Commit 6f04180c authored by Andrii Nakryiko's avatar Andrii Nakryiko
Browse files

Merge branch 'libbpf: Fixes for ring buffer' 

Hou Tao says:

====================

From: Hou Tao <houtao1@huawei.com>

Hi,

The patch set tries to fix the problems found when testing ringbuf by
using 4KB and 2GB size. Patch 1 fixes the probe of ring buffer map on
host with 64KB page (e.g., an ARM64 host). Patch 2 & 3 fix the overflow
of length when mmaping 2GB kernel ringbuf or user ringbuf on libbpf.
Patch 4 just reject the reservation with invalid size.

Please see individual patch for details. And comments are always
welcome.

Change Log:
v2:
 * patch 1: use page size instead of adjust_ringbuf_sz(4096) as main_entries (suggested by Stanislav)
 * patch 2 & 3: use "mmap_sz" instead of "ro_size/wr_size" as name of mmap length (From Andrii)
v1: https://lore.kernel.org/bpf/20221111092642.2333724-1-houtao@huaweicloud.com


====================

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
parents 47df8a2f 05c1558b

tools/lib/bpf/libbpf_probes.c

+1 −1
Original line number Diff line number Diff line
@@ -234,7 +234,7 @@ static int probe_map_create(enum bpf_map_type map_type) 
	case BPF_MAP_TYPE_USER_RINGBUF:

		key_size = 0;

		value_size = 0;

		max_entries = 4096;

		max_entries = sysconf(_SC_PAGE_SIZE);

		break;

	case BPF_MAP_TYPE_STRUCT_OPS:

		/* we'll get -ENOTSUPP for invalid BTF type ID for struct_ops */

tools/lib/bpf/ringbuf.c

+20 −6
Original line number Diff line number Diff line
@@ -77,6 +77,7 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd, 
	__u32 len = sizeof(info);

	struct epoll_event *e;

	struct ring *r;

	__u64 mmap_sz;

	void *tmp;

	int err;
@@ -115,8 +116,7 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd, 
	r->mask = info.max_entries - 1;



	/* Map writable consumer page */

	tmp = mmap(NULL, rb->page_size, PROT_READ | PROT_WRITE, MAP_SHARED,

		   map_fd, 0);

	tmp = mmap(NULL, rb->page_size, PROT_READ | PROT_WRITE, MAP_SHARED, map_fd, 0);

	if (tmp == MAP_FAILED) {

		err = -errno;

		pr_warn("ringbuf: failed to mmap consumer page for map fd=%d: %d\n",
@@ -129,8 +129,12 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd, 
	 * data size to allow simple reading of samples that wrap around the

	 * end of a ring buffer. See kernel implementation for details.

	 * */

	tmp = mmap(NULL, rb->page_size + 2 * info.max_entries, PROT_READ,

		   MAP_SHARED, map_fd, rb->page_size);

	mmap_sz = rb->page_size + 2 * (__u64)info.max_entries;

	if (mmap_sz != (__u64)(size_t)mmap_sz) {

		pr_warn("ringbuf: ring buffer size (%u) is too big\n", info.max_entries);

		return libbpf_err(-E2BIG);

	}

	tmp = mmap(NULL, (size_t)mmap_sz, PROT_READ, MAP_SHARED, map_fd, rb->page_size);

	if (tmp == MAP_FAILED) {

		err = -errno;

		ringbuf_unmap_ring(rb, r);
@@ -348,6 +352,7 @@ static int user_ringbuf_map(struct user_ring_buffer *rb, int map_fd) 
{

	struct bpf_map_info info;

	__u32 len = sizeof(info);

	__u64 mmap_sz;

	void *tmp;

	struct epoll_event *rb_epoll;

	int err;
@@ -384,8 +389,13 @@ static int user_ringbuf_map(struct user_ring_buffer *rb, int map_fd) 
	 * simple reading and writing of samples that wrap around the end of

	 * the buffer.  See the kernel implementation for details.

	 */

	tmp = mmap(NULL, rb->page_size + 2 * info.max_entries,

		   PROT_READ | PROT_WRITE, MAP_SHARED, map_fd, rb->page_size);

	mmap_sz = rb->page_size + 2 * (__u64)info.max_entries;

	if (mmap_sz != (__u64)(size_t)mmap_sz) {

		pr_warn("user ringbuf: ring buf size (%u) is too big\n", info.max_entries);

		return -E2BIG;

	}

	tmp = mmap(NULL, (size_t)mmap_sz, PROT_READ | PROT_WRITE, MAP_SHARED,

		   map_fd, rb->page_size);

	if (tmp == MAP_FAILED) {

		err = -errno;

		pr_warn("user ringbuf: failed to mmap data pages for map fd=%d: %d\n",
@@ -476,6 +486,10 @@ void *user_ring_buffer__reserve(struct user_ring_buffer *rb, __u32 size) 
	__u64 cons_pos, prod_pos;

	struct ringbuf_hdr *hdr;



	/* The top two bits are used as special flags */

	if (size & (BPF_RINGBUF_BUSY_BIT | BPF_RINGBUF_DISCARD_BIT))

		return errno = E2BIG, NULL;



	/* Synchronizes with smp_store_release() in __bpf_user_ringbuf_peek() in

	 * the kernel.

	 */