linux-kernel - [PATCH 01/22] objtool: use sh_info to find the base for .rela sections

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Message-Id: <20200624203200.78870-2-samitolvanen@google.com>
Date:   Wed, 24 Jun 2020 13:31:39 -0700
From:   Sami Tolvanen <samitolvanen@...gle.com>
To:     Masahiro Yamada <masahiroy@...nel.org>,
        Will Deacon <will@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        clang-built-linux@...glegroups.com,
        kernel-hardening@...ts.openwall.com, linux-arch@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kbuild@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        x86@...nel.org, Sami Tolvanen <samitolvanen@...gle.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>
Subject: [PATCH 01/22] objtool: use sh_info to find the base for .rela sections

ELF doesn't require .rela section names to match the base section. Use
the section index in sh_info to find the section instead of looking it
up by name.

LLD, for example, generates a .rela section that doesn't match the base
section name when we merge sections in a linker script for a binary
compiled with -ffunction-sections.

Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Reviewed-by: Kees Cook <keescook@...omium.org>
---
 tools/objtool/elf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 84225679f96d..c1ba92abaa03 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -502,7 +502,7 @@ static int read_relas(struct elf *elf)
 		if (sec->sh.sh_type != SHT_RELA)
 			continue;
 
-		sec->base = find_section_by_name(elf, sec->name + 5);
+		sec->base = find_section_by_index(elf, sec->sh.sh_info);
 		if (!sec->base) {
 			WARN("can't find base section for rela section %s",
 			     sec->name);
-- 
2.27.0.212.ge8ba1cc988-goog