ring-buffer: Flush and stop persistent ring buffer on panic

On real hardware, panic and machine reboot may not flush hardware cache to memory. This means the persistent ring buffer, which relies on a coherent state of memory, may not have its events written to the buffer and they may be lost. Moreover, there may be inconsistency with the counters which are used for validation of the integrity of the persistent ring buffer which may cause all data to be discarded. To avoid this issue, stop recording of the ring buffer on panic and flush the cache of the ring buffer's memory.

Masami Hiramatsu (Google) committed 6 months ago

Commit a494d3c1 parent a254b6d23 files · +65 −0Browse files

Unified · Split

23 files

arch/alpha/include/asm/Kbuild +1 −0
arch/arc/include/asm/Kbuild +1 −0
arch/arm/include/asm/Kbuild +1 −0
arch/arm64/include/asm/ring_buffer.h +10 −0
arch/csky/include/asm/Kbuild +1 −0
arch/hexagon/include/asm/Kbuild +1 −0
arch/loongarch/include/asm/Kbuild +1 −0
arch/m68k/include/asm/Kbuild +1 −0
arch/microblaze/include/asm/Kbuild +1 −0
arch/mips/include/asm/Kbuild +1 −0
arch/nios2/include/asm/Kbuild +1 −0
arch/openrisc/include/asm/Kbuild +1 −0
arch/parisc/include/asm/Kbuild +1 −0
arch/powerpc/include/asm/Kbuild +1 −0
arch/riscv/include/asm/Kbuild +1 −0
arch/s390/include/asm/Kbuild +1 −0
arch/sh/include/asm/Kbuild +1 −0
arch/sparc/include/asm/Kbuild +1 −0
arch/um/include/asm/Kbuild +1 −0
arch/x86/include/asm/Kbuild +1 −0
arch/xtensa/include/asm/Kbuild +1 −0
include/asm-generic/ring_buffer.h +13 −0
kernel/trace/ring_buffer.c +22 −0

arch/alpha/include/asm/Kbuild+1−0

@@ -5,4 +5,5 @@ generic-y += agp.h · 4 unmodified lines
5	5	generic-y += asm-offsets.h
6	6	generic-y += kvm_para.h
7	7	generic-y += mcs_spinlock.h
	8	+generic-y += ring_buffer.h
8	9	generic-y += text-patching.h

arch/arc/include/asm/Kbuild+1−0

@@ -5,5 +5,6 @@ generic-y += extable.h · 4 unmodified lines
5	5	generic-y += kvm_para.h
6	6	generic-y += mcs_spinlock.h
7	7	generic-y += parport.h
	8	+generic-y += ring_buffer.h
8	9	generic-y += user.h
9	10	generic-y += text-patching.h

arch/arm/include/asm/Kbuild+1−0

@@ -3,6 +3,7 @@ generic-y += early_ioremap.h · 2 unmodified lines
3	3	generic-y += extable.h
4	4	generic-y += flat.h
5	5	generic-y += parport.h
	6	+generic-y += ring_buffer.h
6	7
7	8	generated-y += mach-types.h
8	9	generated-y += unistd-nr.h

arch/arm64/include/asm/ring_buffer.h+10−0

@@ -0,0 +1,10 @@
	1	+/* SPDX-License-Identifier: GPL-2.0-only */
	2	+#ifndef _ASM_ARM64_RING_BUFFER_H
	3	+#define _ASM_ARM64_RING_BUFFER_H
	4	+
	5	+#include <asm/cacheflush.h>
	6	+
	7	+/* Flush D-cache on persistent ring buffer */
	8	+#define arch_ring_buffer_flush_range(start, end) dcache_clean_pop(start, end)
	9	+
	10	+#endif /* _ASM_ARM64_RING_BUFFER_H */

arch/csky/include/asm/Kbuild+1−0

@@ -9,6 +9,7 @@ generic-y += qrwlock.h · 8 unmodified lines
9	9	generic-y += qrwlock_types.h
10	10	generic-y += qspinlock.h
11	11	generic-y += parport.h
	12	+generic-y += ring_buffer.h
12	13	generic-y += user.h
13	14	generic-y += vmlinux.lds.h
14	15	generic-y += text-patching.h

arch/hexagon/include/asm/Kbuild+1−0

@@ -5,4 +5,5 @@ generic-y += extable.h · 4 unmodified lines
5	5	generic-y += iomap.h
6	6	generic-y += kvm_para.h
7	7	generic-y += mcs_spinlock.h
	8	+generic-y += ring_buffer.h
8	9	generic-y += text-patching.h

arch/loongarch/include/asm/Kbuild+1−0

@@ -10,5 +10,6 @@ generic-y += qrwlock.h · 9 unmodified lines
10	10	generic-y += user.h
11	11	generic-y += ioctl.h
12	12	generic-y += mmzone.h
	13	+generic-y += ring_buffer.h
13	14	generic-y += statfs.h
14	15	generic-y += text-patching.h

arch/m68k/include/asm/Kbuild+1−0

@@ -3,5 +3,6 @@ generated-y += syscall_table.h · 2 unmodified lines
3	3	generic-y += extable.h
4	4	generic-y += kvm_para.h
5	5	generic-y += mcs_spinlock.h
	6	+generic-y += ring_buffer.h
6	7	generic-y += spinlock.h
7	8	generic-y += text-patching.h

arch/microblaze/include/asm/Kbuild+1−0

@@ -5,6 +5,7 @@ generic-y += extable.h · 4 unmodified lines
5	5	generic-y += kvm_para.h
6	6	generic-y += mcs_spinlock.h
7	7	generic-y += parport.h
	8	+generic-y += ring_buffer.h
8	9	generic-y += syscalls.h
9	10	generic-y += tlb.h
10	11	generic-y += user.h

arch/mips/include/asm/Kbuild+1−0

@@ -12,5 +12,6 @@ generic-y += mcs_spinlock.h · 11 unmodified lines
12	12	generic-y += parport.h
13	13	generic-y += qrwlock.h
14	14	generic-y += qspinlock.h
	15	+generic-y += ring_buffer.h
15	16	generic-y += user.h
16	17	generic-y += text-patching.h

arch/nios2/include/asm/Kbuild+1−0

@@ -5,6 +5,7 @@ generic-y += cmpxchg.h · 4 unmodified lines
5	5	generic-y += extable.h
6	6	generic-y += kvm_para.h
7	7	generic-y += mcs_spinlock.h
	8	+generic-y += ring_buffer.h
8	9	generic-y += spinlock.h
9	10	generic-y += user.h
10	11	generic-y += text-patching.h

arch/openrisc/include/asm/Kbuild+1−0

@@ -8,4 +8,5 @@ generic-y += spinlock_types.h · 7 unmodified lines
8	8	generic-y += spinlock.h
9	9	generic-y += qrwlock_types.h
10	10	generic-y += qrwlock.h
	11	+generic-y += ring_buffer.h
11	12	generic-y += user.h

arch/parisc/include/asm/Kbuild+1−0

@@ -4,4 +4,5 @@ generated-y += syscall_table_64.h · 3 unmodified lines
4	4	generic-y += agp.h
5	5	generic-y += kvm_para.h
6	6	generic-y += mcs_spinlock.h
	7	+generic-y += ring_buffer.h
7	8	generic-y += user.h

arch/powerpc/include/asm/Kbuild+1−0

@@ -5,4 +5,5 @@ generated-y += syscall_table_spu.h · 4 unmodified lines
5	5	generic-y += agp.h
6	6	generic-y += mcs_spinlock.h
7	7	generic-y += qrwlock.h
	8	+generic-y += ring_buffer.h
8	9	generic-y += early_ioremap.h

arch/riscv/include/asm/Kbuild+1−0

@@ -14,5 +14,6 @@ generic-y += ticket_spinlock.h · 13 unmodified lines
14	14	generic-y += qrwlock.h
15	15	generic-y += qrwlock_types.h
16	16	generic-y += qspinlock.h
	17	+generic-y += ring_buffer.h
17	18	generic-y += user.h
18	19	generic-y += vmlinux.lds.h

arch/s390/include/asm/Kbuild+1−0

@@ -7,3 +7,4 @@ generated-y += unistd_nr.h · 6 unmodified lines
7	7	generic-y += asm-offsets.h
8	8	generic-y += mcs_spinlock.h
9	9	generic-y += mmzone.h
	10	+generic-y += ring_buffer.h

arch/sh/include/asm/Kbuild+1−0

@@ -3,4 +3,5 @@ generated-y += syscall_table.h · 2 unmodified lines
3	3	generic-y += kvm_para.h
4	4	generic-y += mcs_spinlock.h
5	5	generic-y += parport.h
	6	+generic-y += ring_buffer.h
6	7	generic-y += text-patching.h

arch/sparc/include/asm/Kbuild+1−0

@@ -4,4 +4,5 @@ generated-y += syscall_table_64.h · 3 unmodified lines
4	4	generic-y += agp.h
5	5	generic-y += kvm_para.h
6	6	generic-y += mcs_spinlock.h
	7	+generic-y += ring_buffer.h
7	8	generic-y += text-patching.h

arch/um/include/asm/Kbuild+1−0

@@ -17,6 +17,7 @@ generic-y += module.lds.h · 16 unmodified lines
17	17	generic-y += parport.h
18	18	generic-y += percpu.h
19	19	generic-y += preempt.h
	20	+generic-y += ring_buffer.h
20	21	generic-y += runtime-const.h
21	22	generic-y += softirq_stack.h
22	23	generic-y += switch_to.h

arch/x86/include/asm/Kbuild+1−0

@@ -14,3 +14,4 @@ generic-y += early_ioremap.h · 13 unmodified lines
14	14	generic-y += fprobe.h
15	15	generic-y += mcs_spinlock.h
16	16	generic-y += mmzone.h
	17	+generic-y += ring_buffer.h

arch/xtensa/include/asm/Kbuild+1−0

@@ -6,5 +6,6 @@ generic-y += mcs_spinlock.h · 5 unmodified lines
6	6	generic-y += parport.h
7	7	generic-y += qrwlock.h
8	8	generic-y += qspinlock.h
	9	+generic-y += ring_buffer.h
9	10	generic-y += user.h
10	11	generic-y += text-patching.h

include/asm-generic/ring_buffer.h+13−0

@@ -0,0 +1,13 @@
	1	+/* SPDX-License-Identifier: GPL-2.0-only */
	2	+/*
	3	+ * Generic arch dependent ring_buffer macros.
	4	+ */
	5	+#ifndef __ASM_GENERIC_RING_BUFFER_H__
	6	+#define __ASM_GENERIC_RING_BUFFER_H__
	7	+
	8	+#include <linux/cacheflush.h>
	9	+
	10	+/* Flush cache on ring buffer range if needed. Do nothing by default. */
	11	+#define arch_ring_buffer_flush_range(start, end) do { } while (0)
	12	+
	13	+#endif /* __ASM_GENERIC_RING_BUFFER_H__ */

kernel/trace/ring_buffer.c+22−0

@@ -7,6 +7,7 @@ · 6 unmodified lines
7	7	#include <linux/ring_buffer_types.h>
8	8	#include <linux/sched/isolation.h>
9	9	#include <linux/trace_recursion.h>
	10	+#include <linux/panic_notifier.h>
10	11	#include <linux/trace_events.h>
11	12	#include <linux/ring_buffer.h>
12	13	#include <linux/trace_clock.h>
@@ -31,6 +32,7 @@ · 18 unmodified lines
31	32	#include <linux/oom.h>
32	33	#include <linux/mm.h>
33	34
	35	+#include <asm/ring_buffer.h>
34	36	#include <asm/local64.h>
35	37	#include <asm/local.h>
36	38	#include <asm/setup.h>
@@ -559,6 +561,7 @@ struct trace_buffer { · 522 unmodified lines
559	561
560	562	unsigned long range_addr_start;
561	563	unsigned long range_addr_end;
	564	+ struct notifier_block flush_nb;
562	565
563	566	struct ring_buffer_meta *meta;
564	567
@@ -2521,6 +2524,16 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) · 1956 unmodified lines
2521	2524	kfree(cpu_buffer);
2522	2525	}
2523	2526
	2527	+/* Stop recording on a persistent buffer and flush cache if needed. */
	2528	+static int rb_flush_buffer_cb(struct notifier_block nb, unsigned long event, void data)
	2529	+{
	2530	+ struct trace_buffer *buffer = container_of(nb, struct trace_buffer, flush_nb);
	2531	+
	2532	+ ring_buffer_record_off(buffer);
	2533	+ arch_ring_buffer_flush_range(buffer->range_addr_start, buffer->range_addr_end);
	2534	+ return NOTIFY_DONE;
	2535	+}
	2536	+
2524	2537	static struct trace_buffer *alloc_buffer(unsigned long size, unsigned flags,
2525	2538	int order, unsigned long start,
2526	2539	unsigned long end,
@@ -2651,6 +2664,12 @@ static struct trace_buffer *alloc_buffer(unsigned long size, unsigned flags, · 124 unmodified lines
2651	2664
2652	2665	mutex_init(&buffer->mutex);
2653	2666
	2667	+ /* Persistent ring buffer needs to flush cache before reboot. */
	2668	+ if (start && end) {
	2669	+ buffer->flush_nb.notifier_call = rb_flush_buffer_cb;
	2670	+ atomic_notifier_chain_register(&panic_notifier_list, &buffer->flush_nb);
	2671	+ }
	2672	+
2654	2673	return_ptr(buffer);
2655	2674
2656	2675	fail_free_buffers:
@@ -2749,6 +2768,9 @@ ring_buffer_free(struct trace_buffer *buffer) · 92 unmodified lines
2749	2768	{
2750	2769	int cpu;
2751	2770
	2771	+ if (buffer->range_addr_start && buffer->range_addr_end)
	2772	+ atomic_notifier_chain_unregister(&panic_notifier_list, &buffer->flush_nb);
	2773	+
2752	2774	cpuhp_state_remove_instance(CPUHP_TRACE_RB_PREPARE, &buffer->node);
2753	2775
2754	2776	irq_work_sync(&buffer->irq_work.work);