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Message-ID: <20190531202132.379386-3-andriin@fb.com>
Date: Fri, 31 May 2019 13:21:26 -0700
From: Andrii Nakryiko <andriin@...com>
To: <andrii.nakryiko@...il.com>, <netdev@...r.kernel.org>,
<bpf@...r.kernel.org>, <ast@...com>, <daniel@...earbox.net>,
<kernel-team@...com>
CC: Andrii Nakryiko <andriin@...com>
Subject: [RFC PATCH bpf-next 2/8] libbpf: extract BTF loading and simplify ELF parsing logic
As a preparation for adding BTF-based BPF map loading, extract .BTF and
.BTF.ext loading logic. Also simplify error handling in
bpf_object__elf_collect() by returning early, as there is no common
clean up to be done.
Signed-off-by: Andrii Nakryiko <andriin@...com>
---
tools/lib/bpf/libbpf.c | 137 ++++++++++++++++++++++-------------------
1 file changed, 75 insertions(+), 62 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ba89d9727137..9e39a0a33aeb 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1078,6 +1078,58 @@ static void bpf_object__sanitize_btf_ext(struct bpf_object *obj)
}
}
+static int bpf_object__load_btf(struct bpf_object *obj,
+ Elf_Data *btf_data,
+ Elf_Data *btf_ext_data)
+{
+ int err = 0;
+
+ if (btf_data) {
+ obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
+ if (IS_ERR(obj->btf)) {
+ pr_warning("Error loading ELF section %s: %d.\n",
+ BTF_ELF_SEC, err);
+ goto out;
+ }
+ err = btf__finalize_data(obj, obj->btf);
+ if (err) {
+ pr_warning("Error finalizing %s: %d.\n",
+ BTF_ELF_SEC, err);
+ goto out;
+ }
+ bpf_object__sanitize_btf(obj);
+ err = btf__load(obj->btf);
+ if (err) {
+ pr_warning("Error loading %s into kernel: %d.\n",
+ BTF_ELF_SEC, err);
+ goto out;
+ }
+ }
+ if (btf_ext_data) {
+ if (!obj->btf) {
+ pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n",
+ BTF_EXT_ELF_SEC, BTF_ELF_SEC);
+ goto out;
+ }
+ obj->btf_ext = btf_ext__new(btf_ext_data->d_buf,
+ btf_ext_data->d_size);
+ if (IS_ERR(obj->btf_ext)) {
+ pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n",
+ BTF_EXT_ELF_SEC, PTR_ERR(obj->btf_ext));
+ obj->btf_ext = NULL;
+ goto out;
+ }
+ bpf_object__sanitize_btf_ext(obj);
+ }
+out:
+ if (err || IS_ERR(obj->btf)) {
+ if (!IS_ERR_OR_NULL(obj->btf))
+ btf__free(obj->btf);
+ obj->btf = NULL;
+ }
+ return 0;
+}
+
static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
{
Elf *elf = obj->efile.elf;
@@ -1102,24 +1154,21 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
if (gelf_getshdr(scn, &sh) != &sh) {
pr_warning("failed to get section(%d) header from %s\n",
idx, obj->path);
- err = -LIBBPF_ERRNO__FORMAT;
- goto out;
+ return -LIBBPF_ERRNO__FORMAT;
}
name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name);
if (!name) {
pr_warning("failed to get section(%d) name from %s\n",
idx, obj->path);
- err = -LIBBPF_ERRNO__FORMAT;
- goto out;
+ return -LIBBPF_ERRNO__FORMAT;
}
data = elf_getdata(scn, 0);
if (!data) {
pr_warning("failed to get section(%d) data from %s(%s)\n",
idx, name, obj->path);
- err = -LIBBPF_ERRNO__FORMAT;
- goto out;
+ return -LIBBPF_ERRNO__FORMAT;
}
pr_debug("section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
idx, name, (unsigned long)data->d_size,
@@ -1130,10 +1179,14 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
err = bpf_object__init_license(obj,
data->d_buf,
data->d_size);
+ if (err)
+ return err;
} else if (strcmp(name, "version") == 0) {
err = bpf_object__init_kversion(obj,
data->d_buf,
data->d_size);
+ if (err)
+ return err;
} else if (strcmp(name, "maps") == 0) {
obj->efile.maps_shndx = idx;
} else if (strcmp(name, BTF_ELF_SEC) == 0) {
@@ -1144,11 +1197,10 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
if (obj->efile.symbols) {
pr_warning("bpf: multiple SYMTAB in %s\n",
obj->path);
- err = -LIBBPF_ERRNO__FORMAT;
- } else {
- obj->efile.symbols = data;
- obj->efile.strtabidx = sh.sh_link;
+ return -LIBBPF_ERRNO__FORMAT;
}
+ obj->efile.symbols = data;
+ obj->efile.strtabidx = sh.sh_link;
} else if (sh.sh_type == SHT_PROGBITS && data->d_size > 0) {
if (sh.sh_flags & SHF_EXECINSTR) {
if (strcmp(name, ".text") == 0)
@@ -1162,6 +1214,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
pr_warning("failed to alloc program %s (%s): %s",
name, obj->path, cp);
+ return err;
}
} else if (strcmp(name, ".data") == 0) {
obj->efile.data = data;
@@ -1173,8 +1226,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
pr_debug("skip section(%d) %s\n", idx, name);
}
} else if (sh.sh_type == SHT_REL) {
+ int nr_reloc = obj->efile.nr_reloc;
void *reloc = obj->efile.reloc;
- int nr_reloc = obj->efile.nr_reloc + 1;
int sec = sh.sh_info; /* points to other section */
/* Only do relo for section with exec instructions */
@@ -1184,79 +1237,39 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
continue;
}
- reloc = reallocarray(reloc, nr_reloc,
+ reloc = reallocarray(reloc, nr_reloc + 1,
sizeof(*obj->efile.reloc));
if (!reloc) {
pr_warning("realloc failed\n");
- err = -ENOMEM;
- } else {
- int n = nr_reloc - 1;
+ return -ENOMEM;
+ }
- obj->efile.reloc = reloc;
- obj->efile.nr_reloc = nr_reloc;
+ obj->efile.reloc = reloc;
+ obj->efile.nr_reloc++;
- obj->efile.reloc[n].shdr = sh;
- obj->efile.reloc[n].data = data;
- }
+ obj->efile.reloc[nr_reloc].shdr = sh;
+ obj->efile.reloc[nr_reloc].data = data;
} else if (sh.sh_type == SHT_NOBITS && strcmp(name, ".bss") == 0) {
obj->efile.bss = data;
obj->efile.bss_shndx = idx;
} else {
pr_debug("skip section(%d) %s\n", idx, name);
}
- if (err)
- goto out;
}
if (!obj->efile.strtabidx || obj->efile.strtabidx >= idx) {
pr_warning("Corrupted ELF file: index of strtab invalid\n");
return -LIBBPF_ERRNO__FORMAT;
}
- if (btf_data) {
- obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
- if (IS_ERR(obj->btf)) {
- pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n",
- BTF_ELF_SEC, PTR_ERR(obj->btf));
- obj->btf = NULL;
- } else {
- err = btf__finalize_data(obj, obj->btf);
- if (!err) {
- bpf_object__sanitize_btf(obj);
- err = btf__load(obj->btf);
- }
- if (err) {
- pr_warning("Error finalizing and loading %s into kernel: %d. Ignored and continue.\n",
- BTF_ELF_SEC, err);
- btf__free(obj->btf);
- obj->btf = NULL;
- err = 0;
- }
- }
- }
- if (btf_ext_data) {
- if (!obj->btf) {
- pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n",
- BTF_EXT_ELF_SEC, BTF_ELF_SEC);
- } else {
- obj->btf_ext = btf_ext__new(btf_ext_data->d_buf,
- btf_ext_data->d_size);
- if (IS_ERR(obj->btf_ext)) {
- pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n",
- BTF_EXT_ELF_SEC,
- PTR_ERR(obj->btf_ext));
- obj->btf_ext = NULL;
- } else {
- bpf_object__sanitize_btf_ext(obj);
- }
- }
- }
+ err = bpf_object__load_btf(obj, btf_data, btf_ext_data);
+ if (err)
+ return err;
if (bpf_object__has_maps(obj)) {
err = bpf_object__init_maps(obj, flags);
if (err)
- goto out;
+ return err;
}
err = bpf_object__init_prog_names(obj);
-out:
return err;
}
--
2.17.1
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