RISC-V: Support SUB32 relocation type in kernel module

Signed-off-by: NZong Li <zong@andestech.com>
Signed-off-by: NPalmer Dabbelt <palmer@sifive.com>

arch/riscv/kernel/module.c

@@ -256,6 +256,13 @@ static int apply_r_riscv_add32_rela(struct module *me, u32 *location,
 	return 0;
 }
 
+static int apply_r_riscv_sub32_rela(struct module *me, u32 *location,
+				    Elf_Addr v)
+{
+	*(u32 *)location -= (*(u32 *)v);
+	return 0;
+}
+
 static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
 				Elf_Addr v) = {
 	[R_RISCV_64]			= apply_r_riscv_64_rela,
@@ -275,6 +282,7 @@ static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
 	[R_RISCV_RELAX]			= apply_r_riscv_relax_rela,
 	[R_RISCV_ALIGN]			= apply_r_riscv_align_rela,
 	[R_RISCV_ADD32]			= apply_r_riscv_add32_rela,
+	[R_RISCV_SUB32]			= apply_r_riscv_sub32_rela,
 };
 
 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,