linux-kernel - [PATCH 7/8] LoongArch: Support R_LARCH

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Date:   Sun, 28 Aug 2022 01:54:35 +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 7/8] LoongArch: Support R_LARCH_PCALA* in modules

GCC >= 13 and GNU assembler >= 2.40 use these relocations to address
local symbols, so we need to add them.

Signed-off-by: Xi Ruoyao <xry111@...111.site>
---
 arch/loongarch/kernel/module.c | 43 ++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/module.c
index 54be05c62145..61ecd174dd03 100644
--- a/arch/loongarch/kernel/module.c
+++ b/arch/loongarch/kernel/module.c
@@ -348,6 +348,48 @@ static int apply_r_larch_abs(struct module *mod, u32 *location, Elf_Addr v,
 
 	return 0;
 }
+
+static int apply_r_larch_pcala(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;
+	/* Use s32 for a sign-extension deliberately. */
+	s32 offset_hi20 = (void *)((v + 0x800) & ~0xfff) -
+		(void *)((Elf_Addr)location & ~0xfff);
+	Elf_Addr anchor = (((Elf_Addr)location) & ~0xfff) + offset_hi20;
+	ptrdiff_t offset_rem = (void *)v - (void *)anchor;
+
+	switch (type) {
+	case R_LARCH_PCALA_HI20:
+		v = offset_hi20 >> 12;
+		break;
+	case R_LARCH_PCALA64_LO20:
+		v = offset_rem >> 32;
+		break;
+	case R_LARCH_PCALA64_HI12:
+		v = offset_rem >> 52;
+		break;
+	default:
+		/* Do nothing. */
+	}
+
+	switch (type) {
+	case R_LARCH_PCALA_HI20:
+	case R_LARCH_PCALA64_LO20:
+		insn->reg1i20_format.immediate = v & 0xfffff;
+		break;
+	case R_LARCH_PCALA_LO12:
+	case R_LARCH_PCALA64_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
@@ -379,6 +421,7 @@ static reloc_rela_handler reloc_rela_handlers[] = {
 	[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,
+	[R_LARCH_PCALA_HI20...R_LARCH_PCALA64_HI12]	     = apply_r_larch_pcala,
 };
 
 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
-- 
2.37.0