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RISC-V: Load purgatory in kexec_file

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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 2022-04-08 18:09:14 +08:00 committed by Palmer Dabbelt
parent 736e30af58
commit 838b3e2848
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GPG key ID: EF4CA1502CCBAB41
1 changed files with 151 additions and 0 deletions
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151
arch/riscv/kernel/elf_kexec.c
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@ -182,6 +182,7 @@ static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
unsigned long new_kernel_pbase = 0UL;
unsigned long initrd_pbase = 0UL;
unsigned long headers_sz;
unsigned long kernel_start;
void *fdt, *headers;
struct elfhdr ehdr;
struct kexec_buf kbuf;
@ -196,6 +197,7 @@ static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
&old_kernel_pbase, &new_kernel_pbase);
if (ret)
goto out;
kernel_start = image->start;
pr_notice("The entry point of kernel at 0x%lx\n", image->start);
/* Add the kernel binary to the image */
@ -246,6 +248,22 @@ static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
cmdline = modified_cmdline;
}
#ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY
/* Add purgatory to the image */
kbuf.top_down = true;
kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
ret = kexec_load_purgatory(image, &kbuf);
if (ret) {
pr_err("Error loading purgatory ret=%d\n", ret);
goto out;
}
ret = kexec_purgatory_get_set_symbol(image, "riscv_kernel_entry",
&kernel_start,
sizeof(kernel_start), 0);
if (ret)
pr_err("Error update purgatory ret=%d\n", ret);
#endif /* CONFIG_ARCH_HAS_KEXEC_PURGATORY */
/* Add the initrd to the image */
if (initrd != NULL) {
kbuf.buffer = initrd;
@ -291,6 +309,139 @@ static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
return ret ? ERR_PTR(ret) : NULL;
}
#define RV_X(x, s, n) (((x) >> (s)) & ((1 << (n)) - 1))
#define RISCV_IMM_BITS 12
#define RISCV_IMM_REACH (1LL << RISCV_IMM_BITS)
#define RISCV_CONST_HIGH_PART(x) \
(((x) + (RISCV_IMM_REACH >> 1)) & ~(RISCV_IMM_REACH - 1))
#define RISCV_CONST_LOW_PART(x) ((x) - RISCV_CONST_HIGH_PART(x))
#define ENCODE_ITYPE_IMM(x) \
(RV_X(x, 0, 12) << 20)
#define ENCODE_BTYPE_IMM(x) \
((RV_X(x, 1, 4) << 8) | (RV_X(x, 5, 6) << 25) | \
(RV_X(x, 11, 1) << 7) | (RV_X(x, 12, 1) << 31))
#define ENCODE_UTYPE_IMM(x) \
(RV_X(x, 12, 20) << 12)
#define ENCODE_JTYPE_IMM(x) \
((RV_X(x, 1, 10) << 21) | (RV_X(x, 11, 1) << 20) | \
(RV_X(x, 12, 8) << 12) | (RV_X(x, 20, 1) << 31))
#define ENCODE_CBTYPE_IMM(x) \
((RV_X(x, 1, 2) << 3) | (RV_X(x, 3, 2) << 10) | (RV_X(x, 5, 1) << 2) | \
(RV_X(x, 6, 2) << 5) | (RV_X(x, 8, 1) << 12))
#define ENCODE_CJTYPE_IMM(x) \
((RV_X(x, 1, 3) << 3) | (RV_X(x, 4, 1) << 11) | (RV_X(x, 5, 1) << 2) | \
(RV_X(x, 6, 1) << 7) | (RV_X(x, 7, 1) << 6) | (RV_X(x, 8, 2) << 9) | \
(RV_X(x, 10, 1) << 8) | (RV_X(x, 11, 1) << 12))
#define ENCODE_UJTYPE_IMM(x) \
(ENCODE_UTYPE_IMM(RISCV_CONST_HIGH_PART(x)) | \
(ENCODE_ITYPE_IMM(RISCV_CONST_LOW_PART(x)) << 32))
#define ENCODE_UITYPE_IMM(x) \
(ENCODE_UTYPE_IMM(x) | (ENCODE_ITYPE_IMM(x) << 32))
#define CLEAN_IMM(type, x) \
((~ENCODE_##type##_IMM((uint64_t)(-1))) & (x))
int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
Elf_Shdr *section,
const Elf_Shdr *relsec,
const Elf_Shdr *symtab)
{
const char *strtab, *name, *shstrtab;
const Elf_Shdr *sechdrs;
Elf_Rela *relas;
int i, r_type;
/* String & section header string table */
sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
strtab = (char *)pi->ehdr + sechdrs[symtab->sh_link].sh_offset;
shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset;
relas = (void *)pi->ehdr + relsec->sh_offset;
for (i = 0; i < relsec->sh_size / sizeof(*relas); i++) {
const Elf_Sym *sym; /* symbol to relocate */
unsigned long addr; /* final location after relocation */
unsigned long val; /* relocated symbol value */
unsigned long sec_base; /* relocated symbol value */
void *loc; /* tmp location to modify */
sym = (void *)pi->ehdr + symtab->sh_offset;
sym += ELF64_R_SYM(relas[i].r_info);
if (sym->st_name)
name = strtab + sym->st_name;
else
name = shstrtab + sechdrs[sym->st_shndx].sh_name;
loc = pi->purgatory_buf;
loc += section->sh_offset;
loc += relas[i].r_offset;
if (sym->st_shndx == SHN_ABS)
sec_base = 0;
else if (sym->st_shndx >= pi->ehdr->e_shnum) {
pr_err("Invalid section %d for symbol %s\n",
sym->st_shndx, name);
return -ENOEXEC;
} else
sec_base = pi->sechdrs[sym->st_shndx].sh_addr;
val = sym->st_value;
val += sec_base;
val += relas[i].r_addend;
addr = section->sh_addr + relas[i].r_offset;
r_type = ELF64_R_TYPE(relas[i].r_info);
switch (r_type) {
case R_RISCV_BRANCH:
*(u32 *)loc = CLEAN_IMM(BTYPE, *(u32 *)loc) |
ENCODE_BTYPE_IMM(val - addr);
break;
case R_RISCV_JAL:
*(u32 *)loc = CLEAN_IMM(JTYPE, *(u32 *)loc) |
ENCODE_JTYPE_IMM(val - addr);
break;
/*
* With no R_RISCV_PCREL_LO12_S, R_RISCV_PCREL_LO12_I
* sym is expected to be next to R_RISCV_PCREL_HI20
* in purgatory relsec. Handle it like R_RISCV_CALL
* sym, instead of searching the whole relsec.
*/
case R_RISCV_PCREL_HI20:
case R_RISCV_CALL:
*(u64 *)loc = CLEAN_IMM(UITYPE, *(u64 *)loc) |
ENCODE_UJTYPE_IMM(val - addr);
break;
case R_RISCV_RVC_BRANCH:
*(u32 *)loc = CLEAN_IMM(CBTYPE, *(u32 *)loc) |
ENCODE_CBTYPE_IMM(val - addr);
break;
case R_RISCV_RVC_JUMP:
*(u32 *)loc = CLEAN_IMM(CJTYPE, *(u32 *)loc) |
ENCODE_CJTYPE_IMM(val - addr);
break;
case R_RISCV_ADD32:
*(u32 *)loc += val;
break;
case R_RISCV_SUB32:
*(u32 *)loc -= val;
break;
/* It has been applied by R_RISCV_PCREL_HI20 sym */
case R_RISCV_PCREL_LO12_I:
case R_RISCV_ALIGN:
case R_RISCV_RELAX:
break;
default:
pr_err("Unknown rela relocation: %d\n", r_type);
return -ENOEXEC;
}
}
return 0;
}
const struct kexec_file_ops elf_kexec_ops = {
.probe = kexec_elf_probe,
.load = elf_kexec_load,