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-rw-r--r--tools/bpf/resolve_btfids/main.c70
1 files changed, 56 insertions, 14 deletions
diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
index 770581740..ef0764d68 100644
--- a/tools/bpf/resolve_btfids/main.c
+++ b/tools/bpf/resolve_btfids/main.c
@@ -70,6 +70,7 @@
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
+#include <linux/btf_ids.h>
#include <linux/rbtree.h>
#include <linux/zalloc.h>
#include <linux/err.h>
@@ -78,7 +79,7 @@
#include <subcmd/parse-options.h>
#define BTF_IDS_SECTION ".BTF_ids"
-#define BTF_ID "__BTF_ID__"
+#define BTF_ID_PREFIX "__BTF_ID__"
#define BTF_STRUCT "struct"
#define BTF_UNION "union"
@@ -89,6 +90,14 @@
#define ADDR_CNT 100
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+# define ELFDATANATIVE ELFDATA2LSB
+#elif __BYTE_ORDER == __BIG_ENDIAN
+# define ELFDATANATIVE ELFDATA2MSB
+#else
+# error "Unknown machine endianness!"
+#endif
+
struct btf_id {
struct rb_node rb_node;
char *name;
@@ -116,6 +125,7 @@ struct object {
int idlist_shndx;
size_t strtabidx;
unsigned long idlist_addr;
+ int encoding;
} efile;
struct rb_root sets;
@@ -161,7 +171,7 @@ static int eprintf(int level, int var, const char *fmt, ...)
static bool is_btf_id(const char *name)
{
- return name && !strncmp(name, BTF_ID, sizeof(BTF_ID) - 1);
+ return name && !strncmp(name, BTF_ID_PREFIX, sizeof(BTF_ID_PREFIX) - 1);
}
static struct btf_id *btf_id__find(struct rb_root *root, const char *name)
@@ -319,6 +329,7 @@ static int elf_collect(struct object *obj)
{
Elf_Scn *scn = NULL;
size_t shdrstrndx;
+ GElf_Ehdr ehdr;
int idx = 0;
Elf *elf;
int fd;
@@ -350,6 +361,13 @@ static int elf_collect(struct object *obj)
return -1;
}
+ if (gelf_getehdr(obj->efile.elf, &ehdr) == NULL) {
+ pr_err("FAILED cannot get ELF header: %s\n",
+ elf_errmsg(-1));
+ return -1;
+ }
+ obj->efile.encoding = ehdr.e_ident[EI_DATA];
+
/*
* Scan all the elf sections and look for save data
* from .BTF_ids section and symbols.
@@ -441,7 +459,7 @@ static int symbols_collect(struct object *obj)
* __BTF_ID__TYPE__vfs_truncate__0
* prefix = ^
*/
- prefix = name + sizeof(BTF_ID) - 1;
+ prefix = name + sizeof(BTF_ID_PREFIX) - 1;
/* struct */
if (!strncmp(prefix, BTF_STRUCT, sizeof(BTF_STRUCT) - 1)) {
@@ -649,19 +667,18 @@ static int cmp_id(const void *pa, const void *pb)
static int sets_patch(struct object *obj)
{
Elf_Data *data = obj->efile.idlist;
- int *ptr = data->d_buf;
struct rb_node *next;
next = rb_first(&obj->sets);
while (next) {
- unsigned long addr, idx;
+ struct btf_id_set8 *set8;
+ struct btf_id_set *set;
+ unsigned long addr, off;
struct btf_id *id;
- int *base;
- int cnt;
id = rb_entry(next, struct btf_id, rb_node);
addr = id->addr[0];
- idx = addr - obj->efile.idlist_addr;
+ off = addr - obj->efile.idlist_addr;
/* sets are unique */
if (id->addr_cnt != 1) {
@@ -670,14 +687,39 @@ static int sets_patch(struct object *obj)
return -1;
}
- idx = idx / sizeof(int);
- base = &ptr[idx] + (id->is_set8 ? 2 : 1);
- cnt = ptr[idx];
+ if (id->is_set) {
+ set = data->d_buf + off;
+ qsort(set->ids, set->cnt, sizeof(set->ids[0]), cmp_id);
+ } else {
+ set8 = data->d_buf + off;
+ /*
+ * Make sure id is at the beginning of the pairs
+ * struct, otherwise the below qsort would not work.
+ */
+ BUILD_BUG_ON(set8->pairs != &set8->pairs[0].id);
+ qsort(set8->pairs, set8->cnt, sizeof(set8->pairs[0]), cmp_id);
- pr_debug("sorting addr %5lu: cnt %6d [%s]\n",
- (idx + 1) * sizeof(int), cnt, id->name);
+ /*
+ * When ELF endianness does not match endianness of the
+ * host, libelf will do the translation when updating
+ * the ELF. This, however, corrupts SET8 flags which are
+ * already in the target endianness. So, let's bswap
+ * them to the host endianness and libelf will then
+ * correctly translate everything.
+ */
+ if (obj->efile.encoding != ELFDATANATIVE) {
+ int i;
+
+ set8->flags = bswap_32(set8->flags);
+ for (i = 0; i < set8->cnt; i++) {
+ set8->pairs[i].flags =
+ bswap_32(set8->pairs[i].flags);
+ }
+ }
+ }
- qsort(base, cnt, id->is_set8 ? sizeof(uint64_t) : sizeof(int), cmp_id);
+ pr_debug("sorting addr %5lu: cnt %6d [%s]\n",
+ off, id->is_set ? set->cnt : set8->cnt, id->name);
next = rb_next(next);
}