From c454a46b5efd8eff8880e88ece2976e60a26bf35 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Fri, 7 Dec 2018 16:42:25 -0800 Subject: bpf: Add bpf_line_info support This patch adds bpf_line_info support. It accepts an array of bpf_line_info objects during BPF_PROG_LOAD. The "line_info", "line_info_cnt" and "line_info_rec_size" are added to the "union bpf_attr". The "line_info_rec_size" makes bpf_line_info extensible in the future. The new "check_btf_line()" ensures the userspace line_info is valid for the kernel to use. When the verifier is translating/patching the bpf_prog (through "bpf_patch_insn_single()"), the line_infos' insn_off is also adjusted by the newly added "bpf_adj_linfo()". If the bpf_prog is jited, this patch also provides the jited addrs (in aux->jited_linfo) for the corresponding line_info.insn_off. "bpf_prog_fill_jited_linfo()" is added to fill the aux->jited_linfo. It is currently called by the x86 jit. Other jits can also use "bpf_prog_fill_jited_linfo()" and it will be done in the followup patches. In the future, if it deemed necessary, a particular jit could also provide its own "bpf_prog_fill_jited_linfo()" implementation. A few "*line_info*" fields are added to the bpf_prog_info such that the user can get the xlated line_info back (i.e. the line_info with its insn_off reflecting the translated prog). The jited_line_info is available if the prog is jited. It is an array of __u64. If the prog is not jited, jited_line_info_cnt is 0. The verifier's verbose log with line_info will be done in a follow up patch. Signed-off-by: Martin KaFai Lau Acked-by: Yonghong Song Signed-off-by: Alexei Starovoitov --- kernel/bpf/core.c | 118 +++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 116 insertions(+), 2 deletions(-) (limited to 'kernel/bpf/core.c') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index a5b223ef7131..5cdd8da0e7f2 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -105,6 +105,91 @@ struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags) } EXPORT_SYMBOL_GPL(bpf_prog_alloc); +int bpf_prog_alloc_jited_linfo(struct bpf_prog *prog) +{ + if (!prog->aux->nr_linfo || !prog->jit_requested) + return 0; + + prog->aux->jited_linfo = kcalloc(prog->aux->nr_linfo, + sizeof(*prog->aux->jited_linfo), + GFP_KERNEL | __GFP_NOWARN); + if (!prog->aux->jited_linfo) + return -ENOMEM; + + return 0; +} + +void bpf_prog_free_jited_linfo(struct bpf_prog *prog) +{ + kfree(prog->aux->jited_linfo); + prog->aux->jited_linfo = NULL; +} + +void bpf_prog_free_unused_jited_linfo(struct bpf_prog *prog) +{ + if (prog->aux->jited_linfo && !prog->aux->jited_linfo[0]) + bpf_prog_free_jited_linfo(prog); +} + +/* The jit engine is responsible to provide an array + * for insn_off to the jited_off mapping (insn_to_jit_off). + * + * The idx to this array is the insn_off. Hence, the insn_off + * here is relative to the prog itself instead of the main prog. + * This array has one entry for each xlated bpf insn. + * + * jited_off is the byte off to the last byte of the jited insn. + * + * Hence, with + * insn_start: + * The first bpf insn off of the prog. The insn off + * here is relative to the main prog. + * e.g. if prog is a subprog, insn_start > 0 + * linfo_idx: + * The prog's idx to prog->aux->linfo and jited_linfo + * + * jited_linfo[linfo_idx] = prog->bpf_func + * + * For i > linfo_idx, + * + * jited_linfo[i] = prog->bpf_func + + * insn_to_jit_off[linfo[i].insn_off - insn_start - 1] + */ +void bpf_prog_fill_jited_linfo(struct bpf_prog *prog, + const u32 *insn_to_jit_off) +{ + u32 linfo_idx, insn_start, insn_end, nr_linfo, i; + const struct bpf_line_info *linfo; + void **jited_linfo; + + if (!prog->aux->jited_linfo) + /* Userspace did not provide linfo */ + return; + + linfo_idx = prog->aux->linfo_idx; + linfo = &prog->aux->linfo[linfo_idx]; + insn_start = linfo[0].insn_off; + insn_end = insn_start + prog->len; + + jited_linfo = &prog->aux->jited_linfo[linfo_idx]; + jited_linfo[0] = prog->bpf_func; + + nr_linfo = prog->aux->nr_linfo - linfo_idx; + + for (i = 1; i < nr_linfo && linfo[i].insn_off < insn_end; i++) + /* The verifier ensures that linfo[i].insn_off is + * strictly increasing + */ + jited_linfo[i] = prog->bpf_func + + insn_to_jit_off[linfo[i].insn_off - insn_start - 1]; +} + +void bpf_prog_free_linfo(struct bpf_prog *prog) +{ + bpf_prog_free_jited_linfo(prog); + kvfree(prog->aux->linfo); +} + struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size, gfp_t gfp_extra_flags) { @@ -294,6 +379,26 @@ static int bpf_adj_branches(struct bpf_prog *prog, u32 pos, u32 delta, return ret; } +static void bpf_adj_linfo(struct bpf_prog *prog, u32 off, u32 delta) +{ + struct bpf_line_info *linfo; + u32 i, nr_linfo; + + nr_linfo = prog->aux->nr_linfo; + if (!nr_linfo || !delta) + return; + + linfo = prog->aux->linfo; + + for (i = 0; i < nr_linfo; i++) + if (off < linfo[i].insn_off) + break; + + /* Push all off < linfo[i].insn_off by delta */ + for (; i < nr_linfo; i++) + linfo[i].insn_off += delta; +} + struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off, const struct bpf_insn *patch, u32 len) { @@ -349,6 +454,8 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off, */ BUG_ON(bpf_adj_branches(prog_adj, off, insn_delta, false)); + bpf_adj_linfo(prog_adj, off, insn_delta); + return prog_adj; } @@ -1591,13 +1698,20 @@ struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err) * be JITed, but falls back to the interpreter. */ if (!bpf_prog_is_dev_bound(fp->aux)) { + *err = bpf_prog_alloc_jited_linfo(fp); + if (*err) + return fp; + fp = bpf_int_jit_compile(fp); -#ifdef CONFIG_BPF_JIT_ALWAYS_ON if (!fp->jited) { + bpf_prog_free_jited_linfo(fp); +#ifdef CONFIG_BPF_JIT_ALWAYS_ON *err = -ENOTSUPP; return fp; - } #endif + } else { + bpf_prog_free_unused_jited_linfo(fp); + } } else { *err = bpf_prog_offload_compile(fp); if (*err) -- cgit v1.2.3