mirror of
https://gitlab.com/bztsrc/posix-uefi.git
synced 2025-01-01 03:25:52 +01:00
114 lines
4.1 KiB
C
114 lines
4.1 KiB
C
#include <uefi.h>
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/*** ELF64 defines and structs ***/
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#define ELFMAG "\177ELF"
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#define SELFMAG 4
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#define EI_CLASS 4 /* File class byte index */
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#define ELFCLASS64 2 /* 64-bit objects */
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#define EI_DATA 5 /* Data encoding byte index */
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#define ELFDATA2LSB 1 /* 2's complement, little endian */
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#define ET_EXEC 2 /* Executable file */
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#define PT_LOAD 1 /* Loadable program segment */
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#ifdef __x86_64__
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#define EM_MACH 62 /* AMD x86-64 architecture */
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#endif
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#ifdef __aarch64__
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#define EM_MACH 183 /* ARM aarch64 architecture */
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#endif
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typedef struct
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{
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uint8_t e_ident[16]; /* Magic number and other info */
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uint16_t e_type; /* Object file type */
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uint16_t e_machine; /* Architecture */
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uint32_t e_version; /* Object file version */
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uint64_t e_entry; /* Entry point virtual address */
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uint64_t e_phoff; /* Program header table file offset */
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uint64_t e_shoff; /* Section header table file offset */
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uint32_t e_flags; /* Processor-specific flags */
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uint16_t e_ehsize; /* ELF header size in bytes */
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uint16_t e_phentsize; /* Program header table entry size */
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uint16_t e_phnum; /* Program header table entry count */
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uint16_t e_shentsize; /* Section header table entry size */
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uint16_t e_shnum; /* Section header table entry count */
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uint16_t e_shstrndx; /* Section header string table index */
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} Elf64_Ehdr;
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typedef struct
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{
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uint32_t p_type; /* Segment type */
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uint32_t p_flags; /* Segment flags */
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uint64_t p_offset; /* Segment file offset */
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uint64_t p_vaddr; /* Segment virtual address */
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uint64_t p_paddr; /* Segment physical address */
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uint64_t p_filesz; /* Segment size in file */
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uint64_t p_memsz; /* Segment size in memory */
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uint64_t p_align; /* Segment alignment */
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} Elf64_Phdr;
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/**
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* Load an ELF executable
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*/
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int main(int argc, char **argv)
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{
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(void)argc;
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(void)argv;
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FILE *f;
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char *buff;
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long int size;
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Elf64_Ehdr *elf;
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Elf64_Phdr *phdr;
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uintptr_t entry;
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int i;
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/* load the file */
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if((f = fopen("\\0E_elfload\\kernel.elf", "r"))) {
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fseek(f, 0, SEEK_END);
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size = ftell(f);
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fseek(f, 0, SEEK_SET);
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buff = malloc(size + 1);
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if(!buff) {
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fprintf(stderr, "unable to allocate memory\n");
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return 1;
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}
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fread(buff, size, 1, f);
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fclose(f);
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} else {
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fprintf(stderr, "Unable to open file\n");
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return 0;
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}
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/* is it a valid ELF executable for this architecture? */
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elf = (Elf64_Ehdr *)buff;
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if(!memcmp(elf->e_ident, ELFMAG, SELFMAG) && /* magic match? */
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elf->e_ident[EI_CLASS] == ELFCLASS64 && /* 64 bit? */
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elf->e_ident[EI_DATA] == ELFDATA2LSB && /* LSB? */
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elf->e_type == ET_EXEC && /* executable object? */
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elf->e_machine == EM_MACH && /* architecture match? */
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elf->e_phnum > 0) { /* has program headers? */
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/* load segments */
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for(phdr = (Elf64_Phdr *)(buff + elf->e_phoff), i = 0;
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i < elf->e_phnum;
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i++, phdr = (Elf64_Phdr *)((uint8_t *)phdr + elf->e_phentsize)) {
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if(phdr->p_type == PT_LOAD) {
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printf("ELF segment %p %d bytes (bss %d bytes)\n", phdr->p_vaddr, phdr->p_filesz,
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phdr->p_memsz - phdr->p_filesz);
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memcpy((void*)phdr->p_vaddr, buff + phdr->p_offset, phdr->p_filesz);
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memset((void*)(phdr->p_vaddr + phdr->p_filesz), 0, phdr->p_memsz - phdr->p_filesz);
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}
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}
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entry = elf->e_entry;
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} else {
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fprintf(stderr, "not a valid ELF executable for this architecture\n");
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return 0;
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}
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/* free resources */
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free(buff);
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/* execute the "kernel" */
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printf("ELF entry point %p\n", entry);
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i = (*((int(* __attribute__((sysv_abi)))(void))(entry)))();
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printf("ELF returned %d\n", i);
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return 0;
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}
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