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Commit fb2426ad authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Alexei Starovoitov
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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.
Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200115230031.1102305-1-kafai@fb.com
parent 188a4866
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Inline Side-by-side
Showing with 102 additions and 96 deletions
tools/lib/bpf/btf.c
View file @ fb2426ad
......@@ -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);
}
tools/lib/bpf/btf.h
View file @ fb2426ad
......@@ -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;
......
tools/lib/bpf/libbpf.c
View file @ fb2426ad
......@@ -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;
......
tools/lib/bpf/libbpf.map
View file @ fb2426ad
......@@ -231,4 +231,5 @@ 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;
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