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diff --git a/Documentation/bpf/map_cgrp_storage.rst b/Documentation/bpf/map_cgrp_storage.rst new file mode 100644 index 000000000000..5d3f603efffa --- /dev/null +++ b/Documentation/bpf/map_cgrp_storage.rst @@ -0,0 +1,109 @@ +.. SPDX-License-Identifier: GPL-2.0-only +.. Copyright (C) 2022 Meta Platforms, Inc. and affiliates. + +========================= +BPF_MAP_TYPE_CGRP_STORAGE +========================= + +The ``BPF_MAP_TYPE_CGRP_STORAGE`` map type represents a local fix-sized +storage for cgroups. It is only available with ``CONFIG_CGROUPS``. +The programs are made available by the same Kconfig. The +data for a particular cgroup can be retrieved by looking up the map +with that cgroup. + +This document describes the usage and semantics of the +``BPF_MAP_TYPE_CGRP_STORAGE`` map type. + +Usage +===== + +The map key must be ``sizeof(int)`` representing a cgroup fd. +To access the storage in a program, use ``bpf_cgrp_storage_get``:: + + void *bpf_cgrp_storage_get(struct bpf_map *map, struct cgroup *cgroup, void *value, u64 flags) + +``flags`` could be 0 or ``BPF_LOCAL_STORAGE_GET_F_CREATE`` which indicates that +a new local storage will be created if one does not exist. + +The local storage can be removed with ``bpf_cgrp_storage_delete``:: + + long bpf_cgrp_storage_delete(struct bpf_map *map, struct cgroup *cgroup) + +The map is available to all program types. + +Examples +======== + +A BPF program example with BPF_MAP_TYPE_CGRP_STORAGE:: + + #include <vmlinux.h> + #include <bpf/bpf_helpers.h> + #include <bpf/bpf_tracing.h> + + struct { + __uint(type, BPF_MAP_TYPE_CGRP_STORAGE); + __uint(map_flags, BPF_F_NO_PREALLOC); + __type(key, int); + __type(value, long); + } cgrp_storage SEC(".maps"); + + SEC("tp_btf/sys_enter") + int BPF_PROG(on_enter, struct pt_regs *regs, long id) + { + struct task_struct *task = bpf_get_current_task_btf(); + long *ptr; + + ptr = bpf_cgrp_storage_get(&cgrp_storage, task->cgroups->dfl_cgrp, 0, + BPF_LOCAL_STORAGE_GET_F_CREATE); + if (ptr) + __sync_fetch_and_add(ptr, 1); + + return 0; + } + +Userspace accessing map declared above:: + + #include <linux/bpf.h> + #include <linux/libbpf.h> + + __u32 map_lookup(struct bpf_map *map, int cgrp_fd) + { + __u32 *value; + value = bpf_map_lookup_elem(bpf_map__fd(map), &cgrp_fd); + if (value) + return *value; + return 0; + } + +Difference Between BPF_MAP_TYPE_CGRP_STORAGE and BPF_MAP_TYPE_CGROUP_STORAGE +============================================================================ + +The old cgroup storage map ``BPF_MAP_TYPE_CGROUP_STORAGE`` has been marked as +deprecated (renamed to ``BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED``). The new +``BPF_MAP_TYPE_CGRP_STORAGE`` map should be used instead. The following +illusates the main difference between ``BPF_MAP_TYPE_CGRP_STORAGE`` and +``BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED``. + +(1). ``BPF_MAP_TYPE_CGRP_STORAGE`` can be used by all program types while + ``BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED`` is available only to cgroup program types + like BPF_CGROUP_INET_INGRESS or BPF_CGROUP_SOCK_OPS, etc. + +(2). ``BPF_MAP_TYPE_CGRP_STORAGE`` supports local storage for more than one + cgroup while ``BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED`` only supports one cgroup + which is attached by a BPF program. + +(3). ``BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED`` allocates local storage at attach time so + ``bpf_get_local_storage()`` always returns non-NULL local storage. + ``BPF_MAP_TYPE_CGRP_STORAGE`` allocates local storage at runtime so + it is possible that ``bpf_cgrp_storage_get()`` may return null local storage. + To avoid such null local storage issue, user space can do + ``bpf_map_update_elem()`` to pre-allocate local storage before a BPF program + is attached. + +(4). ``BPF_MAP_TYPE_CGRP_STORAGE`` supports deleting local storage by a BPF program + while ``BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED`` only deletes storage during + prog detach time. + +So overall, ``BPF_MAP_TYPE_CGRP_STORAGE`` supports all ``BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED`` +functionality and beyond. It is recommended to use ``BPF_MAP_TYPE_CGRP_STORAGE`` +instead of ``BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED``. diff --git a/Documentation/bpf/maps.rst b/Documentation/bpf/maps.rst index f41619e312ac..4906ff0f8382 100644 --- a/Documentation/bpf/maps.rst +++ b/Documentation/bpf/maps.rst @@ -1,52 +1,81 @@ -========= -eBPF maps +======== +BPF maps +======== + +BPF 'maps' provide generic storage of different types for sharing data between +kernel and user space. There are several storage types available, including +hash, array, bloom filter and radix-tree. Several of the map types exist to +support specific BPF helpers that perform actions based on the map contents. The +maps are accessed from BPF programs via BPF helpers which are documented in the +`man-pages`_ for `bpf-helpers(7)`_. + +BPF maps are accessed from user space via the ``bpf`` syscall, which provides +commands to create maps, lookup elements, update elements and delete +elements. More details of the BPF syscall are available in +:doc:`/userspace-api/ebpf/syscall` and in the `man-pages`_ for `bpf(2)`_. + +Map Types ========= -'maps' is a generic storage of different types for sharing data between kernel -and userspace. +.. toctree:: + :maxdepth: 1 + :glob: -The maps are accessed from user space via BPF syscall, which has commands: + map_* -- create a map with given type and attributes - ``map_fd = bpf(BPF_MAP_CREATE, union bpf_attr *attr, u32 size)`` - using attr->map_type, attr->key_size, attr->value_size, attr->max_entries - returns process-local file descriptor or negative error +Usage Notes +=========== -- lookup key in a given map - ``err = bpf(BPF_MAP_LOOKUP_ELEM, union bpf_attr *attr, u32 size)`` - using attr->map_fd, attr->key, attr->value - returns zero and stores found elem into value or negative error +.. c:function:: + int bpf(int command, union bpf_attr *attr, u32 size) -- create or update key/value pair in a given map - ``err = bpf(BPF_MAP_UPDATE_ELEM, union bpf_attr *attr, u32 size)`` - using attr->map_fd, attr->key, attr->value - returns zero or negative error +Use the ``bpf()`` system call to perform the operation specified by +``command``. The operation takes parameters provided in ``attr``. The ``size`` +argument is the size of the ``union bpf_attr`` in ``attr``. -- find and delete element by key in a given map - ``err = bpf(BPF_MAP_DELETE_ELEM, union bpf_attr *attr, u32 size)`` - using attr->map_fd, attr->key +**BPF_MAP_CREATE** -- to delete map: close(fd) - Exiting process will delete maps automatically +Create a map with the desired type and attributes in ``attr``: -userspace programs use this syscall to create/access maps that eBPF programs -are concurrently updating. +.. code-block:: c -maps can have different types: hash, array, bloom filter, radix-tree, etc. + int fd; + union bpf_attr attr = { + .map_type = BPF_MAP_TYPE_ARRAY; /* mandatory */ + .key_size = sizeof(__u32); /* mandatory */ + .value_size = sizeof(__u32); /* mandatory */ + .max_entries = 256; /* mandatory */ + .map_flags = BPF_F_MMAPABLE; + .map_name = "example_array"; + }; -The map is defined by: + fd = bpf(BPF_MAP_CREATE, &attr, sizeof(attr)); - - type - - max number of elements - - key size in bytes - - value size in bytes +Returns a process-local file descriptor on success, or negative error in case of +failure. The map can be deleted by calling ``close(fd)``. Maps held by open +file descriptors will be deleted automatically when a process exits. -Map Types -========= +.. note:: Valid characters for ``map_name`` are ``A-Z``, ``a-z``, ``0-9``, + ``'_'`` and ``'.'``. -.. toctree:: - :maxdepth: 1 - :glob: +**BPF_MAP_LOOKUP_ELEM** + +Lookup key in a given map using ``attr->map_fd``, ``attr->key``, +``attr->value``. Returns zero and stores found elem into ``attr->value`` on +success, or negative error on failure. + +**BPF_MAP_UPDATE_ELEM** + +Create or update key/value pair in a given map using ``attr->map_fd``, ``attr->key``, +``attr->value``. Returns zero on success or negative error on failure. + +**BPF_MAP_DELETE_ELEM** + +Find and delete element by key in a given map using ``attr->map_fd``, +``attr->key``. Returns zero on success or negative error on failure. - map_*
\ No newline at end of file +.. Links: +.. _man-pages: https://www.kernel.org/doc/man-pages/ +.. _bpf(2): https://man7.org/linux/man-pages/man2/bpf.2.html +.. _bpf-helpers(7): https://man7.org/linux/man-pages/man7/bpf-helpers.7.html diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 30f76178608b..62f805f427b7 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1649,13 +1649,8 @@ static void invoke_bpf_prog(struct jit_ctx *ctx, struct bpf_tramp_link *l, struct bpf_prog *p = l->link.prog; int cookie_off = offsetof(struct bpf_tramp_run_ctx, bpf_cookie); - if (p->aux->sleepable) { - enter_prog = (u64)__bpf_prog_enter_sleepable; - exit_prog = (u64)__bpf_prog_exit_sleepable; - } else { - enter_prog = (u64)__bpf_prog_enter; - exit_prog = (u64)__bpf_prog_exit; - } + enter_prog = (u64)bpf_trampoline_enter(p); + exit_prog = (u64)bpf_trampoline_exit(p); if (l->cookie == 0) { /* if cookie is zero, one instruction is enough to store it */ diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 51afd6d0c05f..cec5195602bc 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -904,6 +904,65 @@ static void emit_nops(u8 **pprog, int len) *pprog = prog; } +/* emit the 3-byte VEX prefix + * + * r: same as rex.r, extra bit for ModRM reg field + * x: same as rex.x, extra bit for SIB index field |