| From 4a797aa231b09ecf8d6c84fcb2630d305643c63d Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Wed, 9 Feb 2022 09:54:17 -0500 |
| Subject: perf/core: Fix perf_mmap fail when CONFIG_PERF_USE_VMALLOC enabled |
| |
| From: Zhipeng Xie <xiezhipeng1@huawei.com> |
| |
| [ Upstream commit 60490e7966659b26d74bf1fa4aa8693d9a94ca88 ] |
| |
| This problem can be reproduced with CONFIG_PERF_USE_VMALLOC enabled on |
| both x86_64 and aarch64 arch when using sysdig -B(using ebpf)[1]. |
| sysdig -B works fine after rebuilding the kernel with |
| CONFIG_PERF_USE_VMALLOC disabled. |
| |
| I tracked it down to the if condition event->rb->nr_pages != nr_pages |
| in perf_mmap is true when CONFIG_PERF_USE_VMALLOC is enabled where |
| event->rb->nr_pages = 1 and nr_pages = 2048 resulting perf_mmap to |
| return -EINVAL. This is because when CONFIG_PERF_USE_VMALLOC is |
| enabled, rb->nr_pages is always equal to 1. |
| |
| Arch with CONFIG_PERF_USE_VMALLOC enabled by default: |
| arc/arm/csky/mips/sh/sparc/xtensa |
| |
| Arch with CONFIG_PERF_USE_VMALLOC disabled by default: |
| x86_64/aarch64/... |
| |
| Fix this problem by using data_page_nr() |
| |
| [1] https://github.com/draios/sysdig |
| |
| Fixes: 906010b2134e ("perf_event: Provide vmalloc() based mmap() backing") |
| Signed-off-by: Zhipeng Xie <xiezhipeng1@huawei.com> |
| Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> |
| Link: https://lkml.kernel.org/r/20220209145417.6495-1-xiezhipeng1@huawei.com |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| kernel/events/core.c | 2 +- |
| kernel/events/internal.h | 5 +++++ |
| kernel/events/ring_buffer.c | 5 ----- |
| 3 files changed, 6 insertions(+), 6 deletions(-) |
| |
| diff --git a/kernel/events/core.c b/kernel/events/core.c |
| index 79d8b27cf2fc..9aa6563587d8 100644 |
| --- a/kernel/events/core.c |
| +++ b/kernel/events/core.c |
| @@ -6221,7 +6221,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) |
| again: |
| mutex_lock(&event->mmap_mutex); |
| if (event->rb) { |
| - if (event->rb->nr_pages != nr_pages) { |
| + if (data_page_nr(event->rb) != nr_pages) { |
| ret = -EINVAL; |
| goto unlock; |
| } |
| diff --git a/kernel/events/internal.h b/kernel/events/internal.h |
| index 228801e20788..aa23ffdaf819 100644 |
| --- a/kernel/events/internal.h |
| +++ b/kernel/events/internal.h |
| @@ -116,6 +116,11 @@ static inline int page_order(struct perf_buffer *rb) |
| } |
| #endif |
| |
| +static inline int data_page_nr(struct perf_buffer *rb) |
| +{ |
| + return rb->nr_pages << page_order(rb); |
| +} |
| + |
| static inline unsigned long perf_data_size(struct perf_buffer *rb) |
| { |
| return rb->nr_pages << (PAGE_SHIFT + page_order(rb)); |
| diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c |
| index ef91ae75ca56..4032cd475000 100644 |
| --- a/kernel/events/ring_buffer.c |
| +++ b/kernel/events/ring_buffer.c |
| @@ -856,11 +856,6 @@ void rb_free(struct perf_buffer *rb) |
| } |
| |
| #else |
| -static int data_page_nr(struct perf_buffer *rb) |
| -{ |
| - return rb->nr_pages << page_order(rb); |
| -} |
| - |
| static struct page * |
| __perf_mmap_to_page(struct perf_buffer *rb, unsigned long pgoff) |
| { |
| -- |
| 2.35.1 |
| |