diff options
Diffstat (limited to 'service/arch/x86_64')
| -rw-r--r-- | service/arch/x86_64/dynamic.c | 139 | ||||
| -rw-r--r-- | service/arch/x86_64/rtld_link.S | 36 | ||||
| -rw-r--r-- | service/arch/x86_64/start.S | 30 |
3 files changed, 205 insertions, 0 deletions
diff --git a/service/arch/x86_64/dynamic.c b/service/arch/x86_64/dynamic.c new file mode 100644 index 0000000..02538ec --- /dev/null +++ b/service/arch/x86_64/dynamic.c @@ -0,0 +1,139 @@ +#include <kc.h> + +#include <libc/string.h> +#include <lib/elf.h> + +extern void _rtld_link(void); + +struct elf64_relatab +{ + Elf64_Rela *entries; + size_t size; + size_t entsize; +}; + +struct elf64_symtab +{ + Elf64_Sym *entries; + const char *strings; + size_t strsize; +}; + +struct elf64_dso_info +{ + char *base; + struct elf64_relatab jmprel; + struct elf64_relatab reladyn; + struct elf64_symtab dynsym; + Elf64_Addr *pltgot; +}; + +static struct elf64_dso_info dso_info; + +void kc_dynamic_init(char *base, Elf64_Dyn *dyn) +{ + dso_info = (struct elf64_dso_info) + { + base, + { + elf64_dt_ptr(base, dyn, DT_JMPREL), + elf64_dt_val(dyn, DT_PLTRELSZ), + elf64_dt_val(dyn, DT_PLTREL) == DT_RELA ? sizeof(Elf64_Rela) : -1 + }, + { + elf64_dt_ptr(base, dyn, DT_RELA), + elf64_dt_val(dyn, DT_RELASZ), + elf64_dt_val(dyn, DT_RELAENT) + }, + { + elf64_dt_ptr(base, dyn, DT_SYMTAB), + elf64_dt_ptr(base, dyn, DT_STRTAB), + elf64_dt_val(dyn, DT_STRSZ) + }, + elf64_dt_ptr(base, dyn, DT_PLTGOT) + }; + + if (dso_info.pltgot != nullptr) + { + dso_info.pltgot[1] = (uintptr_t)&dso_info; + dso_info.pltgot[2] = (uintptr_t)_rtld_link; + } + + kc_dynamic_reloc(base, &dso_info.jmprel); + kc_dynamic_reloc(base, &dso_info.reladyn); +} + +void *kc_dynamic_link(struct elf64_dso_info *dso, int index) +{ + struct kjarna_interface *ftab = entry_params->interface; + + int symindex = ELF64_R_SYM(dso->jmprel.entries[index].r_info); + int strindex = dso->dynsym.entries[symindex].st_name; + const char *name = &dso->dynsym.strings[strindex]; + uintptr_t *fixup = (uintptr_t *)(dso->base + dso->jmprel.entries[index].r_offset); + + // TODO: generate a symbol table for kjarna interface + // TODO: implement symbol lookup (maybe hashed too) + if (strcmp(name, "open") == 0) + { + *fixup = (uintptr_t)*ftab->open; + } + else if (strcmp(name, "close") == 0) + { + *fixup = (uintptr_t)*ftab->close; + } + else if (strcmp(name, "read") == 0) + { + *fixup = (uintptr_t)*ftab->read; + } + else if (strcmp(name, "write") == 0) + { + *fixup = (uintptr_t)*ftab->write; + } + else if (strcmp(name, "lseek") == 0) + { + *fixup = (uintptr_t)*ftab->lseek; + } + else if (strcmp(name, "mmap") == 0) + { + *fixup = (uintptr_t)*ftab->mmap; + } + else if (strcmp(name, "munmap") == 0) + { + *fixup = (uintptr_t)*ftab->munmap; + } + else + { + return nullptr; + } + + return fixup; +} + +static void do_rela(char *base, Elf64_Rela *rela) +{ + uintptr_t *fixup = (uintptr_t *)(base + rela->r_offset); + + switch (ELF64_R_TYPE(rela->r_info)) + { + case R_X86_64_JUMP_SLOT: + *fixup += (uintptr_t)base; + break; + case R_X86_64_RELATIVE: + *fixup = (uintptr_t)(rela->r_addend + base); + break; + default: + break; + } +} + +void kc_dynamic_reloc(char *base, struct elf64_relatab *rela) +{ + size_t entries = rela->size / rela->entsize; + + for (size_t i = 0; rela->entries && (i < entries); i++) + { + do_rela(base, &rela->entries[i]); + } +} + diff --git a/service/arch/x86_64/rtld_link.S b/service/arch/x86_64/rtld_link.S new file mode 100644 index 0000000..7300a18 --- /dev/null +++ b/service/arch/x86_64/rtld_link.S @@ -0,0 +1,36 @@ +.section .text + +.extern kc_dynamic_link + +.hidden _rtld_link +.global _rtld_link +.type _rtld_link, @function +_rtld_link: + push %rbp + mov %rsp, %rbp + push %r9 + push %r8 + push %rcx + push %rdx + push %rsi + push %rdi + mov 8(%rbp), %rdi + mov 16(%rbp), %rsi + push %rbp + mov %rsp, %rbp + and $-0x10, %rsp + call kc_dynamic_link + mov %rbp, %rsp + pop %rbp + pop %rdi + pop %rsi + pop %rdx + pop %rcx + pop %r8 + pop %r9 + mov %rbp, %rsp + pop %rbp + add $0x10, %rsp + jmp *(%rax) +.size _rtld_link, . - _rtld_link + diff --git a/service/arch/x86_64/start.S b/service/arch/x86_64/start.S new file mode 100644 index 0000000..a9d5ada --- /dev/null +++ b/service/arch/x86_64/start.S @@ -0,0 +1,30 @@ +.section .text.start + +.extern kc_image_base; +.extern _DYNAMIC; +.extern kc_dynamic_init; +.extern kjarna_entry + +.hidden _start +.global _start +.type _start, @function +_start: + push %rbp + push %rdi + push %rsi + mov %rsp, %rbp + and $-0x10, %rsp + lea kc_image_base(%rip), %rdi + lea _DYNAMIC(%rip), %rsi + call kc_dynamic_init + mov %rbp, %rsp + pop %rsi + pop %rdi + mov %rsp, %rbp + and $-0x10, %rsp + call kjarna_entry + mov %rbp, %rsp + pop %rbp + ret +.size _start, . - _start + |