linux-kernel - [PATCH 5/8] LoongArch: Support R_LARCH

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Date:   Sun, 28 Aug 2022 01:54:33 +0800
From:   Xi Ruoyao <xry111@...111.site>
To:     loongarch@...ts.linux.dev
Cc:     linux-kernel@...r.kernel.org, WANG Xuerui <kernel@...0n.name>,
        Huacai Chen <chenhuacai@...nel.org>,
        Youling Tang <tangyouling@...ngson.cn>,
        Jinyang He <hejinyang@...ngson.cn>,
        Xi Ruoyao <xry111@...111.site>
Subject: [PATCH 5/8] LoongArch: Support R_LARCH_ABS* in modules

Binutils >= 2.40 uses R_LARCH_ABS* for relocations expanding "la.abs"
macro, instead of R_LARCH_PUSH_ABSOLUTE and other stack operations.
Handle R_LARCH_ABS* so we can load modules built with Binutils >= 2.40.

Signed-off-by: Xi Ruoyao <xry111@...111.site>
---
 arch/loongarch/kernel/module.c | 36 ++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/module.c
index e54df4717e4f..54be05c62145 100644
--- a/arch/loongarch/kernel/module.c
+++ b/arch/loongarch/kernel/module.c
@@ -313,6 +313,41 @@ static int apply_r_larch_b26(struct module *mod, u32 *location, Elf_Addr v,
 	return 0;
 }
 
+static int apply_r_larch_abs(struct module *mod, u32 *location, Elf_Addr v,
+			s64 *rela_stack, size_t *rela_stack_top, unsigned int type)
+{
+	union loongarch_instruction *insn = (union loongarch_instruction *)location;
+
+	switch (type) {
+	case R_LARCH_ABS_HI20:
+		v >>= 12;
+		break;
+	case R_LARCH_ABS64_LO20:
+		v >>= 32;
+		break;
+	case R_LARCH_ABS64_HI12:
+		v >>= 52;
+		break;
+	default:
+		/* Do nothing. */
+	}
+
+	switch (type) {
+	case R_LARCH_ABS_HI20:
+	case R_LARCH_ABS64_LO20:
+		insn->reg1i20_format.immediate = v & 0xfffff;
+		break;
+	case R_LARCH_ABS_LO12:
+	case R_LARCH_ABS64_HI12:
+		insn->reg2i12_format.immediate = v & 0xfff;
+		break;
+	default:
+		pr_err("%s: Unsupport relocation type %u\n", mod->name, type);
+		return -EINVAL;
+	}
+
+	return 0;
+}
 /*
  * reloc_handlers_rela() - Apply a particular relocation to a module
  * @mod: the module to apply the reloc to
@@ -343,6 +378,7 @@ 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_B26]					     = apply_r_larch_b26,
+	[R_LARCH_ABS_HI20...R_LARCH_ABS64_HI12]		     = apply_r_larch_abs,
 };
 
 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
-- 
2.37.0