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- #include <ipxe/io.h>
- #include <registers.h>
-
- /*
- * Originally by Eric Biederman
- *
- * Heavily modified by Michael Brown
- *
- */
-
- FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
-
- /* Linker symbols */
- extern char _textdata[];
- extern char _etextdata[];
-
- /* within 1MB of 4GB is too close.
- * MAX_ADDR is the maximum address we can easily do DMA to.
- *
- * Not sure where this constraint comes from, but kept it from Eric's
- * old code - mcb30
- */
- #define MAX_ADDR (0xfff00000UL)
-
- /* Preserve alignment to a 4kB page
- *
- * Required for x86_64, and doesn't hurt for i386.
- */
- #define ALIGN 4096
-
- /**
- * Relocate iPXE
- *
- * @v ebp Maximum address to use for relocation
- * @ret esi Current physical address
- * @ret edi New physical address
- * @ret ecx Length to copy
- *
- * This finds a suitable location for iPXE near the top of 32-bit
- * address space, and returns the physical address of the new location
- * to the prefix in %edi.
- */
- __asmcall void relocate ( struct i386_all_regs *ix86 ) {
- struct memory_map memmap;
- uint32_t start, end, size, padded_size, max;
- uint32_t new_start, new_end;
- unsigned i;
-
- /* Get memory map and current location */
- get_memmap ( &memmap );
- start = virt_to_phys ( _textdata );
- end = virt_to_phys ( _etextdata );
- size = ( end - start );
- padded_size = ( size + ALIGN - 1 );
-
- DBG ( "Relocate: currently at [%x,%x)\n"
- "...need %x bytes for %d-byte alignment\n",
- start, end, padded_size, ALIGN );
-
- /* Determine maximum usable address */
- max = MAX_ADDR;
- if ( ix86->regs.ebp < max ) {
- max = ix86->regs.ebp;
- DBG ( "Limiting relocation to [0,%x)\n", max );
- }
-
- /* Walk through the memory map and find the highest address
- * below 4GB that iPXE will fit into.
- */
- new_end = end;
- for ( i = 0 ; i < memmap.count ; i++ ) {
- struct memory_region *region = &memmap.regions[i];
- uint32_t r_start, r_end;
-
- DBG ( "Considering [%llx,%llx)\n", region->start, region->end);
-
- /* Truncate block to maximum address. This will be
- * less than 4GB, which means that we can get away
- * with using just 32-bit arithmetic after this stage.
- */
- if ( region->start > max ) {
- DBG ( "...starts after max=%x\n", max );
- continue;
- }
- r_start = region->start;
- if ( region->end > max ) {
- DBG ( "...end truncated to max=%x\n", max );
- r_end = max;
- } else {
- r_end = region->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 iPXE */
- if ( ( r_end - r_start ) < size ) {
- DBG ( "...too small (need %x bytes)\n", size );
- continue;
- }
-
- /* If the start address of the iPXE 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
- * iPXE, as well as choosing the highest of all viable
- * blocks.
- */
- if ( ( r_end - size ) > new_end ) {
- new_end = r_end;
- DBG ( "...new best block found.\n" );
- }
- }
-
- /* Calculate new location of iPXE, and align it to the
- * required alignemnt.
- */
- new_start = new_end - padded_size;
- new_start += ( ( start - new_start ) & ( ALIGN - 1 ) );
- new_end = new_start + size;
-
- DBG ( "Relocating from [%x,%x) to [%x,%x)\n",
- start, end, new_start, new_end );
-
- /* Let prefix know what to copy */
- ix86->regs.esi = start;
- ix86->regs.edi = new_start;
- ix86->regs.ecx = size;
- }
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