From 52875a04f4b26e7ef30a288ea096f7cfec0e93cd Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Tue, 22 Jan 2019 22:45:20 -0800 Subject: bpf: verifier: remove dead code Instead of overwriting dead code with jmp -1 instructions remove it completely for root. Adjust verifier state and line info appropriately. v2: - adjust func_info (Alexei); - make sure first instruction retains line info (Alexei). v4: (Yonghong) - remove unnecessary if (!insn to remove) checks; - always keep last line info if first live instruction lacks one. v5: (Martin Lau) - improve and clarify comments. Signed-off-by: Jakub Kicinski Acked-by: Yonghong Song Signed-off-by: Alexei Starovoitov --- include/linux/filter.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/filter.h b/include/linux/filter.h index ad106d845b22..be9af6b4a9e4 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -778,6 +778,7 @@ static inline bool bpf_dump_raw_ok(void) struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off, const struct bpf_insn *patch, u32 len); +int bpf_remove_insns(struct bpf_prog *prog, u32 off, u32 cnt); void bpf_clear_redirect_map(struct bpf_map *map); -- cgit v1.2.3-71-gd317 From 9e4c24e7ee7dfd3898269519103e823892b730d8 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Tue, 22 Jan 2019 22:45:23 -0800 Subject: bpf: verifier: record original instruction index The communication between the verifier and advanced JITs is based on instruction indexes. We have to keep them stable throughout the optimizations otherwise referring to a particular instruction gets messy quickly. Signed-off-by: Jakub Kicinski Reviewed-by: Quentin Monnet Signed-off-by: Alexei Starovoitov --- include/linux/bpf_verifier.h | 1 + kernel/bpf/verifier.c | 8 +++++--- 2 files changed, 6 insertions(+), 3 deletions(-) (limited to 'include/linux') diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 573cca00a0e6..f3ae00ee5516 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -187,6 +187,7 @@ struct bpf_insn_aux_data { int sanitize_stack_off; /* stack slot to be cleared */ bool seen; /* this insn was processed by the verifier */ u8 alu_state; /* used in combination with alu_limit */ + unsigned int orig_idx; /* original instruction index */ }; #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f39bca188a5c..f2c49b4235df 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7371,7 +7371,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, { struct bpf_verifier_env *env; struct bpf_verifier_log *log; - int ret = -EINVAL; + int i, len, ret = -EINVAL; bool is_priv; /* no program is valid */ @@ -7386,12 +7386,14 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, return -ENOMEM; log = &env->log; + len = (*prog)->len; env->insn_aux_data = - vzalloc(array_size(sizeof(struct bpf_insn_aux_data), - (*prog)->len)); + vzalloc(array_size(sizeof(struct bpf_insn_aux_data), len)); ret = -ENOMEM; if (!env->insn_aux_data) goto err_free_env; + for (i = 0; i < len; i++) + env->insn_aux_data[i].orig_idx = i; env->prog = *prog; env->ops = bpf_verifier_ops[env->prog->type]; -- cgit v1.2.3-71-gd317 From 08ca90afba255d05dc3253caa44056e7aecbe8c5 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Tue, 22 Jan 2019 22:45:24 -0800 Subject: bpf: notify offload JITs about optimizations Let offload JITs know when instructions are replaced and optimized out, so they can update their state appropriately. The optimizations are best effort, if JIT returns an error from any callback verifier will stop notifying it as state may now be out of sync, but the verifier continues making progress. Signed-off-by: Jakub Kicinski Reviewed-by: Quentin Monnet Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 7 +++++++ include/linux/bpf_verifier.h | 5 +++++ kernel/bpf/offload.c | 35 +++++++++++++++++++++++++++++++++++ kernel/bpf/verifier.c | 6 ++++++ 4 files changed, 53 insertions(+) (limited to 'include/linux') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index e734f163bd0b..3851529062ec 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -268,9 +268,15 @@ struct bpf_verifier_ops { }; struct bpf_prog_offload_ops { + /* verifier basic callbacks */ int (*insn_hook)(struct bpf_verifier_env *env, int insn_idx, int prev_insn_idx); int (*finalize)(struct bpf_verifier_env *env); + /* verifier optimization callbacks (called after .finalize) */ + int (*replace_insn)(struct bpf_verifier_env *env, u32 off, + struct bpf_insn *insn); + int (*remove_insns)(struct bpf_verifier_env *env, u32 off, u32 cnt); + /* program management callbacks */ int (*prepare)(struct bpf_prog *prog); int (*translate)(struct bpf_prog *prog); void (*destroy)(struct bpf_prog *prog); @@ -283,6 +289,7 @@ struct bpf_prog_offload { void *dev_priv; struct list_head offloads; bool dev_state; + bool opt_failed; void *jited_image; u32 jited_len; }; diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index f3ae00ee5516..0620e418dde5 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -266,5 +266,10 @@ int bpf_prog_offload_verifier_prep(struct bpf_prog *prog); int bpf_prog_offload_verify_insn(struct bpf_verifier_env *env, int insn_idx, int prev_insn_idx); int bpf_prog_offload_finalize(struct bpf_verifier_env *env); +void +bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off, + struct bpf_insn *insn); +void +bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt); #endif /* _LINUX_BPF_VERIFIER_H */ diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c index 54cf2b9c44a4..39dba8c90331 100644 --- a/kernel/bpf/offload.c +++ b/kernel/bpf/offload.c @@ -173,6 +173,41 @@ int bpf_prog_offload_finalize(struct bpf_verifier_env *env) return ret; } +void +bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off, + struct bpf_insn *insn) +{ + const struct bpf_prog_offload_ops *ops; + struct bpf_prog_offload *offload; + int ret = -EOPNOTSUPP; + + down_read(&bpf_devs_lock); + offload = env->prog->aux->offload; + if (offload) { + ops = offload->offdev->ops; + if (!offload->opt_failed && ops->replace_insn) + ret = ops->replace_insn(env, off, insn); + offload->opt_failed |= ret; + } + up_read(&bpf_devs_lock); +} + +void +bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt) +{ + struct bpf_prog_offload *offload; + int ret = -EOPNOTSUPP; + + down_read(&bpf_devs_lock); + offload = env->prog->aux->offload; + if (offload) { + if (!offload->opt_failed && offload->offdev->ops->remove_insns) + ret = offload->offdev->ops->remove_insns(env, off, cnt); + offload->opt_failed |= ret; + } + up_read(&bpf_devs_lock); +} + static void __bpf_prog_offload_destroy(struct bpf_prog *prog) { struct bpf_prog_offload *offload = prog->aux->offload; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f2c49b4235df..8cfe39ef770f 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6558,6 +6558,9 @@ static int verifier_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt) unsigned int orig_prog_len = env->prog->len; int err; + if (bpf_prog_is_dev_bound(env->prog->aux)) + bpf_prog_offload_remove_insns(env, off, cnt); + err = bpf_remove_insns(env->prog, off, cnt); if (err) return err; @@ -6632,6 +6635,9 @@ static void opt_hard_wire_dead_code_branches(struct bpf_verifier_env *env) else continue; + if (bpf_prog_is_dev_bound(env->prog->aux)) + bpf_prog_offload_replace_insn(env, i, &ja); + memcpy(insn, &ja, sizeof(ja)); } } -- cgit v1.2.3-71-gd317