diff options
Diffstat (limited to 'src/arch/i386/prefix/libprefix.S')
| -rw-r--r-- | src/arch/i386/prefix/libprefix.S | 88 |
1 files changed, 58 insertions, 30 deletions
diff --git a/src/arch/i386/prefix/libprefix.S b/src/arch/i386/prefix/libprefix.S index 12cf9184d..406dac393 100644 --- a/src/arch/i386/prefix/libprefix.S +++ b/src/arch/i386/prefix/libprefix.S @@ -17,6 +17,10 @@ * */ + .arch i386 + .section ".prefix.lib", "awx", @progbits + .section ".data16", "aw", @progbits + /** * High memory temporary load address * @@ -27,25 +31,18 @@ * We use the start of an even megabyte so that we don't have to worry * about the current state of the A20 line. * - * We use 4MB rather than 2MB because there is at least one commercial - * PXE ROM ("Broadcom UNDI, PXE-2.1 (build 082) v2.0.4") which stores - * data required by the UNDI ROM loader (yes, the ROM loader; that's - * the component which should be impossible to damage short of - * screwing with the MMU) around the 2MB mark. Sadly, this is not a - * joke. - * + * We use 4MB rather than 2MB because some PXE stack / PMM BIOS + * combinations are known to place data required by other UNDI ROMs + * loader around the 2MB mark. */ -#define HIGHMEM_LOADPOINT ( 4 << 20 ) + .globl HIGHMEM_LOADPOINT + .equ HIGHMEM_LOADPOINT, ( 4 << 20 ) /* Image compression enabled */ #define COMPRESS 1 #define CR0_PE 1 - .arch i386 - .section ".prefix.lib", "awx", @progbits - .section ".data16", "aw", @progbits - /**************************************************************************** * pm_call (real-mode near call) * @@ -223,12 +220,15 @@ copy_bytes: * Returns: * %ds:esi : next source address (will be a multiple of 16) * Corrupts: - * %edi, %ecx, %edx + * %ecx, %edx **************************************************************************** */ .section ".prefix.lib" .code16 install_block: + /* Preserve registers */ + pushl %edi + #if COMPRESS /* Decompress source to destination */ call decompress16 @@ -249,6 +249,8 @@ install_block: addl $0xf, %esi andl $~0xf, %esi + /* Restore registers and return */ + popl %edi ret .size install_block, . - install_block @@ -270,6 +272,7 @@ install_block: */ .section ".prefix.lib" .code16 + .globl alloc_basemem alloc_basemem: /* FBMS => %ax as segment address */ movw $0x40, %ax @@ -308,13 +311,14 @@ alloc_basemem: * Returns: * %esi : next source physical address (will be a multiple of 16) * Corrupts: - * %edi, %ecx, %edx + * %ecx, %edx **************************************************************************** */ .section ".prefix.lib" .code16 install_basemem: /* Preserve registers */ + pushl %edi pushw %ds /* Preserve original %esi */ @@ -335,6 +339,7 @@ install_basemem: /* Restore registers */ popw %ds + popl %edi ret .size install_basemem, . - install_basemem @@ -351,7 +356,7 @@ install_basemem: * Returns: * %esi : next source physical address (will be a multiple of 16) * Corrupts: - * %edi, %ecx, %edx + * %ecx, %edx **************************************************************************** */ @@ -376,17 +381,14 @@ install_highmem: /**************************************************************************** * install (real-mode near call) - * install_prealloc (real-mode near call) * * Install all text and data segments. * * Parameters: - * %ax : .text16 segment address (install_prealloc only) - * %bx : .data16 segment address (install_prealloc only) + * none * Returns: - * %ax : .text16 segment address - * %bx : .data16 segment address - * %edi : .text physical address (if applicable) + * %ax : .text16 segment address + * %bx : .data16 segment address * Corrupts: * none **************************************************************************** @@ -395,26 +397,55 @@ install_highmem: .code16 .globl install install: + /* Preserve registers */ + pushl %esi + pushl %edi /* Allocate space for .text16 and .data16 */ call alloc_basemem + /* Image source = %cs:0000 */ + xorl %esi, %esi + /* Image destination = HIGHMEM_LOADPOINT */ + movl $HIGHMEM_LOADPOINT, %edi + /* Install text and data segments */ + call install_prealloc + /* Restore registers and return */ + popl %edi + popl %esi + ret .size install, . - install + +/**************************************************************************** + * install_prealloc (real-mode near call) + * + * Install all text and data segments. + * + * Parameters: + * %ax : .text16 segment address + * %bx : .data16 segment address + * %esi : Image source physical address (or zero for %cs:0000) + * %edi : Decompression temporary area physical address + * Corrupts: + * none + **************************************************************************** + */ + .section ".prefix.lib" + .code16 .globl install_prealloc install_prealloc: /* Save registers */ + pushal pushw %ds pushw %es - pushl %esi - pushl %ecx - pushl %edx /* Sanity: clear the direction flag asap */ cld /* Calculate physical address of payload (i.e. first source) */ - xorl %esi, %esi + testl %esi, %esi + jnz 1f movw %cs, %si shll $4, %esi - addl $_payload_offset, %esi +1: addl $_payload_offset, %esi /* Install .text16 */ movw %ax, %es @@ -440,7 +471,6 @@ install_prealloc: * prior to reading the E820 memory map and relocating * properly. */ - movl $HIGHMEM_LOADPOINT, %edi movl $_textdata_progbits_size, %ecx movl $_textdata_size, %edx pushl %edi @@ -473,11 +503,9 @@ install_prealloc: #endif /* Restore registers */ - popl %edx - popl %ecx - popl %esi popw %es popw %ds + popal ret .size install_prealloc, . - install_prealloc |