += user.h
diff --git a/arch/parisc/include/asm/Kbuild b/arch/parisc/include/asm/Kbuild
index 4fb596d94c89..d48d158f7241 100644
--- a/arch/parisc/include/asm/Kbuild
+++ b/arch/parisc/include/asm/Kbuild
@@ -4,4 +4,5 @@ generated-y += syscall_table_64.h
 generic-y += agp.h
 generic-y += kvm_para.h
 generic-y += mcs_spinlock.h
+generic-y += ring_buffer.h
 generic-y += user.h
diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild
index 2e23533b67e3..805b5aeebb6f 100644
--- a/arch/powerpc/include/asm/Kbuild
+++ b/arch/powerpc/include/asm/Kbuild
@@ -5,4 +5,5 @@ generated-y += syscall_table_spu.h
 generic-y += agp.h
 generic-y += mcs_spinlock.h
 generic-y += qrwlock.h
+generic-y += ring_buffer.h
 generic-y += early_ioremap.h
diff --git a/arch/riscv/include/asm/Kbuild b/arch/riscv/include/asm/Kbuild
index bd5fc9403295..7721b63642f4 100644
--- a/arch/riscv/include/asm/Kbuild
+++ b/arch/riscv/include/asm/Kbuild
@@ -14,5 +14,6 @@ generic-y += ticket_spinlock.h
 generic-y += qrwlock.h
 generic-y += qrwlock_types.h
 generic-y += qspinlock.h
+generic-y += ring_buffer.h
 generic-y += user.h
 generic-y += vmlinux.lds.h
diff --git a/arch/s390/include/asm/Kbuild b/arch/s390/include/asm/Kbuild
index 80bad7de7a04..0c1fc47c3ba0 100644
--- a/arch/s390/include/asm/Kbuild
+++ b/arch/s390/include/asm/Kbuild
@@ -7,3 +7,4 @@ generated-y += unistd_nr.h
 generic-y += asm-offsets.h
 generic-y += mcs_spinlock.h
 generic-y += mmzone.h
+generic-y += ring_buffer.h
diff --git a/arch/sh/include/asm/Kbuild b/arch/sh/include/asm/Kbuild
index 4d3f10ed8275..f0403d3ee8ab 100644
--- a/arch/sh/include/asm/Kbuild
+++ b/arch/sh/include/asm/Kbuild
@@ -3,4 +3,5 @@ generated-y += syscall_table.h
 generic-y += kvm_para.h
 generic-y += mcs_spinlock.h
 generic-y += parport.h
+generic-y += ring_buffer.h
 generic-y += text-patching.h
diff --git a/arch/sparc/include/asm/Kbuild b/arch/sparc/include/asm/Kbuild
index 17ee8a273aa6..49c6bb326b75 100644
--- a/arch/sparc/include/asm/Kbuild
+++ b/arch/sparc/include/asm/Kbuild
@@ -4,4 +4,5 @@ generated-y += syscall_table_64.h
 generic-y += agp.h
 generic-y += kvm_para.h
 generic-y += mcs_spinlock.h
+generic-y += ring_buffer.h
 generic-y += text-patching.h
diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild
index 1b9b82bbe322..2a1629ba8140 100644
--- a/arch/um/include/asm/Kbuild
+++ b/arch/um/include/asm/Kbuild
@@ -17,6 +17,7 @@ generic-y += module.lds.h
 generic-y += parport.h
 generic-y += percpu.h
 generic-y += preempt.h
+generic-y += ring_buffer.h
 generic-y += runtime-const.h
 generic-y += softirq_stack.h
 generic-y += switch_to.h
diff --git a/arch/x86/include/asm/Kbuild b/arch/x86/include/asm/Kbuild
index 4566000e15c4..078fd2c0d69d 100644
--- a/arch/x86/include/asm/Kbuild
+++ b/arch/x86/include/asm/Kbuild
@@ -14,3 +14,4 @@ generic-y += early_ioremap.h
 generic-y += fprobe.h
 generic-y += mcs_spinlock.h
 generic-y += mmzone.h
+generic-y += ring_buffer.h
diff --git a/arch/xtensa/include/asm/Kbuild b/arch/xtensa/include/asm/Kbuild
index 13fe45dea296..e57af619263a 100644
--- a/arch/xtensa/include/asm/Kbuild
+++ b/arch/xtensa/include/asm/Kbuild
@@ -6,5 +6,6 @@ generic-y += mcs_spinlock.h
 generic-y += parport.h
 generic-y += qrwlock.h
 generic-y += qspinlock.h
+generic-y += ring_buffer.h
 generic-y += user.h
 generic-y += text-patching.h
diff --git a/include/asm-generic/ring_buffer.h b/include/asm-generic/ring_buffer.h
new file mode 100644
index 000000000000..201d2aee1005
--- /dev/null
+++ b/include/asm-generic/ring_buffer.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Generic arch dependent ring_buffer macros.
+ */
+#ifndef __ASM_GENERIC_RING_BUFFER_H__
+#define __ASM_GENERIC_RING_BUFFER_H__
+
+#include <linux/cacheflush.h>
+
+/* Flush cache on ring buffer range if needed. Do nothing by default. */
+#define arch_ring_buffer_flush_range(start, end)	do { } while (0)
+
+#endif /* __ASM_GENERIC_RING_BUFFER_H__ */
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 9b0834134cae..8d3d96e847d8 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -154,7 +154,8 @@ quiet_cmd_check_undefined = NM      $<
               echo "Unexpected symbols in $<:" >&2; \
               echo "$$undefsyms" >&2; \
               false; \
-          fi
+          fi; \
+          touch $@
 
 $(obj)/%.o.checked: $(obj)/%.o $(obj)/undefsyms_base.o FORCE
 	$(call if_changed,check_undefined)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 5326924615a4..7b07d2004cc6 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -7,6 +7,7 @@
 #include <linux/ring_buffer_types.h>
 #include <linux/sched/isolation.h>
 #include <linux/trace_recursion.h>
+#include <linux/panic_notifier.h>
 #include <linux/trace_events.h>
 #include <linux/ring_buffer.h>
 #include <linux/trace_clock.h>
@@ -31,6 +32,7 @@
 #include <linux/oom.h>
 #include <linux/mm.h>
 
+#include <asm/ring_buffer.h>
 #include <asm/local64.h>
 #include <asm/local.h>
 #include <asm/setup.h>
@@ -559,6 +561,7 @@ struct trace_buffer {
 
 	unsigned long			range_addr_start;
 	unsigned long			range_addr_end;
+	struct notifier_block		flush_nb;
 
 	struct ring_buffer_meta		*meta;
 
@@ -2521,6 +2524,16 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer)
 	kfree(cpu_buffer);
 }
 
+/* Stop recording on a persistent buffer and flush cache if needed. */
+static int rb_flush_buffer_cb(struct notifier_block *nb, unsigned long event, void *data)
+{
+	struct trace_buffer *buffer = container_of(nb, struct trace_buffer, flush_nb);
+
+	ring_buffer_record_off(buffer);
+	arch_ring_buffer_flush_range(buffer->range_addr_start, buffer->range_addr_end);
+	return NOTIFY_DONE;
+}
+
 static struct trace_buffer *alloc_buffer(unsigned long size, unsigned flags,
 					 int order, unsigned long start,
 					 unsigned long end,
@@ -2651,6 +2664,12 @@ static struct trace_buffer *alloc_buffer(unsigned long size, unsigned flags,
 
 	mutex_init(&buffer->mutex);
 
+	/* Persistent ring buffer needs to flush cache before reboot. */
+	if (start && end) {
+		buffer->flush_nb.notifier_call = rb_flush_buffer_cb;
+		atomic_notifier_chain_register(&panic_notifier_list, &buffer->flush_nb);
+	}
+
 	return_ptr(buffer);
 
  fail_free_buffers:
@@ -2749,6 +2768,9 @@ ring_buffer_free(struct trace_buffer *buffer)
 {
 	int cpu;
 
+	if (buffer->range_addr_start && buffer->range_addr_end)
+		atomic_notifier_chain_unregister(&panic_notifier_list, &buffer->flush_nb);
+
 	cpuhp_state_remove_instance(CPUHP_TRACE_RB_PREPARE, &buffer->node);
 
 	irq_work_sync(&buffer->irq_work.work);
@@ -5407,6 +5429,7 @@ static void rb_iter_reset(struct ring_buffer_iter *iter)
 	iter->head_page = cpu_buffer->reader_page;
 	iter->head = cpu_buffer->reader_page->read;
 	iter->next_event = iter->head;
+	iter->missed_events = 0;
 
 	iter->cache_reader_page = iter->head_page;
 	iter->cache_read = cpu_buffer->read;
@@ -6086,10 +6109,7 @@ ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts,
  */
 bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter)
 {
-	bool ret = iter->missed_events != 0;
-
-	iter->missed_events = 0;
-	return ret;
+	return iter->missed_events != 0;
 }
 EXPORT_SYMBOL_GPL(ring_buffer_iter_dropped);
 
@@ -6251,7 +6271,7 @@ void ring_buffer_iter_advance(struct ring_buffer_iter *iter)
 	unsigned long flags;
 
 	raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
-
+	iter->missed_events = 0;
 	rb_advance_iter(iter);
 
 	raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
diff --git a/kernel/trace/simple_ring_buffer.c b/kernel/trace/simple_ring_buffer.c
index 02af2297ae5a..f4642f5adda3 100644
--- a/kernel/trace/simple_ring_buffer.c
+++ b/kernel/trace/simple_ring_buffer.c
@@ -395,7 +395,6 @@ int simple_ring_buffer_init_mm(struct simple_rb_per_cpu *cpu_buffer,
 
 	memset(cpu_buffer->meta, 0, sizeof(*cpu_buffer->meta));
 	cpu_buffer->meta->meta_page_size = PAGE_SIZE;
-	cpu_buffer->meta->nr_subbufs = cpu_buffer->nr_pages;
 
 	/* The reader page is not part of the ring initially */
 	page = load_page(desc->page_va[0]);
@@ -431,12 +430,13 @@ int simple_ring_buffer_init_mm(struct simple_rb_per_cpu *cpu_buffer,
 
 	if (ret) {
 		for (i--; i >= 0; i--)
-			unload_page((void *)desc->page_va[i]);
+			unload_page(bpages[i].page);
 		unload_page(cpu_buffer->meta);
 
 		return ret;
 	}
 
+	cpu_buffer->meta->nr_subbufs = cpu_buffer->nr_pages;
 	/* Close the ring */
 	bpage->link.next = &cpu_buffer->tail_page->link;
 	cpu_buffer->tail_page->link.prev = &bpage->link;