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From: Stephen Brennan <stephen.s.brennan@oracle.com>
To: Stephen Brennan <stephen.s.brennan@oracle.com>
Cc: dwarves@vger.kernel.org, bpf@vger.kernel.org,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	alan.maguire@oracle.com, Andrii Nakryiko <andrii@kernel.org>
Subject: [PATCH v2 dwarves 7/9] btf_encoder: allow encoding all variables
Date: Fri,  4 Nov 2022 16:11:01 -0700	[thread overview]
Message-ID: <20221104231103.752040-8-stephen.s.brennan@oracle.com> (raw)
In-Reply-To: <20221104231103.752040-1-stephen.s.brennan@oracle.com>

Add the --encode_all_btf_vars option, which conflicts with
--skip_encoding_btf_vars, and will enable encoding all variables which
have a corresponding STT_OBJECT match in the ELF symbol table. Rework
the btf_encoder_new() signature to include a single enum to specify
which kinds of variables are allowed, and add the necessary logic to
select variables.

Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
---
 btf_encoder.c      | 22 +++++++++++++---------
 btf_encoder.h      |  8 +++++++-
 man-pages/pahole.1 |  6 +++++-
 pahole.c           | 30 ++++++++++++++++++++++++------
 4 files changed, 49 insertions(+), 17 deletions(-)

diff --git a/btf_encoder.c b/btf_encoder.c
index f7acc9a..b3ede15 100644
--- a/btf_encoder.c
+++ b/btf_encoder.c
@@ -65,7 +65,6 @@ struct btf_encoder {
 	struct elf_symtab *symtab;
 	bool		  has_index_type,
 			  need_index_type,
-			  skip_encoding_vars,
 			  raw_output,
 			  verbose,
 			  force,
@@ -74,6 +73,7 @@ struct btf_encoder {
 	uint32_t	  array_index_id;
 	struct elf_secinfo secinfo[MAX_ELF_SEC_CNT];
 	size_t		  seccnt;
+	enum btf_var_option encode_vars;
 	struct {
 		struct var_info *vars;
 		int		var_cnt;
@@ -1247,24 +1247,25 @@ static int btf_encoder__collect_var(struct btf_encoder *encoder, GElf_Sym *sym,
 	return 0;
 }
 
-static int btf_encoder__collect_symbols(struct btf_encoder *encoder, bool collect_percpu_vars)
+static int btf_encoder__collect_symbols(struct btf_encoder *encoder)
 {
 	uint32_t sym_sec_idx;
 	uint32_t core_id;
 	GElf_Sym sym;
+	bool collect_vars = (encoder->encode_vars != BTF_VAR_NONE);
 
 	/* cache variables' addresses, preparing for searching in symtab. */
 	encoder->variables.var_cnt = 0;
 
 	/* search within symtab for percpu variables */
 	elf_symtab__for_each_symbol_index(encoder->symtab, core_id, sym, sym_sec_idx) {
-		if (collect_percpu_vars && btf_encoder__collect_var(encoder, &sym, sym_sec_idx))
+		if (collect_vars && btf_encoder__collect_var(encoder, &sym, sym_sec_idx))
 			return -1;
 		if (btf_encoder__collect_function(encoder, &sym))
 			return -1;
 	}
 
-	if (collect_percpu_vars) {
+	if (collect_vars) {
 		if (encoder->variables.var_cnt)
 			qsort(encoder->variables.vars, encoder->variables.var_cnt, sizeof(encoder->variables.vars[0]), var_cmp);
 
@@ -1425,7 +1426,7 @@ out:
 	return err;
 }
 
-struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filename, struct btf *base_btf, bool skip_encoding_vars, bool force, bool gen_floats, bool verbose)
+struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filename, struct btf *base_btf, enum btf_var_option vars, bool force, bool gen_floats, bool verbose)
 {
 	struct btf_encoder *encoder = zalloc(sizeof(*encoder));
 
@@ -1441,11 +1442,11 @@ struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filenam
 
 		encoder->force		 = force;
 		encoder->gen_floats	 = gen_floats;
-		encoder->skip_encoding_vars = skip_encoding_vars;
 		encoder->verbose	 = verbose;
 		encoder->has_index_type  = false;
 		encoder->need_index_type = false;
 		encoder->array_index_id  = 0;
+		encoder->encode_vars	 = vars;
 
 		GElf_Ehdr ehdr;
 
@@ -1495,17 +1496,20 @@ struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filenam
 			encoder->secinfo[shndx].addr = shdr.sh_addr;
 			encoder->secinfo[shndx].sz = shdr.sh_size;
 			encoder->secinfo[shndx].name = secname;
+			if (encoder->encode_vars == BTF_VAR_ALL)
+				encoder->secinfo[shndx].include = true;
 
 			if (strcmp(secname, PERCPU_SECTION) == 0) {
 				encoder->variables.percpu_shndx = shndx;
-				encoder->secinfo[shndx].include = true;
+				if (encoder->encode_vars != BTF_VAR_NONE)
+					encoder->secinfo[shndx].include = true;
 			}
 		}
 
 		if (!encoder->variables.percpu_shndx && encoder->verbose)
 			printf("%s: '%s' doesn't have '%s' section\n", __func__, cu->filename, PERCPU_SECTION);
 
-		if (btf_encoder__collect_symbols(encoder, !encoder->skip_encoding_vars))
+		if (btf_encoder__collect_symbols(encoder))
 			goto out_delete;
 
 		if (encoder->verbose)
@@ -1671,7 +1675,7 @@ int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu, struct co
 		}
 	}
 
-	if (!encoder->skip_encoding_vars)
+	if (encoder->encode_vars != BTF_VAR_NONE)
 		err = btf_encoder__encode_cu_variables(encoder, type_id_off);
 out:
 	encoder->cu = NULL;
diff --git a/btf_encoder.h b/btf_encoder.h
index a65120c..e03c7cc 100644
--- a/btf_encoder.h
+++ b/btf_encoder.h
@@ -16,7 +16,13 @@ struct btf;
 struct cu;
 struct list_head;
 
-struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filename, struct btf *base_btf, bool skip_encoding_vars, bool force, bool gen_floats, bool verbose);
+enum btf_var_option {
+	BTF_VAR_NONE,
+	BTF_VAR_PERCPU,
+	BTF_VAR_ALL,
+};
+
+struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filename, struct btf *base_btf, enum btf_var_option vars, bool force, bool gen_floats, bool verbose);
 void btf_encoder__delete(struct btf_encoder *encoder);
 
 int btf_encoder__encode(struct btf_encoder *encoder);
diff --git a/man-pages/pahole.1 b/man-pages/pahole.1
index 7460104..e7f5ab5 100644
--- a/man-pages/pahole.1
+++ b/man-pages/pahole.1
@@ -215,7 +215,11 @@ the debugging information.
 
 .TP
 .B \-\-skip_encoding_btf_vars
-Do not encode VARs in BTF.
+TQ
+.B \-\-encode_all_btf_vars
+By default, VARs are encoded only for percpu variables. These options allow
+to skip encoding them, or to encode all variables regardless of whether they are
+percpu. These options are mutually exclusive.
 
 .TP
 .B \-\-skip_encoding_btf_decl_tag
diff --git a/pahole.c b/pahole.c
index 4ddf21f..6ff4e22 100644
--- a/pahole.c
+++ b/pahole.c
@@ -37,7 +37,7 @@ static bool ctf_encode;
 static bool sort_output;
 static bool need_resort;
 static bool first_obj_only;
-static bool skip_encoding_btf_vars;
+static enum btf_var_option encode_btf_vars = BTF_VAR_PERCPU;
 static bool btf_encode_force;
 static const char *base_btf_file;
 
@@ -1222,6 +1222,7 @@ ARGP_PROGRAM_VERSION_HOOK_DEF = dwarves_print_version;
 #define ARGP_languages_exclude	   336
 #define ARGP_skip_encoding_btf_enum64 337
 #define ARGP_skip_emitting_atomic_typedefs 338
+#define ARGP_encode_all_btf_vars   339
 
 static const struct argp_option pahole__options[] = {
 	{
@@ -1533,7 +1534,12 @@ static const struct argp_option pahole__options[] = {
 	{
 		.name = "skip_encoding_btf_vars",
 		.key  = ARGP_skip_encoding_btf_vars,
-		.doc  = "Do not encode VARs in BTF."
+		.doc  = "Do not encode any VARs in BTF (default: only percpu)."
+	},
+	{
+		.name = "encode_all_btf_vars",
+		.key  = ARGP_encode_all_btf_vars,
+		.doc  = "Encode all VARs in BTF (default: only percpu)."
 	},
 	{
 		.name = "btf_encode_force",
@@ -1763,8 +1769,6 @@ static error_t pahole__options_parser(int key, char *arg,
 		conf.range = arg;			break;
 	case ARGP_header_type:
 		conf.header_type = arg;			break;
-	case ARGP_skip_encoding_btf_vars:
-		skip_encoding_btf_vars = true;		break;
 	case ARGP_btf_encode_force:
 		btf_encode_force = true;		break;
 	case ARGP_btf_base:
@@ -1803,6 +1807,20 @@ static error_t pahole__options_parser(int key, char *arg,
 		conf_load.skip_encoding_btf_enum64 = true;	break;
 	case ARGP_skip_emitting_atomic_typedefs:
 		conf.skip_emitting_atomic_typedefs = true;	break;
+	case ARGP_skip_encoding_btf_vars:
+		if (encode_btf_vars != BTF_VAR_PERCPU) {
+			fprintf(stderr, "error: --encode_all_btf_vars and --skip_encoding_btf_vars are mutually exclusive\n");
+			return ARGP_HELP_SEE;
+		}
+		encode_btf_vars = BTF_VAR_NONE;
+		break;
+	case ARGP_encode_all_btf_vars:
+		if (encode_btf_vars != BTF_VAR_PERCPU) {
+			fprintf(stderr, "error: --encode_all_btf_vars and --skip_encoding_btf_vars are mutually exclusive\n");
+			return ARGP_HELP_SEE;
+		}
+		encode_btf_vars = BTF_VAR_ALL;
+		break;
 	default:
 		return ARGP_ERR_UNKNOWN;
 	}
@@ -3037,7 +3055,7 @@ static enum load_steal_kind pahole_stealer(struct cu *cu,
 			 * And, it is used by the thread
 			 * create it.
 			 */
-			btf_encoder = btf_encoder__new(cu, detached_btf_filename, conf_load->base_btf, skip_encoding_btf_vars,
+			btf_encoder = btf_encoder__new(cu, detached_btf_filename, conf_load->base_btf, encode_btf_vars,
 						       btf_encode_force, btf_gen_floats, global_verbose);
 			if (btf_encoder && thr_data) {
 				struct thread_data *thread = thr_data;
@@ -3067,7 +3085,7 @@ static enum load_steal_kind pahole_stealer(struct cu *cu,
 				thread->encoder =
 					btf_encoder__new(cu, detached_btf_filename,
 							 NULL,
-							 skip_encoding_btf_vars,
+							 encode_btf_vars,
 							 btf_encode_force,
 							 btf_gen_floats,
 							 global_verbose);
-- 
2.31.1


  parent reply	other threads:[~2022-11-04 23:11 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-04 23:10 [PATCH v2 dwarves, kernel, libbpf 0/9] Add support for generating BTF for all variables Stephen Brennan
2022-11-04 23:10 ` [PATCH v2 dwarves 1/9] dutil: return ELF section name when looked up by index Stephen Brennan
2022-11-04 23:10 ` [PATCH v2 dwarves 2/9] btf_encoder: Rename percpu structures to variables Stephen Brennan
2022-11-04 23:10 ` [PATCH v2 dwarves 3/9] btf_encoder: cache all ELF section info Stephen Brennan
2022-11-04 23:10 ` [PATCH v2 dwarves 4/9] btf_encoder: make the variable array dynamic Stephen Brennan
2022-11-04 23:10 ` [PATCH v2 dwarves 5/9] btf_encoder: record ELF section for collected variables Stephen Brennan
2022-11-04 23:11 ` [PATCH v2 dwarves 6/9] btf_encoder: collect all variables Stephen Brennan
2022-11-04 23:11 ` Stephen Brennan [this message]
2022-11-04 23:11 ` [PATCH v2 bpf 8/9] libbpf: btf dedup identical struct test needs check for nested structs/arrays Stephen Brennan
2022-11-04 23:11 ` [PATCH v2 kernel 9/9] bpf: add support for CONFIG_DEBUG_INFO_BTF_VARS Stephen Brennan

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