libbpf: misc internal libbpf clean ups around log fixup

Normalize internal constants, field names, and comments related to log
fixup. Also add explicit `ext_idx` alias for relocation where relocation
is pointing to extern description for additional information.

No functional changes, just a clean up before subsequent additions.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230418002148.3255690-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 49cd304..a382ed3 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -333,6 +333,7 @@ struct reloc_desc {
                struct {
                        int map_idx;
                        int sym_off;
+                       int ext_idx;
                };
        };
 };
@@ -4042,7 +4043,7 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
                else
                        reloc_desc->type = RELO_EXTERN_LD64;
                reloc_desc->insn_idx = insn_idx;
-               reloc_desc->sym_off = i; /* sym_off stores extern index */
+               reloc_desc->ext_idx = i;
                return 0;
        }
 
@@ -5811,8 +5812,8 @@ out:
 }
 
 /* base map load ldimm64 special constant, used also for log fixup logic */
-#define MAP_LDIMM64_POISON_BASE 2001000000
-#define MAP_LDIMM64_POISON_PFX "200100"
+#define POISON_LDIMM64_MAP_BASE 2001000000
+#define POISON_LDIMM64_MAP_PFX "200100"
 
 static void poison_map_ldimm64(struct bpf_program *prog, int relo_idx,
                               int insn_idx, struct bpf_insn *insn,
@@ -5834,7 +5835,7 @@ static void poison_map_ldimm64(struct bpf_program *prog, int relo_idx,
                 * invalid func unknown#2001000123
                 * where lower 123 is map index into obj->maps[] array
                 */
-               insn->imm = MAP_LDIMM64_POISON_BASE + map_idx;
+               insn->imm = POISON_LDIMM64_MAP_BASE + map_idx;
 
                insn++;
        }
@@ -5885,7 +5886,7 @@ bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
                        }
                        break;
                case RELO_EXTERN_LD64:
-                       ext = &obj->externs[relo->sym_off];
+                       ext = &obj->externs[relo->ext_idx];
                        if (ext->type == EXT_KCFG) {
                                if (obj->gen_loader) {
                                        insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
@@ -5907,7 +5908,7 @@ bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
                        }
                        break;
                case RELO_EXTERN_CALL:
-                       ext = &obj->externs[relo->sym_off];
+                       ext = &obj->externs[relo->ext_idx];
                        insn[0].src_reg = BPF_PSEUDO_KFUNC_CALL;
                        if (ext->is_set) {
                                insn[0].imm = ext->ksym.kernel_btf_id;
@@ -7022,13 +7023,13 @@ static void fixup_log_missing_map_load(struct bpf_program *prog,
                                       char *buf, size_t buf_sz, size_t log_sz,
                                       char *line1, char *line2, char *line3)
 {
-       /* Expected log for failed and not properly guarded CO-RE relocation:
+       /* Expected log for failed and not properly guarded map reference:
         * line1 -> 123: (85) call unknown#2001000345
         * line2 -> invalid func unknown#2001000345
         * line3 -> <anything else or end of buffer>
         *
         * "123" is the index of the instruction that was poisoned.
-        * "345" in "2001000345" are map index in obj->maps to fetch map name.
+        * "345" in "2001000345" is a map index in obj->maps to fetch map name.
         */
        struct bpf_object *obj = prog->obj;
        const struct bpf_map *map;
@@ -7038,7 +7039,7 @@ static void fixup_log_missing_map_load(struct bpf_program *prog,
        if (sscanf(line1, "%d: (%*d) call unknown#%d\n", &insn_idx, &map_idx) != 2)
                return;
 
-       map_idx -= MAP_LDIMM64_POISON_BASE;
+       map_idx -= POISON_LDIMM64_MAP_BASE;
        if (map_idx < 0 || map_idx >= obj->nr_maps)
                return;
        map = &obj->maps[map_idx];
@@ -7070,20 +7071,21 @@ static void fixup_verifier_log(struct bpf_program *prog, char *buf, size_t buf_s
                if (!cur_line)
                        return;
 
-               /* failed CO-RE relocation case */
                if (str_has_pfx(cur_line, "invalid func unknown#195896080\n")) {
                        prev_line = find_prev_line(buf, cur_line);
                        if (!prev_line)
                                continue;
 
+                       /* failed CO-RE relocation case */
                        fixup_log_failed_core_relo(prog, buf, buf_sz, log_sz,
                                                   prev_line, cur_line, next_line);
                        return;
-               } else if (str_has_pfx(cur_line, "invalid func unknown#"MAP_LDIMM64_POISON_PFX)) {
+               } else if (str_has_pfx(cur_line, "invalid func unknown#"POISON_LDIMM64_MAP_PFX)) {
                        prev_line = find_prev_line(buf, cur_line);
                        if (!prev_line)
                                continue;
 
+                       /* reference to uncreated BPF map */
                        fixup_log_missing_map_load(prog, buf, buf_sz, log_sz,
                                                   prev_line, cur_line, next_line);
                        return;
@@ -7098,7 +7100,7 @@ static int bpf_program_record_relos(struct bpf_program *prog)
 
        for (i = 0; i < prog->nr_reloc; i++) {
                struct reloc_desc *relo = &prog->reloc_desc[i];
-               struct extern_desc *ext = &obj->externs[relo->sym_off];
+               struct extern_desc *ext = &obj->externs[relo->ext_idx];
                int kind;
 
                switch (relo->type) {