From da975dd4818cf42a181910789c096eb6997ed663 Mon Sep 17 00:00:00 2001 From: Zong Li Date: Thu, 15 Mar 2018 16:50:43 +0800 Subject: [PATCH] RISC-V: Support GOT_HI20/CALL_PLT relocation type in kernel module For CALL_PLT, emit the plt entry only when offset is more than 32-bit. For PCREL_LO12, it uses the location of corresponding HI20 to get the address of external symbol. It should check the HI20 type is the PCREL_HI20 or GOT_HI20, because sometime the location will have two or more relocation types. For example: 0: 00000797 auipc a5,0x0 0: R_RISCV_ALIGN *ABS* 0: R_RISCV_GOT_HI20 SYMBOL 4: 0007b783 ld a5,0(a5) # 0 4: R_RISCV_PCREL_LO12_I .L0 4: R_RISCV_RELAX *ABS* Signed-off-by: Zong Li Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/module.c | 62 ++++++++++++++++++++++++++++++++------ 1 file changed, 52 insertions(+), 10 deletions(-) diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c index e0f05034fc21..be717bd7cea7 100644 --- a/arch/riscv/kernel/module.c +++ b/arch/riscv/kernel/module.c @@ -92,6 +92,28 @@ static int apply_r_riscv_pcrel_lo12_s_rela(struct module *me, u32 *location, return 0; } +static int apply_r_riscv_got_hi20_rela(struct module *me, u32 *location, + Elf_Addr v) +{ + s64 offset = (void *)v - (void *)location; + s32 hi20; + + /* Always emit the got entry */ + if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) { + offset = module_emit_got_entry(me, v); + offset = (void *)offset - (void *)location; + } else { + pr_err( + "%s: can not generate the GOT entry for symbol = %016llx 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_call_plt_rela(struct module *me, u32 *location, Elf_Addr v) { @@ -100,10 +122,16 @@ static int apply_r_riscv_call_plt_rela(struct module *me, u32 *location, 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; + /* Only emit the plt entry if offset over 32-bit range */ + if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) { + offset = module_emit_plt_entry(me, v); + offset = (void *)offset - (void *)location; + } else { + 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; @@ -127,6 +155,7 @@ static int (*reloc_handlers_rela[]) (struct module *me, u32 *location, [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_GOT_HI20] = apply_r_riscv_got_hi20_rela, [R_RISCV_CALL_PLT] = apply_r_riscv_call_plt_rela, [R_RISCV_RELAX] = apply_r_riscv_relax_rela, }; @@ -184,25 +213,38 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, 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) { + u32 hi20_type = ELF_RISCV_R_TYPE(rel[j].r_info); + + /* Find the corresponding HI20 relocation entry */ + if (hi20_loc == sym->st_value + && (hi20_type == R_RISCV_PCREL_HI20 + || hi20_type == R_RISCV_GOT_HI20)) { + s32 hi20, lo12; 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; + u64 offset = hi20_sym_val - hi20_loc; + if (IS_ENABLED(CONFIG_MODULE_SECTIONS) + && hi20_type == R_RISCV_GOT_HI20) { + offset = module_emit_got_entry( + me, hi20_sym_val); + offset = offset - hi20_loc; + } + hi20 = (offset + 0x800) & 0xfffff000; + 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", + "%s: Can not find HI20 relocation information\n", me->name); return -EINVAL; }