Benji Dial
e8c6577617
big kernel additions: paging, elf loading, separate kernel and user page allocation it now properly loads and runs sd0:bin/init.elf still need to determine which disk was booted from, and start the init on that disk
116 lines
No EOL
2.4 KiB
C
116 lines
No EOL
2.4 KiB
C
#include <stdint.h>
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#include "drive.h"
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#include "elf.h"
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#include "task.h"
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#include "util.h"
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#include "paging.h"
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#include "pmap.h"
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#define ELF_MAGIC 0x464c457f
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enum {
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ELF_32 = 1,
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ELF_64 = 2
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};
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enum {
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LITTLE_ENDIAN = 1,
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BIG_ENDIAN = 2
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};
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enum {
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//...
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ARCH_X86 = 0x03
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//...
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};
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struct elf_header {
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uint32_t magic;
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uint8_t word_size;
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uint8_t endianness;
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uint8_t elf_version;
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uint8_t target_os;//ignored
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uint8_t os_abi_version;//should be zero
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uint8_t reserved[7];
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uint16_t object_type;//TODO
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uint16_t architecture;//should be ARCH_X86
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uint32_t elf_version_2;
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uint32_t entry_vma;
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uint32_t phtable_fa;
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uint32_t shtable_fa;
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uint32_t flags;
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uint16_t eh_size;
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uint16_t phentry_size;
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uint16_t phtable_count;
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uint16_t shentry_size;
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uint16_t shtable_count;
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uint16_t sh_names_entry;
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} __attribute__ ((packed));
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enum {
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PT_UNUSED = 0,
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PT_LOADME = 1,
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PT_DYNLINK = 2,
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PT_INTERP = 3,
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PT_COMMENT = 4,
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PT_SHARED = 5,
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PT_PHTABLE = 6,
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PT_TL_TMPL = 7
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};
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enum {
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PH_WRITABLE = 0x02
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};
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struct ph_entry {
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uint32_t type;
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uint32_t fa;
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uint32_t vma;//must be page-aligned
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uint32_t pma;//ignored
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uint32_t fs;
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uint32_t vms;
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uint32_t flags;
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uint32_t align;
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} __attribute__ ((packed));
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bool try_elf_run(const struct drive *d, const char *path) {
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file_id_t h = d->get_file(d, path);
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if (!h)
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return false;
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struct elf_header ehead;
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fmcpy(&ehead, d, h, 0, sizeof(struct elf_header));
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if ((ehead.magic != ELF_MAGIC) ||
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(ehead.word_size != ELF_32) ||
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(ehead.endianness != LITTLE_ENDIAN) ||
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ehead.os_abi_version) {
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d->free_file(d, h);
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return false;
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}
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uint32_t phtable_size = ehead.phentry_size * ehead.phtable_count;
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uint16_t phtable_pages = (phtable_size - 1) / 4096 + 1;
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void *phtable = allocate_kernel_pages(phtable_pages);
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fmcpy(phtable, d, h, ehead.phtable_fa, phtable_size);
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void *pd = new_task_pd();
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for (uint32_t phi = 0; phi < ehead.phtable_count; ++phi) {
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struct ph_entry *entry = phtable + phi * ehead.phentry_size;
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if (entry->type != PT_LOADME)
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continue;
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void *pma = pd_user_allocate(pd, entry->vma, (entry->vms - 1) / 4096 + 1, entry->flags & PH_WRITABLE);
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fmcpy(pma, d, h, entry->fa, entry->fs);
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}
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free_pages(phtable, phtable_pages);
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struct task_state tstate;
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tstate.page_directory = pd;
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tstate.ret_addr = ehead.entry_vma;
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new_task(tstate);
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return true;
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} |