user/sven/linux.git/kernel/bpf/ringbuf.c, branch v6.6.25

bpf: Remove unnecessary ring buffer size check

2023-07-05T12:09:45Z

The theoretical maximum size of ring buffer is about 64GB, but now the size of ring buffer is specified by max_entries in bpf_attr and its maximum value is (4GB - 1), and it won't be possible for overflow. So just remove the unnecessary size check in ringbuf_map_alloc() but keep the comments for possible extension in future. Reported-by: Dan Carpenter Signed-off-by: Hou Tao Signed-off-by: Daniel Borkmann Closes: https://lore.kernel.org/bpf/9c636a63-1f3d-442d-9223-96c2dccb9469@moroto.mountain Link: https://lore.kernel.org/bpf/20230704074014.216616-1-houtao@huaweicloud.com

bpf: return long from bpf_map_ops funcs

2023-03-22T22:11:30Z

This patch changes the return types of bpf_map_ops functions to long, where previously int was returned. Using long allows for bpf programs to maintain the sign bit in the absence of sign extension during situations where inlined bpf helper funcs make calls to the bpf_map_ops funcs and a negative error is returned. The definitions of the helper funcs are generated from comments in the bpf uapi header at `include/uapi/linux/bpf.h`. The return type of these helpers was previously changed from int to long in commit bdb7b79b4ce8. For any case where one of the map helpers call the bpf_map_ops funcs that are still returning 32-bit int, a compiler might not include sign extension instructions to properly convert the 32-bit negative value a 64-bit negative value. For example: bpf assembly excerpt of an inlined helper calling a kernel function and checking for a specific error: ; err = bpf_map_update_elem(&mymap, &key, &val, BPF_NOEXIST); ... 46: call 0xffffffffe103291c ; htab_map_update_elem ; if (err && err != -EEXIST) { 4b: cmp $0xffffffffffffffef,%rax ; cmp -EEXIST,%rax kernel function assembly excerpt of return value from `htab_map_update_elem` returning 32-bit int: movl $0xffffffef, %r9d ... movl %r9d, %eax ...results in the comparison: cmp $0xffffffffffffffef, $0x00000000ffffffef Fixes: bdb7b79b4ce8 ("bpf: Switch most helper return values from 32-bit int to 64-bit long") Tested-by: Eduard Zingerman Signed-off-by: JP Kobryn Link: https://lore.kernel.org/r/20230322194754.185781-3-inwardvessel@gmail.com Signed-off-by: Alexei Starovoitov

bpf: ringbuf memory usage

2023-03-07T17:33:42Z

A new helper ringbuf_map_mem_usage() is introduced to calculate ringbuf memory usage. The result as follows, - before 15: ringbuf name count_map flags 0x0 key 0B value 0B max_entries 65536 memlock 0B - after 15: ringbuf name count_map flags 0x0 key 0B value 0B max_entries 65536 memlock 78424B Signed-off-by: Yafang Shao Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20230305124615.12358-8-laoar.shao@gmail.com Signed-off-by: Alexei Starovoitov

mm: replace vma->vm_flags direct modifications with modifier calls

2023-02-10T00:51:39Z

Replace direct modifications to vma->vm_flags with calls to modifier functions to be able to track flag changes and to keep vma locking correctness. [akpm@linux-foundation.org: fix drivers/misc/open-dice.c, per Hyeonggon Yoo] Link: https://lkml.kernel.org/r/20230126193752.297968-5-surenb@google.com Signed-off-by: Suren Baghdasaryan Acked-by: Michal Hocko Acked-by: Mel Gorman Acked-by: Mike Rapoport (IBM) Acked-by: Sebastian Reichel Reviewed-by: Liam R. Howlett Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Andy Lutomirski Cc: Arjun Roy Cc: Axel Rasmussen Cc: David Hildenbrand Cc: David Howells Cc: Davidlohr Bueso Cc: David Rientjes Cc: Eric Dumazet Cc: Greg Thelen Cc: Hugh Dickins Cc: Ingo Molnar Cc: Jann Horn Cc: Joel Fernandes Cc: Johannes Weiner Cc: Kent Overstreet Cc: Laurent Dufour Cc: Lorenzo Stoakes Cc: Matthew Wilcox Cc: Minchan Kim Cc: Paul E. McKenney Cc: Peter Oskolkov Cc: Peter Xu Cc: Peter Zijlstra Cc: Punit Agrawal Cc: Sebastian Andrzej Siewior Cc: Shakeel Butt Cc: Soheil Hassas Yeganeh Cc: Song Liu Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton

bpf: Rename MEM_ALLOC to MEM_RINGBUF

2022-11-15T05:52:45Z

Currently, verifier uses MEM_ALLOC type tag to specially tag memory returned from bpf_ringbuf_reserve helper. However, this is currently only used for this purpose and there is an implicit assumption that it only refers to ringbuf memory (e.g. the check for ARG_PTR_TO_ALLOC_MEM in check_func_arg_reg_off). Hence, rename MEM_ALLOC to MEM_RINGBUF to indicate this special relationship and instead open the use of MEM_ALLOC for more generic allocations made for user types. Also, since ARG_PTR_TO_ALLOC_MEM_OR_NULL is unused, simply drop it. Finally, update selftests using 'alloc_' verifier string to 'ringbuf_'. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20221114191547.1694267-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov

bpf: Add bpf_user_ringbuf_drain() helper

2022-09-21T23:24:58Z

In a prior change, we added a new BPF_MAP_TYPE_USER_RINGBUF map type which will allow user-space applications to publish messages to a ring buffer that is consumed by a BPF program in kernel-space. In order for this map-type to be useful, it will require a BPF helper function that BPF programs can invoke to drain samples from the ring buffer, and invoke callbacks on those samples. This change adds that capability via a new BPF helper function: bpf_user_ringbuf_drain(struct bpf_map *map, void *callback_fn, void *ctx, u64 flags) BPF programs may invoke this function to run callback_fn() on a series of samples in the ring buffer. callback_fn() has the following signature: long callback_fn(struct bpf_dynptr *dynptr, void *context); Samples are provided to the callback in the form of struct bpf_dynptr *'s, which the program can read using BPF helper functions for querying struct bpf_dynptr's. In order to support bpf_ringbuf_drain(), a new PTR_TO_DYNPTR register type is added to the verifier to reflect a dynptr that was allocated by a helper function and passed to a BPF program. Unlike PTR_TO_STACK dynptrs which are allocated on the stack by a BPF program, PTR_TO_DYNPTR dynptrs need not use reference tracking, as the BPF helper is trusted to properly free the dynptr before returning. The verifier currently only supports PTR_TO_DYNPTR registers that are also DYNPTR_TYPE_LOCAL. Note that while the corresponding user-space libbpf logic will be added in a subsequent patch, this patch does contain an implementation of the .map_poll() callback for BPF_MAP_TYPE_USER_RINGBUF maps. This .map_poll() callback guarantees that an epoll-waiting user-space producer will receive at least one event notification whenever at least one sample is drained in an invocation of bpf_user_ringbuf_drain(), provided that the function is not invoked with the BPF_RB_NO_WAKEUP flag. If the BPF_RB_FORCE_WAKEUP flag is provided, a wakeup notification is sent even if no sample was drained. Signed-off-by: David Vernet Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220920000100.477320-3-void@manifault.com

bpf: Define new BPF_MAP_TYPE_USER_RINGBUF map type

2022-09-21T23:24:17Z

We want to support a ringbuf map type where samples are published from user-space, to be consumed by BPF programs. BPF currently supports a kernel -> user-space circular ring buffer via the BPF_MAP_TYPE_RINGBUF map type. We'll need to define a new map type for user-space -> kernel, as none of the helpers exported for BPF_MAP_TYPE_RINGBUF will apply to a user-space producer ring buffer, and we'll want to add one or more helper functions that would not apply for a kernel-producer ring buffer. This patch therefore adds a new BPF_MAP_TYPE_USER_RINGBUF map type definition. The map type is useless in its current form, as there is no way to access or use it for anything until we one or more BPF helpers. A follow-on patch will therefore add a new helper function that allows BPF programs to run callbacks on samples that are published to the ring buffer. Signed-off-by: David Vernet Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220920000100.477320-2-void@manifault.com

bpf: Use bpf_map_area_alloc consistently on bpf map creation

2022-08-10T18:50:43Z

Let's use the generic helper bpf_map_area_alloc() instead of the open-coded kzalloc helpers in bpf maps creation path. Signed-off-by: Yafang Shao Link: https://lore.kernel.org/r/20220810151840.16394-5-laoar.shao@gmail.com Signed-off-by: Alexei Starovoitov

bpf: Make __GFP_NOWARN consistent in bpf map creation

2022-08-10T18:49:25Z

Some of the bpf maps are created with __GFP_NOWARN, i.e. arraymap, bloom_filter, bpf_local_storage, bpf_struct_ops, lpm_trie, queue_stack_maps, reuseport_array, stackmap and xskmap, while others are created without __GFP_NOWARN, i.e. cpumap, devmap, hashtab, local_storage, offload, ringbuf and sock_map. But there are not key differences between the creation of these maps. So let make this allocation flag consistent in all bpf maps creation. Then we can use a generic helper to alloc all bpf maps. Signed-off-by: Yafang Shao Link: https://lore.kernel.org/r/20220810151840.16394-4-laoar.shao@gmail.com Signed-off-by: Alexei Starovoitov

bpf: Use bpf_map_area_free instread of kvfree

2022-08-10T18:48:44Z

bpf_map_area_alloc() should be paired with bpf_map_area_free(). Signed-off-by: Yafang Shao Link: https://lore.kernel.org/r/20220810151840.16394-3-laoar.shao@gmail.com Signed-off-by: Alexei Starovoitov