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[relocate] Preserve page alignment during relocation 

Signed-off-by: Michael Brown <mcb30@ipxe.org>
pull/45/head
Michael Brown 2016-02-19 02:38:48 +00:00
parent 6eb1c927a3
commit bfe6e3e90e
1 changed files with 10 additions and 12 deletions
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22
src/arch/x86/core/relocate.c
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@ -10,14 +10,6 @@
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
/*
* 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 ( ( size_t ) _max_align )
/* Linker symbols */
extern char _textdata[];
extern char _etextdata[];
@ -30,6 +22,12 @@ extern char _etextdata[];
*/
#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
*
@ -53,11 +51,11 @@ __asmcall void relocate ( struct i386_all_regs *ix86 ) {
start = virt_to_phys ( _textdata );
end = virt_to_phys ( _etextdata );
size = ( end - start );
padded_size = ( size + max_align - 1 );
padded_size = ( size + ALIGN - 1 );
DBG ( "Relocate: currently at [%x,%x)\n"
"...need %x bytes for %zd-byte alignment\n",
start, end, padded_size, max_align );
"...need %x bytes for %d-byte alignment\n",
start, end, padded_size, ALIGN );
/* Determine maximum usable address */
max = MAX_ADDR;
@ -125,7 +123,7 @@ __asmcall void relocate ( struct i386_all_regs *ix86 ) {
* required alignemnt.
*/
new_start = new_end - padded_size;
new_start += ( start - new_start ) & ( max_align - 1 );
new_start += ( ( start - new_start ) & ( ALIGN - 1 ) );
new_end = new_start + size;
DBG ( "Relocating from [%x,%x) to [%x,%x)\n",