| /* |
| * 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 ) |
| |
| .text |
| .arch i386 |
| .code16 |
| |
| #define SMAP 0x534d4150 |
| |
| /* Most documentation refers to the E820 buffer as being 20 bytes, and |
| * the API makes it perfectly legitimate to pass only a 20-byte buffer |
| * and expect to get valid data. However, some morons at ACPI decided |
| * to extend the data structure by adding an extra "extended |
| * attributes" field and by including critical information within this |
| * field, such as whether or not the region is enabled. A caller who |
| * passes in only a 20-byte buffer therefore risks getting very, very |
| * misleading information. |
| * |
| * I have personally witnessed an HP BIOS that returns a value of |
| * 0x0009 in the extended attributes field. If we don't pass this |
| * value through to the caller, 32-bit WinPE will die, usually with a |
| * PAGE_FAULT_IN_NONPAGED_AREA blue screen of death. |
| * |
| * Allow a ridiculously large maximum value (64 bytes) for the E820 |
| * buffer as a guard against insufficiently creative idiots in the |
| * future. |
| */ |
| #define E820MAXSIZE 64 |
| |
| /**************************************************************************** |
| * |
| * Allowed memory windows |
| * |
| * There are two ways to view this list. The first is as a list of |
| * (non-overlapping) allowed memory regions, sorted by increasing |
| * address. The second is as a list of (non-overlapping) hidden |
| * memory regions, again sorted by increasing address. The second |
| * view is offset by half an entry from the first: think about this |
| * for a moment and it should make sense. |
| * |
| * xxx_memory_window is used to indicate an "allowed region" |
| * structure, hidden_xxx_memory is used to indicate a "hidden region" |
| * structure. Each structure is 16 bytes in length. |
| * |
| **************************************************************************** |
| */ |
| .section ".data16", "aw", @progbits |
| .align 16 |
| .globl hidemem_base |
| .globl hidemem_umalloc |
| .globl hidemem_textdata |
| memory_windows: |
| base_memory_window: .long 0x00000000, 0x00000000 /* Start of memory */ |
| |
| hidemem_base: .long 0x000a0000, 0x00000000 /* Changes at runtime */ |
| ext_memory_window: .long 0x000a0000, 0x00000000 /* 640kB mark */ |
| |
| hidemem_umalloc: .long 0xffffffff, 0xffffffff /* Changes at runtime */ |
| .long 0xffffffff, 0xffffffff /* Changes at runtime */ |
| |
| hidemem_textdata: .long 0xffffffff, 0xffffffff /* Changes at runtime */ |
| .long 0xffffffff, 0xffffffff /* Changes at runtime */ |
| |
| .long 0xffffffff, 0xffffffff /* End of memory */ |
| memory_windows_end: |
| |
| /**************************************************************************** |
| * Truncate region to memory window |
| * |
| * Parameters: |
| * %edx:%eax Start of region |
| * %ecx:%ebx Length of region |
| * %si Memory window |
| * Returns: |
| * %edx:%eax Start of windowed region |
| * %ecx:%ebx Length of windowed region |
| **************************************************************************** |
| */ |
| .section ".text16", "ax", @progbits |
| window_region: |
| /* Convert (start,len) to (start, end) */ |
| addl %eax, %ebx |
| adcl %edx, %ecx |
| /* Truncate to window start */ |
| cmpl 4(%si), %edx |
| jne 1f |
| cmpl 0(%si), %eax |
| 1: jae 2f |
| movl 4(%si), %edx |
| movl 0(%si), %eax |
| 2: /* Truncate to window end */ |
| cmpl 12(%si), %ecx |
| jne 1f |
| cmpl 8(%si), %ebx |
| 1: jbe 2f |
| movl 12(%si), %ecx |
| movl 8(%si), %ebx |
| 2: /* Convert (start, end) back to (start, len) */ |
| subl %eax, %ebx |
| sbbl %edx, %ecx |
| /* If length is <0, set length to 0 */ |
| jae 1f |
| xorl %ebx, %ebx |
| xorl %ecx, %ecx |
| ret |
| .size window_region, . - window_region |
| |
| /**************************************************************************** |
| * Patch "memory above 1MB" figure |
| * |
| * Parameters: |
| * %ax Memory above 1MB, in 1kB blocks |
| * Returns: |
| * %ax Modified memory above 1M in 1kB blocks |
| **************************************************************************** |
| */ |
| .section ".text16", "ax", @progbits |
| patch_1m: |
| pushal |
| /* Convert to (start,len) format and call truncate */ |
| xorl %ecx, %ecx |
| movzwl %ax, %ebx |
| shll $10, %ebx |
| xorl %edx, %edx |
| movl $0x100000, %eax |
| movw $ext_memory_window, %si |
| call window_region |
| /* Convert back to "memory above 1MB" format and return via %ax */ |
| pushfw |
| shrl $10, %ebx |
| popfw |
| movw %sp, %bp |
| movw %bx, 28(%bp) |
| popal |
| ret |
| .size patch_1m, . - patch_1m |
| |
| /**************************************************************************** |
| * Patch "memory above 16MB" figure |
| * |
| * Parameters: |
| * %bx Memory above 16MB, in 64kB blocks |
| * Returns: |
| * %bx Modified memory above 16M in 64kB blocks |
| **************************************************************************** |
| */ |
| .section ".text16", "ax", @progbits |
| patch_16m: |
| pushal |
| /* Convert to (start,len) format and call truncate */ |
| xorl %ecx, %ecx |
| shll $16, %ebx |
| xorl %edx, %edx |
| movl $0x1000000, %eax |
| movw $ext_memory_window, %si |
| call window_region |
| /* Convert back to "memory above 16MB" format and return via %bx */ |
| pushfw |
| shrl $16, %ebx |
| popfw |
| movw %sp, %bp |
| movw %bx, 16(%bp) |
| popal |
| ret |
| .size patch_16m, . - patch_16m |
| |
| /**************************************************************************** |
| * Patch "memory between 1MB and 16MB" and "memory above 16MB" figures |
| * |
| * Parameters: |
| * %ax Memory between 1MB and 16MB, in 1kB blocks |
| * %bx Memory above 16MB, in 64kB blocks |
| * Returns: |
| * %ax Modified memory between 1MB and 16MB, in 1kB blocks |
| * %bx Modified memory above 16MB, in 64kB blocks |
| **************************************************************************** |
| */ |
| .section ".text16", "ax", @progbits |
| patch_1m_16m: |
| call patch_1m |
| call patch_16m |
| /* If 1M region is no longer full-length, kill off the 16M region */ |
| cmpw $( 15 * 1024 ), %ax |
| je 1f |
| xorw %bx, %bx |
| 1: ret |
| .size patch_1m_16m, . - patch_1m_16m |
| |
| /**************************************************************************** |
| * Get underlying e820 memory region to underlying_e820 buffer |
| * |
| * Parameters: |
| * As for INT 15,e820 |
| * Returns: |
| * As for INT 15,e820 |
| * |
| * Wraps the underlying INT 15,e820 call so that the continuation |
| * value (%ebx) is a 16-bit simple sequence counter (with the high 16 |
| * bits ignored), and termination is always via CF=1 rather than |
| * %ebx=0. |
| * |
| **************************************************************************** |
| */ |
| .section ".text16", "ax", @progbits |
| get_underlying_e820: |
| |
| /* If the requested region is in the cache, return it */ |
| cmpw %bx, underlying_e820_index |
| jne 2f |
| pushw %di |
| pushw %si |
| movw $underlying_e820_cache, %si |
| cmpl underlying_e820_cache_size, %ecx |
| jbe 1f |
| movl underlying_e820_cache_size, %ecx |
| 1: pushl %ecx |
| rep movsb |
| popl %ecx |
| popw %si |
| popw %di |
| incw %bx |
| movl %edx, %eax |
| clc |
| ret |
| 2: |
| /* If the requested region is earlier than the cached region, |
| * invalidate the cache. |
| */ |
| cmpw %bx, underlying_e820_index |
| jbe 1f |
| movw $0xffff, underlying_e820_index |
| 1: |
| /* If the cache is invalid, reset the underlying %ebx */ |
| cmpw $0xffff, underlying_e820_index |
| jne 1f |
| andl $0, underlying_e820_ebx |
| 1: |
| /* If the cache is valid but the continuation value is zero, |
| * this means that the previous underlying call returned with |
| * %ebx=0. Return with CF=1 in this case. |
| */ |
| cmpw $0xffff, underlying_e820_index |
| je 1f |
| cmpl $0, underlying_e820_ebx |
| jne 1f |
| stc |
| ret |
| 1: |
| /* Get the next region into the cache */ |
| pushl %eax |
| pushl %ebx |
| pushl %ecx |
| pushl %edx |
| pushl %esi /* Some implementations corrupt %esi, so we */ |
| pushl %edi /* preserve %esi, %edi and %ebp to be paranoid */ |
| pushl %ebp |
| pushw %es |
| pushw %ds |
| popw %es |
| movw $underlying_e820_cache, %di |
| cmpl $E820MAXSIZE, %ecx |
| jbe 1f |
| movl $E820MAXSIZE, %ecx |
| 1: movl underlying_e820_ebx, %ebx |
| stc |
| pushfw |
| lcall *%cs:int15_vector |
| popw %es |
| popl %ebp |
| popl %edi |
| popl %esi |
| /* Check for error return from underlying e820 call */ |
| jc 2f /* CF set: error */ |
| cmpl $SMAP, %eax |
| je 3f /* 'SMAP' missing: error */ |
| 2: /* An error occurred: return values returned by underlying e820 call */ |
| stc /* Force CF set if SMAP was missing */ |
| addr32 leal 16(%esp), %esp /* avoid changing other flags */ |
| ret |
| 3: /* No error occurred */ |
| movl %ebx, underlying_e820_ebx |
| movl %ecx, underlying_e820_cache_size |
| popl %edx |
| popl %ecx |
| popl %ebx |
| popl %eax |
| /* Mark cache as containing this result */ |
| incw underlying_e820_index |
| |
| /* Loop until found */ |
| jmp get_underlying_e820 |
| .size get_underlying_e820, . - get_underlying_e820 |
| |
| .section ".data16", "aw", @progbits |
| underlying_e820_index: |
| .word 0xffff /* Initialise to an invalid value */ |
| .size underlying_e820_index, . - underlying_e820_index |
| |
| .section ".bss16", "aw", @nobits |
| underlying_e820_ebx: |
| .long 0 |
| .size underlying_e820_ebx, . - underlying_e820_ebx |
| |
| .section ".bss16", "aw", @nobits |
| underlying_e820_cache: |
| .space E820MAXSIZE |
| .size underlying_e820_cache, . - underlying_e820_cache |
| |
| .section ".bss16", "aw", @nobits |
| underlying_e820_cache_size: |
| .long 0 |
| .size underlying_e820_cache_size, . - underlying_e820_cache_size |
| |
| /**************************************************************************** |
| * Get windowed e820 region, without empty region stripping |
| * |
| * Parameters: |
| * As for INT 15,e820 |
| * Returns: |
| * As for INT 15,e820 |
| * |
| * Wraps the underlying INT 15,e820 call so that each underlying |
| * region is returned N times, windowed to fit within N visible-memory |
| * windows. Termination is always via CF=1. |
| * |
| **************************************************************************** |
| */ |
| .section ".text16", "ax", @progbits |
| get_windowed_e820: |
| |
| /* Preserve registers */ |
| pushl %esi |
| pushw %bp |
| |
| /* Split %ebx into %si:%bx, store original %bx in %bp */ |
| pushl %ebx |
| popw %bp |
| popw %si |
| |
| /* %si == 0 => start of memory_windows list */ |
| testw %si, %si |
| jne 1f |
| movw $memory_windows, %si |
| 1: |
| /* Get (cached) underlying e820 region to buffer */ |
| call get_underlying_e820 |
| jc 99f /* Abort on error */ |
| |
| /* Preserve registers */ |
| pushal |
| /* start => %edx:%eax, len => %ecx:%ebx */ |
| movl %es:0(%di), %eax |
| movl %es:4(%di), %edx |
| movl %es:8(%di), %ebx |
| movl %es:12(%di), %ecx |
| /* Truncate region to current window */ |
| call window_region |
| 1: /* Store modified values in e820 map entry */ |
| movl %eax, %es:0(%di) |
| movl %edx, %es:4(%di) |
| movl %ebx, %es:8(%di) |
| movl %ecx, %es:12(%di) |
| /* Restore registers */ |
| popal |
| |
| /* Derive continuation value for next call */ |
| addw $16, %si |
| cmpw $memory_windows_end, %si |
| jne 1f |
| /* End of memory windows: reset %si and allow %bx to continue */ |
| xorw %si, %si |
| jmp 2f |
| 1: /* More memory windows to go: restore original %bx */ |
| movw %bp, %bx |
| 2: /* Construct %ebx from %si:%bx */ |
| pushw %si |
| pushw %bx |
| popl %ebx |
| |
| 98: /* Clear CF */ |
| clc |
| 99: /* Restore registers and return */ |
| popw %bp |
| popl %esi |
| ret |
| .size get_windowed_e820, . - get_windowed_e820 |
| |
| /**************************************************************************** |
| * Get windowed e820 region, with empty region stripping |
| * |
| * Parameters: |
| * As for INT 15,e820 |
| * Returns: |
| * As for INT 15,e820 |
| * |
| * Wraps the underlying INT 15,e820 call so that each underlying |
| * region is returned up to N times, windowed to fit within N |
| * visible-memory windows. Empty windows are never returned. |
| * Termination is always via CF=1. |
| * |
| **************************************************************************** |
| */ |
| .section ".text16", "ax", @progbits |
| get_nonempty_e820: |
| |
| /* Record entry parameters */ |
| pushl %eax |
| pushl %ecx |
| pushl %edx |
| |
| /* Get next windowed region */ |
| call get_windowed_e820 |
| jc 99f /* abort on error */ |
| |
| /* If region is non-empty, finish here */ |
| cmpl $0, %es:8(%di) |
| jne 98f |
| cmpl $0, %es:12(%di) |
| jne 98f |
| |
| /* Region was empty: restore entry parameters and go to next region */ |
| popl %edx |
| popl %ecx |
| popl %eax |
| jmp get_nonempty_e820 |
| |
| 98: /* Clear CF */ |
| clc |
| 99: /* Return values from underlying call */ |
| addr32 leal 12(%esp), %esp /* avoid changing flags */ |
| ret |
| .size get_nonempty_e820, . - get_nonempty_e820 |
| |
| /**************************************************************************** |
| * Get mangled e820 region, with empty region stripping |
| * |
| * Parameters: |
| * As for INT 15,e820 |
| * Returns: |
| * As for INT 15,e820 |
| * |
| * Wraps the underlying INT 15,e820 call so that underlying regions |
| * are windowed to the allowed memory regions. Empty regions are |
| * stripped from the map. Termination is always via %ebx=0. |
| * |
| **************************************************************************** |
| */ |
| .section ".text16", "ax", @progbits |
| get_mangled_e820: |
| |
| /* Get a nonempty region */ |
| call get_nonempty_e820 |
| jc 99f /* Abort on error */ |
| |
| /* Peek ahead to see if there are any further nonempty regions */ |
| pushal |
| pushw %es |
| movw %sp, %bp |
| subw %cx, %sp |
| movl $0xe820, %eax |
| movl $SMAP, %edx |
| pushw %ss |
| popw %es |
| movw %sp, %di |
| call get_nonempty_e820 |
| movw %bp, %sp |
| popw %es |
| popal |
| jnc 99f /* There are further nonempty regions */ |
| |
| /* No futher nonempty regions: zero %ebx and clear CF */ |
| xorl %ebx, %ebx |
| |
| 99: /* Return */ |
| ret |
| .size get_mangled_e820, . - get_mangled_e820 |
| |
| /**************************************************************************** |
| * Set/clear CF on the stack as appropriate, assumes stack is as it should |
| * be immediately before IRET |
| **************************************************************************** |
| */ |
| patch_cf: |
| pushw %bp |
| movw %sp, %bp |
| setc 8(%bp) /* Set/reset CF; clears PF, AF, ZF, SF */ |
| popw %bp |
| ret |
| |
| /**************************************************************************** |
| * INT 15,e820 handler |
| **************************************************************************** |
| */ |
| .section ".text16", "ax", @progbits |
| int15_e820: |
| pushw %ds |
| pushw %cs:rm_ds |
| popw %ds |
| call get_mangled_e820 |
| popw %ds |
| call patch_cf |
| iret |
| .size int15_e820, . - int15_e820 |
| |
| /**************************************************************************** |
| * INT 15,e801 handler |
| **************************************************************************** |
| */ |
| .section ".text16", "ax", @progbits |
| int15_e801: |
| /* Call previous handler */ |
| pushfw |
| lcall *%cs:int15_vector |
| call patch_cf |
| /* Edit result */ |
| pushw %ds |
| pushw %cs:rm_ds |
| popw %ds |
| call patch_1m_16m |
| xchgw %ax, %cx |
| xchgw %bx, %dx |
| call patch_1m_16m |
| xchgw %ax, %cx |
| xchgw %bx, %dx |
| popw %ds |
| iret |
| .size int15_e801, . - int15_e801 |
| |
| /**************************************************************************** |
| * INT 15,88 handler |
| **************************************************************************** |
| */ |
| .section ".text16", "ax", @progbits |
| int15_88: |
| /* Call previous handler */ |
| pushfw |
| lcall *%cs:int15_vector |
| call patch_cf |
| /* Edit result */ |
| pushw %ds |
| pushw %cs:rm_ds |
| popw %ds |
| call patch_1m |
| popw %ds |
| iret |
| .size int15_88, . - int15_88 |
| |
| /**************************************************************************** |
| * INT 15 handler |
| **************************************************************************** |
| */ |
| .section ".text16", "ax", @progbits |
| .globl int15 |
| int15: |
| /* See if we want to intercept this call */ |
| pushfw |
| cmpw $0xe820, %ax |
| jne 1f |
| cmpl $SMAP, %edx |
| jne 1f |
| popfw |
| jmp int15_e820 |
| 1: cmpw $0xe801, %ax |
| jne 2f |
| popfw |
| jmp int15_e801 |
| 2: cmpb $0x88, %ah |
| jne 3f |
| popfw |
| jmp int15_88 |
| 3: popfw |
| ljmp *%cs:int15_vector |
| .size int15, . - int15 |
| |
| .section ".text16.data", "aw", @progbits |
| .globl int15_vector |
| int15_vector: |
| .long 0 |
| .size int15_vector, . - int15_vector |
