os_vm_address_t copy_core_bytes(int fd, os_vm_offset_t offset,
os_vm_address_t addr, int len)
{
unsigned char buf[4096];
int c,x;
int old_fd = lseek(fd, 0, SEEK_CUR);
if(len & (4096-1)){
fprintf(stderr, "cant copy a slice of core because slice-length is not of page size(4096)\n");
exit(-1);
}
if(old_fd < 0){
fprintf(stderr, "cant perform lseek() on corefile\n");
}
lseek(fd, offset, SEEK_SET);
if(fd < 0){
fprintf(stderr, "cant perform lseek(%u,%lu,SEEK_SET) on corefile\n", fd, offset);
}
for(x = 0; x < len; x += 4096){
c = read(fd, buf, 4096);
if(c != 4096){
fprintf(stderr, "cant read memory area from corefile at position %lu, got %d\n", offset + x, c);
exit(-1);
}
memcpy(addr+x, buf, 4096);
}
os_flush_icache(addr, len);
return addr;
}
void arch_write_linkage_table_jmp(void* reloc_addr, void *target_addr)
{
/*
ldr reg, [pc, #4]
bx reg
nop
address
BX is needed for thumb interworking, without it it could take just two words with
ldr pc, [pc, #-4]
address
*/
int* inst_ptr;
unsigned inst;
inst_ptr = (int*) reloc_addr;
// ldr reg, [pc, #4]
inst = 0xe59f0000 | LINKAGE_TEMP_REG << 12 | 4;
*inst_ptr++ = inst;
// bx reg
inst = 0xe12fff10 | LINKAGE_TEMP_REG;
*inst_ptr++ = inst;
// nop aka mov r0, r0
inst = 0xe1a00000;
*inst_ptr++ = inst;
// address
*inst_ptr++ = target_addr;
os_flush_icache((os_vm_address_t) reloc_addr, (char*) inst_ptr - (char*) reloc_addr);
}
