pahole: Allow encoding BTF into a detached file
Previously the newly encoded BTF info was stored into a ELF section in
the file where the DWARF info was obtained, but it is useful to just
dump it into a separate file, do it.
$ ls -la vmlinux.btf
ls: cannot access 'vmlinux.btf': No such file or directory
$ pahole -j vmlinux.btf vmlinux
$ ls -la vmlinux.btf
-rw-r-----. 1 acme acme 4630082 Jun 1 16:15 vmlinux.btf
$ pahole -C list_head ./vmlinux.btf
struct list_head {
struct list_head * next; /* 0 8 */
struct list_head * prev; /* 8 8 */
/* size: 16, cachelines: 1, members: 2 */
/* last cacheline: 16 bytes */
};
acme@toolbox pahole]$ pahole -C raw_spinlock_t ./vmlinux.btf
typedef struct raw_spinlock raw_spinlock_t;
acme@toolbox pahole]$ pahole -EC raw_spinlock ./vmlinux.btf
struct raw_spinlock {
/* typedef arch_spinlock_t */ struct qspinlock {
union {
/* typedef atomic_t */ struct {
int counter; /* 0 4 */
} val; /* 0 4 */
struct {
/* typedef u8 -> __u8 */ unsigned char locked; /* 0 1 */
/* typedef u8 -> __u8 */ unsigned char pending; /* 1 1 */
}; /* 0 2 */
struct {
/* typedef u16 -> __u16 */ short unsigned int locked_pending; /* 0 2 */
/* typedef u16 -> __u16 */ short unsigned int tail; /* 2 2 */
}; /* 0 4 */
}; /* 0 4 */
} raw_lock; /* 0 4 */
/* size: 4, cachelines: 1, members: 1 */
/* last cacheline: 4 bytes */
};
⬢[acme@toolbox pahole]$
Requested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo
parent
22a76fbc8b
commit
89be5646a0
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@ -21,6 +21,14 @@
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#include <stdlib.h> /* for qsort() and bsearch() */
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#include <inttypes.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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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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/*
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* This corresponds to the same macro defined in
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* include/linux/kallsyms.h
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@ -267,14 +275,62 @@ static struct btf_elf *btfe;
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static uint32_t array_index_id;
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static bool has_index_type;
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int btf_encoder__encode()
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static int btf__encode_as_raw_file(struct btf *btf, const char *filename)
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{
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uint32_t raw_btf_size;
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const void *raw_btf_data;
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int fd, err;
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/* Empty file, nothing to do, so... done! */
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if (btf__get_nr_types(btf) == 0)
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return 0;
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if (btf__dedup(btf, NULL, NULL)) {
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fprintf(stderr, "%s: btf__dedup failed!\n", __func__);
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return -1;
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}
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raw_btf_data = btf__get_raw_data(btf, &raw_btf_size);
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if (raw_btf_data == NULL) {
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fprintf(stderr, "%s: btf__get_raw_data failed!\n", __func__);
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return -1;
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}
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fd = open(filename, O_WRONLY | O_CREAT, 0640);
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if (fd < 0) {
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fprintf(stderr, "%s: Couldn't open %s for writing the raw BTF info: %s\n", __func__, filename, strerror(errno));
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return -1;
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}
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err = write(fd, raw_btf_data, raw_btf_size);
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if (err < 0)
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fprintf(stderr, "%s: Couldn't write the raw BTF info to %s: %s\n", __func__, filename, strerror(errno));
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close(fd);
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if (err != raw_btf_size) {
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fprintf(stderr, "%s: Could only write %d bytes to %s of raw BTF info out of %d, aborting\n", __func__, err, filename, raw_btf_size);
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unlink(filename);
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err = -1;
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} else {
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/* go from bytes written == raw_btf_size to an indication that all went fine */
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err = 0;
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}
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return err;
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}
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int btf_encoder__encode(const char *filename)
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{
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int err;
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if (gobuffer__size(&btfe->percpu_secinfo) != 0)
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btf_elf__add_datasec_type(btfe, PERCPU_SECTION, &btfe->percpu_secinfo);
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err = btf_elf__encode(btfe, 0);
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if (filename == NULL)
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err = btf_elf__encode(btfe, 0);
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else
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err = btf__encode_as_raw_file(btfe->btf, filename);
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delete_functions();
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btf_elf__delete(btfe);
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btfe = NULL;
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@ -412,7 +468,7 @@ static bool has_arg_names(struct cu *cu, struct ftype *ftype)
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}
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int cu__encode_btf(struct cu *cu, int verbose, bool force,
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bool skip_encoding_vars)
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bool skip_encoding_vars, const char *detached_btf_filename)
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{
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uint32_t type_id_off;
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uint32_t core_id;
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@ -425,7 +481,7 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force,
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btf_elf__force = force;
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if (btfe && strcmp(btfe->filename, cu->filename)) {
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err = btf_encoder__encode();
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err = btf_encoder__encode(detached_btf_filename);
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if (err)
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goto out;
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@ -11,9 +11,9 @@
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struct cu;
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int btf_encoder__encode();
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int btf_encoder__encode(const char *filename);
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int cu__encode_btf(struct cu *cu, int verbose, bool force,
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bool skip_encoding_vars);
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bool skip_encoding_vars, const char *detached_btf_filename);
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#endif /* _BTF_ENCODER_H_ */
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@ -189,6 +189,10 @@ features such as BPF CO-RE (Compile Once - Run Everywhere).
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See \fIhttps://nakryiko.com/posts/bpf-portability-and-co-re/\fR.
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.TP
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.B \-j, \-\-btf_encode_detached=FILENAME
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Same thing as -J/--btf_encode, but storing the raw BTF info into a separate file.
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.TP
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.B \-\-btf_encode_force
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Ignore those symbols found invalid when encoding BTF.
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12
pahole.c
12
pahole.c
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@ -26,6 +26,7 @@
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#include "lib/bpf/src/libbpf.h"
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#include "pahole_strings.h"
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static char *detached_btf_filename;
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static bool btf_encode;
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static bool ctf_encode;
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static bool first_obj_only;
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@ -1152,6 +1153,12 @@ static const struct argp_option pahole__options[] = {
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.key = 'J',
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.doc = "Encode as BTF",
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},
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{
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.name = "btf_encode_detached",
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.key = 'j',
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.arg = "FILENAME",
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.doc = "Encode as BTF in a detached file",
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},
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{
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.name = "skip_encoding_btf_vars",
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.key = ARGP_skip_encoding_btf_vars,
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@ -1223,6 +1230,7 @@ static error_t pahole__options_parser(int key, char *arg,
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conf_load.extra_dbg_info = 1; break;
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case 'i': find_containers = 1;
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class_name = arg; break;
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case 'j': detached_btf_filename = arg; // fallthru
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case 'J': btf_encode = 1;
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conf_load.get_addr_info = true;
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no_bitfield_type_recode = true; break;
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@ -2458,7 +2466,7 @@ static enum load_steal_kind pahole_stealer(struct cu *cu,
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if (btf_encode) {
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if (cu__encode_btf(cu, global_verbose, btf_encode_force,
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skip_encoding_btf_vars)) {
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skip_encoding_btf_vars, detached_btf_filename)) {
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fprintf(stderr, "Encountered error while encoding BTF.\n");
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exit(1);
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}
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@ -2872,7 +2880,7 @@ try_sole_arg_as_class_names:
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header = NULL;
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if (btf_encode) {
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err = btf_encoder__encode();
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err = btf_encoder__encode(detached_btf_filename);
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if (err) {
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fputs("Failed to encode BTF\n", stderr);
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goto out_cus_delete;
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