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bpf: Add BTF_ID_LIST_GLOBAL in btf_ids.h

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Existing BTF_ID_LIST used a local static variable
to store btf_ids. This patch provided a new macro
BTF_ID_LIST_GLOBAL to store btf_ids in a global
variable which can be shared among multiple files.

The existing BTF_ID_LIST is still retained.
Two reasons. First, BTF_ID_LIST is also used to build
btf_ids for helper arguments which typically
is an array of 5. Since typically different
helpers have different signature, it makes
little sense to share them. Second, some
current computed btf_ids are indeed local.
If later those btf_ids are shared between
different files, they can use BTF_ID_LIST_GLOBAL then.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/bpf/20200720163401.1393159-1-yhs@fb.com
This commit is contained in:
Yonghong Song 2020-07-20 09:34:01 -07:00 committed by Alexei Starovoitov
parent d8dfe5bfe8
commit 0f12e584b2
3 changed files with 39 additions and 14 deletions
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10
include/linux/btf_ids.h
View File

@ -57,17 +57,20 @@ asm( \
* .zero 4
*
*/
#define __BTF_ID_LIST(name) \
#define __BTF_ID_LIST(name, scope) \
asm( \
".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \
".local " #name "; \n" \
"." #scope " " #name "; \n" \
#name ":; \n" \
".popsection; \n"); \
#define BTF_ID_LIST(name) \
__BTF_ID_LIST(name) \
__BTF_ID_LIST(name, local) \
extern u32 name[];
#define BTF_ID_LIST_GLOBAL(name) \
__BTF_ID_LIST(name, globl)
/*
* The BTF_ID_UNUSED macro defines 4 zero bytes.
* It's used when we want to define 'unused' entry
@ -90,6 +93,7 @@ asm( \
#define BTF_ID_LIST(name) static u32 name[5];
#define BTF_ID(prefix, name)
#define BTF_ID_UNUSED
#define BTF_ID_LIST_GLOBAL(name) u32 name[1];
#endif /* CONFIG_DEBUG_INFO_BTF */

10
tools/include/linux/btf_ids.h
View File

@ -57,17 +57,20 @@ asm( \
* .zero 4
*
*/
#define __BTF_ID_LIST(name) \
#define __BTF_ID_LIST(name, scope) \
asm( \
".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \
".local " #name "; \n" \
"." #scope " " #name "; \n" \
#name ":; \n" \
".popsection; \n"); \
#define BTF_ID_LIST(name) \
__BTF_ID_LIST(name) \
__BTF_ID_LIST(name, local) \
extern u32 name[];
#define BTF_ID_LIST_GLOBAL(name) \
__BTF_ID_LIST(name, globl)
/*
* The BTF_ID_UNUSED macro defines 4 zero bytes.
* It's used when we want to define 'unused' entry
@ -90,6 +93,7 @@ asm( \
#define BTF_ID_LIST(name) static u32 name[5];
#define BTF_ID(prefix, name)
#define BTF_ID_UNUSED
#define BTF_ID_LIST_GLOBAL(name) u32 name[1];
#endif /* CONFIG_DEBUG_INFO_BTF */

33
tools/testing/selftests/bpf/prog_tests/resolve_btfids.c
View File

@ -28,7 +28,17 @@ struct symbol test_symbols[] = {
{ "func", BTF_KIND_FUNC, -1 },
};
BTF_ID_LIST(test_list)
BTF_ID_LIST(test_list_local)
BTF_ID_UNUSED
BTF_ID(typedef, S)
BTF_ID(typedef, T)
BTF_ID(typedef, U)
BTF_ID(struct, S)
BTF_ID(union, U)
BTF_ID(func, func)
extern __u32 test_list_global[];
BTF_ID_LIST_GLOBAL(test_list_global)
BTF_ID_UNUSED
BTF_ID(typedef, S)
BTF_ID(typedef, T)
@ -94,18 +104,25 @@ static int resolve_symbols(void)
int test_resolve_btfids(void)
{
unsigned int i;
__u32 *test_list, *test_lists[] = { test_list_local, test_list_global };
unsigned int i, j;
int ret = 0;
if (resolve_symbols())
return -1;
/* Check BTF_ID_LIST(test_list) IDs */
for (i = 0; i < ARRAY_SIZE(test_symbols) && !ret; i++) {
ret = CHECK(test_list[i] != test_symbols[i].id,
"id_check",
"wrong ID for %s (%d != %d)\n", test_symbols[i].name,
test_list[i], test_symbols[i].id);
/* Check BTF_ID_LIST(test_list_local) and
* BTF_ID_LIST_GLOBAL(test_list_global) IDs
*/
for (j = 0; j < ARRAY_SIZE(test_lists); j++) {
test_list = test_lists[j];
for (i = 0; i < ARRAY_SIZE(test_symbols) && !ret; i++) {
ret = CHECK(test_list[i] != test_symbols[i].id,
"id_check",
"wrong ID for %s (%d != %d)\n",
test_symbols[i].name,
test_list[i], test_symbols[i].id);
}
}
return ret;