From: Yonghong Song <yhs@fb.com>
To: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
<dwarves@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>, <bpf@vger.kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>, <kernel-team@fb.com>,
Martin KaFai Lau <kafai@fb.com>
Subject: [PATCH dwarves 1/2] dwarf_loader: parse dwarf tag DW_TAG_LLVM_annotation
Date: Sun, 19 Sep 2021 17:35:50 -0700 [thread overview]
Message-ID: <20210920003550.3525047-1-yhs@fb.com> (raw)
In-Reply-To: <20210920003545.3524231-1-yhs@fb.com>
Parse dwarf tag DW_TAG_LLVM_annotation. Only record
annotations with btf_tag name which corresponds to
btf_tag attributes in C code. Such information will
be used later by btf_encoder for BTF conversion.
LLVM implementation only supports btf_tag annotations
on struct/union, func, func parameter and variable ([1]).
So we only check existence of corresponding DW tags
in these places. A flag "--skip_encoding_btf_tag"
is introduced if for whatever reason this feature
needs to be disabled.
[1] https://reviews.llvm.org/D106614
Signed-off-by: Yonghong Song <yhs@fb.com>
---
dwarf_loader.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++----
dwarves.h | 10 ++++++
pahole.c | 8 +++++
3 files changed, 97 insertions(+), 6 deletions(-)
diff --git a/dwarf_loader.c b/dwarf_loader.c
index 0213e42..48e1bf0 100644
--- a/dwarf_loader.c
+++ b/dwarf_loader.c
@@ -52,6 +52,10 @@
#define DW_OP_addrx 0xa1
#endif
+#ifndef DW_TAG_LLVM_annotation
+#define DW_TAG_LLVM_annotation 0x6000
+#endif
+
static pthread_mutex_t libdw__lock = PTHREAD_MUTEX_INITIALIZER;
static uint32_t hashtags__bits = 12;
@@ -602,6 +606,7 @@ static void namespace__init(struct namespace *namespace, Dwarf_Die *die,
{
tag__init(&namespace->tag, cu, die);
INIT_LIST_HEAD(&namespace->tags);
+ INIT_LIST_HEAD(&namespace->annots);
namespace->name = attr_string(die, DW_AT_name, conf);
namespace->nr_tags = 0;
namespace->shared_tags = 0;
@@ -719,6 +724,7 @@ static struct variable *variable__new(Dwarf_Die *die, struct cu *cu, struct conf
/* non-defining declaration of an object */
var->declaration = dwarf_hasattr(die, DW_AT_declaration);
var->scope = VSCOPE_UNKNOWN;
+ INIT_LIST_HEAD(&var->annots);
var->ip.addr = 0;
if (!var->declaration && cu->has_addr_info)
var->scope = dwarf__location(die, &var->ip.addr, &var->location);
@@ -854,6 +860,51 @@ static int tag__recode_dwarf_bitfield(struct tag *tag, struct cu *cu, uint16_t b
return -ENOMEM;
}
+static int add_llvm_annotation(Dwarf_Die *die, int component_idx, struct conf_load *conf,
+ struct list_head *head)
+{
+ struct llvm_annotation *annot;
+ const char *name;
+
+ if (conf->skip_encoding_btf_tag)
+ return 0;
+
+ /* Only handle btf_tag annotation for now. */
+ name = attr_string(die, DW_AT_name, conf);
+ if (strcmp(name, "btf_tag") != 0)
+ return 0;
+
+ annot = zalloc(sizeof(*annot));
+ if (!annot)
+ return -ENOMEM;
+
+ annot->value = attr_string(die, DW_AT_const_value, conf);
+ annot->component_idx = component_idx;
+ list_add_tail(&annot->node, head);
+ return 0;
+}
+
+static int add_child_llvm_annotations(Dwarf_Die *die, int component_idx,
+ struct conf_load *conf, struct list_head *head)
+{
+ Dwarf_Die child;
+ int ret;
+
+ if (!dwarf_haschildren(die) || dwarf_child(die, &child) != 0)
+ return 0;
+
+ die = &child;
+ do {
+ if (dwarf_tag(die) == DW_TAG_LLVM_annotation) {
+ ret = add_llvm_annotation(die, component_idx, conf, head);
+ if (ret)
+ return ret;
+ }
+ } while (dwarf_siblingof(die, die) == 0);
+
+ return 0;
+}
+
int class_member__dwarf_recode_bitfield(struct class_member *member,
struct cu *cu)
{
@@ -1092,6 +1143,7 @@ static struct function *function__new(Dwarf_Die *die, struct cu *cu, struct conf
func->accessibility = attr_numeric(die, DW_AT_accessibility);
func->virtuality = attr_numeric(die, DW_AT_virtuality);
INIT_LIST_HEAD(&func->vtable_node);
+ INIT_LIST_HEAD(&func->annots);
INIT_LIST_HEAD(&func->tool_node);
func->vtable_entry = -1;
if (dwarf_hasattr(die, DW_AT_vtable_elem_location))
@@ -1304,16 +1356,21 @@ static struct tag *die__create_new_string_type(Dwarf_Die *die, struct cu *cu)
static struct tag *die__create_new_parameter(Dwarf_Die *die,
struct ftype *ftype,
struct lexblock *lexblock,
- struct cu *cu, struct conf_load *conf)
+ struct cu *cu, struct conf_load *conf,
+ int param_idx)
{
struct parameter *parm = parameter__new(die, cu, conf);
if (parm == NULL)
return NULL;
- if (ftype != NULL)
+ if (ftype != NULL) {
ftype__add_parameter(ftype, parm);
- else {
+ if (param_idx >= 0) {
+ if (add_child_llvm_annotations(die, param_idx, conf, &(tag__function(&ftype->tag)->annots)))
+ return NULL;
+ }
+ } else {
/*
* DW_TAG_formal_parameters on a non DW_TAG_subprogram nor
* DW_TAG_subroutine_type tag happens sometimes, likely due to
@@ -1346,7 +1403,10 @@ static struct tag *die__create_new_variable(Dwarf_Die *die, struct cu *cu, struc
{
struct variable *var = variable__new(die, cu, conf);
- return var ? &var->ip.tag : NULL;
+ if (var == NULL || add_child_llvm_annotations(die, -1, conf, &var->annots))
+ return NULL;
+
+ return &var->ip.tag;
}
static struct tag *die__create_new_subroutine_type(Dwarf_Die *die,
@@ -1371,7 +1431,7 @@ static struct tag *die__create_new_subroutine_type(Dwarf_Die *die,
tag__print_not_supported(dwarf_tag(die));
continue;
case DW_TAG_formal_parameter:
- tag = die__create_new_parameter(die, ftype, NULL, cu, conf);
+ tag = die__create_new_parameter(die, ftype, NULL, cu, conf, -1);
break;
case DW_TAG_unspecified_parameters:
ftype->unspec_parms = 1;
@@ -1455,6 +1515,7 @@ static int die__process_class(Dwarf_Die *die, struct type *class,
struct cu *cu, struct conf_load *conf)
{
const bool is_union = tag__is_union(&class->namespace.tag);
+ int member_idx = 0;
do {
switch (dwarf_tag(die)) {
@@ -1497,8 +1558,15 @@ static int die__process_class(Dwarf_Die *die, struct type *class,
type__add_member(class, member);
cu__hash(cu, &member->tag);
+ if (add_child_llvm_annotations(die, member_idx, conf, &class->namespace.annots))
+ return -ENOMEM;
+ member_idx++;
}
continue;
+ case DW_TAG_LLVM_annotation:
+ if (add_llvm_annotation(die, -1, conf, &class->namespace.annots))
+ return -ENOMEM;
+ continue;
default: {
struct tag *tag = die__process_tag(die, cu, 0, conf);
@@ -1699,6 +1767,7 @@ static struct tag *die__create_new_inline_expansion(Dwarf_Die *die,
static int die__process_function(Dwarf_Die *die, struct ftype *ftype,
struct lexblock *lexblock, struct cu *cu, struct conf_load *conf)
{
+ int param_idx = 0;
Dwarf_Die child;
struct tag *tag;
@@ -1742,7 +1811,7 @@ static int die__process_function(Dwarf_Die *die, struct ftype *ftype,
tag__print_not_supported(dwarf_tag(die));
continue;
case DW_TAG_formal_parameter:
- tag = die__create_new_parameter(die, ftype, lexblock, cu, conf);
+ tag = die__create_new_parameter(die, ftype, lexblock, cu, conf, param_idx++);
break;
case DW_TAG_variable:
tag = die__create_new_variable(die, cu, conf);
@@ -1771,6 +1840,10 @@ static int die__process_function(Dwarf_Die *die, struct ftype *ftype,
if (die__create_new_lexblock(die, cu, lexblock, conf) != 0)
goto out_enomem;
continue;
+ case DW_TAG_LLVM_annotation:
+ if (add_llvm_annotation(die, -1, conf, &(tag__function(&ftype->tag)->annots)))
+ goto out_enomem;
+ continue;
default:
tag = die__process_tag(die, cu, 0, conf);
diff --git a/dwarves.h b/dwarves.h
index 0b69312..30d33fa 100644
--- a/dwarves.h
+++ b/dwarves.h
@@ -58,6 +58,7 @@ struct conf_load {
bool ignore_inline_expansions;
bool ignore_labels;
bool ptr_table_stats;
+ bool skip_encoding_btf_tag;
uint8_t hashtable_bits;
uint8_t max_hashtable_bits;
uint16_t kabi_prefix_len;
@@ -594,6 +595,12 @@ static inline struct ptr_to_member_type *
return (struct ptr_to_member_type *)tag;
}
+struct llvm_annotation {
+ const char *value;
+ int16_t component_idx;
+ struct list_head node;
+};
+
/** struct namespace - base class for enums, structs, unions, typedefs, etc
*
* @tags - class_member, enumerators, etc
@@ -605,6 +612,7 @@ struct namespace {
uint16_t nr_tags;
uint8_t shared_tags;
struct list_head tags;
+ struct list_head annots;
};
static inline struct namespace *tag__namespace(const struct tag *tag)
@@ -686,6 +694,7 @@ struct variable {
enum vscope scope;
struct location location;
struct hlist_node tool_hnode;
+ struct list_head annots;
struct variable *spec;
};
@@ -818,6 +827,7 @@ struct function {
uint8_t btf:1;
int32_t vtable_entry;
struct list_head vtable_node;
+ struct list_head annots;
/* fields used by tools */
union {
struct list_head tool_node;
diff --git a/pahole.c b/pahole.c
index 7f1771b..80271b5 100644
--- a/pahole.c
+++ b/pahole.c
@@ -1124,6 +1124,7 @@ ARGP_PROGRAM_VERSION_HOOK_DEF = dwarves_print_version;
#define ARGP_sort_output 328
#define ARGP_hashbits 329
#define ARGP_devel_stats 330
+#define ARGP_skip_encoding_btf_tag 331
static const struct argp_option pahole__options[] = {
{
@@ -1494,6 +1495,11 @@ static const struct argp_option pahole__options[] = {
.key = ARGP_devel_stats,
.doc = "Print internal data structures stats",
},
+ {
+ .name = "skip_encoding_btf_tag",
+ .key = ARGP_skip_encoding_btf_tag,
+ .doc = "Do not encode TAGs in BTF."
+ },
{
.name = NULL,
}
@@ -1642,6 +1648,8 @@ static error_t pahole__options_parser(int key, char *arg,
conf_load.hashtable_bits = atoi(arg); break;
case ARGP_devel_stats:
conf_load.ptr_table_stats = true; break;
+ case ARGP_skip_encoding_btf_tag:
+ conf_load.skip_encoding_btf_tag = true; break;
default:
return ARGP_ERR_UNKNOWN;
}
--
2.30.2
next prev parent reply other threads:[~2021-09-20 0:36 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-20 0:35 [PATCH dwarves 0/2] generate BTF_KIND_TAG types from DW_TAG_LLVM_annotation dwarf tags Yonghong Song
2021-09-20 0:35 ` Yonghong Song [this message]
2021-09-21 21:57 ` [PATCH dwarves 1/2] dwarf_loader: parse dwarf tag DW_TAG_LLVM_annotation Andrii Nakryiko
2021-09-20 0:35 ` [PATCH dwarves 2/2] btf_encoder: generate BTF_KIND_TAG from llvm annotations Yonghong Song
2021-09-21 22:02 ` Andrii Nakryiko
2021-09-22 1:16 ` Yonghong Song
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210920003550.3525047-1-yhs@fb.com \
--to=yhs@fb.com \
--cc=andrii@kernel.org \
--cc=arnaldo.melo@gmail.com \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=dwarves@vger.kernel.org \
--cc=kafai@fb.com \
--cc=kernel-team@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).