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Merge branch 'libbpf: Fixes for ring buffer'

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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: Andrii Nakryiko <andrii@kernel.org>
This commit is contained in:
Andrii Nakryiko 2022-11-17 15:46:06 -08:00
commit 6f04180ca6
2 changed files with 21 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
tools/lib/bpf/libbpf_probes.c
View File

@ -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 */

26
tools/lib/bpf/ringbuf.c
View File

@ -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.
*/