diff mbox series

[bpf-next,v3,10/15] libbpf: replace elf_state->st_ops_* fields with SEC_ST_OPS sec_type

Message ID 20240304225156.24765-11-eddyz87@gmail.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series libbpf: type suffixes and autocreate flag for struct_ops maps | expand

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Commit Message

Eduard Zingerman March 4, 2024, 10:51 p.m. UTC 
The next patch would add two new section names for struct_ops maps.
To make working with multiple struct_ops sections more convenient:
- remove fields like elf_state->st_ops_{shndx,link_shndx};
- mark section descriptions hosting struct_ops as
  elf_sec_desc->sec_type == SEC_ST_OPS;

After these changes struct_ops sections could be processed uniformly
by iterating bpf_object->efile.secs entries.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
---
 tools/lib/bpf/libbpf.c | 62 ++++++++++++++++++++++--------------------
 1 file changed, 33 insertions(+), 29 deletions(-)

Comments

Andrii Nakryiko March 5, 2024, 7:53 p.m. UTC | #1 
On Mon, Mar 4, 2024 at 2:52 PM Eduard Zingerman <eddyz87@gmail.com> wrote:
>
> The next patch would add two new section names for struct_ops maps.
> To make working with multiple struct_ops sections more convenient:
> - remove fields like elf_state->st_ops_{shndx,link_shndx};
> - mark section descriptions hosting struct_ops as
>   elf_sec_desc->sec_type == SEC_ST_OPS;
>
> After these changes struct_ops sections could be processed uniformly
> by iterating bpf_object->efile.secs entries.
>
> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
> ---
>  tools/lib/bpf/libbpf.c | 62 ++++++++++++++++++++++--------------------
>  1 file changed, 33 insertions(+), 29 deletions(-)
>

Makes sense and a good generalization!

Acked-by: Andrii Nakryiko <andrii@kernel.org>

[...]

> @@ -1268,7 +1266,7 @@ static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj)
>  }
>
>  static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name,
> -                               int shndx, Elf_Data *data, __u32 map_flags)
> +                               int shndx, Elf_Data *data)
>  {
>         const struct btf_type *type, *datasec;
>         const struct btf_var_secinfo *vsi;
> @@ -1330,7 +1328,8 @@ static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name,
>                 map->def.key_size = sizeof(int);
>                 map->def.value_size = type->size;
>                 map->def.max_entries = 1;
> -               map->def.map_flags = map_flags;
> +               map->def.map_flags = strcmp(sec_name, STRUCT_OPS_LINK_SEC) == 0
> +                                  ? BPF_F_LINK : 0;

Does it fit in under 100 characters? if yes, please keep on a single line

>
>                 map->st_ops = calloc(1, sizeof(*map->st_ops));
>                 if (!map->st_ops)

[...]
Eduard Zingerman March 6, 2024, 1:08 a.m. UTC | #2 
On Tue, 2024-03-05 at 11:53 -0800, Andrii Nakryiko wrote:
> On Mon, Mar 4, 2024 at 2:52 PM Eduard Zingerman <eddyz87@gmail.com> wrote:
> > 
> > The next patch would add two new section names for struct_ops maps.
> > To make working with multiple struct_ops sections more convenient:
> > - remove fields like elf_state->st_ops_{shndx,link_shndx};
> > - mark section descriptions hosting struct_ops as
> >   elf_sec_desc->sec_type == SEC_ST_OPS;
> > 
> > After these changes struct_ops sections could be processed uniformly
> > by iterating bpf_object->efile.secs entries.
> > 
> > Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
> > ---
> >  tools/lib/bpf/libbpf.c | 62 ++++++++++++++++++++++--------------------
> >  1 file changed, 33 insertions(+), 29 deletions(-)
> > 
> 
> Makes sense and a good generalization!

Thank you.

[...]

> > @@ -1330,7 +1328,8 @@ static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name,
> >                 map->def.key_size = sizeof(int);
> >                 map->def.value_size = type->size;
> >                 map->def.max_entries = 1;
> > -               map->def.map_flags = map_flags;
> > +               map->def.map_flags = strcmp(sec_name, STRUCT_OPS_LINK_SEC) == 0
> > +                                  ? BPF_F_LINK : 0;
> 
> Does it fit in under 100 characters? if yes, please keep on a single line

Done

[...]
diff mbox series

Patch

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ce39ae34fec0..4ef3902e65db 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -612,6 +612,7 @@  enum sec_type {
 	SEC_BSS,
 	SEC_DATA,
 	SEC_RODATA,
+	SEC_ST_OPS,
 };
 
 struct elf_sec_desc {
@@ -627,8 +628,6 @@  struct elf_state {
 	Elf *elf;
 	Elf64_Ehdr *ehdr;
 	Elf_Data *symbols;
-	Elf_Data *st_ops_data;
-	Elf_Data *st_ops_link_data;
 	size_t shstrndx; /* section index for section name strings */
 	size_t strtabidx;
 	struct elf_sec_desc *secs;
@@ -637,8 +636,7 @@  struct elf_state {
 	__u32 btf_maps_sec_btf_id;
 	int text_shndx;
 	int symbols_shndx;
-	int st_ops_shndx;
-	int st_ops_link_shndx;
+	bool has_st_ops;
 };
 
 struct usdt_manager;
@@ -1268,7 +1266,7 @@  static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj)
 }
 
 static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name,
-				int shndx, Elf_Data *data, __u32 map_flags)
+				int shndx, Elf_Data *data)
 {
 	const struct btf_type *type, *datasec;
 	const struct btf_var_secinfo *vsi;
@@ -1330,7 +1328,8 @@  static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name,
 		map->def.key_size = sizeof(int);
 		map->def.value_size = type->size;
 		map->def.max_entries = 1;
-		map->def.map_flags = map_flags;
+		map->def.map_flags = strcmp(sec_name, STRUCT_OPS_LINK_SEC) == 0
+				   ? BPF_F_LINK : 0;
 
 		map->st_ops = calloc(1, sizeof(*map->st_ops));
 		if (!map->st_ops)
@@ -1365,15 +1364,25 @@  static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name,
 
 static int bpf_object_init_struct_ops(struct bpf_object *obj)
 {
-	int err;
+	const char *sec_name;
+	int sec_idx, err;
 
-	err = init_struct_ops_maps(obj, STRUCT_OPS_SEC, obj->efile.st_ops_shndx,
-				   obj->efile.st_ops_data, 0);
-	err = err ?: init_struct_ops_maps(obj, STRUCT_OPS_LINK_SEC,
-					  obj->efile.st_ops_link_shndx,
-					  obj->efile.st_ops_link_data,
-					  BPF_F_LINK);
-	return err;
+	for (sec_idx = 0; sec_idx < obj->efile.sec_cnt; ++sec_idx) {
+		struct elf_sec_desc *desc = &obj->efile.secs[sec_idx];
+
+		if (desc->sec_type != SEC_ST_OPS)
+			continue;
+
+		sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
+		if (!sec_name)
+			return -LIBBPF_ERRNO__FORMAT;
+
+		err = init_struct_ops_maps(obj, sec_name, sec_idx, desc->data);
+		if (err)
+			return err;
+	}
+
+	return 0;
 }
 
 static struct bpf_object *bpf_object__new(const char *path,
@@ -1411,8 +1420,6 @@  static struct bpf_object *bpf_object__new(const char *path,
 	obj->efile.obj_buf = obj_buf;
 	obj->efile.obj_buf_sz = obj_buf_sz;
 	obj->efile.btf_maps_shndx = -1;
-	obj->efile.st_ops_shndx = -1;
-	obj->efile.st_ops_link_shndx = -1;
 	obj->kconfig_map_idx = -1;
 
 	obj->kern_version = get_kernel_version();
@@ -1429,8 +1436,6 @@  static void bpf_object__elf_finish(struct bpf_object *obj)
 	elf_end(obj->efile.elf);
 	obj->efile.elf = NULL;
 	obj->efile.symbols = NULL;
-	obj->efile.st_ops_data = NULL;
-	obj->efile.st_ops_link_data = NULL;
 
 	zfree(&obj->efile.secs);
 	obj->efile.sec_cnt = 0;
@@ -2975,14 +2980,13 @@  static int bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
 static bool libbpf_needs_btf(const struct bpf_object *obj)
 {
 	return obj->efile.btf_maps_shndx >= 0 ||
-	       obj->efile.st_ops_shndx >= 0 ||
-	       obj->efile.st_ops_link_shndx >= 0 ||
+	       obj->efile.has_st_ops ||
 	       obj->nr_extern > 0;
 }
 
 static bool kernel_needs_btf(const struct bpf_object *obj)
 {
-	return obj->efile.st_ops_shndx >= 0 || obj->efile.st_ops_link_shndx >= 0;
+	return obj->efile.has_st_ops;
 }
 
 static int bpf_object__init_btf(struct bpf_object *obj,
@@ -3683,12 +3687,12 @@  static int bpf_object__elf_collect(struct bpf_object *obj)
 				sec_desc->sec_type = SEC_RODATA;
 				sec_desc->shdr = sh;
 				sec_desc->data = data;
-			} else if (strcmp(name, STRUCT_OPS_SEC) == 0) {
-				obj->efile.st_ops_data = data;
-				obj->efile.st_ops_shndx = idx;
-			} else if (strcmp(name, STRUCT_OPS_LINK_SEC) == 0) {
-				obj->efile.st_ops_link_data = data;
-				obj->efile.st_ops_link_shndx = idx;
+			} else if (strcmp(name, STRUCT_OPS_SEC) == 0 ||
+				   strcmp(name, STRUCT_OPS_LINK_SEC) == 0) {
+				sec_desc->sec_type = SEC_ST_OPS;
+				sec_desc->shdr = sh;
+				sec_desc->data = data;
+				obj->efile.has_st_ops = true;
 			} else {
 				pr_info("elf: skipping unrecognized data section(%d) %s\n",
 					idx, name);
@@ -7001,12 +7005,12 @@  static int bpf_object__collect_relos(struct bpf_object *obj)
 		data = sec_desc->data;
 		idx = shdr->sh_info;
 
-		if (shdr->sh_type != SHT_REL) {
+		if (shdr->sh_type != SHT_REL || idx < 0 || idx >= obj->efile.sec_cnt) {
 			pr_warn("internal error at %d\n", __LINE__);
 			return -LIBBPF_ERRNO__INTERNAL;
 		}
 
-		if (idx == obj->efile.st_ops_shndx || idx == obj->efile.st_ops_link_shndx)
+		if (obj->efile.secs[idx].sec_type == SEC_ST_OPS)
 			err = bpf_object__collect_st_ops_relos(obj, shdr, data);
 		else if (idx == obj->efile.btf_maps_shndx)
 			err = bpf_object__collect_map_relos(obj, shdr, data);