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From:   Youling Tang <tangyouling@loongson.cn>
To:     Josh Poimboeuf <jpoimboe@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Huacai Chen <chenhuacai@kernel.org>,
        madvenka@linux.microsoft.com
Cc:     chenzhongjin@huawei.com, WANG Xuerui <kernel@xen0n.name>,
        Xi Ruoyao <xry111@xry111.site>, live-patching@vger.kernel.org,
        linux-kernel@vger.kernel.org, loongarch@lists.linux.dev,
        tangyouling00@gmail.com, youling.tang@outlook.com
Subject: [RFC PATCH v1 17/23] LoongArch: Support R_LARCH_32_PCREL relocation type in kernel module
Date:   Tue, 20 Jun 2023 15:52:04 +0800
Message-Id: <1687247526-32258-3-git-send-email-tangyouling@loongson.cn>
In-Reply-To: <1687247526-32258-1-git-send-email-tangyouling@loongson.cn>
References: <1687247526-32258-1-git-send-email-tangyouling@loongson.cn>
Precedence: bulk

Fix "unsupported relocation type" errors caused by adding ORC support,
which generates unsupported relocation types.

The reason is because the generated '.rela.orc_unwind_ip' section will
contain the R_LARCH_32_PCCREL type.

Relocation section '.rela.orc_unwind_ip' at offset 0x1fb58 contains 600 entries:
  Offset          Info           Type           Sym. Value    Sym. Name + Addend
000000000000  000300000063 R_LARCH_32_PCREL  0000000000000000 .text + 0
000000000004  000300000063 R_LARCH_32_PCREL  0000000000000000 .text + 64

Signed-off-by: Youling Tang <tangyouling@loongson.cn>
---
 arch/loongarch/kernel/module.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/module.c
index 44f31b1958b1..3cc31701c76a 100644
--- a/arch/loongarch/kernel/module.c
+++ b/arch/loongarch/kernel/module.c
@@ -368,6 +368,15 @@ static int apply_r_larch_got_pc(struct module *mod,
 	return apply_r_larch_pcala(mod, location, got, rela_stack, rela_stack_top, type);
 }
 
+static int apply_r_larch_32_pcrel(struct module *mod, u32 *location, Elf_Addr v,
+			s64 *rela_stack, size_t *rela_stack_top, unsigned int type)
+{
+	ptrdiff_t offset = (void *)v - (void *)location;
+
+	*(u32 *)location = offset;
+	return 0;
+}
+
 /*
  * reloc_handlers_rela() - Apply a particular relocation to a module
  * @mod: the module to apply the reloc to
@@ -397,6 +406,7 @@ static reloc_rela_handler reloc_rela_handlers[] = {
 	[R_LARCH_SOP_POP_32_S_10_5 ... R_LARCH_SOP_POP_32_U] = apply_r_larch_sop_imm_field,
 	[R_LARCH_ADD32 ... R_LARCH_SUB64]		     = apply_r_larch_add_sub,
 	[R_LARCH_PCALA_HI20...R_LARCH_PCALA64_HI12]	     = apply_r_larch_pcala,
+	[R_LARCH_32_PCREL]				     = apply_r_larch_32_pcrel,
 };
 
 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
-- 
2.39.2