netdev - [PATCH bpf-next 11/15] libbpf: Record extern sym relocation first

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Date:   Mon, 15 Mar 2021 18:14:45 -0700
From:   Martin KaFai Lau <kafai@...com>
To:     <bpf@...r.kernel.org>
CC:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, <kernel-team@...com>,
        <netdev@...r.kernel.org>
Subject: [PATCH bpf-next 11/15] libbpf: Record extern sym relocation first

This patch records the extern sym relocs first before recording
subprog relocs.  The later patch will have relocs for extern
kernel function call which is also using BPF_JMP | BPF_CALL.
It will be easier to handle the extern symbols first in
the later patch.

Signed-off-by: Martin KaFai Lau <kafai@...com>
---
 tools/lib/bpf/libbpf.c | 50 +++++++++++++++++++++---------------------
 1 file changed, 25 insertions(+), 25 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 8f924aece736..0a60fcb2fba2 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -3416,31 +3416,7 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
 
 	reloc_desc->processed = false;
 
-	/* sub-program call relocation */
-	if (insn->code == (BPF_JMP | BPF_CALL)) {
-		if (insn->src_reg != BPF_PSEUDO_CALL) {
-			pr_warn("prog '%s': incorrect bpf_call opcode\n", prog->name);
-			return -LIBBPF_ERRNO__RELOC;
-		}
-		/* text_shndx can be 0, if no default "main" program exists */
-		if (!shdr_idx || shdr_idx != obj->efile.text_shndx) {
-			sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
-			pr_warn("prog '%s': bad call relo against '%s' in section '%s'\n",
-				prog->name, sym_name, sym_sec_name);
-			return -LIBBPF_ERRNO__RELOC;
-		}
-		if (sym->st_value % BPF_INSN_SZ) {
-			pr_warn("prog '%s': bad call relo against '%s' at offset %zu\n",
-				prog->name, sym_name, (size_t)sym->st_value);
-			return -LIBBPF_ERRNO__RELOC;
-		}
-		reloc_desc->type = RELO_CALL;
-		reloc_desc->insn_idx = insn_idx;
-		reloc_desc->sym_off = sym->st_value;
-		return 0;
-	}
-
-	if (!is_ldimm64(insn)) {
+	if (insn->code != (BPF_JMP | BPF_CALL) && !is_ldimm64(insn)) {
 		pr_warn("prog '%s': invalid relo against '%s' for insns[%d].code 0x%x\n",
 			prog->name, sym_name, insn_idx, insn->code);
 		return -LIBBPF_ERRNO__RELOC;
@@ -3469,6 +3445,30 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
 		return 0;
 	}
 
+	/* sub-program call relocation */
+	if (insn->code == (BPF_JMP | BPF_CALL)) {
+		if (insn->src_reg != BPF_PSEUDO_CALL) {
+			pr_warn("prog '%s': incorrect bpf_call opcode\n", prog->name);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		/* text_shndx can be 0, if no default "main" program exists */
+		if (!shdr_idx || shdr_idx != obj->efile.text_shndx) {
+			sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
+			pr_warn("prog '%s': bad call relo against '%s' in section '%s'\n",
+				prog->name, sym_name, sym_sec_name);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		if (sym->st_value % BPF_INSN_SZ) {
+			pr_warn("prog '%s': bad call relo against '%s' at offset %zu\n",
+				prog->name, sym_name, (size_t)sym->st_value);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		reloc_desc->type = RELO_CALL;
+		reloc_desc->insn_idx = insn_idx;
+		reloc_desc->sym_off = sym->st_value;
+		return 0;
+	}
+
 	if (!shdr_idx || shdr_idx >= SHN_LORESERVE) {
 		pr_warn("prog '%s': invalid relo against '%s' in special section 0x%x; forgot to initialize global var?..\n",
 			prog->name, sym_name, shdr_idx);
-- 
2.30.2