bpf: btf: support proper non-jit func info

Commit 838e96904ff3 ("bpf: Introduce bpf_func_info")
added bpf func info support. The userspace is able
to get better ksym's for bpf programs with jit, and
is able to print out func prototypes.

For a program containing func-to-func calls, the existing
implementation returns user specified number of function
calls and BTF types if jit is enabled. If the jit is not
enabled, it only returns the type for the main function.

This is undesirable. Interpreter may still be used
and we should keep feature identical regardless of
whether jit is enabled or not.
This patch fixed this discrepancy.

Fixes: 838e96904ff3 ("bpf: Introduce bpf_func_info")
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 7f0e225bf630b6c36edecc0c366a869ca5e9cf99..e82b7039fc66d80c52118a0cde2be22e006e901a 100644 (file)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -299,7 +299,8 @@ struct bpf_prog_aux {
        u32 max_pkt_offset;
        u32 stack_depth;
        u32 id;
-       u32 func_cnt;
+       u32 func_cnt; /* used by non-func prog as the number of func progs */
+       u32 func_idx; /* 0 for non-func prog, the index in func array for func prog */
        bool offload_requested;
        struct bpf_prog **func;
        void *jit_data; /* JIT specific data. arch dependent */
@@ -317,7 +318,8 @@ struct bpf_prog_aux {
 #endif
        struct bpf_prog_offload *offload;
        struct btf *btf;
-       u32 type_id; /* type id for this prog/func */
+       struct bpf_func_info *func_info;
+       u32 func_info_cnt;
        union {
                struct work_struct work;
                struct rcu_head rcu;

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 204382f46fd888113fd9043b92bef84e5da48cf5..11f5df1092d9baddeb8dc902fcee4e2f528a9a07 100644 (file)
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -204,7 +204,6 @@ static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log)
 struct bpf_subprog_info {
        u32 start; /* insn idx of function entry point */
        u16 stack_depth; /* max. stack depth used by this function */
-       u32 type_id; /* btf type_id for this subprog */
 };
 
 /* single container for all structs

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 16d77012ad3efc9b996782636be6b006576b5300..002d67c62c8b75ab0e4d9e9899dcf8c448a266e9 100644 (file)
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -411,7 +411,8 @@ static void bpf_get_prog_name(const struct bpf_prog *prog, char *sym)
 
        /* prog->aux->name will be ignored if full btf name is available */
        if (prog->aux->btf) {
-               type = btf_type_by_id(prog->aux->btf, prog->aux->type_id);
+               type = btf_type_by_id(prog->aux->btf,
+                                     prog->aux->func_info[prog->aux->func_idx].type_id);
                func_name = btf_name_by_offset(prog->aux->btf, type->name_off);
                snprintf(sym, (size_t)(end - sym), "_%s", func_name);
                return;

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 9983778081021f21c918c823edeee8d7b25f62f3..85cbeec06e50d05ae1612882d4d4b7f9e4338a64 100644 (file)
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1214,6 +1214,7 @@ static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock)
                bpf_prog_free_id(prog, do_idr_lock);
                bpf_prog_kallsyms_del_all(prog);
                btf_put(prog->aux->btf);
+               kvfree(prog->aux->func_info);
 
                call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu);
        }
@@ -2219,46 +2220,28 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
        }
 
        if (prog->aux->btf) {
+               u32 krec_size = sizeof(struct bpf_func_info);
                u32 ucnt, urec_size;
 
                info.btf_id = btf_id(prog->aux->btf);
 
                ucnt = info.func_info_cnt;
-               info.func_info_cnt = prog->aux->func_cnt ? : 1;
+               info.func_info_cnt = prog->aux->func_info_cnt;
                urec_size = info.func_info_rec_size;
-               info.func_info_rec_size = sizeof(struct bpf_func_info);
+               info.func_info_rec_size = krec_size;
                if (ucnt) {
                        /* expect passed-in urec_size is what the kernel expects */
                        if (urec_size != info.func_info_rec_size)
                                return -EINVAL;
 
                        if (bpf_dump_raw_ok()) {
-                               struct bpf_func_info kern_finfo;
                                char __user *user_finfo;
-                               u32 i, insn_offset;
 
                                user_finfo = u64_to_user_ptr(info.func_info);
-                               if (prog->aux->func_cnt) {
-                                       ucnt = min_t(u32, info.func_info_cnt, ucnt);
-                                       insn_offset = 0;
-                                       for (i = 0; i < ucnt; i++) {
-                                               kern_finfo.insn_offset = insn_offset;
-                                               kern_finfo.type_id = prog->aux->func[i]->aux->type_id;
-                                               if (copy_to_user(user_finfo, &kern_finfo,
-                                                                sizeof(kern_finfo)))
-                                                       return -EFAULT;
-
-                                               /* func[i]->len holds the prog len */
-                                               insn_offset += prog->aux->func[i]->len;
-                                               user_finfo += urec_size;
-                                       }
-                               } else {
-                                       kern_finfo.insn_offset = 0;
-                                       kern_finfo.type_id = prog->aux->type_id;
-                                       if (copy_to_user(user_finfo, &kern_finfo,
-                                                        sizeof(kern_finfo)))
-                                               return -EFAULT;
-                               }
+                               ucnt = min_t(u32, info.func_info_cnt, ucnt);
+                               if (copy_to_user(user_finfo, prog->aux->func_info,
+                                                krec_size * ucnt))
+                                       return -EFAULT;
                        } else {
                                info.func_info_cnt = 0;
                        }

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index f102c4fd0c5afca78e55687bfd9409b76a813f85..05d95c0e4a262166b9c5b85db8f129b84ed43e25 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4650,7 +4650,7 @@ static int check_btf_func(struct bpf_prog *prog, struct bpf_verifier_env *env,
 {
        u32 i, nfuncs, urec_size, min_size, prev_offset;
        u32 krec_size = sizeof(struct bpf_func_info);
-       struct bpf_func_info krecord = {};
+       struct bpf_func_info *krecord = NULL;
        const struct btf_type *type;
        void __user *urecord;
        struct btf *btf;
@@ -4682,6 +4682,12 @@ static int check_btf_func(struct bpf_prog *prog, struct bpf_verifier_env *env,
        urecord = u64_to_user_ptr(attr->func_info);
        min_size = min_t(u32, krec_size, urec_size);
 
+       krecord = kvcalloc(nfuncs, krec_size, GFP_KERNEL | __GFP_NOWARN);
+       if (!krecord) {
+               ret = -ENOMEM;
+               goto free_btf;
+       }
+
        for (i = 0; i < nfuncs; i++) {
                ret = bpf_check_uarg_tail_zero(urecord, krec_size, urec_size);
                if (ret) {
@@ -4696,59 +4702,69 @@ static int check_btf_func(struct bpf_prog *prog, struct bpf_verifier_env *env,
                        goto free_btf;
                }
 
-               if (copy_from_user(&krecord, urecord, min_size)) {
+               if (copy_from_user(&krecord[i], urecord, min_size)) {
                        ret = -EFAULT;
                        goto free_btf;
                }
 
                /* check insn_offset */
                if (i == 0) {
-                       if (krecord.insn_offset) {
+                       if (krecord[i].insn_offset) {
                                verbose(env,
                                        "nonzero insn_offset %u for the first func info record",
-                                       krecord.insn_offset);
+                                       krecord[i].insn_offset);
                                ret = -EINVAL;
                                goto free_btf;
                        }
-               } else if (krecord.insn_offset <= prev_offset) {
+               } else if (krecord[i].insn_offset <= prev_offset) {
                        verbose(env,
                                "same or smaller insn offset (%u) than previous func info record (%u)",
-                               krecord.insn_offset, prev_offset);
+                               krecord[i].insn_offset, prev_offset);
                        ret = -EINVAL;
                        goto free_btf;
                }
 
-               if (env->subprog_info[i].start != krecord.insn_offset) {
+               if (env->subprog_info[i].start != krecord[i].insn_offset) {
                        verbose(env, "func_info BTF section doesn't match subprog layout in BPF program\n");
                        ret = -EINVAL;
                        goto free_btf;
                }
 
                /* check type_id */
-               type = btf_type_by_id(btf, krecord.type_id);
+               type = btf_type_by_id(btf, krecord[i].type_id);
                if (!type || BTF_INFO_KIND(type->info) != BTF_KIND_FUNC) {
                        verbose(env, "invalid type id %d in func info",
-                               krecord.type_id);
+                               krecord[i].type_id);
                        ret = -EINVAL;
                        goto free_btf;
                }
 
-               if (i == 0)
-                       prog->aux->type_id = krecord.type_id;
-               env->subprog_info[i].type_id = krecord.type_id;
-
-               prev_offset = krecord.insn_offset;
+               prev_offset = krecord[i].insn_offset;
                urecord += urec_size;
        }
 
        prog->aux->btf = btf;
+       prog->aux->func_info = krecord;
+       prog->aux->func_info_cnt = nfuncs;
        return 0;
 
 free_btf:
        btf_put(btf);
+       kvfree(krecord);
        return ret;
 }
 
+static void adjust_btf_func(struct bpf_verifier_env *env)
+{
+       int i;
+
+       if (!env->prog->aux->func_info)
+               return;
+
+       for (i = 0; i < env->subprog_cnt; i++)
+               env->prog->aux->func_info[i].insn_offset = env->subprog_info[i].start;
+}
+
 /* check %cur's range satisfies %old's */
 static bool range_within(struct bpf_reg_state *old,
                         struct bpf_reg_state *cur)
@@ -6043,15 +6059,17 @@ static int jit_subprogs(struct bpf_verifier_env *env)
                if (bpf_prog_calc_tag(func[i]))
                        goto out_free;
                func[i]->is_func = 1;
+               func[i]->aux->func_idx = i;
+               /* the btf and func_info will be freed only at prog->aux */
+               func[i]->aux->btf = prog->aux->btf;
+               func[i]->aux->func_info = prog->aux->func_info;
+
                /* Use bpf_prog_F_tag to indicate functions in stack traces.
                 * Long term would need debug info to populate names
                 */
                func[i]->aux->name[0] = 'F';
                func[i]->aux->stack_depth = env->subprog_info[i].stack_depth;
                func[i]->jit_requested = 1;
-               /* the btf will be freed only at prog->aux */
-               func[i]->aux->btf = prog->aux->btf;
-               func[i]->aux->type_id = env->subprog_info[i].type_id;
                func[i] = bpf_int_jit_compile(func[i]);
                if (!func[i]->jited) {
                        err = -ENOTSUPP;
@@ -6572,6 +6590,9 @@ skip_full_check:
                convert_pseudo_ld_imm64(env);
        }
 
+       if (ret == 0)
+               adjust_btf_func(env);
+
 err_release_maps:
        if (!env->prog->aux->used_maps)
                /* if we didn't copy map pointers into bpf_prog_info, release