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authorMartin KaFai Lau <kafai@fb.com>2018-12-08 01:42:25 +0100
committerAlexei Starovoitov <ast@kernel.org>2018-12-09 22:54:38 +0100
commitc454a46b5efd8eff8880e88ece2976e60a26bf35 (patch)
treefa0791a8524e5a13b2798ba6fee34d517df3dfa4 /kernel/bpf/core.c
parentMerge branch 'support-alu32_arsh' (diff)
downloadlinux-c454a46b5efd8eff8880e88ece2976e60a26bf35.tar.xz
linux-c454a46b5efd8eff8880e88ece2976e60a26bf35.zip
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 <kafai@fb.com> Acked-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf/core.c')
-rw-r--r--kernel/bpf/core.c118
1 files changed, 116 insertions, 2 deletions
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)