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| author | Joanne Koong <joannelkoong@gmail.com> | 2022-03-17 21:55:52 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-03-20 18:55:05 -0700 |
| commit | b00fa38a9c1cba044a32a601b49a55a18ed719d1 (patch) | |
| tree | 871c74ded225f4bd7108f611a7a8e86f1642e16c /kernel/bpf/verifier.c | |
| parent | a8fee96202e279441d0e52d83eb100bd4a6d6272 (diff) | |
| download | linux-b00fa38a9c1cba044a32a601b49a55a18ed719d1.tar.bz2 | |
bpf: Enable non-atomic allocations in local storage
Currently, local storage memory can only be allocated atomically
(GFP_ATOMIC). This restriction is too strict for sleepable bpf
programs.
In this patch, the verifier detects whether the program is sleepable,
and passes the corresponding GFP_KERNEL or GFP_ATOMIC flag as a
5th argument to bpf_task/sk/inode_storage_get. This flag will propagate
down to the local storage functions that allocate memory.
Please note that bpf_task/sk/inode_storage_update_elem functions are
invoked by userspace applications through syscalls. Preemption is
disabled before bpf_task/sk/inode_storage_update_elem is called, which
means they will always have to allocate memory atomically.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20220318045553.3091807-2-joannekoong@fb.com
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 0287176bfe9a..6347dcdee1fd 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -13492,6 +13492,26 @@ static int do_misc_fixups(struct bpf_verifier_env *env) goto patch_call_imm; } + if (insn->imm == BPF_FUNC_task_storage_get || + insn->imm == BPF_FUNC_sk_storage_get || + insn->imm == BPF_FUNC_inode_storage_get) { + if (env->prog->aux->sleepable) + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__s32)GFP_KERNEL); + else + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__s32)GFP_ATOMIC); + insn_buf[1] = *insn; + cnt = 2; + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + goto patch_call_imm; + } + /* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup * and other inlining handlers are currently limited to 64 bit * only. |