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- #include "virtaddr.h"
- #include "memsizes.h"
- #include "osdep.h"
- #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.
- *
- */
-
- /*
- * relocate() must be called without any hardware resources pointing
- * at the current copy of Etherboot. The easiest way to achieve this
- * is to call relocate() from within arch_initialise(), before the NIC
- * gets touched in any way.
- *
- */
-
- /*
- * The linker passes in the symbol _max_align, which is the alignment
- * that we must preserve, in bytes.
- *
- */
- extern char _max_align[];
- #define max_align ( ( unsigned int ) _max_align )
-
- /* Linker symbols */
- extern char _text[];
- extern char _end[];
-
- #undef DBG
- #ifdef DEBUG_RELOCATE
- #define DBG(...) printf ( __VA_ARGS__ )
- #else
- #define DBG(...)
- #endif
-
- 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, including enough space to
- * pad it to the required alignment
- */
- size = _end - _text + max_align - 1;
-
- /* Current end address of Etherboot. If the current etherboot
- * is beyond MAX_ADDR pretend it is at the lowest possible
- * address.
- */
- eaddr = virt_to_phys(_end);
- if ( eaddr > MAX_ADDR ) {
- eaddr = 0;
- }
-
- DBG ( "Relocate: currently at [%x,%x)\n"
- "...need %x bytes for %d-byte alignment\n",
- virt_to_phys ( _text ), eaddr, size, max_align );
-
- for ( i = 0; i < meminfo.map_count; i++ ) {
- unsigned long r_start, r_end;
-
- DBG ( "Considering [%x%x,%x%x)\n",
- ( unsigned long ) ( meminfo.map[i].addr >> 32 ),
- ( unsigned long ) meminfo.map[i].addr,
- ( unsigned long )
- ( ( meminfo.map[i].addr + meminfo.map[i].size ) >> 32 ),
- ( unsigned long )
- ( meminfo.map[i].addr + meminfo.map[i].size ) );
-
- /* Check block is usable memory */
- if (meminfo.map[i].type != E820_RAM) {
- DBG ( "...not RAM\n" );
- continue;
- }
-
- /* Truncate block to MAX_ADDR. This will be less than
- * 4GB, which means that we can get away with using
- * just 32-bit arithmetic after this stage.
- */
- if ( meminfo.map[i].addr > MAX_ADDR ) {
- DBG ( "...starts after MAX_ADDR=%x\n", MAX_ADDR );
- continue;
- }
- r_start = meminfo.map[i].addr;
- if ( meminfo.map[i].addr + meminfo.map[i].size > MAX_ADDR ) {
- r_end = MAX_ADDR;
- DBG ( "...end truncated to MAX_ADDR=%x\n", MAX_ADDR );
- } else {
- r_end = meminfo.map[i].addr + meminfo.map[i].size;
- }
-
- /* Shrink the range down to use only even megabytes
- * (i.e. A20=0).
- */
- if ( ( r_end - 1 ) & 0x100000 ) {
- /* If last byte that might be used (r_end-1)
- * is in an odd megabyte, round down r_end to
- * the top of the next even megabyte.
- */
- r_end = ( r_end - 1 ) & ~0xfffff;
- DBG ( "...end truncated to %x "
- "(avoid ending in odd megabyte)\n",
- r_end );
- } else if ( ( r_end - size ) & 0x100000 ) {
- /* If the last byte that might be used
- * (r_end-1) is in an even megabyte, but the
- * first byte that might be used (r_end-size)
- * is an odd megabyte, round down to the top
- * of the next even megabyte.
- *
- * Make sure that we don't accidentally wrap
- * r_end below 0.
- */
- if ( r_end > 0x100000 ) {
- r_end = ( r_end - 0x100000 ) & ~0xfffff;
- DBG ( "...end truncated to %x "
- "(avoid starting in odd megabyte)\n",
- r_end );
- }
- }
-
- DBG ( "...usable portion is [%x,%x)\n", r_start, r_end );
-
- /* If we have rounded down r_end below r_ start, skip
- * this block.
- */
- if ( r_end < r_start ) {
- DBG ( "...truncated to negative size\n" );
- continue;
- }
-
- /* Check that there is enough space to fit in Etherboot */
- if ( r_end - r_start < size ) {
- DBG ( "...too small (need %x bytes)\n", size );
- continue;
- }
-
- /* If the start address of the Etherboot we would
- * place in this block is higher than the end address
- * of the current highest block, use this block.
- *
- * Note that this avoids overlaps with the current
- * Etherboot, as well as choosing the highest of all
- * viable blocks.
- */
- if ( r_end - size > eaddr ) {
- eaddr = r_end;
- DBG ( "...new best block found.\n" );
- }
- }
-
- DBG ( "New location will be in [%x,%x)\n", eaddr - size, eaddr );
-
- /* Calculate new location of Etherboot, and align it to the
- * required alignemnt.
- */
- addr = eaddr - size;
- addr += ( virt_to_phys ( _text ) - addr ) & ( max_align - 1 );
- DBG ( "After alignment, new location is [%x,%x)\n",
- addr, addr + _end - _text );
-
- if ( addr != virt_to_phys ( _text ) ) {
- DBG ( "Relocating _text from: [%lx,%lx) to [%lx,%lx)\n",
- virt_to_phys ( _text ), virt_to_phys ( _end ),
- addr, addr + _end - _text );
-
- relocate_to ( addr );
- }
- }
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