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bpf: add queue and stack maps
Queue/stack maps implement a FIFO/LIFO data storage for ebpf programs. These maps support peek, pop and push operations that are exposed to eBPF programs through the new bpf_map[peek/pop/push] helpers. Those operations are exposed to userspace applications through the already existing syscalls in the following way: BPF_MAP_LOOKUP_ELEM -> peek BPF_MAP_LOOKUP_AND_DELETE_ELEM -> pop BPF_MAP_UPDATE_ELEM -> push Queue/stack maps are implemented using a buffer, tail and head indexes, hence BPF_F_NO_PREALLOC is not supported. As opposite to other maps, queue and stack do not use RCU for protecting maps values, the bpf_map[peek/pop] have a ARG_PTR_TO_UNINIT_MAP_VALUE argument that is a pointer to a memory zone where to save the value of a map. Basically the same as ARG_PTR_TO_UNINIT_MEM, but the size has not be passed as an extra argument. Our main motivation for implementing queue/stack maps was to keep track of a pool of elements, like network ports in a SNAT, however we forsee other use cases, like for exampling saving last N kernel events in a map and then analysing from userspace. Signed-off-by:Mauricio Vasquez B <mauricio.vasquez@polito.it> Acked-by:
Song Liu <songliubraving@fb.com> Signed-off-by:
Alexei Starovoitov <ast@kernel.org>
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- include/linux/bpf.h 6 additions, 0 deletionsinclude/linux/bpf.h
- include/linux/bpf_types.h 2 additions, 0 deletionsinclude/linux/bpf_types.h
- include/uapi/linux/bpf.h 28 additions, 1 deletioninclude/uapi/linux/bpf.h
- kernel/bpf/Makefile 1 addition, 1 deletionkernel/bpf/Makefile
- kernel/bpf/core.c 3 additions, 0 deletionskernel/bpf/core.c
- kernel/bpf/helpers.c 43 additions, 0 deletionskernel/bpf/helpers.c
- kernel/bpf/queue_stack_maps.c 288 additions, 0 deletionskernel/bpf/queue_stack_maps.c
- kernel/bpf/syscall.c 6 additions, 0 deletionskernel/bpf/syscall.c
- kernel/bpf/verifier.c 18 additions, 1 deletionkernel/bpf/verifier.c
- net/core/filter.c 6 additions, 0 deletionsnet/core/filter.c
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