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boot: rudimentary kaslr

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This commit is contained in:
K. Lange 2023-11-10 16:34:54 +09:00
parent a8b506ad33
commit b65bbf13a3
1 changed files with 9 additions and 1 deletions
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10
boot/multiboot.c
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@ -60,10 +60,18 @@ static uintptr_t ramdisk_len = 0;
uintptr_t final_offset = 0;
uintptr_t _xmain = 0;
static inline uint64_t read_tsc(void) {
uint32_t lo, hi;
asm volatile ( "rdtsc" : "=a"(lo), "=d"(hi) );
return ((uint64_t)hi << 32) | (uint64_t)lo;
}
static int load_aout(uint32_t * hdr) {
uintptr_t base_offset = (uintptr_t)hdr - (uintptr_t)kernel_load_start;
uintptr_t hdr_offset = hdr[3] - base_offset;
size_t xtra = 0x100000;
uint32_t rando = 0;
asm volatile ( "rdtsc" : "=a"(rando), "=d"((uint32_t){0}) );
size_t xtra = (rando & 0xFF) << 12;
memcpy((void*)(uintptr_t)hdr[4] + xtra, kernel_load_start + (hdr[4] - hdr_offset), (hdr[5] - hdr[4]));
memset((void*)(uintptr_t)hdr[5] + xtra, 0, (hdr[6] - hdr[5]));