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From: Daniel Borkmann <daniel@iogearbox.net>
To: bpf@vger.kernel.org
Cc: ast@kernel.org, joe@wand.net.nz, yhs@fb.com,
	andrii.nakryiko@gmail.com, kafai@fb.com,
	Daniel Borkmann <daniel@iogearbox.net>
Subject: [PATCH bpf-next v3 09/15] bpf, libbpf: refactor relocation handling
Date: Wed,  3 Apr 2019 20:23:00 +0200	[thread overview]
Message-ID: <94818e3ea5da4ac475a63858472751e68383a451.1554314902.git.daniel@iogearbox.net> (raw)
In-Reply-To: <cover.1554314902.git.daniel@iogearbox.net>
In-Reply-To: <cover.1554314902.git.daniel@iogearbox.net>

From: Joe Stringer <joe@wand.net.nz>

Adjust the code for relocations slightly with no functional changes,
so that upcoming patches that will introduce support for relocations
into the .data, .rodata and .bss sections can be added independent
of these changes.

Signed-off-by: Joe Stringer <joe@wand.net.nz>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
---
 tools/lib/bpf/libbpf.c | 62 ++++++++++++++++++++++++++------------------------
 1 file changed, 32 insertions(+), 30 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 11c25d9..9e25358 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -865,20 +865,20 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
 				obj->efile.symbols = data;
 				obj->efile.strtabidx = sh.sh_link;
 			}
-		} else if ((sh.sh_type == SHT_PROGBITS) &&
-			   (sh.sh_flags & SHF_EXECINSTR) &&
-			   (data->d_size > 0)) {
-			if (strcmp(name, ".text") == 0)
-				obj->efile.text_shndx = idx;
-			err = bpf_object__add_program(obj, data->d_buf,
-						      data->d_size, name, idx);
-			if (err) {
-				char errmsg[STRERR_BUFSIZE];
-				char *cp = libbpf_strerror_r(-err, errmsg,
-							     sizeof(errmsg));
-
-				pr_warning("failed to alloc program %s (%s): %s",
-					   name, obj->path, cp);
+		} else if (sh.sh_type == SHT_PROGBITS && data->d_size > 0) {
+			if (sh.sh_flags & SHF_EXECINSTR) {
+				if (strcmp(name, ".text") == 0)
+					obj->efile.text_shndx = idx;
+				err = bpf_object__add_program(obj, data->d_buf,
+							      data->d_size, name, idx);
+				if (err) {
+					char errmsg[STRERR_BUFSIZE];
+					char *cp = libbpf_strerror_r(-err, errmsg,
+								     sizeof(errmsg));
+
+					pr_warning("failed to alloc program %s (%s): %s",
+						   name, obj->path, cp);
+				}
 			}
 		} else if (sh.sh_type == SHT_REL) {
 			void *reloc = obj->efile.reloc;
@@ -1040,24 +1040,26 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 			return -LIBBPF_ERRNO__RELOC;
 		}
 
-		/* TODO: 'maps' is sorted. We can use bsearch to make it faster. */
-		for (map_idx = 0; map_idx < nr_maps; map_idx++) {
-			if (maps[map_idx].offset == sym.st_value) {
-				pr_debug("relocation: find map %zd (%s) for insn %u\n",
-					 map_idx, maps[map_idx].name, insn_idx);
-				break;
+		if (sym.st_shndx == maps_shndx) {
+			/* TODO: 'maps' is sorted. We can use bsearch to make it faster. */
+			for (map_idx = 0; map_idx < nr_maps; map_idx++) {
+				if (maps[map_idx].offset == sym.st_value) {
+					pr_debug("relocation: find map %zd (%s) for insn %u\n",
+						 map_idx, maps[map_idx].name, insn_idx);
+					break;
+				}
 			}
-		}
 
-		if (map_idx >= nr_maps) {
-			pr_warning("bpf relocation: map_idx %d large than %d\n",
-				   (int)map_idx, (int)nr_maps - 1);
-			return -LIBBPF_ERRNO__RELOC;
-		}
+			if (map_idx >= nr_maps) {
+				pr_warning("bpf relocation: map_idx %d large than %d\n",
+					   (int)map_idx, (int)nr_maps - 1);
+				return -LIBBPF_ERRNO__RELOC;
+			}
 
-		prog->reloc_desc[i].type = RELO_LD64;
-		prog->reloc_desc[i].insn_idx = insn_idx;
-		prog->reloc_desc[i].map_idx = map_idx;
+			prog->reloc_desc[i].type = RELO_LD64;
+			prog->reloc_desc[i].insn_idx = insn_idx;
+			prog->reloc_desc[i].map_idx = map_idx;
+		}
 	}
 	return 0;
 }
@@ -1419,7 +1421,7 @@ bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
 			}
 			insns[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
 			insns[insn_idx].imm = obj->maps[map_idx].fd;
-		} else {
+		} else if (prog->reloc_desc[i].type == RELO_CALL) {
 			err = bpf_program__reloc_text(prog, obj,
 						      &prog->reloc_desc[i]);
 			if (err)
-- 
2.9.5


  parent reply	other threads:[~2019-04-03 18:23 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-03 18:22 [PATCH bpf-next v3 00/15] BPF support for global data Daniel Borkmann
2019-04-03 18:22 ` [PATCH bpf-next v3 01/15] bpf: implement lookup-free direct value access for maps Daniel Borkmann
2019-04-03 18:22 ` [PATCH bpf-next v3 02/15] bpf: add program side {rd,wr}only support " Daniel Borkmann
2019-04-03 18:22 ` [PATCH bpf-next v3 03/15] bpf: add syscall side map lock support Daniel Borkmann
2019-04-03 18:22 ` [PATCH bpf-next v3 04/15] bpf: allow . char as part of the object name Daniel Borkmann
2019-04-03 18:22 ` [PATCH bpf-next v3 05/15] bpf: add specification for BTF Var and DataSec kinds Daniel Borkmann
2019-04-03 18:22 ` [PATCH bpf-next v3 06/15] bpf: kernel side support for BTF Var and DataSec Daniel Borkmann
2019-04-04 19:20   ` Martin Lau
2019-04-05  7:03     ` Martin Lau
2019-04-05  7:44       ` Daniel Borkmann
2019-04-03 18:22 ` [PATCH bpf-next v3 07/15] bpf: allow for key-less BTF in array map Daniel Borkmann
2019-04-03 18:22 ` [PATCH bpf-next v3 08/15] bpf: sync {btf,bpf}.h uapi header from tools infrastructure Daniel Borkmann
2019-04-03 18:23 ` Daniel Borkmann [this message]
2019-04-03 18:23 ` [PATCH bpf-next v3 10/15] bpf, libbpf: support global data/bss/rodata sections Daniel Borkmann
2019-04-03 18:23 ` [PATCH bpf-next v3 11/15] bpf, libbpf: add support for BTF Var and DataSec Daniel Borkmann
2019-04-03 18:23 ` [PATCH bpf-next v3 12/15] bpf: bpftool support for dumping data/bss/rodata sections Daniel Borkmann
2019-04-03 18:23 ` [PATCH bpf-next v3 13/15] bpf, selftest: test {rd,wr}only flags and direct value access Daniel Borkmann
2019-04-03 18:23 ` [PATCH bpf-next v3 14/15] bpf, selftest: test global data/bss/rodata sections Daniel Borkmann
2019-04-03 18:23 ` [PATCH bpf-next v3 15/15] bpf, selftest: add test cases for BTF Var and DataSec Daniel Borkmann

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