Hello all,
This patch series offers improvements to the way .BTF_ids section data is created and later patched by resolve_btfids.
Patch #1 simplifies the byte-order translation in resolve_btfids while making it more resilient to future .BTF_ids encoding updates.
Patch #2 makes sure all BTF ID data is 4-byte aligned, and not only the .BTF_ids used for vmlinux.
Patch #3 syncs the above changes in btf_ids.h to tools/include, obviating a previous alignment fix in selftests/bpf.
Feedback and suggestions are welcome!
Best regards, Tony
Tony Ambardar (3): tools/resolve_btfids: Simplify handling cross-endian compilation bpf: btf: Ensure natural alignment of .BTF_ids section tools/bpf, selftests/bpf : Sync btf_ids.h to tools
include/linux/btf_ids.h | 1 + tools/bpf/resolve_btfids/main.c | 60 +++++--------- tools/include/linux/btf_ids.h | 80 +++++++++++++++++-- .../selftests/bpf/prog_tests/resolve_btfids.c | 6 -- 4 files changed, 97 insertions(+), 50 deletions(-)
Initially, the .BTF_ids section was created zero-filled and then patched with BTF IDs by resolve_btfids on the build host. Patching was done in native endianness and thus failed to work for cross-endian compile targets. This was fixed in [1] by using libelf-based translation to output patched data in target byte order.
The addition of 8-byte BTF sets in [2] lead to .BTF_ids creation with both target-endian values and zero-filled data to be later patched. This again broke cross-endian compilation as the already-correct target-endian values were translated on output by libelf [1]. The problem was worked around [3] by manually converting BTF SET8 values to native endianness, so that final libelf output translation yields data in target byte order.
Simplify and make the code more robust against future changes like [2] by employing libelf-based endian translation on both input and output, which is typical of libelf usage.
[1]: 61e8aeda9398 ("bpf: Fix libelf endian handling in resolv_btfids") [2]: ef2c6f370a63 ("tools/resolve_btfids: Add support for 8-byte BTF sets") [3]: 903fad439466 ("tools/resolve_btfids: Fix cross-compilation to non-host endianness")
CC: Viktor Malik vmalik@redhat.com Signed-off-by: Tony Ambardar tony.ambardar@gmail.com --- tools/bpf/resolve_btfids/main.c | 60 ++++++++++++--------------------- 1 file changed, 22 insertions(+), 38 deletions(-)
diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c index d54aaa0619df..9f1ab23ed014 100644 --- a/tools/bpf/resolve_btfids/main.c +++ b/tools/bpf/resolve_btfids/main.c @@ -90,14 +90,6 @@
#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; @@ -125,7 +117,6 @@ struct object { int idlist_shndx; size_t strtabidx; unsigned long idlist_addr; - int encoding; } efile;
struct rb_root sets; @@ -325,11 +316,30 @@ static int compressed_section_fix(Elf *elf, Elf_Scn *scn, GElf_Shdr *sh) return 0; }
+static int btfids_endian_fix(struct object *obj) +{ + Elf_Data *btfids = obj->efile.idlist; + Elf *elf = obj->efile.elf; + int file_byteorder; + + /* This should always succeed due to prior ELF checks */ + file_byteorder = elf_getident(elf, NULL)[EI_DATA]; + + /* Set type to ensure endian translation occurs, and manually invoke + * translation on input since .BTF_ids section as created disables it. + */ + btfids->d_type = ELF_T_WORD; + if (gelf_xlatetom(elf, btfids, btfids, file_byteorder) == NULL) { + pr_err("FAILED xlatetom .BTF_ids data: %s\n", elf_errmsg(-1)); + return -1; + } + return 0; +} + static int elf_collect(struct object *obj) { Elf_Scn *scn = NULL; size_t shdrstrndx; - GElf_Ehdr ehdr; int idx = 0; Elf *elf; int fd; @@ -361,13 +371,6 @@ 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. @@ -409,6 +412,8 @@ static int elf_collect(struct object *obj) obj->efile.idlist = data; obj->efile.idlist_shndx = idx; obj->efile.idlist_addr = sh.sh_addr; + if (btfids_endian_fix(obj)) + return -1; } else if (!strcmp(name, BTF_BASE_ELF_SEC)) { /* If a .BTF.base section is found, do not resolve * BTF ids relative to vmlinux; resolve relative @@ -706,24 +711,6 @@ static int sets_patch(struct object *obj) */ BUILD_BUG_ON((u32 *)set8->pairs != &set8->pairs[0].id); qsort(set8->pairs, set8->cnt, sizeof(set8->pairs[0]), cmp_id); - - /* - * 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); - } - } }
pr_debug("sorting addr %5lu: cnt %6d [%s]\n", @@ -748,9 +735,6 @@ static int symbols_patch(struct object *obj) if (sets_patch(obj)) return -1;
- /* Set type to ensure endian translation occurs. */ - obj->efile.idlist->d_type = ELF_T_WORD; - elf_flagdata(obj->efile.idlist, ELF_C_SET, ELF_F_DIRTY);
err = elf_update(obj->efile.elf, ELF_C_WRITE);
On Fri, 2024-09-20 at 00:49 -0700, Tony Ambardar wrote:
Initially, the .BTF_ids section was created zero-filled and then patched with BTF IDs by resolve_btfids on the build host. Patching was done in native endianness and thus failed to work for cross-endian compile targets. This was fixed in [1] by using libelf-based translation to output patched data in target byte order.
The addition of 8-byte BTF sets in [2] lead to .BTF_ids creation with both target-endian values and zero-filled data to be later patched. This again broke cross-endian compilation as the already-correct target-endian values were translated on output by libelf [1]. The problem was worked around [3] by manually converting BTF SET8 values to native endianness, so that final libelf output translation yields data in target byte order.
Simplify and make the code more robust against future changes like [2] by employing libelf-based endian translation on both input and output, which is typical of libelf usage.
CC: Viktor Malik vmalik@redhat.com Signed-off-by: Tony Ambardar tony.ambardar@gmail.com
Acked-by: Eduard Zingerman eddyz87@gmail.com
[...]
On Fri, Sep 20, 2024 at 12:49:11AM -0700, Tony Ambardar wrote:
SNIP
+static int btfids_endian_fix(struct object *obj) +{
- Elf_Data *btfids = obj->efile.idlist;
- Elf *elf = obj->efile.elf;
- int file_byteorder;
- /* This should always succeed due to prior ELF checks */
- file_byteorder = elf_getident(elf, NULL)[EI_DATA];
- /* Set type to ensure endian translation occurs, and manually invoke
* translation on input since .BTF_ids section as created disables it.*/- btfids->d_type = ELF_T_WORD;
- if (gelf_xlatetom(elf, btfids, btfids, file_byteorder) == NULL) {
pr_err("FAILED xlatetom .BTF_ids data: %s\n", elf_errmsg(-1));return -1;- }
- return 0;
+}
static int elf_collect(struct object *obj) { Elf_Scn *scn = NULL; size_t shdrstrndx;
- GElf_Ehdr ehdr; int idx = 0; Elf *elf; int fd;
@@ -361,13 +371,6 @@ 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.
@@ -409,6 +412,8 @@ static int elf_collect(struct object *obj) obj->efile.idlist = data; obj->efile.idlist_shndx = idx; obj->efile.idlist_addr = sh.sh_addr;
if (btfids_endian_fix(obj))return -1;
nit, it'd be bit more clear to me without using the btfids_endian_fix function and just unwind it in here.. but anyway lgtm
Acked-by: Jiri Olsa jolsa@kernel.org
jirka
} else if (!strcmp(name, BTF_BASE_ELF_SEC)) { /* If a .BTF.base section is found, do not resolve * BTF ids relative to vmlinux; resolve relative@@ -706,24 +711,6 @@ static int sets_patch(struct object *obj) */ BUILD_BUG_ON((u32 *)set8->pairs != &set8->pairs[0].id); qsort(set8->pairs, set8->cnt, sizeof(set8->pairs[0]), cmp_id);
/** 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);}}pr_debug("sorting addr %5lu: cnt %6d [%s]\n", @@ -748,9 +735,6 @@ static int symbols_patch(struct object *obj) if (sets_patch(obj)) return -1;
- /* Set type to ensure endian translation occurs. */
- obj->efile.idlist->d_type = ELF_T_WORD;
- elf_flagdata(obj->efile.idlist, ELF_C_SET, ELF_F_DIRTY);
err = elf_update(obj->efile.elf, ELF_C_WRITE); -- 2.34.1
On 9/20/24 09:49, Tony Ambardar wrote:
Initially, the .BTF_ids section was created zero-filled and then patched with BTF IDs by resolve_btfids on the build host. Patching was done in native endianness and thus failed to work for cross-endian compile targets. This was fixed in [1] by using libelf-based translation to output patched data in target byte order.
The addition of 8-byte BTF sets in [2] lead to .BTF_ids creation with both target-endian values and zero-filled data to be later patched. This again broke cross-endian compilation as the already-correct target-endian values were translated on output by libelf [1]. The problem was worked around [3] by manually converting BTF SET8 values to native endianness, so that final libelf output translation yields data in target byte order.
Simplify and make the code more robust against future changes like [2] by employing libelf-based endian translation on both input and output, which is typical of libelf usage.
CC: Viktor Malik vmalik@redhat.com Signed-off-by: Tony Ambardar tony.ambardar@gmail.com
Acked-by: Viktor Malik vmalik@redhat.com
tools/bpf/resolve_btfids/main.c | 60 ++++++++++++--------------------- 1 file changed, 22 insertions(+), 38 deletions(-)
diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c index d54aaa0619df..9f1ab23ed014 100644 --- a/tools/bpf/resolve_btfids/main.c +++ b/tools/bpf/resolve_btfids/main.c @@ -90,14 +90,6 @@ #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; @@ -125,7 +117,6 @@ struct object { int idlist_shndx; size_t strtabidx; unsigned long idlist_addr;
int encoding;struct rb_root sets; @@ -325,11 +316,30 @@ static int compressed_section_fix(Elf *elf, Elf_Scn *scn, GElf_Shdr *sh) return 0; } +static int btfids_endian_fix(struct object *obj) +{
- Elf_Data *btfids = obj->efile.idlist;
- Elf *elf = obj->efile.elf;
- int file_byteorder;
- /* This should always succeed due to prior ELF checks */
- file_byteorder = elf_getident(elf, NULL)[EI_DATA];
- /* Set type to ensure endian translation occurs, and manually invoke
* translation on input since .BTF_ids section as created disables it.*/- btfids->d_type = ELF_T_WORD;
- if (gelf_xlatetom(elf, btfids, btfids, file_byteorder) == NULL) {
pr_err("FAILED xlatetom .BTF_ids data: %s\n", elf_errmsg(-1));return -1;- }
- return 0;
+}
static int elf_collect(struct object *obj) { Elf_Scn *scn = NULL; size_t shdrstrndx;
- GElf_Ehdr ehdr; int idx = 0; Elf *elf; int fd;
@@ -361,13 +371,6 @@ 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.
@@ -409,6 +412,8 @@ static int elf_collect(struct object *obj) obj->efile.idlist = data; obj->efile.idlist_shndx = idx; obj->efile.idlist_addr = sh.sh_addr;
if (btfids_endian_fix(obj))return -1;@@ -706,24 +711,6 @@ static int sets_patch(struct object *obj) */ BUILD_BUG_ON((u32 *)set8->pairs != &set8->pairs[0].id); qsort(set8->pairs, set8->cnt, sizeof(set8->pairs[0]), cmp_id);
/** 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);}}pr_debug("sorting addr %5lu: cnt %6d [%s]\n", @@ -748,9 +735,6 @@ static int symbols_patch(struct object *obj) if (sets_patch(obj)) return -1;
- /* Set type to ensure endian translation occurs. */
- obj->efile.idlist->d_type = ELF_T_WORD;
- elf_flagdata(obj->efile.idlist, ELF_C_SET, ELF_F_DIRTY);
err = elf_update(obj->efile.elf, ELF_C_WRITE);
While building of vmlinux employs a linker script to align the .BTF_ids section to 4 bytes, other usage leaves .BTF_ids unaligned and may lead to problems (e.g. [1]). Post-processing and libelf-based endian translation by resolve_btfids may also potentially suffer from misalignment.
Update encoding macros in btf_ids.h to always align BTF ID data to 4 bytes.
[1]: 3effc06a4dde ("selftests/bpf: Fix alignment of .BTF_ids")
Signed-off-by: Tony Ambardar tony.ambardar@gmail.com --- include/linux/btf_ids.h | 1 + 1 file changed, 1 insertion(+)
diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h index c0e3e1426a82..c10b163dc340 100644 --- a/include/linux/btf_ids.h +++ b/include/linux/btf_ids.h @@ -89,6 +89,7 @@ word \ #define __BTF_ID_LIST(name, scope) \ asm( \ ".pushsection " BTF_IDS_SECTION ","a"; \n" \ +".balign 4, 0; \n" \ "." #scope " " #name "; \n" \ #name ":; \n" \ ".popsection; \n");
On Fri, 2024-09-20 at 00:49 -0700, Tony Ambardar wrote:
While building of vmlinux employs a linker script to align the .BTF_ids section to 4 bytes, other usage leaves .BTF_ids unaligned and may lead to problems (e.g. [1]). Post-processing and libelf-based endian translation by resolve_btfids may also potentially suffer from misalignment.
Update encoding macros in btf_ids.h to always align BTF ID data to 4 bytes.
Signed-off-by: Tony Ambardar tony.ambardar@gmail.com
include/linux/btf_ids.h | 1 + 1 file changed, 1 insertion(+)
diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h index c0e3e1426a82..c10b163dc340 100644 --- a/include/linux/btf_ids.h +++ b/include/linux/btf_ids.h @@ -89,6 +89,7 @@ word \ #define __BTF_ID_LIST(name, scope) \ asm( \ ".pushsection " BTF_IDS_SECTION ","a"; \n" \ +".balign 4, 0; \n" \ "." #scope " " #name "; \n" \ #name ":; \n" \ ".popsection; \n");
This forces all id list symbols to be aligned on 4 bytes. Should the same be done for __BTF_SET_START?
Also, is it guaranteed that all btf ids are organized in lists and sets? Grepping through the code it seems they are, but it looks like resolve_btfids does not really enforce this, simply looking for symbols matching a special name __BTF_ID__<type>__<symbol>[__<id>] .
On Sat, Sep 21, 2024 at 02:46:17AM -0700, Eduard Zingerman wrote:
On Fri, 2024-09-20 at 00:49 -0700, Tony Ambardar wrote:
While building of vmlinux employs a linker script to align the .BTF_ids section to 4 bytes, other usage leaves .BTF_ids unaligned and may lead to problems (e.g. [1]). Post-processing and libelf-based endian translation by resolve_btfids may also potentially suffer from misalignment.
Update encoding macros in btf_ids.h to always align BTF ID data to 4 bytes.
Signed-off-by: Tony Ambardar tony.ambardar@gmail.com
include/linux/btf_ids.h | 1 + 1 file changed, 1 insertion(+)
diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h index c0e3e1426a82..c10b163dc340 100644 --- a/include/linux/btf_ids.h +++ b/include/linux/btf_ids.h @@ -89,6 +89,7 @@ word \ #define __BTF_ID_LIST(name, scope) \ asm( \ ".pushsection " BTF_IDS_SECTION ","a"; \n" \ +".balign 4, 0; \n" \ "." #scope " " #name "; \n" \ #name ":; \n" \ ".popsection; \n");
This forces all id list symbols to be aligned on 4 bytes. Should the same be done for __BTF_SET_START?
it seems all the set macros use __BTF_ID_LIST, so it should be taken care of by that
Also, is it guaranteed that all btf ids are organized in lists and sets? Grepping through the code it seems they are, but it looks like resolve_btfids does not really enforce this, simply looking for symbols matching a special name __BTF_ID__<type>__<symbol>[__<id>] .
yes, you need the BTF_ID to be part of list or set to be able to access it
resolve_btfids does not enforce some loose BTF_ID definition without list/set, but that does not seem to be a problem
thanks, jirka
On Mon, 2024-09-23 at 12:54 +0200, Jiri Olsa wrote:
[...]
diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h index c0e3e1426a82..c10b163dc340 100644 --- a/include/linux/btf_ids.h +++ b/include/linux/btf_ids.h @@ -89,6 +89,7 @@ word \ #define __BTF_ID_LIST(name, scope) \ asm( \ ".pushsection " BTF_IDS_SECTION ","a"; \n" \ +".balign 4, 0; \n" \ "." #scope " " #name "; \n" \ #name ":; \n" \ ".popsection; \n");
This forces all id list symbols to be aligned on 4 bytes. Should the same be done for __BTF_SET_START?
it seems all the set macros use __BTF_ID_LIST, so it should be taken care of by that
Apologies, I don't know how I missed __BTF_ID_LIST invocation in the __BTF_SET_START definition :(
Also, is it guaranteed that all btf ids are organized in lists and sets? Grepping through the code it seems they are, but it looks like resolve_btfids does not really enforce this, simply looking for symbols matching a special name __BTF_ID__<type>__<symbol>[__<id>] .
yes, you need the BTF_ID to be part of list or set to be able to access it
resolve_btfids does not enforce some loose BTF_ID definition without list/set, but that does not seem to be a problem
Understood, thank you.
Update to include latest changes, including BTF_SET8 support and correct alignment of .BTF_ids sections, and remove the now-redundant alignment fix introduced in 3effc06a4dde ("selftests/bpf: Fix alignment of .BTF_ids").
CC: Jean-Philippe Brucker jean-philippe@linaro.org Signed-off-by: Tony Ambardar tony.ambardar@gmail.com --- tools/include/linux/btf_ids.h | 80 +++++++++++++++++-- .../selftests/bpf/prog_tests/resolve_btfids.c | 6 -- 2 files changed, 74 insertions(+), 12 deletions(-)
diff --git a/tools/include/linux/btf_ids.h b/tools/include/linux/btf_ids.h index 72ea363d434d..3ba37d00e3ae 100644 --- a/tools/include/linux/btf_ids.h +++ b/tools/include/linux/btf_ids.h @@ -10,6 +10,9 @@ struct btf_id_set { u32 ids[]; };
+/* This flag implies BTF_SET8 holds kfunc(s) */ +#define BTF_SET8_KFUNCS (1 << 0) + struct btf_id_set8 { u32 cnt; u32 flags; @@ -21,7 +24,8 @@ struct btf_id_set8 {
#ifdef CONFIG_DEBUG_INFO_BTF
-#include <linux/compiler.h> /* for __PASTE */ +#include <linux/compiler.h> /* for __PASTE and __maybe_unused */ +#include <linux/stringify.h>
/* * Following macros help to define lists of BTF IDs placed @@ -35,7 +39,7 @@ struct btf_id_set8 {
#define BTF_IDS_SECTION ".BTF_ids"
-#define ____BTF_ID(symbol) \ +#define ____BTF_ID(symbol, word) \ asm( \ ".pushsection " BTF_IDS_SECTION ","a"; \n" \ ".local " #symbol " ; \n" \ @@ -43,10 +47,11 @@ asm( \ ".size " #symbol ", 4; \n" \ #symbol ": \n" \ ".zero 4 \n" \ +word \ ".popsection; \n");
-#define __BTF_ID(symbol) \ - ____BTF_ID(symbol) +#define __BTF_ID(symbol, word) \ + ____BTF_ID(symbol, word)
#define __ID(prefix) \ __PASTE(__PASTE(prefix, __COUNTER__), __LINE__) @@ -56,7 +61,14 @@ asm( \ * to 4 zero bytes. */ #define BTF_ID(prefix, name) \ - __BTF_ID(__ID(__BTF_ID__##prefix##__##name##__)) + __BTF_ID(__ID(__BTF_ID__##prefix##__##name##__), "") + +#define ____BTF_ID_FLAGS(prefix, name, flags) \ + __BTF_ID(__ID(__BTF_ID__##prefix##__##name##__), ".long " #flags "\n") +#define __BTF_ID_FLAGS(prefix, name, flags, ...) \ + ____BTF_ID_FLAGS(prefix, name, flags) +#define BTF_ID_FLAGS(prefix, name, ...) \ + __BTF_ID_FLAGS(prefix, name, ##__VA_ARGS__, 0)
/* * The BTF_ID_LIST macro defines pure (unsorted) list @@ -76,6 +88,7 @@ asm( \ #define __BTF_ID_LIST(name, scope) \ asm( \ ".pushsection " BTF_IDS_SECTION ","a"; \n" \ +".balign 4, 0; \n" \ "." #scope " " #name "; \n" \ #name ":; \n" \ ".popsection; \n"); @@ -155,10 +168,58 @@ asm( \ ".popsection; \n"); \ extern struct btf_id_set name;
+/* + * The BTF_SET8_START/END macros pair defines sorted list of + * BTF IDs and their flags plus its members count, with the + * following layout: + * + * BTF_SET8_START(list) + * BTF_ID_FLAGS(type1, name1, flags) + * BTF_ID_FLAGS(type2, name2, flags) + * BTF_SET8_END(list) + * + * __BTF_ID__set8__list: + * .zero 8 + * list: + * __BTF_ID__type1__name1__3: + * .zero 4 + * .word (1 << 0) | (1 << 2) + * __BTF_ID__type2__name2__5: + * .zero 4 + * .word (1 << 3) | (1 << 1) | (1 << 2) + * + */ +#define __BTF_SET8_START(name, scope, flags) \ +__BTF_ID_LIST(name, local) \ +asm( \ +".pushsection " BTF_IDS_SECTION ","a"; \n" \ +"." #scope " __BTF_ID__set8__" #name "; \n" \ +"__BTF_ID__set8__" #name ":; \n" \ +".zero 4 \n" \ +".long " __stringify(flags) "\n" \ +".popsection; \n"); + +#define BTF_SET8_START(name) \ +__BTF_SET8_START(name, local, 0) + +#define BTF_SET8_END(name) \ +asm( \ +".pushsection " BTF_IDS_SECTION ","a"; \n" \ +".size __BTF_ID__set8__" #name ", .-" #name " \n" \ +".popsection; \n"); \ +extern struct btf_id_set8 name; + +#define BTF_KFUNCS_START(name) \ +__BTF_SET8_START(name, local, BTF_SET8_KFUNCS) + +#define BTF_KFUNCS_END(name) \ +BTF_SET8_END(name) + #else
-#define BTF_ID_LIST(name) static u32 __maybe_unused name[5]; +#define BTF_ID_LIST(name) static u32 __maybe_unused name[64]; #define BTF_ID(prefix, name) +#define BTF_ID_FLAGS(prefix, name, ...) #define BTF_ID_UNUSED #define BTF_ID_LIST_GLOBAL(name, n) u32 __maybe_unused name[n]; #define BTF_ID_LIST_SINGLE(name, prefix, typename) static u32 __maybe_unused name[1]; @@ -166,6 +227,10 @@ extern struct btf_id_set name; #define BTF_SET_START(name) static struct btf_id_set __maybe_unused name = { 0 }; #define BTF_SET_START_GLOBAL(name) static struct btf_id_set __maybe_unused name = { 0 }; #define BTF_SET_END(name) +#define BTF_SET8_START(name) static struct btf_id_set8 __maybe_unused name = { 0 }; +#define BTF_SET8_END(name) +#define BTF_KFUNCS_START(name) static struct btf_id_set8 __maybe_unused name = { .flags = BTF_SET8_KFUNCS }; +#define BTF_KFUNCS_END(name)
#endif /* CONFIG_DEBUG_INFO_BTF */
@@ -215,5 +280,8 @@ MAX_BTF_TRACING_TYPE, };
extern u32 btf_tracing_ids[]; +extern u32 bpf_cgroup_btf_id[]; +extern u32 bpf_local_storage_map_btf_id[]; +extern u32 btf_bpf_map_id[];
#endif diff --git a/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c b/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c index 51544372f52e..c3c021e3783e 100644 --- a/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c +++ b/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c @@ -28,12 +28,6 @@ struct symbol test_symbols[] = { { "func", BTF_KIND_FUNC, -1 }, };
-/* Align the .BTF_ids section to 4 bytes */ -asm ( -".pushsection " BTF_IDS_SECTION " ,"a"; \n" -".balign 4, 0; \n" -".popsection; \n"); - BTF_ID_LIST(test_list_local) BTF_ID_UNUSED BTF_ID(typedef, S)
On Fri, Sep 20, 2024 at 12:49:10AM -0700, Tony Ambardar wrote:
Hello all,
This patch series offers improvements to the way .BTF_ids section data is created and later patched by resolve_btfids.
Patch #1 simplifies the byte-order translation in resolve_btfids while making it more resilient to future .BTF_ids encoding updates.
Patch #2 makes sure all BTF ID data is 4-byte aligned, and not only the .BTF_ids used for vmlinux.
Patch #3 syncs the above changes in btf_ids.h to tools/include, obviating a previous alignment fix in selftests/bpf.
Feedback and suggestions are welcome!
Best regards, Tony
nice, thanks for the fix
Jean-Philippe, Viktor, any chance you could check/test this patchset? it changes your recent cross building fixes
thanks, jirka
Tony Ambardar (3): tools/resolve_btfids: Simplify handling cross-endian compilation bpf: btf: Ensure natural alignment of .BTF_ids section tools/bpf, selftests/bpf : Sync btf_ids.h to tools
include/linux/btf_ids.h | 1 + tools/bpf/resolve_btfids/main.c | 60 +++++--------- tools/include/linux/btf_ids.h | 80 +++++++++++++++++-- .../selftests/bpf/prog_tests/resolve_btfids.c | 6 -- 4 files changed, 97 insertions(+), 50 deletions(-)
-- 2.34.1
linux-kselftest-mirror@lists.linaro.org
-
Eduard Zingerman -
Jiri Olsa -
Tony Ambardar -
Viktor Malik