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RISC-V: Load purgatory in kexec_file
This patch supports kexec_file to load and relocate purgatory. It works well on riscv64 QEMU, being tested with devmem. Signed-off-by: Li Zhengyu <lizhengyu3@huawei.com> Link: https://lore.kernel.org/r/20220408100914.150110-7-lizhengyu3@huawei.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Li Zhengyu
Palmer Dabbelt
parent
736e30af58
commit
838b3e2848
1 changed files with 151 additions and 0 deletions
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@ -182,6 +182,7 @@ static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
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unsigned long new_kernel_pbase = 0UL;
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unsigned long initrd_pbase = 0UL;
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unsigned long headers_sz;
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unsigned long kernel_start;
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void *fdt, *headers;
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struct elfhdr ehdr;
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struct kexec_buf kbuf;
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@ -196,6 +197,7 @@ static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
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&old_kernel_pbase, &new_kernel_pbase);
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if (ret)
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goto out;
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kernel_start = image->start;
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pr_notice("The entry point of kernel at 0x%lx\n", image->start);
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/* Add the kernel binary to the image */
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@ -246,6 +248,22 @@ static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
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cmdline = modified_cmdline;
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}
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#ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY
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/* Add purgatory to the image */
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kbuf.top_down = true;
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kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
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ret = kexec_load_purgatory(image, &kbuf);
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if (ret) {
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pr_err("Error loading purgatory ret=%d\n", ret);
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goto out;
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}
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ret = kexec_purgatory_get_set_symbol(image, "riscv_kernel_entry",
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&kernel_start,
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sizeof(kernel_start), 0);
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if (ret)
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pr_err("Error update purgatory ret=%d\n", ret);
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#endif /* CONFIG_ARCH_HAS_KEXEC_PURGATORY */
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/* Add the initrd to the image */
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if (initrd != NULL) {
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kbuf.buffer = initrd;
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@ -291,6 +309,139 @@ static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
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return ret ? ERR_PTR(ret) : NULL;
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}
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#define RV_X(x, s, n) (((x) >> (s)) & ((1 << (n)) - 1))
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#define RISCV_IMM_BITS 12
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#define RISCV_IMM_REACH (1LL << RISCV_IMM_BITS)
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#define RISCV_CONST_HIGH_PART(x) \
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(((x) + (RISCV_IMM_REACH >> 1)) & ~(RISCV_IMM_REACH - 1))
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#define RISCV_CONST_LOW_PART(x) ((x) - RISCV_CONST_HIGH_PART(x))
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#define ENCODE_ITYPE_IMM(x) \
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(RV_X(x, 0, 12) << 20)
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#define ENCODE_BTYPE_IMM(x) \
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((RV_X(x, 1, 4) << 8) | (RV_X(x, 5, 6) << 25) | \
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(RV_X(x, 11, 1) << 7) | (RV_X(x, 12, 1) << 31))
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#define ENCODE_UTYPE_IMM(x) \
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(RV_X(x, 12, 20) << 12)
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#define ENCODE_JTYPE_IMM(x) \
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((RV_X(x, 1, 10) << 21) | (RV_X(x, 11, 1) << 20) | \
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(RV_X(x, 12, 8) << 12) | (RV_X(x, 20, 1) << 31))
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#define ENCODE_CBTYPE_IMM(x) \
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((RV_X(x, 1, 2) << 3) | (RV_X(x, 3, 2) << 10) | (RV_X(x, 5, 1) << 2) | \
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(RV_X(x, 6, 2) << 5) | (RV_X(x, 8, 1) << 12))
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#define ENCODE_CJTYPE_IMM(x) \
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((RV_X(x, 1, 3) << 3) | (RV_X(x, 4, 1) << 11) | (RV_X(x, 5, 1) << 2) | \
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(RV_X(x, 6, 1) << 7) | (RV_X(x, 7, 1) << 6) | (RV_X(x, 8, 2) << 9) | \
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(RV_X(x, 10, 1) << 8) | (RV_X(x, 11, 1) << 12))
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#define ENCODE_UJTYPE_IMM(x) \
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(ENCODE_UTYPE_IMM(RISCV_CONST_HIGH_PART(x)) | \
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(ENCODE_ITYPE_IMM(RISCV_CONST_LOW_PART(x)) << 32))
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#define ENCODE_UITYPE_IMM(x) \
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(ENCODE_UTYPE_IMM(x) | (ENCODE_ITYPE_IMM(x) << 32))
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#define CLEAN_IMM(type, x) \
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((~ENCODE_##type##_IMM((uint64_t)(-1))) & (x))
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int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
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Elf_Shdr *section,
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const Elf_Shdr *relsec,
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const Elf_Shdr *symtab)
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{
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const char *strtab, *name, *shstrtab;
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const Elf_Shdr *sechdrs;
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Elf_Rela *relas;
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int i, r_type;
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/* String & section header string table */
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sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
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strtab = (char *)pi->ehdr + sechdrs[symtab->sh_link].sh_offset;
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shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset;
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relas = (void *)pi->ehdr + relsec->sh_offset;
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for (i = 0; i < relsec->sh_size / sizeof(*relas); i++) {
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const Elf_Sym *sym; /* symbol to relocate */
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unsigned long addr; /* final location after relocation */
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unsigned long val; /* relocated symbol value */
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unsigned long sec_base; /* relocated symbol value */
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void *loc; /* tmp location to modify */
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sym = (void *)pi->ehdr + symtab->sh_offset;
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sym += ELF64_R_SYM(relas[i].r_info);
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if (sym->st_name)
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name = strtab + sym->st_name;
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else
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name = shstrtab + sechdrs[sym->st_shndx].sh_name;
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loc = pi->purgatory_buf;
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loc += section->sh_offset;
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loc += relas[i].r_offset;
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if (sym->st_shndx == SHN_ABS)
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sec_base = 0;
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else if (sym->st_shndx >= pi->ehdr->e_shnum) {
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pr_err("Invalid section %d for symbol %s\n",
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sym->st_shndx, name);
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return -ENOEXEC;
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} else
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sec_base = pi->sechdrs[sym->st_shndx].sh_addr;
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val = sym->st_value;
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val += sec_base;
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val += relas[i].r_addend;
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addr = section->sh_addr + relas[i].r_offset;
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r_type = ELF64_R_TYPE(relas[i].r_info);
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switch (r_type) {
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case R_RISCV_BRANCH:
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*(u32 *)loc = CLEAN_IMM(BTYPE, *(u32 *)loc) |
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ENCODE_BTYPE_IMM(val - addr);
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break;
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case R_RISCV_JAL:
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*(u32 *)loc = CLEAN_IMM(JTYPE, *(u32 *)loc) |
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ENCODE_JTYPE_IMM(val - addr);
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break;
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/*
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* With no R_RISCV_PCREL_LO12_S, R_RISCV_PCREL_LO12_I
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* sym is expected to be next to R_RISCV_PCREL_HI20
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* in purgatory relsec. Handle it like R_RISCV_CALL
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* sym, instead of searching the whole relsec.
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*/
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case R_RISCV_PCREL_HI20:
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case R_RISCV_CALL:
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*(u64 *)loc = CLEAN_IMM(UITYPE, *(u64 *)loc) |
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ENCODE_UJTYPE_IMM(val - addr);
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break;
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case R_RISCV_RVC_BRANCH:
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*(u32 *)loc = CLEAN_IMM(CBTYPE, *(u32 *)loc) |
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ENCODE_CBTYPE_IMM(val - addr);
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break;
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case R_RISCV_RVC_JUMP:
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*(u32 *)loc = CLEAN_IMM(CJTYPE, *(u32 *)loc) |
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ENCODE_CJTYPE_IMM(val - addr);
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break;
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case R_RISCV_ADD32:
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*(u32 *)loc += val;
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break;
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case R_RISCV_SUB32:
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*(u32 *)loc -= val;
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break;
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/* It has been applied by R_RISCV_PCREL_HI20 sym */
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case R_RISCV_PCREL_LO12_I:
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case R_RISCV_ALIGN:
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case R_RISCV_RELAX:
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break;
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default:
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pr_err("Unknown rela relocation: %d\n", r_type);
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return -ENOEXEC;
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}
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}
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return 0;
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}
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const struct kexec_file_ops elf_kexec_ops = {
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.probe = kexec_elf_probe,
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.load = elf_kexec_load,
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