From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3D2641DF73A; Thu, 21 May 2026 13:47:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779371225; cv=none; b=j40WQ4vj/pewDGgFfmeM0zkvHkHD3djwYfrPinQbi7OFoL+wnwvKYd0u0dyLjYcEx5Y3tEneDospQVfj1feNMQJ1LRb4AbBsr7Fw1RrGfqybqIJRLpZwrQkP7uyM28QG1Qyrbom3HwteL/Xe/XBoKqFIIxoGVToHGkKqt3CMIEY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779371225; c=relaxed/simple; bh=F3iikO8Uz4EAcJ0IAlwvXdvSQl038zdaQaUE1ubP9Cg=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=tlAEj+ttgvoz9Y8fC3nsrEisxP1adO3U5Atz5VTwQAmWh3ZkxpN2OL0mbPoPg3y3EnfYdfw8TcS2NTIoiouXvSYOZQYD7naCEDr3R8VYivpW9mBpXUjPp7gm5KNSfaly0ZoocHoVQ1FDsyPyLMUNqSj+gZpMFlaoHIi6nTdiSFg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ns0D8nbR; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Ns0D8nbR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ECAB11F00A3C; Thu, 21 May 2026 13:47:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779371224; bh=nF7qMQGaaHbZQ+n3UDyZ5sDFLWW9T5KuUMLMWM67Bfw=; h=Date:From:To:Cc:Subject:References; b=Ns0D8nbRmiQhLgEyTwiF9KWItApa+lSh6E77szodT4VyJyY1YuxAF8LATpazvxPtn 2sCkDV6Kit5/XU6S+EOg2c1+XUj72a5ablaBn6zQtoDVJm2SrYbSeWkP/RQng2jF8u 8ZntpkxdjyjFrUl0nQuAavSaFCKISo7mV5DqpDknYd2zU8GToknii7cHA9wdTZzIbn ibFtGsl1HCcQ83lIHP6YANoZIgf3hynkphhsp/l+22xiQwYGadBOn+wiulghu4BUiU qGeJgAHTmTU+4ag0TVKSj1dB5wHpVlXATtEuRL7TTnRh1AErtttqrBz2Ej+qP4JPN+ CLk+J/8aOr6/w== Received: from rostedt by gandalf with local (Exim 4.99.2) (envelope-from ) id 1wQ3kD-00000005MQz-1DyS; Thu, 21 May 2026 09:47:25 -0400 Message-ID: <20260521134725.147297264@kernel.org> User-Agent: quilt/0.69 Date: Thu, 21 May 2026 09:47:12 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , stable@vger.kernel.org, Will Deacon , Ian Rogers , Catalin Marinas , Geert Uytterhoeven Subject: [for-linus][PATCH 2/5] ring-buffer: Flush and stop persistent ring buffer on panic References: <20260521134710.628917428@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 From: "Masami Hiramatsu (Google)" 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 --- 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 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 + +/* 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 + +/* 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 fcd93d49851e..7b07d2004cc6 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -7,6 +7,7 @@ #include #include #include +#include #include #include #include @@ -31,6 +32,7 @@ #include #include +#include #include #include #include @@ -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); -- 2.53.0