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#ifndef NORELOCATE
#include "etherboot.h"
/* by Eric Biederman */
/* On some platforms etherboot is compiled as a shared library, and we use
* the ELF pic support to make it relocateable. This works very nicely
* for code, but since no one has implemented PIC data yet pointer
* values in variables are a a problem. Global variables are a
* pain but the return addresses on the stack are the worst. On these
* platforms relocate_to will restart etherboot, to ensure the stack
* is reinitialize and hopefully get the global variables
* appropriately reinitialized as well.
*
*/
void relocate(void)
{
unsigned long addr, eaddr, size;
unsigned i;
/* Walk through the memory map and find the highest address
* below 4GB that etherboot will fit into. Ensure etherboot
* lies entirely within a range with A20=0. This means that
* even if something screws up the state of the A20 line, the
* etherboot code is still visible and we have a chance to
* diagnose the problem.
*/
/* First find the size of etherboot */
addr = virt_to_phys(_text);
eaddr = virt_to_phys(_end);
size = (eaddr - addr + 0xf) & ~0xf;
/* If the current etherboot is beyond MAX_ADDR pretend it is
* at the lowest possible address.
*/
if (eaddr > MAX_ADDR) {
eaddr = 0;
}
for(i = 0; i < meminfo.map_count; i++) {
unsigned long r_start, r_end;
if (meminfo.map[i].type != E820_RAM) {
continue;
}
if (meminfo.map[i].addr > MAX_ADDR) {
continue;
}
if (meminfo.map[i].size > MAX_ADDR) {
continue;
}
r_start = meminfo.map[i].addr;
r_end = r_start + meminfo.map[i].size;
/* Make the addresses 16 byte (128 bit) aligned */
r_start = (r_start + 15) & ~15;
r_end = r_end & ~15;
if (r_end < r_start) {
r_end = MAX_ADDR;
}
if (r_end < size) {
/* Avoid overflow weirdness when r_end - size < 0 */
continue;
}
/* Shrink the range down to use only even megabytes
* (i.e. A20=0).
*/
if ( r_end & 0x100000 ) {
/* If r_end is in an odd megabyte, round down
* r_end to the top of the next even megabyte.
*/
r_end = r_end & ~0xfffff;
} else if ( ( r_end - size ) & 0x100000 ) {
/* If r_end is in an even megabyte, but the
* start of Etherboot would be in an odd
* megabyte, round down to the top of the next
* even megabyte.
*/
r_end = ( r_end - 0x100000 ) & ~0xfffff;
}
/* If we have rounded down r_end below r_ start, skip
* this block.
*/
if ( r_end < r_start ) {
continue;
}
if (eaddr < r_end - size) {
addr = r_end - size;
eaddr = r_end;
}
}
if (addr != virt_to_phys(_text)) {
unsigned long old_addr = virt_to_phys(_text);
printf("Relocating _text from: [%lx,%lx) to [%lx,%lx)\n",
old_addr, virt_to_phys(_end),
addr, eaddr);
arch_relocate_to(addr);
cleanup();
relocate_to(addr);
arch_relocated_from(old_addr);
}
}
#endif /* NORELOCATE */
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