linux-kernel - [PATCH v4 18/18] objtool: Clean up elf

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Date:   Fri, 01 May 2020 22:29:07 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     x86@...nel.org
Cc:     peterz@...radead.org, linux-kernel@...r.kernel.org,
        rostedt@...dmis.org, mhiramat@...nel.org, bristot@...hat.com,
        jbaron@...mai.com, torvalds@...ux-foundation.org,
        tglx@...utronix.de, mingo@...nel.org, namit@...are.com,
        hpa@...or.com, luto@...nel.org, ard.biesheuvel@...aro.org,
        jpoimboe@...hat.com, pbonzini@...hat.com,
        mathieu.desnoyers@...icios.com
Subject: [PATCH v4 18/18] objtool: Clean up elf_write() condition

With there being multiple ways to change the ELF data, let's more
concisely track modification.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 tools/objtool/check.c |    2 +-
 tools/objtool/elf.c   |    8 +++++++-
 tools/objtool/elf.h   |    3 ++-
 3 files changed, 10 insertions(+), 3 deletions(-)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2904,7 +2904,7 @@ int check(const char *_objname, bool orc
 			goto out;
 	}
 
-	if (orc || !list_empty(&file.static_call_list)) {
+	if (file.elf->changed) {
 		ret = elf_write(file.elf);
 		if (ret < 0)
 			goto out;
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -703,6 +703,8 @@ struct section *elf_create_section(struc
 	elf_hash_add(elf->section_hash, &sec->hash, sec->idx);
 	elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
 
+	elf->changed = true;
+
 	return sec;
 }
 
@@ -769,7 +771,7 @@ int elf_rebuild_rela_section(struct sect
 	return 0;
 }
 
-int elf_write(const struct elf *elf)
+int elf_write(struct elf *elf)
 {
 	struct section *sec;
 	Elf_Scn *s;
@@ -786,6 +788,8 @@ int elf_write(const struct elf *elf)
 				WARN_ELF("gelf_update_shdr");
 				return -1;
 			}
+
+			sec->changed = false;
 		}
 	}
 
@@ -798,6 +802,8 @@ int elf_write(const struct elf *elf)
 		return -1;
 	}
 
+	elf->changed = false;
+
 	return 0;
 }
 
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -77,6 +77,7 @@ struct elf {
 	Elf *elf;
 	GElf_Ehdr ehdr;
 	int fd;
+	bool changed;
 	char *name;
 	struct list_head sections;
 	DECLARE_HASHTABLE(symbol_hash, ELF_HASH_BITS);
@@ -118,7 +119,7 @@ struct elf *elf_open_read(const char *na
 struct section *elf_create_section(struct elf *elf, const char *name, unsigned int sh_flags, size_t entsize, int nr);
 struct section *elf_create_rela_section(struct elf *elf, struct section *base);
 void elf_add_rela(struct elf *elf, struct rela *rela);
-int elf_write(const struct elf *elf);
+int elf_write(struct elf *elf);
 void elf_close(struct elf *elf);
 
 struct section *find_section_by_name(const struct elf *elf, const char *name);