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Message-ID: <20200115230031.1102305-1-kafai@fb.com>
Date: Wed, 15 Jan 2020 15:00:31 -0800
From: Martin KaFai Lau <kafai@...com>
To: <bpf@...r.kernel.org>
CC: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
David Miller <davem@...emloft.net>, <kernel-team@...com>,
<netdev@...r.kernel.org>
Subject: [PATCH v3 bpf-next 3/5] libbpf: Expose bpf_find_kernel_btf as a LIBBPF_API
This patch exposes bpf_find_kernel_btf() as a LIBBPF_API.
It will be used in 'bpftool map dump' in a following patch
to dump a map with btf_vmlinux_value_type_id set.
bpf_find_kernel_btf() is renamed to libbpf_find_kernel_btf()
and moved to btf.c. As <linux/kernel.h> is included,
some of the max/min type casting needs to be fixed.
Acked-by: Andrii Nakryiko <andriin@...com>
Signed-off-by: Martin KaFai Lau <kafai@...com>
---
tools/lib/bpf/btf.c | 102 ++++++++++++++++++++++++++++++++++++---
tools/lib/bpf/btf.h | 2 +
tools/lib/bpf/libbpf.c | 93 ++---------------------------------
tools/lib/bpf/libbpf.map | 1 +
4 files changed, 102 insertions(+), 96 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index cfeb6a44480b..3d1c25fc97ae 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -8,6 +8,10 @@
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
+#include <sys/utsname.h>
+#include <sys/param.h>
+#include <sys/stat.h>
+#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/btf.h>
#include <gelf.h>
@@ -20,8 +24,8 @@
/* make sure libbpf doesn't use kernel-only integer typedefs */
#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
-#define BTF_MAX_NR_TYPES 0x7fffffff
-#define BTF_MAX_STR_OFFSET 0x7fffffff
+#define BTF_MAX_NR_TYPES 0x7fffffffU
+#define BTF_MAX_STR_OFFSET 0x7fffffffU
static struct btf_type btf_void;
@@ -53,7 +57,7 @@ static int btf_add_type(struct btf *btf, struct btf_type *t)
if (btf->types_size == BTF_MAX_NR_TYPES)
return -E2BIG;
- expand_by = max(btf->types_size >> 2, 16);
+ expand_by = max(btf->types_size >> 2, 16U);
new_size = min(BTF_MAX_NR_TYPES, btf->types_size + expand_by);
new_types = realloc(btf->types, sizeof(*new_types) * new_size);
@@ -289,7 +293,7 @@ int btf__align_of(const struct btf *btf, __u32 id)
switch (kind) {
case BTF_KIND_INT:
case BTF_KIND_ENUM:
- return min(sizeof(void *), t->size);
+ return min(sizeof(void *), (size_t)t->size);
case BTF_KIND_PTR:
return sizeof(void *);
case BTF_KIND_TYPEDEF:
@@ -1401,7 +1405,7 @@ static int btf_dedup_hypot_map_add(struct btf_dedup *d,
if (d->hypot_cnt == d->hypot_cap) {
__u32 *new_list;
- d->hypot_cap += max(16, d->hypot_cap / 2);
+ d->hypot_cap += max((size_t)16, d->hypot_cap / 2);
new_list = realloc(d->hypot_list, sizeof(__u32) * d->hypot_cap);
if (!new_list)
return -ENOMEM;
@@ -1697,7 +1701,7 @@ static int btf_dedup_strings(struct btf_dedup *d)
if (strs.cnt + 1 > strs.cap) {
struct btf_str_ptr *new_ptrs;
- strs.cap += max(strs.cnt / 2, 16);
+ strs.cap += max(strs.cnt / 2, 16U);
new_ptrs = realloc(strs.ptrs,
sizeof(strs.ptrs[0]) * strs.cap);
if (!new_ptrs) {
@@ -2931,3 +2935,89 @@ static int btf_dedup_remap_types(struct btf_dedup *d)
}
return 0;
}
+
+static struct btf *btf_load_raw(const char *path)
+{
+ struct btf *btf;
+ size_t read_cnt;
+ struct stat st;
+ void *data;
+ FILE *f;
+
+ if (stat(path, &st))
+ return ERR_PTR(-errno);
+
+ data = malloc(st.st_size);
+ if (!data)
+ return ERR_PTR(-ENOMEM);
+
+ f = fopen(path, "rb");
+ if (!f) {
+ btf = ERR_PTR(-errno);
+ goto cleanup;
+ }
+
+ read_cnt = fread(data, 1, st.st_size, f);
+ fclose(f);
+ if (read_cnt < st.st_size) {
+ btf = ERR_PTR(-EBADF);
+ goto cleanup;
+ }
+
+ btf = btf__new(data, read_cnt);
+
+cleanup:
+ free(data);
+ return btf;
+}
+
+/*
+ * Probe few well-known locations for vmlinux kernel image and try to load BTF
+ * data out of it to use for target BTF.
+ */
+struct btf *libbpf_find_kernel_btf(void)
+{
+ struct {
+ const char *path_fmt;
+ bool raw_btf;
+ } locations[] = {
+ /* try canonical vmlinux BTF through sysfs first */
+ { "/sys/kernel/btf/vmlinux", true /* raw BTF */ },
+ /* fall back to trying to find vmlinux ELF on disk otherwise */
+ { "/boot/vmlinux-%1$s" },
+ { "/lib/modules/%1$s/vmlinux-%1$s" },
+ { "/lib/modules/%1$s/build/vmlinux" },
+ { "/usr/lib/modules/%1$s/kernel/vmlinux" },
+ { "/usr/lib/debug/boot/vmlinux-%1$s" },
+ { "/usr/lib/debug/boot/vmlinux-%1$s.debug" },
+ { "/usr/lib/debug/lib/modules/%1$s/vmlinux" },
+ };
+ char path[PATH_MAX + 1];
+ struct utsname buf;
+ struct btf *btf;
+ int i;
+
+ uname(&buf);
+
+ for (i = 0; i < ARRAY_SIZE(locations); i++) {
+ snprintf(path, PATH_MAX, locations[i].path_fmt, buf.release);
+
+ if (access(path, R_OK))
+ continue;
+
+ if (locations[i].raw_btf)
+ btf = btf_load_raw(path);
+ else
+ btf = btf__parse_elf(path, NULL);
+
+ pr_debug("loading kernel BTF '%s': %ld\n",
+ path, IS_ERR(btf) ? PTR_ERR(btf) : 0);
+ if (IS_ERR(btf))
+ continue;
+
+ return btf;
+ }
+
+ pr_warn("failed to find valid kernel BTF\n");
+ return ERR_PTR(-ESRCH);
+}
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 8d73f7f5551f..70c1b7ec2bd0 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -102,6 +102,8 @@ LIBBPF_API int btf_ext__reloc_line_info(const struct btf *btf,
LIBBPF_API __u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext);
LIBBPF_API __u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext);
+LIBBPF_API struct btf *libbpf_find_kernel_btf(void);
+
struct btf_dedup_opts {
unsigned int dedup_table_size;
bool dont_resolve_fwds;
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 23868883477f..3afaca9bce1d 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -73,7 +73,6 @@
#define __printf(a, b) __attribute__((format(printf, a, b)))
-static struct btf *bpf_find_kernel_btf(void);
static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
static struct bpf_program *bpf_object__find_prog_by_idx(struct bpf_object *obj,
int idx);
@@ -848,7 +847,7 @@ static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj)
continue;
if (!kern_btf) {
- kern_btf = bpf_find_kernel_btf();
+ kern_btf = libbpf_find_kernel_btf();
if (IS_ERR(kern_btf))
return PTR_ERR(kern_btf);
}
@@ -4300,92 +4299,6 @@ static int bpf_core_reloc_insn(struct bpf_program *prog,
return 0;
}
-static struct btf *btf_load_raw(const char *path)
-{
- struct btf *btf;
- size_t read_cnt;
- struct stat st;
- void *data;
- FILE *f;
-
- if (stat(path, &st))
- return ERR_PTR(-errno);
-
- data = malloc(st.st_size);
- if (!data)
- return ERR_PTR(-ENOMEM);
-
- f = fopen(path, "rb");
- if (!f) {
- btf = ERR_PTR(-errno);
- goto cleanup;
- }
-
- read_cnt = fread(data, 1, st.st_size, f);
- fclose(f);
- if (read_cnt < st.st_size) {
- btf = ERR_PTR(-EBADF);
- goto cleanup;
- }
-
- btf = btf__new(data, read_cnt);
-
-cleanup:
- free(data);
- return btf;
-}
-
-/*
- * Probe few well-known locations for vmlinux kernel image and try to load BTF
- * data out of it to use for target BTF.
- */
-static struct btf *bpf_find_kernel_btf(void)
-{
- struct {
- const char *path_fmt;
- bool raw_btf;
- } locations[] = {
- /* try canonical vmlinux BTF through sysfs first */
- { "/sys/kernel/btf/vmlinux", true /* raw BTF */ },
- /* fall back to trying to find vmlinux ELF on disk otherwise */
- { "/boot/vmlinux-%1$s" },
- { "/lib/modules/%1$s/vmlinux-%1$s" },
- { "/lib/modules/%1$s/build/vmlinux" },
- { "/usr/lib/modules/%1$s/kernel/vmlinux" },
- { "/usr/lib/debug/boot/vmlinux-%1$s" },
- { "/usr/lib/debug/boot/vmlinux-%1$s.debug" },
- { "/usr/lib/debug/lib/modules/%1$s/vmlinux" },
- };
- char path[PATH_MAX + 1];
- struct utsname buf;
- struct btf *btf;
- int i;
-
- uname(&buf);
-
- for (i = 0; i < ARRAY_SIZE(locations); i++) {
- snprintf(path, PATH_MAX, locations[i].path_fmt, buf.release);
-
- if (access(path, R_OK))
- continue;
-
- if (locations[i].raw_btf)
- btf = btf_load_raw(path);
- else
- btf = btf__parse_elf(path, NULL);
-
- pr_debug("loading kernel BTF '%s': %ld\n",
- path, IS_ERR(btf) ? PTR_ERR(btf) : 0);
- if (IS_ERR(btf))
- continue;
-
- return btf;
- }
-
- pr_warn("failed to find valid kernel BTF\n");
- return ERR_PTR(-ESRCH);
-}
-
/* Output spec definition in the format:
* [<type-id>] (<type-name>) + <raw-spec> => <offset>@<spec>,
* where <spec> is a C-syntax view of recorded field access, e.g.: x.a[3].b
@@ -4620,7 +4533,7 @@ bpf_core_reloc_fields(struct bpf_object *obj, const char *targ_btf_path)
if (targ_btf_path)
targ_btf = btf__parse_elf(targ_btf_path, NULL);
else
- targ_btf = bpf_find_kernel_btf();
+ targ_btf = libbpf_find_kernel_btf();
if (IS_ERR(targ_btf)) {
pr_warn("failed to get target BTF: %ld\n", PTR_ERR(targ_btf));
return PTR_ERR(targ_btf);
@@ -6595,7 +6508,7 @@ static int bpf_object__collect_struct_ops_map_reloc(struct bpf_object *obj,
int libbpf_find_vmlinux_btf_id(const char *name,
enum bpf_attach_type attach_type)
{
- struct btf *btf = bpf_find_kernel_btf();
+ struct btf *btf = libbpf_find_kernel_btf();
char raw_tp_btf[128] = BTF_PREFIX;
char *dst = raw_tp_btf + sizeof(BTF_PREFIX) - 1;
const char *btf_name;
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index a19f04e6e3d9..fad8fefacfdb 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -227,4 +227,5 @@ LIBBPF_0.0.7 {
bpf_program__is_struct_ops;
bpf_program__set_struct_ops;
btf__align_of;
+ libbpf_find_kernel_btf;
} LIBBPF_0.0.6;
--
2.17.1
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