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From:   Matt Helsley <mhelsley@vmware.com>
To:     <linux-kernel@vger.kernel.org>
CC:     Josh Poimboeuf <jpoimboe@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Julien Thierry <jthierry@redhat.com>,
        Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
        Matt Helsley <mhelsley@vmware.com>
Subject: [RFC][PATCH v5 49/51] objtool: mcount: Remove relocation size check
Date:   Thu, 18 Jun 2020 13:38:35 -0700
Message-ID: <6daddf400359443d5b8a2d765794524d896e3d55.1592510545.git.mhelsley@vmware.com>
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Rather than use the size of the relocations check the section
header type directly to see if the mcount relocations should
be rel or rela relocations.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 tools/objtool/elf.c    |  4 ++--
 tools/objtool/elf.h    |  2 +-
 tools/objtool/mcount.c | 15 +++++----------
 3 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 733e10d4a574..4948df31bba0 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -642,8 +642,8 @@ static int read_relocs(struct elf *elf)
 
 		sec->base->reloc = sec;
 		sec->mcountable = relocs_mcountable(sec);
-		if (sec->mcountable && !elf->mcount_rel_entsize)
-			elf->mcount_rel_entsize = sec->sh.sh_entsize;
+		if (sec->mcountable)
+			elf->mcount_r_addends = (sec->sh.sh_type == SHT_RELA);
 
 		nr_reloc = 0;
 		for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index 8ece1ca79cca..f298e327af01 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -87,8 +87,8 @@ struct elf {
 	Elf *elf;
 	GElf_Ehdr ehdr;
 	int fd;
-	size_t mcount_rel_entsize;
 	bool changed;
+	bool mcount_r_addends;
 	char *name;
 	struct list_head sections;
 	DECLARE_HASHTABLE(symbol_hash, ELF_HASH_BITS);
diff --git a/tools/objtool/mcount.c b/tools/objtool/mcount.c
index 9527924af56b..084bbc02de0c 100644
--- a/tools/objtool/mcount.c
+++ b/tools/objtool/mcount.c
@@ -368,22 +368,17 @@ static void fill_mcount_locs(GElf_Sxword r_offset, GElf_Addr **rbuf,
 }
 
 /* Overall supervision for Elf32 ET_REL file. */
-static int do_mcount(unsigned const reltype, size_t rela_size)
+static int do_mcount(unsigned const reltype)
 {
-	GElf_Sxword r_offset = 0;
-
 	struct section *sec, *mlocs, *mrels;
 	const char * const mc_name =  "__mcount_loc";
-
-	const unsigned int rel_entsize = lf->mcount_rel_entsize;
+	GElf_Sxword r_offset = 0;
 	int result = -1;
-	bool is_rela;
+	const bool is_rela = lf->mcount_r_addends;
 
 	if (find_section_by_name(lf, "__mcount_loc") != NULL)
 		return 0;
 
-	is_rela = (rela_size == rel_entsize);
-
 	/* add section: __mcount_loc */
 	mlocs = elf_create_section(lf, mc_name, sizeof(GElf_Addr), 0);
 	if (!mlocs)
@@ -562,7 +557,7 @@ static int do_file(char const *const fname)
 			is_fake_mcount = MIPS_is_fake_mcount;
 		}
 		loc_size = 4;
-		rc = do_mcount(reltype, sizeof(Elf32_Rela));
+		rc = do_mcount(reltype);
 		break;
 	case ELFCLASS64: {
 		if (lf->ehdr.e_ehsize != sizeof(Elf64_Ehdr)
@@ -580,7 +575,7 @@ static int do_file(char const *const fname)
 			is_fake_mcount = MIPS_is_fake_mcount;
 		}
 		loc_size = 8;
-		rc = do_mcount(reltype, sizeof(Elf64_Rela));
+		rc = do_mcount(reltype);
 		break;
 	}
 	}  /* end switch */
-- 
2.20.1