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From:   Julien Thierry <jthierry@redhat.com>
To:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc:     catalin.marinas@arm.com, will@kernel.org, ardb@kernel.org,
        masahiroy@kernel.org, keescook@chromium.org,
        michal.lkml@markovi.net, jpoimboe@redhat.com, peterz@infradead.org,
        mark.rutland@arm.com, broonie@kernel.org,
        linux-efi@vger.kernel.org, linux-hardening@vger.kernel.org,
        Julien Thierry <jthierry@redhat.com>
Subject: [RFC PATCH 15/17] objtool: arm64: Handle supported relocations in alternatives
Date:   Wed, 20 Jan 2021 18:37:58 +0100
Message-Id: <20210120173800.1660730-16-jthierry@redhat.com>
In-Reply-To: <20210120173800.1660730-1-jthierry@redhat.com>
References: <20210120173800.1660730-1-jthierry@redhat.com>
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Based on get_alt_insn() in arch/arm64/kernel/alternative.c, arm64
alternative code adapts offsets for static branches and adrp
instructions.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
---
 tools/objtool/arch/arm64/special.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/objtool/arch/arm64/special.c b/tools/objtool/arch/arm64/special.c
index c9c3e0bfd581..d47e5590ed60 100644
--- a/tools/objtool/arch/arm64/special.c
+++ b/tools/objtool/arch/arm64/special.c
@@ -30,7 +30,11 @@ bool arch_support_alt_relocation(struct special_alt *special_alt,
 				 struct instruction *insn,
 				 struct reloc *reloc)
 {
-	return false;
+	u32 opcode = *(u32 *)(insn->sec->data->d_buf + insn->offset);
+
+	return aarch64_insn_is_branch_imm(opcode) ||
+	       aarch64_insn_is_adrp(opcode) ||
+	       !aarch64_insn_uses_literal(opcode);
 }
 
 static struct section *get_switch_table_info_section(struct objtool_file *file)
-- 
2.25.4