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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 );
-
- /*
- * 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 _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)
-
- /**
- * Relocate iPXE
- *
- * @v ix86 x86 register dump from prefix
- * @ret ix86 x86 registers to return to prefix
- *
- * 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;
- unsigned long start, end, size, padded_size;
- unsigned long 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 + max_align - 1 );
-
- DBG ( "Relocate: currently at [%lx,%lx)\n"
- "...need %lx bytes for %d-byte alignment\n",
- start, end, padded_size, max_align );
-
- /* 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];
- unsigned long r_start, r_end;
-
- DBG ( "Considering [%llx,%llx)\n", region->start, region->end);
-
- /* 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 ( region->start > MAX_ADDR ) {
- DBG ( "...starts after MAX_ADDR=%lx\n", MAX_ADDR );
- continue;
- }
- r_start = region->start;
- if ( region->end > MAX_ADDR ) {
- DBG ( "...end truncated to MAX_ADDR=%lx\n", MAX_ADDR );
- r_end = MAX_ADDR;
- } else {
- r_end = region->end;
- }
- DBG ( "...usable portion is [%lx,%lx)\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 %lx 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 ) & ( max_align - 1 );
- new_end = new_start + size;
-
- DBG ( "Relocating from [%lx,%lx) to [%lx,%lx)\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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