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72 lines
2.1 KiB
C++
72 lines
2.1 KiB
C++
#include "elf_load.hpp"
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#include "elf_format.hpp"
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#include <algorithm>
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#include <cstring>
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//constexpr unsigned int ELF_LOAD_ADDR = 0x10000000;
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static const unsigned char elf_header[] = { '\177', 'E', 'L', 'F' };
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template<typename T>
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constexpr static auto ptr_from_offset(void *base, uint32_t offset)
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{
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return reinterpret_cast<T>(reinterpret_cast<uint8_t *>(base) + offset);
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}
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//static Elf32_Shdr *find_section(Elf32_Ehdr *ehdr, const char *name);
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namespace elf {
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entry_t load(void *elf_data)
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{
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// Check the ELF's header signature
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auto ehdr = reinterpret_cast<Elf32_Ehdr *>(elf_data);
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if (!std::equal(ehdr->e_ident, ehdr->e_ident + 4, elf_header))
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return nullptr;
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// Iterate through program header LOAD sections
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bool loaded = false;
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auto phdr = ptr_from_offset<Elf32_Phdr *>(elf_data, ehdr->e_phoff);
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for (Elf32_Half i = 0; i < ehdr->e_phnum; i++) {
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if (phdr->p_type == PT_LOAD) {
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if (phdr->p_filesz == 0) {
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std::memset(reinterpret_cast<void *>(phdr->p_vaddr),
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0,
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phdr->p_memsz);
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} else {
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std::memcpy(reinterpret_cast<void *>(phdr->p_vaddr),
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ptr_from_offset<void *>(elf_data, phdr->p_offset),
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phdr->p_filesz);
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if (!loaded)
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loaded = true;
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}
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}
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phdr = ptr_from_offset<Elf32_Phdr *>(phdr, ehdr->e_phentsize);
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}
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return loaded ? reinterpret_cast<entry_t>(ehdr->e_entry) : nullptr;
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}
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} // namespace elf
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//Elf32_Shdr *find_section(Elf32_Ehdr *ehdr, const char *name)
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//{
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// auto shdr = ptr_from_offset<Elf32_Shdr *>(ehdr, ehdr->e_shoff);
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// auto shdr_str = ptr_from_offset<Elf32_Shdr *>(ehdr,
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// ehdr->e_shoff + ehdr->e_shstrndx * ehdr->e_shentsize);
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//
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// for (Elf32_Half i = 0; i < ehdr->e_shnum; i++) {
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// char *section = ptr_from_offset<char *>(ehdr, shdr_str->sh_offset) + shdr->sh_name;
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// if (!strcmp(section, name))
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// return shdr;
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//
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// shdr = ptr_from_offset<Elf32_Shdr *>(shdr, ehdr->e_shentsize);
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// }
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//
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// return 0;
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//}
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