[PATCH v4 4/4] LoongArch: Support modules with new relocation types

[Xi Ruoyao <xry111@xry111.site>]

If GAS 2.40 and/or GCC 13 is used to build the kernel, the modules will
contain R_LARCH_B26, R_LARCH_PCALA_HI20, R_LARCH_PCALA_LO12,
R_LARCH_GOT_PC_HI20, and R_LARCH_GOT_PC_LO12 relocations.  Support them
in the module loader to allow a kernel built with latest toolchain
capable to load the modules.

Signed-off-by: Xi Ruoyao <xry111@xry111.site>
---
 arch/loongarch/include/asm/elf.h        | 37 +++++++++++
 arch/loongarch/kernel/module-sections.c | 12 +++-
 arch/loongarch/kernel/module.c          | 85 +++++++++++++++++++++++++
 3 files changed, 132 insertions(+), 2 deletions(-)

diff --git a/arch/loongarch/include/asm/elf.h b/arch/loongarch/include/asm/elf.h
index 5f3ff4781fda..7af0cebf28d7 100644
--- a/arch/loongarch/include/asm/elf.h
+++ b/arch/loongarch/include/asm/elf.h
@@ -74,6 +74,43 @@
 #define R_LARCH_SUB64				56
 #define R_LARCH_GNU_VTINHERIT			57
 #define R_LARCH_GNU_VTENTRY			58
+#define R_LARCH_B16				64
+#define R_LARCH_B21				65
+#define R_LARCH_B26				66
+#define R_LARCH_ABS_HI20			67
+#define R_LARCH_ABS_LO12			68
+#define R_LARCH_ABS64_LO20			69
+#define R_LARCH_ABS64_HI12			70
+#define R_LARCH_PCALA_HI20			71
+#define R_LARCH_PCALA_LO12			72
+#define R_LARCH_PCALA64_LO20			73
+#define R_LARCH_PCALA64_HI12			74
+#define R_LARCH_GOT_PC_HI20			75
+#define R_LARCH_GOT_PC_LO12			76
+#define R_LARCH_GOT64_PC_LO20			77
+#define R_LARCH_GOT64_PC_HI12			78
+#define R_LARCH_GOT_HI20			79
+#define R_LARCH_GOT_LO12			80
+#define R_LARCH_GOT64_LO20			81
+#define R_LARCH_GOT64_HI12			82
+#define R_LARCH_TLS_LE_HI20			83
+#define R_LARCH_TLS_LE_LO12			84
+#define R_LARCH_TLS_LE64_LO20			85
+#define R_LARCH_TLS_LE64_HI12			86
+#define R_LARCH_TLS_IE_PC_HI20			87
+#define R_LARCH_TLS_IE_PC_LO12			88
+#define R_LARCH_TLS_IE64_PC_LO20		89
+#define R_LARCH_TLS_IE64_PC_HI12		90
+#define R_LARCH_TLS_IE_HI20			91
+#define R_LARCH_TLS_IE_LO12			92
+#define R_LARCH_TLS_IE64_LO20			93
+#define R_LARCH_TLS_IE64_HI12			94
+#define R_LARCH_TLS_LD_PC_HI20			95
+#define R_LARCH_TLS_LD_HI20			96
+#define R_LARCH_TLS_GD_PC_HI20			97
+#define R_LARCH_TLS_GD_HI20			98
+#define R_LARCH_32_PCREL			99
+#define R_LARCH_RELAX				100
 
 #ifndef ELF_ARCH
 
diff --git a/arch/loongarch/kernel/module-sections.c b/arch/loongarch/kernel/module-sections.c
index 36a77771d18c..8c0e4ad048cc 100644
--- a/arch/loongarch/kernel/module-sections.c
+++ b/arch/loongarch/kernel/module-sections.c
@@ -76,12 +76,20 @@ static void count_max_entries(Elf_Rela *relas, int num,
 
 	for (i = 0; i < num; i++) {
 		type = ELF_R_TYPE(relas[i].r_info);
-		if (type == R_LARCH_SOP_PUSH_PLT_PCREL) {
+		switch (type) {
+		case R_LARCH_SOP_PUSH_PLT_PCREL:
+		case R_LARCH_B26:
 			if (!duplicate_rela(relas, i))
 				(*plts)++;
-		} else if (type == R_LARCH_SOP_PUSH_GPREL)
+			break;
+		case R_LARCH_SOP_PUSH_GPREL:
+		case R_LARCH_GOT_PC_HI20:
 			if (!duplicate_rela(relas, i))
 				(*gots)++;
+			break;
+		default:
+			/* Do nothing. */
+		}
 	}
 }
 
diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/module.c
index 3ac4fbb5f109..c7b40150e1f0 100644
--- a/arch/loongarch/kernel/module.c
+++ b/arch/loongarch/kernel/module.c
@@ -291,6 +291,86 @@ static int apply_r_larch_add_sub(struct module *mod, u32 *location, Elf_Addr v,
 	}
 }
 
+static int apply_r_larch_b26(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;
+	union loongarch_instruction *insn = (union loongarch_instruction *)location;
+
+	if (offset >= SZ_128M)
+		v = module_emit_plt_entry(mod, v);
+
+	if (offset < -SZ_128M)
+		v = module_emit_plt_entry(mod, v);
+
+	offset = (void *)v - (void *)location;
+
+	if (offset & 3) {
+		pr_err("module %s: jump offset = 0x%llx unaligned! dangerous R_LARCH_B26 (%u) relocation\n",
+				mod->name, (long long)offset, type);
+		return -ENOEXEC;
+	}
+
+	if (!signed_imm_check(offset, 28)) {
+		pr_err("module %s: jump offset = 0x%llx overflow! dangerous R_LARCH_B26 (%u) relocation\n",
+				mod->name, (long long)offset, type);
+		return -ENOEXEC;
+	}
+
+	offset >>= 2;
+	insn->reg0i26_format.immediate_l = offset & 0xffff;
+	insn->reg0i26_format.immediate_h = (offset >> 16) & 0x3ff;
+	return 0;
+}
+
+static int apply_r_larch_pcala_hi20(struct module *mod, u32 *location,
+		Elf_Addr v, s64 *rela_stack, size_t *rela_stack_top,
+		unsigned int type)
+{
+	ptrdiff_t offset = (void *)((v + 0x800) & ~0xfff) -
+		(void *)((Elf_Addr)location & ~0xfff);
+	union loongarch_instruction *insn = (union loongarch_instruction *)location;
+
+	if (!signed_imm_check(offset, 32)) {
+		pr_err("module %s: PCALA offset = 0x%llx does not fit in 32-bit signed and is unsupported by kernel! dangerous %s (%u) relocation\n",
+				mod->name, (long long)offset, __func__, type);
+		return -ENOEXEC;
+	}
+
+	insn->reg1i20_format.immediate = (offset >> 12) & 0xfffff;
+	return 0;
+}
+
+static int apply_r_larch_got_pc_hi20(struct module *mod, u32 *location,
+		Elf_Addr v, s64 *rela_stack, size_t *rela_stack_top,
+		unsigned int type)
+{
+	Elf_Addr got = module_emit_got_entry(mod, v);
+
+	return apply_r_larch_pcala_hi20(mod, location, got, rela_stack,
+			rela_stack_top, type);
+}
+
+static int apply_r_larch_pcala_lo12(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;
+
+	insn->reg2i12_format.immediate = v & 0xfff;
+	return 0;
+}
+
+static int apply_r_larch_got_pc_lo12(struct module *mod, u32 *location,
+		Elf_Addr v, s64 *rela_stack, size_t *rela_stack_top,
+		unsigned int type)
+{
+	Elf_Addr got = module_emit_got_entry(mod, v);
+
+	return apply_r_larch_pcala_lo12(mod, location, got, rela_stack,
+			rela_stack_top, type);
+}
+
 /*
  * reloc_handlers_rela() - Apply a particular relocation to a module
  * @mod: the module to apply the reloc to
@@ -321,6 +401,11 @@ static reloc_rela_handler reloc_rela_handlers[] = {
 	[R_LARCH_SOP_SUB ... R_LARCH_SOP_IF_ELSE] 	     = apply_r_larch_sop,
 	[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_PCALA_HI20]				     = apply_r_larch_pcala_hi20,
+	[R_LARCH_PCALA_LO12]				     = apply_r_larch_pcala_lo12,
+	[R_LARCH_GOT_PC_HI20]				     = apply_r_larch_got_pc_hi20,
+	[R_LARCH_GOT_PC_LO12]				     = apply_r_larch_got_pc_lo12,
 };
 
 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
-- 
2.37.0