diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index c3a5e6cbb940..77dc0b25140e 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -6852,10 +6852,10 @@ static void rb_setup_ids_meta_page(struct ring_buffer_per_cpu *cpu_buffer, /* install subbuf ID to kern VA translation */ cpu_buffer->subbuf_ids = subbuf_ids; - meta->meta_page_size = PAGE_SIZE; meta->meta_struct_len = sizeof(*meta); meta->nr_subbufs = nr_subbufs; meta->subbuf_size = cpu_buffer->buffer->subbuf_size + BUF_PAGE_HDR_SIZE; + meta->meta_page_size = meta->subbuf_size; rb_update_meta_page(cpu_buffer); } @@ -6949,6 +6949,12 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, !(vma->vm_flags & VM_MAYSHARE)) return -EPERM; + subbuf_order = cpu_buffer->buffer->subbuf_order; + subbuf_pages = 1 << subbuf_order; + + if (subbuf_order && pgoff % subbuf_pages) + return -EINVAL; + /* * Make sure the mapping cannot become writable later. Also tell the VM * to not touch these pages (VM_DONTCOPY | VM_DONTEXPAND). @@ -6958,11 +6964,8 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, lockdep_assert_held(&cpu_buffer->mapping_lock); - subbuf_order = cpu_buffer->buffer->subbuf_order; - subbuf_pages = 1 << subbuf_order; - nr_subbufs = cpu_buffer->nr_pages + 1; /* + reader-subbuf */ - nr_pages = ((nr_subbufs) << subbuf_order) - pgoff + 1; /* + meta-page */ + nr_pages = ((nr_subbufs + 1) << subbuf_order) - pgoff; /* + meta-page */ nr_vma_pages = vma_pages(vma); if (!nr_vma_pages || nr_vma_pages > nr_pages) @@ -6975,20 +6978,24 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, return -ENOMEM; if (!pgoff) { + unsigned long meta_page_padding; + pages[p++] = virt_to_page(cpu_buffer->meta_page); /* - * TODO: Align sub-buffers on their size, once - * vm_insert_pages() supports the zero-page. + * Pad with the zero-page to align the meta-page with the + * sub-buffers. */ + meta_page_padding = subbuf_pages - 1; + while (meta_page_padding-- && p < nr_pages) { + unsigned long __maybe_unused zero_addr = + vma->vm_start + (PAGE_SIZE * p); + + pages[p++] = ZERO_PAGE(zero_addr); + } } else { /* Skip the meta-page */ - pgoff--; - - if (pgoff % subbuf_pages) { - err = -EINVAL; - goto out; - } + pgoff -= subbuf_pages; s += pgoff / subbuf_pages; } diff --git a/tools/testing/selftests/ring-buffer/map_test.c b/tools/testing/selftests/ring-buffer/map_test.c index a9006fa7097e..4bb0192e43f3 100644 --- a/tools/testing/selftests/ring-buffer/map_test.c +++ b/tools/testing/selftests/ring-buffer/map_test.c @@ -228,6 +228,20 @@ TEST_F(map, data_mmap) data = mmap(NULL, data_len, PROT_READ, MAP_SHARED, desc->cpu_fd, meta_len); ASSERT_EQ(data, MAP_FAILED); + + /* Verify meta-page padding */ + if (desc->meta->meta_page_size > getpagesize()) { + void *addr; + + data_len = desc->meta->meta_page_size; + data = mmap(NULL, data_len, + PROT_READ, MAP_SHARED, desc->cpu_fd, 0); + ASSERT_NE(data, MAP_FAILED); + + addr = (void *)((unsigned long)data + getpagesize()); + ASSERT_EQ(*((int *)addr), 0); + munmap(data, data_len); + } } FIXTURE(snapshot) {