diff options
Diffstat (limited to 'src/arch/i386/prefix/libprefix.S')
| -rw-r--r-- | src/arch/i386/prefix/libprefix.S | 91 |
1 files changed, 86 insertions, 5 deletions
diff --git a/src/arch/i386/prefix/libprefix.S b/src/arch/i386/prefix/libprefix.S index 61549618..56ca64d9 100644 --- a/src/arch/i386/prefix/libprefix.S +++ b/src/arch/i386/prefix/libprefix.S @@ -537,17 +537,20 @@ install_block: .code16 .globl alloc_basemem alloc_basemem: + /* Preserve registers */ + pushw %fs + /* FBMS => %ax as segment address */ - movw $0x40, %ax - movw %ax, %fs + pushw $0x40 + popw %fs movw %fs:0x13, %ax shlw $6, %ax - /* .data16 segment address */ + /* Calculate .data16 segment address */ subw $_data16_memsz_pgh, %ax pushw %ax - /* .text16 segment address */ + /* Calculate .text16 segment address */ subw $_text16_memsz_pgh, %ax pushw %ax @@ -555,13 +558,68 @@ alloc_basemem: shrw $6, %ax movw %ax, %fs:0x13 - /* Return */ + /* Retrieve .text16 and .data16 segment addresses */ popw %ax popw %bx + + /* Restore registers and return */ + popw %fs ret .size alloc_basemem, . - alloc_basemem /**************************************************************************** + * free_basemem (real-mode near call) + * + * Free space allocated with alloc_basemem. + * + * Parameters: + * %ax : .text16 segment address + * %bx : .data16 segment address + * Returns: + * %ax : 0 if successfully freed + * Corrupts: + * none + **************************************************************************** + */ + .section ".text16" + .code16 + .globl free_basemem +free_basemem: + /* Preserve registers */ + pushw %fs + + /* Check FBMS counter */ + pushw %ax + shrw $6, %ax + pushw $0x40 + popw %fs + cmpw %ax, %fs:0x13 + popw %ax + jne 1f + + /* Check hooked interrupt count */ + cmpw $0, %cs:hooked_bios_interrupts + jne 1f + + /* OK to free memory */ + addw $_text16_memsz_pgh, %ax + addw $_data16_memsz_pgh, %ax + shrw $6, %ax + movw %ax, %fs:0x13 + xorw %ax, %ax + +1: /* Restore registers and return */ + popw %fs + ret + .size free_basemem, . - free_basemem + + .section ".text16.data" + .globl hooked_bios_interrupts +hooked_bios_interrupts: + .word 0 + .size hooked_bios_interrupts, . - hooked_bios_interrupts + +/**************************************************************************** * install (real-mode near call) * * Install all text and data segments. @@ -709,6 +767,29 @@ prot_call_vector: .size prot_call_vector, . - prot_call_vector #endif +/**************************************************************************** + * uninstall (real-mode near call) + * + * Uninstall all text and data segments. + * + * Parameters: + * %ax : .text16 segment address + * %bx : .data16 segment address + * Returns: + * none + * Corrupts: + * none + **************************************************************************** + */ + .section ".text16" + .code16 + .globl uninstall +uninstall: + call free_basemem + ret + .size uninstall, . - uninstall + + /* File split information for the compressor */ #if COMPRESS |