diff options
Diffstat (limited to 'arch/riscv/kernel/module.c')
| -rw-r--r-- | arch/riscv/kernel/module.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c new file mode 100644 index 000000000000..e0f05034fc21 --- /dev/null +++ b/arch/riscv/kernel/module.c @@ -0,0 +1,217 @@ +/* + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * Copyright (C) 2017 Zihao Yu + */ + +#include <linux/elf.h> +#include <linux/err.h> +#include <linux/errno.h> +#include <linux/moduleloader.h> + +static int apply_r_riscv_64_rela(struct module *me, u32 *location, Elf_Addr v) +{ + *(u64 *)location = v; + return 0; +} + +static int apply_r_riscv_branch_rela(struct module *me, u32 *location, + Elf_Addr v) +{ + s64 offset = (void *)v - (void *)location; + u32 imm12 = (offset & 0x1000) << (31 - 12); + u32 imm11 = (offset & 0x800) >> (11 - 7); + u32 imm10_5 = (offset & 0x7e0) << (30 - 10); + u32 imm4_1 = (offset & 0x1e) << (11 - 4); + + *location = (*location & 0x1fff07f) | imm12 | imm11 | imm10_5 | imm4_1; + return 0; +} + +static int apply_r_riscv_jal_rela(struct module *me, u32 *location, + Elf_Addr v) +{ + s64 offset = (void *)v - (void *)location; + u32 imm20 = (offset & 0x100000) << (31 - 20); + u32 imm19_12 = (offset & 0xff000); + u32 imm11 = (offset & 0x800) << (20 - 11); + u32 imm10_1 = (offset & 0x7fe) << (30 - 10); + + *location = (*location & 0xfff) | imm20 | imm19_12 | imm11 | imm10_1; + return 0; +} + +static int apply_r_riscv_pcrel_hi20_rela(struct module *me, u32 *location, + Elf_Addr v) +{ + s64 offset = (void *)v - (void *)location; + s32 hi20; + + if (offset != (s32)offset) { + pr_err( + "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n", + me->name, v, location); + return -EINVAL; + } + + hi20 = (offset + 0x800) & 0xfffff000; + *location = (*location & 0xfff) | hi20; + return 0; +} + +static int apply_r_riscv_pcrel_lo12_i_rela(struct module *me, u32 *location, + Elf_Addr v) +{ + /* + * v is the lo12 value to fill. It is calculated before calling this + * handler. + */ + *location = (*location & 0xfffff) | ((v & 0xfff) << 20); + return 0; +} + +static int apply_r_riscv_pcrel_lo12_s_rela(struct module *me, u32 *location, + Elf_Addr v) +{ + /* + * v is the lo12 value to fill. It is calculated before calling this + * handler. + */ + u32 imm11_5 = (v & 0xfe0) << (31 - 11); + u32 imm4_0 = (v & 0x1f) << (11 - 4); + + *location = (*location & 0x1fff07f) | imm11_5 | imm4_0; + return 0; +} + +static int apply_r_riscv_call_plt_rela(struct module *me, u32 *location, + Elf_Addr v) +{ + s64 offset = (void *)v - (void *)location; + s32 fill_v = offset; + u32 hi20, lo12; + + if (offset != fill_v) { + pr_err( + "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n", + me->name, v, location); + return -EINVAL; + } + + hi20 = (offset + 0x800) & 0xfffff000; + lo12 = (offset - hi20) & 0xfff; + *location = (*location & 0xfff) | hi20; + *(location + 1) = (*(location + 1) & 0xfffff) | (lo12 << 20); + return 0; +} + +static int apply_r_riscv_relax_rela(struct module *me, u32 *location, + Elf_Addr v) +{ + return 0; +} + +static int (*reloc_handlers_rela[]) (struct module *me, u32 *location, + Elf_Addr v) = { + [R_RISCV_64] = apply_r_riscv_64_rela, + [R_RISCV_BRANCH] = apply_r_riscv_branch_rela, + [R_RISCV_JAL] = apply_r_riscv_jal_rela, + [R_RISCV_PCREL_HI20] = apply_r_riscv_pcrel_hi20_rela, + [R_RISCV_PCREL_LO12_I] = apply_r_riscv_pcrel_lo12_i_rela, + [R_RISCV_PCREL_LO12_S] = apply_r_riscv_pcrel_lo12_s_rela, + [R_RISCV_CALL_PLT] = apply_r_riscv_call_plt_rela, + [R_RISCV_RELAX] = apply_r_riscv_relax_rela, +}; + +int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, + unsigned int symindex, unsigned int relsec, + struct module *me) +{ + Elf_Rela *rel = (void *) sechdrs[relsec].sh_addr; + int (*handler)(struct module *me, u32 *location, Elf_Addr v); + Elf_Sym *sym; + u32 *location; + unsigned int i, type; + Elf_Addr v; + int res; + + pr_debug("Applying relocate section %u to %u\n", relsec, + sechdrs[relsec].sh_info); + + for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { + /* This is where to make the change */ + location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr + + rel[i].r_offset; + /* This is the symbol it is referring to */ + sym = (Elf_Sym *)sechdrs[symindex].sh_addr + + ELF_RISCV_R_SYM(rel[i].r_info); + if (IS_ERR_VALUE(sym->st_value)) { + /* Ignore unresolved weak symbol */ + if (ELF_ST_BIND(sym->st_info) == STB_WEAK) + continue; + pr_warning("%s: Unknown symbol %s\n", + me->name, strtab + sym->st_name); + return -ENOENT; + } + + type = ELF_RISCV_R_TYPE(rel[i].r_info); + + if (type < ARRAY_SIZE(reloc_handlers_rela)) + handler = reloc_handlers_rela[type]; + else + handler = NULL; + + if (!handler) { + pr_err("%s: Unknown relocation type %u\n", + me->name, type); + return -EINVAL; + } + + v = sym->st_value + rel[i].r_addend; + + if (type == R_RISCV_PCREL_LO12_I || type == R_RISCV_PCREL_LO12_S) { + unsigned int j; + + for (j = 0; j < sechdrs[relsec].sh_size / sizeof(*rel); j++) { + u64 hi20_loc = + sechdrs[sechdrs[relsec].sh_info].sh_addr + + rel[j].r_offset; + /* Find the corresponding HI20 PC-relative relocation entry */ + if (hi20_loc == sym->st_value) { + Elf_Sym *hi20_sym = + (Elf_Sym *)sechdrs[symindex].sh_addr + + ELF_RISCV_R_SYM(rel[j].r_info); + u64 hi20_sym_val = + hi20_sym->st_value + + rel[j].r_addend; + /* Calculate lo12 */ + s64 offset = hi20_sym_val - hi20_loc; + s32 hi20 = (offset + 0x800) & 0xfffff000; + s32 lo12 = offset - hi20; + v = lo12; + break; + } + } + if (j == sechdrs[relsec].sh_size / sizeof(*rel)) { + pr_err( + "%s: Can not find HI20 PC-relative relocation information\n", + me->name); + return -EINVAL; + } + } + + res = handler(me, location, v); + if (res) + return res; + } + + return 0; +} |