diff options
Diffstat (limited to 'gpxe/src/arch/i386/firmware/pcbios/hidemem.c')
| -rw-r--r-- | gpxe/src/arch/i386/firmware/pcbios/hidemem.c | 220 |
1 files changed, 0 insertions, 220 deletions
diff --git a/gpxe/src/arch/i386/firmware/pcbios/hidemem.c b/gpxe/src/arch/i386/firmware/pcbios/hidemem.c deleted file mode 100644 index 17082c35..00000000 --- a/gpxe/src/arch/i386/firmware/pcbios/hidemem.c +++ /dev/null @@ -1,220 +0,0 @@ -/* Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>. - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public License as - * published by the Free Software Foundation; either version 2 of the - * License, or any later version. - * - * This program is distributed in the hope that it will be useful, but - * WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. - */ - -FILE_LICENCE ( GPL2_OR_LATER ); - -#include <assert.h> -#include <realmode.h> -#include <biosint.h> -#include <basemem.h> -#include <fakee820.h> -#include <gpxe/init.h> -#include <gpxe/memmap.h> -#include <gpxe/hidemem.h> - -/** Set to true if you want to test a fake E820 map */ -#define FAKE_E820 0 - -/** Alignment for hidden memory regions */ -#define ALIGN_HIDDEN 4096 /* 4kB page alignment should be enough */ - -/** - * A hidden region of gPXE - * - * This represents a region that will be edited out of the system's - * memory map. - * - * This structure is accessed by assembly code, so must not be - * changed. - */ -struct hidden_region { - /** Physical start address */ - uint64_t start; - /** Physical end address */ - uint64_t end; -}; - -/** Hidden base memory */ -extern struct hidden_region __data16 ( hidemem_base ); -#define hidemem_base __use_data16 ( hidemem_base ) - -/** Hidden umalloc memory */ -extern struct hidden_region __data16 ( hidemem_umalloc ); -#define hidemem_umalloc __use_data16 ( hidemem_umalloc ) - -/** Hidden text memory */ -extern struct hidden_region __data16 ( hidemem_textdata ); -#define hidemem_textdata __use_data16 ( hidemem_textdata ) - -/** Assembly routine in e820mangler.S */ -extern void int15(); - -/** Vector for storing original INT 15 handler */ -extern struct segoff __text16 ( int15_vector ); -#define int15_vector __use_text16 ( int15_vector ) - -/* The linker defines these symbols for us */ -extern char _textdata[]; -extern char _etextdata[]; -extern char _text16_memsz[]; -#define _text16_memsz ( ( unsigned int ) _text16_memsz ) -extern char _data16_memsz[]; -#define _data16_memsz ( ( unsigned int ) _data16_memsz ) - -/** - * Hide region of memory from system memory map - * - * @v region Hidden memory region - * @v start Start of region - * @v end End of region - */ -static void hide_region ( struct hidden_region *region, - physaddr_t start, physaddr_t end ) { - - /* Some operating systems get a nasty shock if a region of the - * E820 map seems to start on a non-page boundary. Make life - * safer by rounding out our edited region. - */ - region->start = ( start & ~( ALIGN_HIDDEN - 1 ) ); - region->end = ( ( end + ALIGN_HIDDEN - 1 ) & ~( ALIGN_HIDDEN - 1 ) ); - - DBG ( "Hiding region [%llx,%llx)\n", region->start, region->end ); -} - -/** - * Hide used base memory - * - */ -void hide_basemem ( void ) { - /* Hide from the top of free base memory to 640kB. Don't use - * hide_region(), because we don't want this rounded to the - * nearest page boundary. - */ - hidemem_base.start = ( get_fbms() * 1024 ); -} - -/** - * Hide umalloc() region - * - */ -void hide_umalloc ( physaddr_t start, physaddr_t end ) { - assert ( end <= virt_to_phys ( _textdata ) ); - hide_region ( &hidemem_umalloc, start, end ); -} - -/** - * Hide .text and .data - * - */ -void hide_textdata ( void ) { - hide_region ( &hidemem_textdata, virt_to_phys ( _textdata ), - virt_to_phys ( _etextdata ) ); -} - -/** - * Hide Etherboot - * - * Installs an INT 15 handler to edit Etherboot out of the memory map - * returned by the BIOS. - */ -static void hide_etherboot ( void ) { - struct memory_map memmap; - unsigned int rm_ds_top; - unsigned int rm_cs_top; - unsigned int fbms; - - /* Dump memory map before mangling */ - DBG ( "Hiding gPXE from system memory map\n" ); - get_memmap ( &memmap ); - - /* Hook in fake E820 map, if we're testing one */ - if ( FAKE_E820 ) { - DBG ( "Hooking in fake E820 map\n" ); - fake_e820(); - get_memmap ( &memmap ); - } - - /* Initialise the hidden regions */ - hide_basemem(); - hide_umalloc ( virt_to_phys ( _textdata ), virt_to_phys ( _textdata ) ); - hide_textdata(); - - /* Some really moronic BIOSes bring up the PXE stack via the - * UNDI loader entry point and then don't bother to unload it - * before overwriting the code and data segments. If this - * happens, we really don't want to leave INT 15 hooked, - * because that will cause any loaded OS to die horribly as - * soon as it attempts to fetch the system memory map. - * - * We use a heuristic to guess whether or not we are being - * loaded sensibly. - */ - rm_cs_top = ( ( ( rm_cs << 4 ) + _text16_memsz + 1024 - 1 ) >> 10 ); - rm_ds_top = ( ( ( rm_ds << 4 ) + _data16_memsz + 1024 - 1 ) >> 10 ); - fbms = get_fbms(); - if ( ( rm_cs_top < fbms ) && ( rm_ds_top < fbms ) ) { - DBG ( "Detected potentially unsafe UNDI load at CS=%04x " - "DS=%04x FBMS=%dkB\n", rm_cs, rm_ds, fbms ); - DBG ( "Disabling INT 15 memory hiding\n" ); - return; - } - - /* Hook INT 15 */ - hook_bios_interrupt ( 0x15, ( unsigned int ) int15, - &int15_vector ); - - /* Dump memory map after mangling */ - DBG ( "Hidden gPXE from system memory map\n" ); - get_memmap ( &memmap ); -} - -/** - * Unhide Etherboot - * - * Uninstalls the INT 15 handler installed by hide_etherboot(), if - * possible. - */ -static void unhide_etherboot ( int flags __unused ) { - - /* If we have more than one hooked interrupt at this point, it - * means that some other vector is still hooked, in which case - * we can't safely unhook INT 15 because we need to keep our - * memory protected. (We expect there to be at least one - * hooked interrupt, because INT 15 itself is still hooked). - */ - if ( hooked_bios_interrupts > 1 ) { - DBG ( "Cannot unhide: %d interrupt vectors still hooked\n", - hooked_bios_interrupts ); - return; - } - - /* Try to unhook INT 15. If it fails, then just leave it - * hooked; it takes care of protecting itself. :) - */ - unhook_bios_interrupt ( 0x15, ( unsigned int ) int15, - &int15_vector ); - - /* Unhook fake E820 map, if used */ - if ( FAKE_E820 ) - unfake_e820(); -} - -/** Hide Etherboot startup function */ -struct startup_fn hide_etherboot_startup_fn __startup_fn ( STARTUP_EARLY ) = { - .startup = hide_etherboot, - .shutdown = unhide_etherboot, -}; |