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: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200115230031.1102305-1-kafai@fb.com
This commit is contained in:
Martin KaFai Lau
Alexei Starovoitov
parent
188a486619
commit
fb2426ad00
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@ -8,6 +8,10 @@
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#include <fcntl.h>
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#include <unistd.h>
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#include <errno.h>
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#include <sys/utsname.h>
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <linux/kernel.h>
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#include <linux/err.h>
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#include <linux/btf.h>
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#include <gelf.h>
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@ -20,8 +24,8 @@
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/* make sure libbpf doesn't use kernel-only integer typedefs */
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#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
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#define BTF_MAX_NR_TYPES 0x7fffffff
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#define BTF_MAX_STR_OFFSET 0x7fffffff
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#define BTF_MAX_NR_TYPES 0x7fffffffU
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#define BTF_MAX_STR_OFFSET 0x7fffffffU
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static struct btf_type btf_void;
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@ -53,7 +57,7 @@ static int btf_add_type(struct btf *btf, struct btf_type *t)
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if (btf->types_size == BTF_MAX_NR_TYPES)
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return -E2BIG;
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expand_by = max(btf->types_size >> 2, 16);
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expand_by = max(btf->types_size >> 2, 16U);
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new_size = min(BTF_MAX_NR_TYPES, btf->types_size + expand_by);
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new_types = realloc(btf->types, sizeof(*new_types) * new_size);
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@ -289,7 +293,7 @@ int btf__align_of(const struct btf *btf, __u32 id)
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switch (kind) {
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case BTF_KIND_INT:
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case BTF_KIND_ENUM:
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return min(sizeof(void *), t->size);
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return min(sizeof(void *), (size_t)t->size);
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case BTF_KIND_PTR:
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return sizeof(void *);
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case BTF_KIND_TYPEDEF:
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@ -1401,7 +1405,7 @@ static int btf_dedup_hypot_map_add(struct btf_dedup *d,
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if (d->hypot_cnt == d->hypot_cap) {
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__u32 *new_list;
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d->hypot_cap += max(16, d->hypot_cap / 2);
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d->hypot_cap += max((size_t)16, d->hypot_cap / 2);
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new_list = realloc(d->hypot_list, sizeof(__u32) * d->hypot_cap);
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if (!new_list)
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return -ENOMEM;
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@ -1697,7 +1701,7 @@ static int btf_dedup_strings(struct btf_dedup *d)
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if (strs.cnt + 1 > strs.cap) {
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struct btf_str_ptr *new_ptrs;
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strs.cap += max(strs.cnt / 2, 16);
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strs.cap += max(strs.cnt / 2, 16U);
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new_ptrs = realloc(strs.ptrs,
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sizeof(strs.ptrs[0]) * strs.cap);
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if (!new_ptrs) {
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@ -2931,3 +2935,89 @@ static int btf_dedup_remap_types(struct btf_dedup *d)
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}
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return 0;
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}
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static struct btf *btf_load_raw(const char *path)
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{
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struct btf *btf;
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size_t read_cnt;
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struct stat st;
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void *data;
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FILE *f;
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if (stat(path, &st))
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return ERR_PTR(-errno);
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data = malloc(st.st_size);
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if (!data)
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return ERR_PTR(-ENOMEM);
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f = fopen(path, "rb");
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if (!f) {
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btf = ERR_PTR(-errno);
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goto cleanup;
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}
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read_cnt = fread(data, 1, st.st_size, f);
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fclose(f);
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if (read_cnt < st.st_size) {
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btf = ERR_PTR(-EBADF);
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goto cleanup;
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}
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btf = btf__new(data, read_cnt);
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cleanup:
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free(data);
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return btf;
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}
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/*
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* Probe few well-known locations for vmlinux kernel image and try to load BTF
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* data out of it to use for target BTF.
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*/
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struct btf *libbpf_find_kernel_btf(void)
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{
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struct {
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const char *path_fmt;
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bool raw_btf;
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} locations[] = {
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/* try canonical vmlinux BTF through sysfs first */
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{ "/sys/kernel/btf/vmlinux", true /* raw BTF */ },
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/* fall back to trying to find vmlinux ELF on disk otherwise */
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{ "/boot/vmlinux-%1$s" },
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{ "/lib/modules/%1$s/vmlinux-%1$s" },
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{ "/lib/modules/%1$s/build/vmlinux" },
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{ "/usr/lib/modules/%1$s/kernel/vmlinux" },
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{ "/usr/lib/debug/boot/vmlinux-%1$s" },
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{ "/usr/lib/debug/boot/vmlinux-%1$s.debug" },
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{ "/usr/lib/debug/lib/modules/%1$s/vmlinux" },
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};
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char path[PATH_MAX + 1];
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struct utsname buf;
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struct btf *btf;
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int i;
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uname(&buf);
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for (i = 0; i < ARRAY_SIZE(locations); i++) {
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snprintf(path, PATH_MAX, locations[i].path_fmt, buf.release);
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if (access(path, R_OK))
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continue;
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if (locations[i].raw_btf)
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btf = btf_load_raw(path);
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else
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btf = btf__parse_elf(path, NULL);
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pr_debug("loading kernel BTF '%s': %ld\n",
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path, IS_ERR(btf) ? PTR_ERR(btf) : 0);
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if (IS_ERR(btf))
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continue;
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return btf;
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}
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pr_warn("failed to find valid kernel BTF\n");
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return ERR_PTR(-ESRCH);
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}
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@ -102,6 +102,8 @@ LIBBPF_API int btf_ext__reloc_line_info(const struct btf *btf,
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LIBBPF_API __u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext);
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LIBBPF_API __u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext);
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LIBBPF_API struct btf *libbpf_find_kernel_btf(void);
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struct btf_dedup_opts {
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unsigned int dedup_table_size;
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bool dont_resolve_fwds;
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@ -73,7 +73,6 @@
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#define __printf(a, b) __attribute__((format(printf, a, b)))
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static struct btf *bpf_find_kernel_btf(void);
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static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
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static struct bpf_program *bpf_object__find_prog_by_idx(struct bpf_object *obj,
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int idx);
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@ -848,7 +847,7 @@ static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj)
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continue;
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if (!kern_btf) {
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kern_btf = bpf_find_kernel_btf();
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kern_btf = libbpf_find_kernel_btf();
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if (IS_ERR(kern_btf))
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return PTR_ERR(kern_btf);
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}
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@ -4300,92 +4299,6 @@ static int bpf_core_reloc_insn(struct bpf_program *prog,
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return 0;
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}
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static struct btf *btf_load_raw(const char *path)
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{
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struct btf *btf;
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size_t read_cnt;
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struct stat st;
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void *data;
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FILE *f;
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if (stat(path, &st))
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return ERR_PTR(-errno);
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data = malloc(st.st_size);
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if (!data)
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return ERR_PTR(-ENOMEM);
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f = fopen(path, "rb");
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if (!f) {
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btf = ERR_PTR(-errno);
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goto cleanup;
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}
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read_cnt = fread(data, 1, st.st_size, f);
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fclose(f);
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if (read_cnt < st.st_size) {
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btf = ERR_PTR(-EBADF);
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goto cleanup;
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}
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btf = btf__new(data, read_cnt);
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cleanup:
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free(data);
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return btf;
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}
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/*
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* Probe few well-known locations for vmlinux kernel image and try to load BTF
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* data out of it to use for target BTF.
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*/
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static struct btf *bpf_find_kernel_btf(void)
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{
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struct {
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const char *path_fmt;
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bool raw_btf;
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} locations[] = {
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/* try canonical vmlinux BTF through sysfs first */
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{ "/sys/kernel/btf/vmlinux", true /* raw BTF */ },
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/* fall back to trying to find vmlinux ELF on disk otherwise */
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{ "/boot/vmlinux-%1$s" },
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{ "/lib/modules/%1$s/vmlinux-%1$s" },
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{ "/lib/modules/%1$s/build/vmlinux" },
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{ "/usr/lib/modules/%1$s/kernel/vmlinux" },
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{ "/usr/lib/debug/boot/vmlinux-%1$s" },
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{ "/usr/lib/debug/boot/vmlinux-%1$s.debug" },
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{ "/usr/lib/debug/lib/modules/%1$s/vmlinux" },
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};
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char path[PATH_MAX + 1];
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struct utsname buf;
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struct btf *btf;
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int i;
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uname(&buf);
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for (i = 0; i < ARRAY_SIZE(locations); i++) {
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snprintf(path, PATH_MAX, locations[i].path_fmt, buf.release);
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if (access(path, R_OK))
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continue;
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if (locations[i].raw_btf)
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btf = btf_load_raw(path);
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else
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btf = btf__parse_elf(path, NULL);
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pr_debug("loading kernel BTF '%s': %ld\n",
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path, IS_ERR(btf) ? PTR_ERR(btf) : 0);
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if (IS_ERR(btf))
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continue;
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return btf;
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}
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pr_warn("failed to find valid kernel BTF\n");
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return ERR_PTR(-ESRCH);
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}
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/* Output spec definition in the format:
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* [<type-id>] (<type-name>) + <raw-spec> => <offset>@<spec>,
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* where <spec> is a C-syntax view of recorded field access, e.g.: x.a[3].b
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@ -4620,7 +4533,7 @@ bpf_core_reloc_fields(struct bpf_object *obj, const char *targ_btf_path)
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if (targ_btf_path)
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targ_btf = btf__parse_elf(targ_btf_path, NULL);
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else
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targ_btf = bpf_find_kernel_btf();
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targ_btf = libbpf_find_kernel_btf();
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if (IS_ERR(targ_btf)) {
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pr_warn("failed to get target BTF: %ld\n", PTR_ERR(targ_btf));
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return PTR_ERR(targ_btf);
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@ -6595,7 +6508,7 @@ static int bpf_object__collect_struct_ops_map_reloc(struct bpf_object *obj,
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int libbpf_find_vmlinux_btf_id(const char *name,
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enum bpf_attach_type attach_type)
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{
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struct btf *btf = bpf_find_kernel_btf();
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struct btf *btf = libbpf_find_kernel_btf();
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char raw_tp_btf[128] = BTF_PREFIX;
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char *dst = raw_tp_btf + sizeof(BTF_PREFIX) - 1;
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const char *btf_name;
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@ -231,4 +231,5 @@ LIBBPF_0.0.7 {
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bpf_program__is_struct_ops;
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bpf_program__set_struct_ops;
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btf__align_of;
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libbpf_find_kernel_btf;
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} LIBBPF_0.0.6;
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