From dc518afa8eb71ffb7bcf8aef0ce2d9338df87d07 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Fri, 29 May 2026 21:02:19 -0400 Subject: [PATCH] ring-buffer: Flush and stop persistent ring buffer on panic [ Upstream commit a494d3c8d5392bcdff83c2a593df0c160ff9f322 ] 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. Fixes: e645535a954a ("tracing: Add option to use memmapped memory for trace boot instance") Cc: stable@vger.kernel.org Cc: Will Deacon Cc: Mathieu Desnoyers Cc: Ian Rogers Link: https://patch.msgid.link/177751969602.2136606.12031934362587643488.stgit@mhiramat.tok.corp.google.com Signed-off-by: Masami Hiramatsu (Google) Acked-by: Catalin Marinas Acked-by: Geert Uytterhoeven Signed-off-by: Steven Rostedt Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/alpha/include/asm/Kbuild | 1 + arch/arc/include/asm/Kbuild | 1 + arch/arm/include/asm/Kbuild | 1 + arch/arm64/include/asm/ring_buffer.h | 10 ++++++++++ arch/csky/include/asm/Kbuild | 1 + arch/hexagon/include/asm/Kbuild | 1 + arch/loongarch/include/asm/Kbuild | 1 + arch/m68k/include/asm/Kbuild | 1 + arch/microblaze/include/asm/Kbuild | 1 + arch/mips/include/asm/Kbuild | 1 + arch/nios2/include/asm/Kbuild | 1 + arch/openrisc/include/asm/Kbuild | 1 + arch/parisc/include/asm/Kbuild | 1 + arch/powerpc/include/asm/Kbuild | 1 + arch/riscv/include/asm/Kbuild | 1 + arch/s390/include/asm/Kbuild | 1 + arch/sh/include/asm/Kbuild | 1 + arch/sparc/include/asm/Kbuild | 1 + arch/um/include/asm/Kbuild | 1 + arch/x86/include/asm/Kbuild | 1 + arch/xtensa/include/asm/Kbuild | 1 + include/asm-generic/ring_buffer.h | 13 +++++++++++++ kernel/trace/ring_buffer.c | 22 ++++++++++++++++++++++ 23 files changed, 65 insertions(+) create mode 100644 arch/arm64/include/asm/ring_buffer.h create mode 100644 include/asm-generic/ring_buffer.h diff --git a/arch/alpha/include/asm/Kbuild b/arch/alpha/include/asm/Kbuild index 396caece6d6d..80a12a603553 100644 --- a/arch/alpha/include/asm/Kbuild +++ b/arch/alpha/include/asm/Kbuild @@ -5,3 +5,4 @@ generic-y += agp.h generic-y += asm-offsets.h generic-y += kvm_para.h generic-y += mcs_spinlock.h +generic-y += ring_buffer.h diff --git a/arch/arc/include/asm/Kbuild b/arch/arc/include/asm/Kbuild index 49285a3ce239..ccc466802b5c 100644 --- a/arch/arc/include/asm/Kbuild +++ b/arch/arc/include/asm/Kbuild @@ -5,4 +5,5 @@ 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 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 + +/* 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 9a9bc65b57a9..c98d8be2330a 100644 --- a/arch/csky/include/asm/Kbuild +++ b/arch/csky/include/asm/Kbuild @@ -9,5 +9,6 @@ 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 diff --git a/arch/hexagon/include/asm/Kbuild b/arch/hexagon/include/asm/Kbuild index 8c1a78c8f527..10a1426d95e8 100644 --- a/arch/hexagon/include/asm/Kbuild +++ b/arch/hexagon/include/asm/Kbuild @@ -5,3 +5,4 @@ generic-y += extable.h generic-y += iomap.h generic-y += kvm_para.h generic-y += mcs_spinlock.h +generic-y += ring_buffer.h diff --git a/arch/loongarch/include/asm/Kbuild b/arch/loongarch/include/asm/Kbuild index 5b5a6c90e6e2..7850eedda3b3 100644 --- a/arch/loongarch/include/asm/Kbuild +++ b/arch/loongarch/include/asm/Kbuild @@ -9,5 +9,6 @@ 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 += param.h diff --git a/arch/m68k/include/asm/Kbuild b/arch/m68k/include/asm/Kbuild index 0dbf9c5c6fae..8ea462cd10e7 100644 --- a/arch/m68k/include/asm/Kbuild +++ b/arch/m68k/include/asm/Kbuild @@ -3,4 +3,5 @@ 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 diff --git a/arch/microblaze/include/asm/Kbuild b/arch/microblaze/include/asm/Kbuild index a055f5dbe00a..0ed312ae61ef 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 7ba67a0d6c97..a6bb06820e7c 100644 --- a/arch/mips/include/asm/Kbuild +++ b/arch/mips/include/asm/Kbuild @@ -12,4 +12,5 @@ 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 diff --git a/arch/nios2/include/asm/Kbuild b/arch/nios2/include/asm/Kbuild index 0d09829ed144..378ddebc1db3 100644 --- a/arch/nios2/include/asm/Kbuild +++ b/arch/nios2/include/asm/Kbuild @@ -5,5 +5,6 @@ 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 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 e5fdc336c9b2..12537f780e2c 100644 --- a/arch/powerpc/include/asm/Kbuild +++ b/arch/powerpc/include/asm/Kbuild @@ -6,4 +6,5 @@ generic-y += agp.h generic-y += kvm_types.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 1461af12da6e..ad6978567e5f 100644 --- a/arch/riscv/include/asm/Kbuild +++ b/arch/riscv/include/asm/Kbuild @@ -11,5 +11,6 @@ generic-y += spinlock.h generic-y += spinlock_types.h generic-y += qrwlock.h generic-y += qrwlock_types.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 297bf7157968..2b367fa4de8e 100644 --- a/arch/s390/include/asm/Kbuild +++ b/arch/s390/include/asm/Kbuild @@ -8,3 +8,4 @@ generic-y += asm-offsets.h generic-y += kvm_types.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 fc44d9c88b41..edbf46a7ea4c 100644 --- a/arch/sh/include/asm/Kbuild +++ b/arch/sh/include/asm/Kbuild @@ -3,3 +3,4 @@ generated-y += syscall_table.h generic-y += kvm_para.h generic-y += mcs_spinlock.h generic-y += parport.h +generic-y += ring_buffer.h diff --git a/arch/sparc/include/asm/Kbuild b/arch/sparc/include/asm/Kbuild index 43b0ae4c2c21..9aa7a7e1242d 100644 --- a/arch/sparc/include/asm/Kbuild +++ b/arch/sparc/include/asm/Kbuild @@ -4,3 +4,4 @@ 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 diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild index 18f902da8e99..abe7a9fe13c8 100644 --- a/arch/um/include/asm/Kbuild +++ b/arch/um/include/asm/Kbuild @@ -19,6 +19,7 @@ generic-y += param.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 6c23d1661b17..269b1ed3f12e 100644 --- a/arch/x86/include/asm/Kbuild +++ b/arch/x86/include/asm/Kbuild @@ -12,3 +12,4 @@ generated-y += xen-hypercalls.h generic-y += early_ioremap.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 fa07c686cbcc..a5875956392a 100644 --- a/arch/xtensa/include/asm/Kbuild +++ b/arch/xtensa/include/asm/Kbuild @@ -7,4 +7,5 @@ generic-y += param.h generic-y += parport.h generic-y += qrwlock.h generic-y += qspinlock.h +generic-y += ring_buffer.h generic-y += user.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 + +/* 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/ring_buffer.c b/kernel/trace/ring_buffer.c index cf2044b4a2ea..4deeb613c556 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -5,6 +5,7 @@ * Copyright (C) 2008 Steven Rostedt */ #include +#include #include #include #include @@ -29,6 +30,7 @@ #include #include +#include #include #include @@ -549,6 +551,7 @@ struct trace_buffer { unsigned long range_addr_start; unsigned long range_addr_end; + struct notifier_block flush_nb; long last_text_delta; long last_data_delta; @@ -2316,6 +2319,16 @@ 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, @@ -2421,6 +2434,12 @@ 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 buffer; fail_free_buffers: @@ -2512,6 +2531,9 @@ 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);