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Date:   Sun, 4 Oct 2020 16:30:50 +0200
From:   Vasily Gorbik <gor@linux.ibm.com>
To:     Josh Poimboeuf <jpoimboe@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>
Cc:     Masami Hiramatsu <mhiramat@kernel.org>,
        David Laight <David.Laight@aculab.com>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
        Miroslav Benes <mbenes@suse.cz>,
        Alexandre Chartre <alexandre.chartre@oracle.com>,
        Julien Thierry <jthierry@redhat.com>,
        linux-kernel@vger.kernel.org
Subject: [RFC PATCH v4 3/4] objtool: correct rebuilding of reloc sections
Message-ID: <patch-3.thread-a8def4.git-2ef676be9306.your-ad-here.call-01601818410-ext-7687@work.hours>
References: <20201002160114.7yb7z7aeijhchpwl@treble>
 <cover.thread-a8def4.your-ad-here.call-01601818410-ext-7687@work.hours>
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From: Martin Schwidefsky <schwidefsky@de.ibm.com>

Currently relocations generated in elf_rebuild_rel_reloc_section/
elf_rebuild_rela_reloc_section functions are broken if the objtool is
built and run on big endian system. E.g. the following errors pop up
during x86 cross compilation:
x86_64-9.1.0-ld: fs/efivarfs/inode.o: bad reloc symbol index (0x2000000 >=
		0x22) for offset 0 in section `.orc_unwind_ip'
x86_64-9.1.0-ld: final link failed: bad value

To address that convert those functions to do things similar to
elf_write_reloc(), reuse gelf_update_rel/gelf_update_rela libelf library
functions.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Co-developed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
---
 tools/objtool/elf.c | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 4e1d7460574b..5c0341b0cde3 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -829,25 +829,27 @@ static int elf_rebuild_rel_reloc_section(struct section *sec, int nr)
 {
 	struct reloc *reloc;
 	int idx = 0, size;
-	GElf_Rel *relocs;
+	void *buf;
 
 	/* Allocate a buffer for relocations */
-	size = nr * sizeof(*relocs);
-	relocs = malloc(size);
-	if (!relocs) {
+	size = nr * sizeof(GElf_Rel);
+	buf = malloc(size);
+	if (!buf) {
 		perror("malloc");
 		return -1;
 	}
 
-	sec->data->d_buf = relocs;
+	sec->data->d_buf = buf;
 	sec->data->d_size = size;
+	sec->data->d_type = ELF_T_REL;
 
 	sec->sh.sh_size = size;
 
 	idx = 0;
 	list_for_each_entry(reloc, &sec->reloc_list, list) {
-		relocs[idx].r_offset = reloc->offset;
-		relocs[idx].r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
+		reloc->rel.r_offset = reloc->offset;
+		reloc->rel.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
+		gelf_update_rel(sec->data, idx, &reloc->rel);
 		idx++;
 	}
 
@@ -858,26 +860,28 @@ static int elf_rebuild_rela_reloc_section(struct section *sec, int nr)
 {
 	struct reloc *reloc;
 	int idx = 0, size;
-	GElf_Rela *relocs;
+	void *buf;
 
 	/* Allocate a buffer for relocations with addends */
-	size = nr * sizeof(*relocs);
-	relocs = malloc(size);
-	if (!relocs) {
+	size = nr * sizeof(GElf_Rela);
+	buf = malloc(size);
+	if (!buf) {
 		perror("malloc");
 		return -1;
 	}
 
-	sec->data->d_buf = relocs;
+	sec->data->d_buf = buf;
 	sec->data->d_size = size;
+	sec->data->d_type = ELF_T_RELA;
 
 	sec->sh.sh_size = size;
 
 	idx = 0;
 	list_for_each_entry(reloc, &sec->reloc_list, list) {
-		relocs[idx].r_offset = reloc->offset;
-		relocs[idx].r_addend = reloc->addend;
-		relocs[idx].r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
+		reloc->rela.r_offset = reloc->offset;
+		reloc->rela.r_addend = reloc->addend;
+		reloc->rela.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
+		gelf_update_rela(sec->data, idx, &reloc->rela);
 		idx++;
 	}
 
-- 
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