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| author |   Namhyung Kim <namhyung@kernel.org> | 2024-10-10 16:25:04 -0700 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2024-10-16 09:21:03 -0700 |
| commit | a992d7a3979120fbd7c13435d27b3da8d9ed095a (patch) | |
| tree | ac4a2fe921d176f96bc30919136ae1f00b7be387 | |
| parent | bpf: Add kmem_cache iterator (diff) | |
| download | wireguard-linux-a992d7a3979120fbd7c13435d27b3da8d9ed095a.tar.xz wireguard-linux-a992d7a3979120fbd7c13435d27b3da8d9ed095a.zip | |
mm/bpf: Add bpf_get_kmem_cache() kfunc
The bpf_get_kmem_cache() is to get a slab cache information from a
virtual address like virt_to_cache(). If the address is a pointer
to a slab object, it'd return a valid kmem_cache pointer, otherwise
NULL is returned.
It doesn't grab a reference count of the kmem_cache so the caller is
responsible to manage the access. The returned point is marked as
PTR_UNTRUSTED.
The intended use case for now is to symbolize locks in slab objects
from the lock contention tracepoints.
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev> (mm/*)
Acked-by: Vlastimil Babka <vbabka@suse.cz> #mm/slab
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20241010232505.1339892-3-namhyung@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
| -rw-r--r-- | kernel/bpf/helpers.c | 1 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 5 | ||||
| -rw-r--r-- | mm/slab_common.c | 19 |
3 files changed, 25 insertions, 0 deletions
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 4053f279ed4c..aaaefefdf692 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -3090,6 +3090,7 @@ BTF_ID_FLAGS(func, bpf_iter_bits_new, KF_ITER_NEW) BTF_ID_FLAGS(func, bpf_iter_bits_next, KF_ITER_NEXT | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_iter_bits_destroy, KF_ITER_DESTROY) BTF_ID_FLAGS(func, bpf_copy_from_user_str, KF_SLEEPABLE) +BTF_ID_FLAGS(func, bpf_get_kmem_cache) BTF_KFUNCS_END(common_btf_ids) static const struct btf_kfunc_id_set common_kfunc_set = { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index cfc62e0776bf..f514247ba8ba 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -11259,6 +11259,7 @@ enum special_kfunc_type { KF_bpf_preempt_enable, KF_bpf_iter_css_task_new, KF_bpf_session_cookie, + KF_bpf_get_kmem_cache, }; BTF_SET_START(special_kfunc_set) @@ -11324,6 +11325,7 @@ BTF_ID(func, bpf_session_cookie) #else BTF_ID_UNUSED #endif +BTF_ID(func, bpf_get_kmem_cache) static bool is_kfunc_ret_null(struct bpf_kfunc_call_arg_meta *meta) { @@ -12834,6 +12836,9 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, regs[BPF_REG_0].type = PTR_TO_BTF_ID; regs[BPF_REG_0].btf_id = ptr_type_id; + if (meta.func_id == special_kfunc_list[KF_bpf_get_kmem_cache]) + regs[BPF_REG_0].type |= PTR_UNTRUSTED; + if (is_iter_next_kfunc(&meta)) { struct bpf_reg_state *cur_iter; diff --git a/mm/slab_common.c b/mm/slab_common.c index 744324465615..f97a95289562 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1322,6 +1322,25 @@ size_t ksize(const void *objp) } EXPORT_SYMBOL(ksize); +#ifdef CONFIG_BPF_SYSCALL +#include <linux/btf.h> + +__bpf_kfunc_start_defs(); + +__bpf_kfunc struct kmem_cache *bpf_get_kmem_cache(u64 addr) +{ + struct slab *slab; + + if (!virt_addr_valid((void *)(long)addr)) + return NULL; + + slab = virt_to_slab((void *)(long)addr); + return slab ? slab->slab_cache : NULL; +} + +__bpf_kfunc_end_defs(); +#endif /* CONFIG_BPF_SYSCALL */ + /* Tracepoints definitions. */ EXPORT_TRACEPOINT_SYMBOL(kmalloc); EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); |