* [PATCH dwarves v6 0/3] pahole: Inject kfunc decl tags into BTF
@ 2024-03-25 17:53 Daniel Xu
2024-03-25 17:53 ` [PATCH dwarves v6 1/3] gobuffer: Add gobuffer__sort() helper Daniel Xu
` (3 more replies)
0 siblings, 4 replies; 9+ messages in thread
From: Daniel Xu @ 2024-03-25 17:53 UTC (permalink / raw
To: acme, jolsa, quentin, alan.maguire, eddyz87
Cc: andrii.nakryiko, ast, daniel, bpf
This patchset teaches pahole to parse symbols in .BTF_ids section in
vmlinux and discover exported kfuncs. Pahole then takes the list of
kfuncs and injects a BTF_KIND_DECL_TAG for each kfunc.
Example of encoding:
$ bpftool btf dump file .tmp_vmlinux.btf | rg "DECL_TAG 'bpf_kfunc'" | wc -l
121
$ bpftool btf dump file .tmp_vmlinux.btf | rg 56337
[56337] FUNC 'bpf_ct_change_timeout' type_id=56336 linkage=static
[127861] DECL_TAG 'bpf_kfunc' type_id=56337 component_idx=-1
This enables downstream users and tools to dynamically discover which
kfuncs are available on a system by parsing vmlinux or module BTF, both
available in /sys/kernel/btf.
This feature is enabled with --btf_features=decl_tag,decl_tag_kfuncs.
=== Changelog ===
Changes from v5:
* Add gobuffer__sort() helper
* Use strstarts() instead of strncmp()
* Use uint64_t instead of size_t
* Add clarifying comments for get_func_name()
Changes from v4:
* Update man page with decl_tag_kfuncs feature
* Fix release mode build warnings
* Add elf_getshrstrndx() error checking
* Disable tagging if decl_tag feature is off
* Fix malformed func name handling
Changes from v3:
* Guard kfunc tagging behind feature flag
* Use struct btf_id_set8 definition
* Remove unnecessary member from btf_encoder
* Fix code styling
Changes from v2:
* More reliably detect kfunc membership in set8 by tracking set addr ranges
* Rename some variables/functions to be more clear about kfunc vs func
Changes from v1:
* Fix resource leaks
* Fix callee -> caller typo
* Rename btf_decl_tag from kfunc -> bpf_kfunc
* Only grab btf_id_set funcs tagged kfunc
* Presort btf func list
Daniel Xu (3):
gobuffer: Add gobuffer__sort() helper
pahole: Add --btf_feature=decl_tag_kfuncs feature
pahole: Inject kfunc decl tags into BTF
btf_encoder.c | 374 +++++++++++++++++++++++++++++++++++++++++++++
dwarves.h | 1 +
gobuffer.c | 5 +
gobuffer.h | 2 +
man-pages/pahole.1 | 1 +
pahole.c | 1 +
6 files changed, 384 insertions(+)
--
2.44.0
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH dwarves v6 1/3] gobuffer: Add gobuffer__sort() helper
2024-03-25 17:53 [PATCH dwarves v6 0/3] pahole: Inject kfunc decl tags into BTF Daniel Xu
@ 2024-03-25 17:53 ` Daniel Xu
2024-04-17 9:20 ` Alan Maguire
2024-03-25 17:53 ` [PATCH dwarves v6 2/3] pahole: Add --btf_feature=decl_tag_kfuncs feature Daniel Xu
` (2 subsequent siblings)
3 siblings, 1 reply; 9+ messages in thread
From: Daniel Xu @ 2024-03-25 17:53 UTC (permalink / raw
To: acme, jolsa, quentin, alan.maguire, eddyz87
Cc: andrii.nakryiko, ast, daniel, bpf
Add a helper to sort the gobuffer. Trivial wrapper around qsort().
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
---
gobuffer.c | 5 +++++
gobuffer.h | 2 ++
2 files changed, 7 insertions(+)
diff --git a/gobuffer.c b/gobuffer.c
index 02b2084..4655339 100644
--- a/gobuffer.c
+++ b/gobuffer.c
@@ -102,6 +102,11 @@ void gobuffer__copy(const struct gobuffer *gb, void *dest)
}
}
+void gobuffer__sort(struct gobuffer *gb, unsigned int size, int (*compar)(const void *, const void *))
+{
+ qsort((void *)gb->entries, gb->nr_entries, size, compar);
+}
+
const void *gobuffer__compress(struct gobuffer *gb, unsigned int *size)
{
z_stream z = {
diff --git a/gobuffer.h b/gobuffer.h
index a12c5c8..cd218b6 100644
--- a/gobuffer.h
+++ b/gobuffer.h
@@ -21,6 +21,8 @@ void __gobuffer__delete(struct gobuffer *gb);
void gobuffer__copy(const struct gobuffer *gb, void *dest);
+void gobuffer__sort(struct gobuffer *gb, unsigned int size, int (*compar)(const void *, const void *));
+
int gobuffer__add(struct gobuffer *gb, const void *s, unsigned int len);
int gobuffer__allocate(struct gobuffer *gb, unsigned int len);
--
2.44.0
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH dwarves v6 2/3] pahole: Add --btf_feature=decl_tag_kfuncs feature
2024-03-25 17:53 [PATCH dwarves v6 0/3] pahole: Inject kfunc decl tags into BTF Daniel Xu
2024-03-25 17:53 ` [PATCH dwarves v6 1/3] gobuffer: Add gobuffer__sort() helper Daniel Xu
@ 2024-03-25 17:53 ` Daniel Xu
2024-03-25 17:53 ` [PATCH dwarves v6 3/3] pahole: Inject kfunc decl tags into BTF Daniel Xu
2024-04-02 20:24 ` [PATCH dwarves v6 0/3] " Arnaldo Carvalho de Melo
3 siblings, 0 replies; 9+ messages in thread
From: Daniel Xu @ 2024-03-25 17:53 UTC (permalink / raw
To: acme, jolsa, quentin, alan.maguire, eddyz87
Cc: andrii.nakryiko, ast, daniel, bpf
Add a feature flag to guard tagging of kfuncs. The next commit will
implement the actual tagging.
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
---
btf_encoder.c | 2 ++
dwarves.h | 1 +
man-pages/pahole.1 | 1 +
pahole.c | 1 +
4 files changed, 5 insertions(+)
diff --git a/btf_encoder.c b/btf_encoder.c
index e1e3529..850e36f 100644
--- a/btf_encoder.c
+++ b/btf_encoder.c
@@ -75,6 +75,7 @@ struct btf_encoder {
verbose,
force,
gen_floats,
+ tag_kfuncs,
is_rel;
uint32_t array_index_id;
struct {
@@ -1659,6 +1660,7 @@ struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filenam
encoder->force = conf_load->btf_encode_force;
encoder->gen_floats = conf_load->btf_gen_floats;
encoder->skip_encoding_vars = conf_load->skip_encoding_btf_vars;
+ encoder->tag_kfuncs = conf_load->btf_decl_tag_kfuncs;
encoder->verbose = verbose;
encoder->has_index_type = false;
encoder->need_index_type = false;
diff --git a/dwarves.h b/dwarves.h
index 2393a6c..2a679bb 100644
--- a/dwarves.h
+++ b/dwarves.h
@@ -87,6 +87,7 @@ struct conf_load {
bool skip_encoding_btf_vars;
bool btf_gen_floats;
bool btf_encode_force;
+ bool btf_decl_tag_kfuncs;
uint8_t hashtable_bits;
uint8_t max_hashtable_bits;
uint16_t kabi_prefix_len;
diff --git a/man-pages/pahole.1 b/man-pages/pahole.1
index 2be165d..5ea41ff 100644
--- a/man-pages/pahole.1
+++ b/man-pages/pahole.1
@@ -308,6 +308,7 @@ Encode BTF using the specified feature list, or specify 'all' for all features s
in some CUs and not others, or when the same
function name has inconsistent BTF descriptions
in different CUs.
+ decl_tag_kfuncs Inject a BTF_KIND_DECL_TAG for each discovered kfunc.
.fi
So for example, specifying \-\-btf_encode=var,enum64 will result in a BTF encoding that (as well as encoding basic BTF information) will contain variables and enum64 values.
diff --git a/pahole.c b/pahole.c
index 0b9c2de..353a080 100644
--- a/pahole.c
+++ b/pahole.c
@@ -1281,6 +1281,7 @@ struct btf_feature {
BTF_FEATURE(enum64, skip_encoding_btf_enum64, true),
BTF_FEATURE(optimized_func, btf_gen_optimized, false),
BTF_FEATURE(consistent_func, skip_encoding_btf_inconsistent_proto, false),
+ BTF_FEATURE(decl_tag_kfuncs, btf_decl_tag_kfuncs, false),
};
#define BTF_MAX_FEATURE_STR 1024
--
2.44.0
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH dwarves v6 3/3] pahole: Inject kfunc decl tags into BTF
2024-03-25 17:53 [PATCH dwarves v6 0/3] pahole: Inject kfunc decl tags into BTF Daniel Xu
2024-03-25 17:53 ` [PATCH dwarves v6 1/3] gobuffer: Add gobuffer__sort() helper Daniel Xu
2024-03-25 17:53 ` [PATCH dwarves v6 2/3] pahole: Add --btf_feature=decl_tag_kfuncs feature Daniel Xu
@ 2024-03-25 17:53 ` Daniel Xu
2024-04-17 9:32 ` Alan Maguire
2024-04-02 20:24 ` [PATCH dwarves v6 0/3] " Arnaldo Carvalho de Melo
3 siblings, 1 reply; 9+ messages in thread
From: Daniel Xu @ 2024-03-25 17:53 UTC (permalink / raw
To: acme, jolsa, quentin, alan.maguire, eddyz87
Cc: andrii.nakryiko, ast, daniel, bpf
This commit teaches pahole to parse symbols in .BTF_ids section in
vmlinux and discover exported kfuncs. Pahole then takes the list of
kfuncs and injects a BTF_KIND_DECL_TAG for each kfunc.
Example of encoding:
$ bpftool btf dump file .tmp_vmlinux.btf | rg "DECL_TAG 'bpf_kfunc'" | wc -l
121
$ bpftool btf dump file .tmp_vmlinux.btf | rg 56337
[56337] FUNC 'bpf_ct_change_timeout' type_id=56336 linkage=static
[127861] DECL_TAG 'bpf_kfunc' type_id=56337 component_idx=-1
This enables downstream users and tools to dynamically discover which
kfuncs are available on a system by parsing vmlinux or module BTF, both
available in /sys/kernel/btf.
This feature is enabled with --btf_features=decl_tag,decl_tag_kfuncs.
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
---
btf_encoder.c | 372 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 372 insertions(+)
diff --git a/btf_encoder.c b/btf_encoder.c
index 850e36f..d326404 100644
--- a/btf_encoder.c
+++ b/btf_encoder.c
@@ -34,6 +34,21 @@
#include <pthread.h>
#define BTF_ENCODER_MAX_PROTO 512
+#define BTF_IDS_SECTION ".BTF_ids"
+#define BTF_ID_FUNC_PFX "__BTF_ID__func__"
+#define BTF_ID_SET8_PFX "__BTF_ID__set8__"
+#define BTF_SET8_KFUNCS (1 << 0)
+#define BTF_KFUNC_TYPE_TAG "bpf_kfunc"
+
+/* Adapted from include/linux/btf_ids.h */
+struct btf_id_set8 {
+ uint32_t cnt;
+ uint32_t flags;
+ struct {
+ uint32_t id;
+ uint32_t flags;
+ } pairs[];
+};
/* state used to do later encoding of saved functions */
struct btf_encoder_state {
@@ -75,6 +90,7 @@ struct btf_encoder {
verbose,
force,
gen_floats,
+ skip_encoding_decl_tag,
tag_kfuncs,
is_rel;
uint32_t array_index_id;
@@ -94,6 +110,17 @@ struct btf_encoder {
} functions;
};
+struct btf_func {
+ const char *name;
+ int type_id;
+};
+
+/* Half open interval representing range of addresses containing kfuncs */
+struct btf_kfunc_set_range {
+ uint64_t start;
+ uint64_t end;
+};
+
static LIST_HEAD(encoders);
static pthread_mutex_t encoders__lock = PTHREAD_MUTEX_INITIALIZER;
@@ -1363,8 +1390,343 @@ out:
return err;
}
+/* Returns if `sym` points to a kfunc set */
+static int is_sym_kfunc_set(GElf_Sym *sym, const char *name, Elf_Data *idlist, size_t idlist_addr)
+{
+ void *ptr = idlist->d_buf;
+ struct btf_id_set8 *set;
+ int off;
+
+ /* kfuncs are only found in BTF_SET8's */
+ if (!strstarts(name, BTF_ID_SET8_PFX))
+ return false;
+
+ off = sym->st_value - idlist_addr;
+ if (off >= idlist->d_size) {
+ fprintf(stderr, "%s: symbol '%s' out of bounds\n", __func__, name);
+ return false;
+ }
+
+ /* Check the set8 flags to see if it was marked as kfunc */
+ set = ptr + off;
+ return set->flags & BTF_SET8_KFUNCS;
+}
+
+/*
+ * Parse BTF_ID symbol and return the func name.
+ *
+ * Returns:
+ * Caller-owned string containing func name if successful.
+ * NULL if !func or on error.
+ */
+static char *get_func_name(const char *sym)
+{
+ char *func, *end;
+
+ /* Example input: __BTF_ID__func__vfs_close__1
+ *
+ * The goal is to strip the prefix and suffix such that we only
+ * return vfs_close.
+ */
+
+ if (!strstarts(sym, BTF_ID_FUNC_PFX))
+ return NULL;
+
+ /* Strip prefix and handle malformed input such as __BTF_ID__func___ */
+ func = strdup(sym + sizeof(BTF_ID_FUNC_PFX) - 1);
+ if (strlen(func) < 2) {
+ free(func);
+ return NULL;
+ }
+
+ /* Strip suffix */
+ end = strrchr(func, '_');
+ if (!end || *(end - 1) != '_') {
+ free(func);
+ return NULL;
+ }
+ *(end - 1) = '\0';
+
+ return func;
+}
+
+static int btf_func_cmp(const void *_a, const void *_b)
+{
+ const struct btf_func *a = _a;
+ const struct btf_func *b = _b;
+
+ return strcmp(a->name, b->name);
+}
+
+/*
+ * Collects all functions described in BTF.
+ * Returns non-zero on error.
+ */
+static int btf_encoder__collect_btf_funcs(struct btf_encoder *encoder, struct gobuffer *funcs)
+{
+ struct btf *btf = encoder->btf;
+ int nr_types, type_id;
+ int err = -1;
+
+ /* First collect all the func entries into an array */
+ nr_types = btf__type_cnt(btf);
+ for (type_id = 1; type_id < nr_types; type_id++) {
+ const struct btf_type *type;
+ struct btf_func func = {};
+ const char *name;
+
+ type = btf__type_by_id(btf, type_id);
+ if (!type) {
+ fprintf(stderr, "%s: malformed BTF, can't resolve type for ID %d\n",
+ __func__, type_id);
+ err = -EINVAL;
+ goto out;
+ }
+
+ if (!btf_is_func(type))
+ continue;
+
+ name = btf__name_by_offset(btf, type->name_off);
+ if (!name) {
+ fprintf(stderr, "%s: malformed BTF, can't resolve name for ID %d\n",
+ __func__, type_id);
+ err = -EINVAL;
+ goto out;
+ }
+
+ func.name = name;
+ func.type_id = type_id;
+ err = gobuffer__add(funcs, &func, sizeof(func));
+ if (err < 0)
+ goto out;
+ }
+
+ /* Now that we've collected funcs, sort them by name */
+ gobuffer__sort(funcs, sizeof(struct btf_func), btf_func_cmp);
+
+ err = 0;
+out:
+ return err;
+}
+
+static int btf_encoder__tag_kfunc(struct btf_encoder *encoder, struct gobuffer *funcs, const char *kfunc)
+{
+ struct btf_func key = { .name = kfunc };
+ struct btf *btf = encoder->btf;
+ struct btf_func *target;
+ const void *base;
+ unsigned int cnt;
+ int err = -1;
+
+ base = gobuffer__entries(funcs);
+ cnt = gobuffer__nr_entries(funcs);
+ target = bsearch(&key, base, cnt, sizeof(key), btf_func_cmp);
+ if (!target) {
+ fprintf(stderr, "%s: failed to find kfunc '%s' in BTF\n", __func__, kfunc);
+ goto out;
+ }
+
+ /* Note we are unconditionally adding the btf_decl_tag even
+ * though vmlinux may already contain btf_decl_tags for kfuncs.
+ * We are ok to do this b/c we will later btf__dedup() to remove
+ * any duplicates.
+ */
+ err = btf__add_decl_tag(btf, BTF_KFUNC_TYPE_TAG, target->type_id, -1);
+ if (err < 0) {
+ fprintf(stderr, "%s: failed to insert kfunc decl tag for '%s': %d\n",
+ __func__, kfunc, err);
+ goto out;
+ }
+
+ err = 0;
+out:
+ return err;
+}
+
+static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder)
+{
+ const char *filename = encoder->filename;
+ struct gobuffer btf_kfunc_ranges = {};
+ struct gobuffer btf_funcs = {};
+ Elf_Data *symbols = NULL;
+ Elf_Data *idlist = NULL;
+ Elf_Scn *symscn = NULL;
+ int symbols_shndx = -1;
+ size_t idlist_addr = 0;
+ int fd = -1, err = -1;
+ int idlist_shndx = -1;
+ size_t strtabidx = 0;
+ Elf_Scn *scn = NULL;
+ Elf *elf = NULL;
+ GElf_Shdr shdr;
+ size_t strndx;
+ char *secname;
+ int nr_syms;
+ int i = 0;
+
+ fd = open(filename, O_RDONLY);
+ if (fd < 0) {
+ fprintf(stderr, "Cannot open %s\n", filename);
+ goto out;
+ }
+
+ if (elf_version(EV_CURRENT) == EV_NONE) {
+ elf_error("Cannot set libelf version");
+ goto out;
+ }
+
+ elf = elf_begin(fd, ELF_C_READ, NULL);
+ if (elf == NULL) {
+ elf_error("Cannot update ELF file");
+ goto out;
+ }
+
+ /* Locate symbol table and .BTF_ids sections */
+ if (elf_getshdrstrndx(elf, &strndx) < 0)
+ goto out;
+
+ while ((scn = elf_nextscn(elf, scn)) != NULL) {
+ Elf_Data *data;
+
+ i++;
+ if (!gelf_getshdr(scn, &shdr)) {
+ elf_error("Failed to get ELF section(%d) hdr", i);
+ goto out;
+ }
+
+ secname = elf_strptr(elf, strndx, shdr.sh_name);
+ if (!secname) {
+ elf_error("Failed to get ELF section(%d) hdr name", i);
+ goto out;
+ }
+
+ data = elf_getdata(scn, 0);
+ if (!data) {
+ elf_error("Failed to get ELF section(%d) data", i);
+ goto out;
+ }
+
+ if (shdr.sh_type == SHT_SYMTAB) {
+ symbols_shndx = i;
+ symscn = scn;
+ symbols = data;
+ strtabidx = shdr.sh_link;
+ } else if (!strcmp(secname, BTF_IDS_SECTION)) {
+ idlist_shndx = i;
+ idlist_addr = shdr.sh_addr;
+ idlist = data;
+ }
+ }
+
+ /* Cannot resolve symbol or .BTF_ids sections. Nothing to do. */
+ if (symbols_shndx == -1 || idlist_shndx == -1) {
+ err = 0;
+ goto out;
+ }
+
+ if (!gelf_getshdr(symscn, &shdr)) {
+ elf_error("Failed to get ELF symbol table header");
+ goto out;
+ }
+ nr_syms = shdr.sh_size / shdr.sh_entsize;
+
+ err = btf_encoder__collect_btf_funcs(encoder, &btf_funcs);
+ if (err) {
+ fprintf(stderr, "%s: failed to collect BTF funcs\n", __func__);
+ goto out;
+ }
+
+ /* First collect all kfunc set ranges.
+ *
+ * Note we choose not to sort these ranges and accept a linear
+ * search when doing lookups. Reasoning is that the number of
+ * sets is ~O(100) and not worth the additional code to optimize.
+ */
+ for (i = 0; i < nr_syms; i++) {
+ struct btf_kfunc_set_range range = {};
+ const char *name;
+ GElf_Sym sym;
+
+ if (!gelf_getsym(symbols, i, &sym)) {
+ elf_error("Failed to get ELF symbol(%d)", i);
+ goto out;
+ }
+
+ if (sym.st_shndx != idlist_shndx)
+ continue;
+
+ name = elf_strptr(elf, strtabidx, sym.st_name);
+ if (!is_sym_kfunc_set(&sym, name, idlist, idlist_addr))
+ continue;
+
+ range.start = sym.st_value;
+ range.end = sym.st_value + sym.st_size;
+ gobuffer__add(&btf_kfunc_ranges, &range, sizeof(range));
+ }
+
+ /* Now inject BTF with kfunc decl tag for detected kfuncs */
+ for (i = 0; i < nr_syms; i++) {
+ const struct btf_kfunc_set_range *ranges;
+ unsigned int ranges_cnt;
+ char *func, *name;
+ GElf_Sym sym;
+ bool found;
+ int err;
+ int j;
+
+ if (!gelf_getsym(symbols, i, &sym)) {
+ elf_error("Failed to get ELF symbol(%d)", i);
+ goto out;
+ }
+
+ if (sym.st_shndx != idlist_shndx)
+ continue;
+
+ name = elf_strptr(elf, strtabidx, sym.st_name);
+ func = get_func_name(name);
+ if (!func)
+ continue;
+
+ /* Check if function belongs to a kfunc set */
+ ranges = gobuffer__entries(&btf_kfunc_ranges);
+ ranges_cnt = gobuffer__nr_entries(&btf_kfunc_ranges);
+ found = false;
+ for (j = 0; j < ranges_cnt; j++) {
+ size_t addr = sym.st_value;
+
+ if (ranges[j].start <= addr && addr < ranges[j].end) {
+ found = true;
+ break;
+ }
+ }
+ if (!found) {
+ free(func);
+ continue;
+ }
+
+ err = btf_encoder__tag_kfunc(encoder, &btf_funcs, func);
+ if (err) {
+ fprintf(stderr, "%s: failed to tag kfunc '%s'\n", __func__, func);
+ free(func);
+ goto out;
+ }
+ free(func);
+ }
+
+ err = 0;
+out:
+ __gobuffer__delete(&btf_funcs);
+ __gobuffer__delete(&btf_kfunc_ranges);
+ if (elf)
+ elf_end(elf);
+ if (fd != -1)
+ close(fd);
+ return err;
+}
+
int btf_encoder__encode(struct btf_encoder *encoder)
{
+ bool should_tag_kfuncs;
int err;
/* for single-threaded case, saved funcs are added here */
@@ -1377,6 +1739,15 @@ int btf_encoder__encode(struct btf_encoder *encoder)
if (btf__type_cnt(encoder->btf) == 1)
return 0;
+ /* Note vmlinux may already contain btf_decl_tag's for kfuncs. So
+ * take care to call this before btf_dedup().
+ */
+ should_tag_kfuncs = encoder->tag_kfuncs && !encoder->skip_encoding_decl_tag;
+ if (should_tag_kfuncs && btf_encoder__tag_kfuncs(encoder)) {
+ fprintf(stderr, "%s: failed to tag kfuncs!\n", __func__);
+ return -1;
+ }
+
if (btf__dedup(encoder->btf, NULL)) {
fprintf(stderr, "%s: btf__dedup failed!\n", __func__);
return -1;
@@ -1660,6 +2031,7 @@ struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filenam
encoder->force = conf_load->btf_encode_force;
encoder->gen_floats = conf_load->btf_gen_floats;
encoder->skip_encoding_vars = conf_load->skip_encoding_btf_vars;
+ encoder->skip_encoding_decl_tag = conf_load->skip_encoding_btf_decl_tag;
encoder->tag_kfuncs = conf_load->btf_decl_tag_kfuncs;
encoder->verbose = verbose;
encoder->has_index_type = false;
--
2.44.0
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH dwarves v6 0/3] pahole: Inject kfunc decl tags into BTF
2024-03-25 17:53 [PATCH dwarves v6 0/3] pahole: Inject kfunc decl tags into BTF Daniel Xu
` (2 preceding siblings ...)
2024-03-25 17:53 ` [PATCH dwarves v6 3/3] pahole: Inject kfunc decl tags into BTF Daniel Xu
@ 2024-04-02 20:24 ` Arnaldo Carvalho de Melo
3 siblings, 0 replies; 9+ messages in thread
From: Arnaldo Carvalho de Melo @ 2024-04-02 20:24 UTC (permalink / raw
To: Daniel Xu
Cc: jolsa, quentin, alan.maguire, eddyz87, andrii.nakryiko, ast,
daniel, bpf
On Mon, Mar 25, 2024 at 11:53:36AM -0600, Daniel Xu wrote:
> This patchset teaches pahole to parse symbols in .BTF_ids section in
> vmlinux and discover exported kfuncs. Pahole then takes the list of
> kfuncs and injects a BTF_KIND_DECL_TAG for each kfunc.
>
> Example of encoding:
>
> $ bpftool btf dump file .tmp_vmlinux.btf | rg "DECL_TAG 'bpf_kfunc'" | wc -l
> 121
>
> $ bpftool btf dump file .tmp_vmlinux.btf | rg 56337
> [56337] FUNC 'bpf_ct_change_timeout' type_id=56336 linkage=static
> [127861] DECL_TAG 'bpf_kfunc' type_id=56337 component_idx=-1
>
> This enables downstream users and tools to dynamically discover which
> kfuncs are available on a system by parsing vmlinux or module BTF, both
> available in /sys/kernel/btf.
>
> This feature is enabled with --btf_features=decl_tag,decl_tag_kfuncs.
>
> === Changelog ===
I'm a bit lagged on my backlog, will try and process these soon,
- Arnaldo
> Changes from v5:
> * Add gobuffer__sort() helper
> * Use strstarts() instead of strncmp()
> * Use uint64_t instead of size_t
> * Add clarifying comments for get_func_name()
>
> Changes from v4:
> * Update man page with decl_tag_kfuncs feature
> * Fix release mode build warnings
> * Add elf_getshrstrndx() error checking
> * Disable tagging if decl_tag feature is off
> * Fix malformed func name handling
>
> Changes from v3:
> * Guard kfunc tagging behind feature flag
> * Use struct btf_id_set8 definition
> * Remove unnecessary member from btf_encoder
> * Fix code styling
>
> Changes from v2:
> * More reliably detect kfunc membership in set8 by tracking set addr ranges
> * Rename some variables/functions to be more clear about kfunc vs func
>
> Changes from v1:
> * Fix resource leaks
> * Fix callee -> caller typo
> * Rename btf_decl_tag from kfunc -> bpf_kfunc
> * Only grab btf_id_set funcs tagged kfunc
> * Presort btf func list
>
> Daniel Xu (3):
> gobuffer: Add gobuffer__sort() helper
> pahole: Add --btf_feature=decl_tag_kfuncs feature
> pahole: Inject kfunc decl tags into BTF
>
> btf_encoder.c | 374 +++++++++++++++++++++++++++++++++++++++++++++
> dwarves.h | 1 +
> gobuffer.c | 5 +
> gobuffer.h | 2 +
> man-pages/pahole.1 | 1 +
> pahole.c | 1 +
> 6 files changed, 384 insertions(+)
>
> --
> 2.44.0
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH dwarves v6 1/3] gobuffer: Add gobuffer__sort() helper
2024-03-25 17:53 ` [PATCH dwarves v6 1/3] gobuffer: Add gobuffer__sort() helper Daniel Xu
@ 2024-04-17 9:20 ` Alan Maguire
2024-04-17 13:40 ` Arnaldo Carvalho de Melo
0 siblings, 1 reply; 9+ messages in thread
From: Alan Maguire @ 2024-04-17 9:20 UTC (permalink / raw
To: Daniel Xu, acme, jolsa, quentin, eddyz87
Cc: andrii.nakryiko, ast, daniel, bpf
On 25/03/2024 17:53, Daniel Xu wrote:
> Add a helper to sort the gobuffer. Trivial wrapper around qsort().
>
> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
> ---
> gobuffer.c | 5 +++++
> gobuffer.h | 2 ++
> 2 files changed, 7 insertions(+)
>
> diff --git a/gobuffer.c b/gobuffer.c
> index 02b2084..4655339 100644
> --- a/gobuffer.c
> +++ b/gobuffer.c
> @@ -102,6 +102,11 @@ void gobuffer__copy(const struct gobuffer *gb, void *dest)
> }
> }
>
> +void gobuffer__sort(struct gobuffer *gb, unsigned int size, int (*compar)(const void *, const void *))
> +{
> + qsort((void *)gb->entries, gb->nr_entries, size, compar);
nit shouldn't need to cast char * gb->entries to void * ; not worth
respinning the series for though unless there are other issues
> +}
> +
> const void *gobuffer__compress(struct gobuffer *gb, unsigned int *size)
> {
> z_stream z = {
> diff --git a/gobuffer.h b/gobuffer.h
> index a12c5c8..cd218b6 100644
> --- a/gobuffer.h
> +++ b/gobuffer.h
> @@ -21,6 +21,8 @@ void __gobuffer__delete(struct gobuffer *gb);
>
> void gobuffer__copy(const struct gobuffer *gb, void *dest);
>
> +void gobuffer__sort(struct gobuffer *gb, unsigned int size, int (*compar)(const void *, const void *));
> +
> int gobuffer__add(struct gobuffer *gb, const void *s, unsigned int len);
> int gobuffer__allocate(struct gobuffer *gb, unsigned int len);
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH dwarves v6 3/3] pahole: Inject kfunc decl tags into BTF
2024-03-25 17:53 ` [PATCH dwarves v6 3/3] pahole: Inject kfunc decl tags into BTF Daniel Xu
@ 2024-04-17 9:32 ` Alan Maguire
0 siblings, 0 replies; 9+ messages in thread
From: Alan Maguire @ 2024-04-17 9:32 UTC (permalink / raw
To: Daniel Xu, acme, jolsa, quentin, eddyz87
Cc: andrii.nakryiko, ast, daniel, bpf
On 25/03/2024 17:53, Daniel Xu wrote:
> This commit teaches pahole to parse symbols in .BTF_ids section in
> vmlinux and discover exported kfuncs. Pahole then takes the list of
> kfuncs and injects a BTF_KIND_DECL_TAG for each kfunc.
>
> Example of encoding:
>
> $ bpftool btf dump file .tmp_vmlinux.btf | rg "DECL_TAG 'bpf_kfunc'" | wc -l
> 121
>
> $ bpftool btf dump file .tmp_vmlinux.btf | rg 56337
> [56337] FUNC 'bpf_ct_change_timeout' type_id=56336 linkage=static
> [127861] DECL_TAG 'bpf_kfunc' type_id=56337 component_idx=-1
>
> This enables downstream users and tools to dynamically discover which
> kfuncs are available on a system by parsing vmlinux or module BTF, both
> available in /sys/kernel/btf.
>
> This feature is enabled with --btf_features=decl_tag,decl_tag_kfuncs.
>
> Acked-by: Jiri Olsa <jolsa@kernel.org>
> Tested-by: Jiri Olsa <jolsa@kernel.org>
> Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
> Tested-by: Alan Maguire <alan.maguire@oracle.com>
I re-tested for both vmlinux and a module with a kfunc (nf_nat); both
generated decl_tags pointing at the kfunc functions so all working
great. Nice work!
> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
> ---
> btf_encoder.c | 372 ++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 372 insertions(+)
>
> diff --git a/btf_encoder.c b/btf_encoder.c
> index 850e36f..d326404 100644
> --- a/btf_encoder.c
> +++ b/btf_encoder.c
> @@ -34,6 +34,21 @@
> #include <pthread.h>
>
> #define BTF_ENCODER_MAX_PROTO 512
> +#define BTF_IDS_SECTION ".BTF_ids"
> +#define BTF_ID_FUNC_PFX "__BTF_ID__func__"
> +#define BTF_ID_SET8_PFX "__BTF_ID__set8__"
> +#define BTF_SET8_KFUNCS (1 << 0)
> +#define BTF_KFUNC_TYPE_TAG "bpf_kfunc"
> +
> +/* Adapted from include/linux/btf_ids.h */
> +struct btf_id_set8 {
> + uint32_t cnt;
> + uint32_t flags;
> + struct {
> + uint32_t id;
> + uint32_t flags;
> + } pairs[];
> +};
>
> /* state used to do later encoding of saved functions */
> struct btf_encoder_state {
> @@ -75,6 +90,7 @@ struct btf_encoder {
> verbose,
> force,
> gen_floats,
> + skip_encoding_decl_tag,
> tag_kfuncs,
> is_rel;
> uint32_t array_index_id;
> @@ -94,6 +110,17 @@ struct btf_encoder {
> } functions;
> };
>
> +struct btf_func {
> + const char *name;
> + int type_id;
> +};
> +
> +/* Half open interval representing range of addresses containing kfuncs */
> +struct btf_kfunc_set_range {
> + uint64_t start;
> + uint64_t end;
> +};
> +
> static LIST_HEAD(encoders);
> static pthread_mutex_t encoders__lock = PTHREAD_MUTEX_INITIALIZER;
>
> @@ -1363,8 +1390,343 @@ out:
> return err;
> }
>
> +/* Returns if `sym` points to a kfunc set */
> +static int is_sym_kfunc_set(GElf_Sym *sym, const char *name, Elf_Data *idlist, size_t idlist_addr)
> +{
> + void *ptr = idlist->d_buf;
> + struct btf_id_set8 *set;
> + int off;
> +
> + /* kfuncs are only found in BTF_SET8's */
> + if (!strstarts(name, BTF_ID_SET8_PFX))
> + return false;
> +
> + off = sym->st_value - idlist_addr;
> + if (off >= idlist->d_size) {
> + fprintf(stderr, "%s: symbol '%s' out of bounds\n", __func__, name);
> + return false;
> + }
> +
> + /* Check the set8 flags to see if it was marked as kfunc */
> + set = ptr + off;
> + return set->flags & BTF_SET8_KFUNCS;
> +}
> +
> +/*
> + * Parse BTF_ID symbol and return the func name.
> + *
> + * Returns:
> + * Caller-owned string containing func name if successful.
> + * NULL if !func or on error.
> + */
> +static char *get_func_name(const char *sym)
> +{
> + char *func, *end;
> +
> + /* Example input: __BTF_ID__func__vfs_close__1
> + *
> + * The goal is to strip the prefix and suffix such that we only
> + * return vfs_close.
> + */
> +
> + if (!strstarts(sym, BTF_ID_FUNC_PFX))
> + return NULL;
> +
> + /* Strip prefix and handle malformed input such as __BTF_ID__func___ */
> + func = strdup(sym + sizeof(BTF_ID_FUNC_PFX) - 1);
> + if (strlen(func) < 2) {
> + free(func);
> + return NULL;
> + }
> +
> + /* Strip suffix */
> + end = strrchr(func, '_');
> + if (!end || *(end - 1) != '_') {
> + free(func);
> + return NULL;
> + }
> + *(end - 1) = '\0';
> +
> + return func;
> +}
> +
> +static int btf_func_cmp(const void *_a, const void *_b)
> +{
> + const struct btf_func *a = _a;
> + const struct btf_func *b = _b;
> +
> + return strcmp(a->name, b->name);
> +}
> +
> +/*
> + * Collects all functions described in BTF.
> + * Returns non-zero on error.
> + */
> +static int btf_encoder__collect_btf_funcs(struct btf_encoder *encoder, struct gobuffer *funcs)
> +{
> + struct btf *btf = encoder->btf;
> + int nr_types, type_id;
> + int err = -1;
> +
> + /* First collect all the func entries into an array */
> + nr_types = btf__type_cnt(btf);
> + for (type_id = 1; type_id < nr_types; type_id++) {
> + const struct btf_type *type;
> + struct btf_func func = {};
> + const char *name;
> +
> + type = btf__type_by_id(btf, type_id);
> + if (!type) {
> + fprintf(stderr, "%s: malformed BTF, can't resolve type for ID %d\n",
> + __func__, type_id);
> + err = -EINVAL;
> + goto out;
> + }
> +
> + if (!btf_is_func(type))
> + continue;
> +
> + name = btf__name_by_offset(btf, type->name_off);
> + if (!name) {
> + fprintf(stderr, "%s: malformed BTF, can't resolve name for ID %d\n",
> + __func__, type_id);
> + err = -EINVAL;
> + goto out;
> + }
> +
> + func.name = name;
> + func.type_id = type_id;
> + err = gobuffer__add(funcs, &func, sizeof(func));
> + if (err < 0)
> + goto out;
> + }
> +
> + /* Now that we've collected funcs, sort them by name */
> + gobuffer__sort(funcs, sizeof(struct btf_func), btf_func_cmp);
> +
> + err = 0;
> +out:
> + return err;
> +}
> +
> +static int btf_encoder__tag_kfunc(struct btf_encoder *encoder, struct gobuffer *funcs, const char *kfunc)
> +{
> + struct btf_func key = { .name = kfunc };
> + struct btf *btf = encoder->btf;
> + struct btf_func *target;
> + const void *base;
> + unsigned int cnt;
> + int err = -1;
> +
> + base = gobuffer__entries(funcs);
> + cnt = gobuffer__nr_entries(funcs);
> + target = bsearch(&key, base, cnt, sizeof(key), btf_func_cmp);
> + if (!target) {
> + fprintf(stderr, "%s: failed to find kfunc '%s' in BTF\n", __func__, kfunc);
> + goto out;
> + }
> +
> + /* Note we are unconditionally adding the btf_decl_tag even
> + * though vmlinux may already contain btf_decl_tags for kfuncs.
> + * We are ok to do this b/c we will later btf__dedup() to remove
> + * any duplicates.
> + */
> + err = btf__add_decl_tag(btf, BTF_KFUNC_TYPE_TAG, target->type_id, -1);
> + if (err < 0) {
> + fprintf(stderr, "%s: failed to insert kfunc decl tag for '%s': %d\n",
> + __func__, kfunc, err);
> + goto out;
> + }
> +
> + err = 0;
> +out:
> + return err;
> +}
> +
> +static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder)
> +{
> + const char *filename = encoder->filename;
> + struct gobuffer btf_kfunc_ranges = {};
> + struct gobuffer btf_funcs = {};
> + Elf_Data *symbols = NULL;
> + Elf_Data *idlist = NULL;
> + Elf_Scn *symscn = NULL;
> + int symbols_shndx = -1;
> + size_t idlist_addr = 0;
> + int fd = -1, err = -1;
> + int idlist_shndx = -1;
> + size_t strtabidx = 0;
> + Elf_Scn *scn = NULL;
> + Elf *elf = NULL;
> + GElf_Shdr shdr;
> + size_t strndx;
> + char *secname;
> + int nr_syms;
> + int i = 0;
> +
> + fd = open(filename, O_RDONLY);
> + if (fd < 0) {
> + fprintf(stderr, "Cannot open %s\n", filename);
> + goto out;
> + }
> +
> + if (elf_version(EV_CURRENT) == EV_NONE) {
> + elf_error("Cannot set libelf version");
> + goto out;
> + }
> +
> + elf = elf_begin(fd, ELF_C_READ, NULL);
> + if (elf == NULL) {
> + elf_error("Cannot update ELF file");
> + goto out;
> + }
> +
> + /* Locate symbol table and .BTF_ids sections */
> + if (elf_getshdrstrndx(elf, &strndx) < 0)
> + goto out;
> +
> + while ((scn = elf_nextscn(elf, scn)) != NULL) {
> + Elf_Data *data;
> +
> + i++;
> + if (!gelf_getshdr(scn, &shdr)) {
> + elf_error("Failed to get ELF section(%d) hdr", i);
> + goto out;
> + }
> +
> + secname = elf_strptr(elf, strndx, shdr.sh_name);
> + if (!secname) {
> + elf_error("Failed to get ELF section(%d) hdr name", i);
> + goto out;
> + }
> +
> + data = elf_getdata(scn, 0);
> + if (!data) {
> + elf_error("Failed to get ELF section(%d) data", i);
> + goto out;
> + }
> +
> + if (shdr.sh_type == SHT_SYMTAB) {
> + symbols_shndx = i;
> + symscn = scn;
> + symbols = data;
> + strtabidx = shdr.sh_link;
> + } else if (!strcmp(secname, BTF_IDS_SECTION)) {
> + idlist_shndx = i;
> + idlist_addr = shdr.sh_addr;
> + idlist = data;
> + }
> + }
> +
> + /* Cannot resolve symbol or .BTF_ids sections. Nothing to do. */
> + if (symbols_shndx == -1 || idlist_shndx == -1) {
> + err = 0;
> + goto out;
> + }
> +
> + if (!gelf_getshdr(symscn, &shdr)) {
> + elf_error("Failed to get ELF symbol table header");
> + goto out;
> + }
> + nr_syms = shdr.sh_size / shdr.sh_entsize;
> +
> + err = btf_encoder__collect_btf_funcs(encoder, &btf_funcs);
> + if (err) {
> + fprintf(stderr, "%s: failed to collect BTF funcs\n", __func__);
> + goto out;
> + }
> +
> + /* First collect all kfunc set ranges.
> + *
> + * Note we choose not to sort these ranges and accept a linear
> + * search when doing lookups. Reasoning is that the number of
> + * sets is ~O(100) and not worth the additional code to optimize.
> + */
> + for (i = 0; i < nr_syms; i++) {
> + struct btf_kfunc_set_range range = {};
> + const char *name;
> + GElf_Sym sym;
> +
> + if (!gelf_getsym(symbols, i, &sym)) {
> + elf_error("Failed to get ELF symbol(%d)", i);
> + goto out;
> + }
> +
> + if (sym.st_shndx != idlist_shndx)
> + continue;
> +
> + name = elf_strptr(elf, strtabidx, sym.st_name);
> + if (!is_sym_kfunc_set(&sym, name, idlist, idlist_addr))
> + continue;
> +
> + range.start = sym.st_value;
> + range.end = sym.st_value + sym.st_size;
> + gobuffer__add(&btf_kfunc_ranges, &range, sizeof(range));
> + }
> +
> + /* Now inject BTF with kfunc decl tag for detected kfuncs */
> + for (i = 0; i < nr_syms; i++) {
> + const struct btf_kfunc_set_range *ranges;
> + unsigned int ranges_cnt;
> + char *func, *name;
> + GElf_Sym sym;
> + bool found;
> + int err;
> + int j;
> +
> + if (!gelf_getsym(symbols, i, &sym)) {
> + elf_error("Failed to get ELF symbol(%d)", i);
> + goto out;
> + }
> +
> + if (sym.st_shndx != idlist_shndx)
> + continue;
> +
> + name = elf_strptr(elf, strtabidx, sym.st_name);
> + func = get_func_name(name);
> + if (!func)
> + continue;
> +
> + /* Check if function belongs to a kfunc set */
> + ranges = gobuffer__entries(&btf_kfunc_ranges);
> + ranges_cnt = gobuffer__nr_entries(&btf_kfunc_ranges);
> + found = false;
> + for (j = 0; j < ranges_cnt; j++) {
> + size_t addr = sym.st_value;
> +
> + if (ranges[j].start <= addr && addr < ranges[j].end) {
> + found = true;
> + break;
> + }
> + }
> + if (!found) {
> + free(func);
> + continue;
> + }
> +
> + err = btf_encoder__tag_kfunc(encoder, &btf_funcs, func);
> + if (err) {
> + fprintf(stderr, "%s: failed to tag kfunc '%s'\n", __func__, func);
> + free(func);
> + goto out;
> + }
> + free(func);
> + }
> +
> + err = 0;
> +out:
> + __gobuffer__delete(&btf_funcs);
> + __gobuffer__delete(&btf_kfunc_ranges);
> + if (elf)
> + elf_end(elf);
> + if (fd != -1)
> + close(fd);
> + return err;
> +}
> +
> int btf_encoder__encode(struct btf_encoder *encoder)
> {
> + bool should_tag_kfuncs;
> int err;
>
> /* for single-threaded case, saved funcs are added here */
> @@ -1377,6 +1739,15 @@ int btf_encoder__encode(struct btf_encoder *encoder)
> if (btf__type_cnt(encoder->btf) == 1)
> return 0;
>
> + /* Note vmlinux may already contain btf_decl_tag's for kfuncs. So
> + * take care to call this before btf_dedup().
> + */
> + should_tag_kfuncs = encoder->tag_kfuncs && !encoder->skip_encoding_decl_tag;
> + if (should_tag_kfuncs && btf_encoder__tag_kfuncs(encoder)) {
> + fprintf(stderr, "%s: failed to tag kfuncs!\n", __func__);
> + return -1;
> + }
> +
> if (btf__dedup(encoder->btf, NULL)) {
> fprintf(stderr, "%s: btf__dedup failed!\n", __func__);
> return -1;
> @@ -1660,6 +2031,7 @@ struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filenam
> encoder->force = conf_load->btf_encode_force;
> encoder->gen_floats = conf_load->btf_gen_floats;
> encoder->skip_encoding_vars = conf_load->skip_encoding_btf_vars;
> + encoder->skip_encoding_decl_tag = conf_load->skip_encoding_btf_decl_tag;
> encoder->tag_kfuncs = conf_load->btf_decl_tag_kfuncs;
> encoder->verbose = verbose;
> encoder->has_index_type = false;
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH dwarves v6 1/3] gobuffer: Add gobuffer__sort() helper
2024-04-17 9:20 ` Alan Maguire
@ 2024-04-17 13:40 ` Arnaldo Carvalho de Melo
2024-04-18 9:31 ` Alan Maguire
0 siblings, 1 reply; 9+ messages in thread
From: Arnaldo Carvalho de Melo @ 2024-04-17 13:40 UTC (permalink / raw
To: Alan Maguire
Cc: Daniel Xu, jolsa, quentin, eddyz87, andrii.nakryiko, ast, daniel,
bpf
On Wed, Apr 17, 2024 at 10:20:41AM +0100, Alan Maguire wrote:
> On 25/03/2024 17:53, Daniel Xu wrote:
> > Add a helper to sort the gobuffer. Trivial wrapper around qsort().
> >
> > Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
> Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
> > ---
> > gobuffer.c | 5 +++++
> > gobuffer.h | 2 ++
> > 2 files changed, 7 insertions(+)
> >
> > diff --git a/gobuffer.c b/gobuffer.c
> > index 02b2084..4655339 100644
> > --- a/gobuffer.c
> > +++ b/gobuffer.c
> > @@ -102,6 +102,11 @@ void gobuffer__copy(const struct gobuffer *gb, void *dest)
> > }
> > }
> >
> > +void gobuffer__sort(struct gobuffer *gb, unsigned int size, int (*compar)(const void *, const void *))
> > +{
> > + qsort((void *)gb->entries, gb->nr_entries, size, compar);
>
> nit shouldn't need to cast char * gb->entries to void * ; not worth
> respinning the series for though unless there are other issues
I can remove that while applying the series, which I'm doing now.
- Arnaldo
> > +}
> > +
> > const void *gobuffer__compress(struct gobuffer *gb, unsigned int *size)
> > {
> > z_stream z = {
> > diff --git a/gobuffer.h b/gobuffer.h
> > index a12c5c8..cd218b6 100644
> > --- a/gobuffer.h
> > +++ b/gobuffer.h
> > @@ -21,6 +21,8 @@ void __gobuffer__delete(struct gobuffer *gb);
> >
> > void gobuffer__copy(const struct gobuffer *gb, void *dest);
> >
> > +void gobuffer__sort(struct gobuffer *gb, unsigned int size, int (*compar)(const void *, const void *));
> > +
> > int gobuffer__add(struct gobuffer *gb, const void *s, unsigned int len);
> > int gobuffer__allocate(struct gobuffer *gb, unsigned int len);
> >
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH dwarves v6 1/3] gobuffer: Add gobuffer__sort() helper
2024-04-17 13:40 ` Arnaldo Carvalho de Melo
@ 2024-04-18 9:31 ` Alan Maguire
0 siblings, 0 replies; 9+ messages in thread
From: Alan Maguire @ 2024-04-18 9:31 UTC (permalink / raw
To: Arnaldo Carvalho de Melo
Cc: Daniel Xu, jolsa, quentin, eddyz87, andrii.nakryiko, ast, daniel,
bpf
On 17/04/2024 14:40, Arnaldo Carvalho de Melo wrote:
> On Wed, Apr 17, 2024 at 10:20:41AM +0100, Alan Maguire wrote:
>> On 25/03/2024 17:53, Daniel Xu wrote:
>>> Add a helper to sort the gobuffer. Trivial wrapper around qsort().
>>>
>>> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
>> Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
>>> ---
>>> gobuffer.c | 5 +++++
>>> gobuffer.h | 2 ++
>>> 2 files changed, 7 insertions(+)
>>>
>>> diff --git a/gobuffer.c b/gobuffer.c
>>> index 02b2084..4655339 100644
>>> --- a/gobuffer.c
>>> +++ b/gobuffer.c
>>> @@ -102,6 +102,11 @@ void gobuffer__copy(const struct gobuffer *gb, void *dest)
>>> }
>>> }
>>>
>>> +void gobuffer__sort(struct gobuffer *gb, unsigned int size, int (*compar)(const void *, const void *))
>>> +{
>>> + qsort((void *)gb->entries, gb->nr_entries, size, compar);
>>
>> nit shouldn't need to cast char * gb->entries to void * ; not worth
>> respinning the series for though unless there are other issues
>
> I can remove that while applying the series, which I'm doing now.
>
great, thanks! BTW patch 2 will probably require a small tweak for
merging into next:
- BTF_FEATURE(decl_tag_kfuncs, btf_decl_tag_kfuncs, false),
+ BTF_FEATURE(decl_tag_kfuncs, btf_decl_tag_kfuncs, false, true),
this will ensure it is considered a standard feature and is enabled for
"all"; for readability it might make sense to position it wth the other
features prior to
BTF_FEATURE(reproducible_build, reproducible_build, false, false),
...since then we'd have the standard features grouped before the
non-standard ones, making it a bit more readable; not a big deal tho.
thanks!
> - Arnaldo
>
>>> +}
>>> +
>>> const void *gobuffer__compress(struct gobuffer *gb, unsigned int *size)
>>> {
>>> z_stream z = {
>>> diff --git a/gobuffer.h b/gobuffer.h
>>> index a12c5c8..cd218b6 100644
>>> --- a/gobuffer.h
>>> +++ b/gobuffer.h
>>> @@ -21,6 +21,8 @@ void __gobuffer__delete(struct gobuffer *gb);
>>>
>>> void gobuffer__copy(const struct gobuffer *gb, void *dest);
>>>
>>> +void gobuffer__sort(struct gobuffer *gb, unsigned int size, int (*compar)(const void *, const void *));
>>> +
>>> int gobuffer__add(struct gobuffer *gb, const void *s, unsigned int len);
>>> int gobuffer__allocate(struct gobuffer *gb, unsigned int len);
>>>
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2024-04-18 9:32 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2024-03-25 17:53 [PATCH dwarves v6 0/3] pahole: Inject kfunc decl tags into BTF Daniel Xu
2024-03-25 17:53 ` [PATCH dwarves v6 1/3] gobuffer: Add gobuffer__sort() helper Daniel Xu
2024-04-17 9:20 ` Alan Maguire
2024-04-17 13:40 ` Arnaldo Carvalho de Melo
2024-04-18 9:31 ` Alan Maguire
2024-03-25 17:53 ` [PATCH dwarves v6 2/3] pahole: Add --btf_feature=decl_tag_kfuncs feature Daniel Xu
2024-03-25 17:53 ` [PATCH dwarves v6 3/3] pahole: Inject kfunc decl tags into BTF Daniel Xu
2024-04-17 9:32 ` Alan Maguire
2024-04-02 20:24 ` [PATCH dwarves v6 0/3] " Arnaldo Carvalho de Melo
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