mirror of https://github.com/ipxe/ipxe.git
[comboot] Use built-in interrupt reflector
We now have the ability to handle interrupts while in protected mode, and so no longer need to set up a dedicated interrupt descriptor table while running COM32 executables. Signed-off-by: Michael Brown <mcb30@ipxe.org>pull/17/head
Michael Brown
parent
23b671daf4
commit
aaf276ccd4
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@ -41,13 +41,6 @@ FILE_LICENCE ( GPL2_OR_LATER );
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#include <ipxe/init.h>
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#include <ipxe/io.h>
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struct idt_register com32_external_idtr = {
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.limit = COM32_NUM_IDT_ENTRIES * sizeof ( struct idt_descriptor ) - 1,
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.base = COM32_IDT
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};
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struct idt_register com32_internal_idtr;
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/**
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* Execute COMBOOT image
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*
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@ -95,8 +88,6 @@ static int com32_exec_loop ( struct image *image ) {
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unregister_image ( image );
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__asm__ __volatile__ (
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"sidt com32_internal_idtr\n\t"
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"lidt com32_external_idtr\n\t" /* Set up IDT */
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"movl %%esp, (com32_internal_esp)\n\t" /* Save internal virtual address space ESP */
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"movl (com32_external_esp), %%esp\n\t" /* Switch to COM32 ESP (top of available memory) */
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"call _virt_to_phys\n\t" /* Switch to flat physical address space */
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@ -110,8 +101,7 @@ static int com32_exec_loop ( struct image *image ) {
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"pushl $6\n\t" /* Number of additional arguments */
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"call *%6\n\t" /* Execute image */
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"cli\n\t" /* Disable interrupts */
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"call _phys_to_virt\n\t" /* Switch back to internal virtual address space */
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"lidt com32_internal_idtr\n\t" /* Switch back to internal IDT (for debugging) */
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"call _phys_to_virt\n\t" /* Switch back to internal virtual address space */
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"movl (com32_internal_esp), %%esp\n\t" /* Switch back to internal stack */
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:
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:
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@ -201,55 +191,25 @@ static int com32_identify ( struct image *image ) {
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/**
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* Load COM32 image into memory and set up the IDT
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* Load COM32 image into memory
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* @v image COM32 image
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* @ret rc Return status code
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*/
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static int com32_load_image ( struct image *image ) {
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physaddr_t com32_irq_wrapper_phys;
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struct idt_descriptor *idt;
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struct ijb_entry *ijb;
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size_t filesz, memsz;
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userptr_t buffer;
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int rc, i;
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int rc;
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/* The interrupt descriptor table, interrupt jump buffer, and
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* image data are all contiguous in memory. Prepare them all at once.
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*/
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filesz = image->len +
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COM32_NUM_IDT_ENTRIES * sizeof ( struct idt_descriptor ) +
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COM32_NUM_IDT_ENTRIES * sizeof ( struct ijb_entry );
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filesz = image->len;
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memsz = filesz;
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buffer = phys_to_user ( COM32_IDT );
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buffer = phys_to_user ( COM32_START_PHYS );
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if ( ( rc = prep_segment ( buffer, filesz, memsz ) ) != 0 ) {
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DBGC ( image, "COM32 %p: could not prepare segment: %s\n",
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image, strerror ( rc ) );
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return rc;
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}
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/* Write the IDT and IJB */
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idt = phys_to_virt ( COM32_IDT );
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ijb = phys_to_virt ( COM32_IJB );
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com32_irq_wrapper_phys = virt_to_phys ( com32_irq_wrapper );
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for ( i = 0; i < COM32_NUM_IDT_ENTRIES; i++ ) {
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uint32_t ijb_address = virt_to_phys ( &ijb[i] );
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idt[i].offset_low = ijb_address & 0xFFFF;
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idt[i].selector = PHYSICAL_CS;
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idt[i].flags = IDT_INTERRUPT_GATE_FLAGS;
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idt[i].offset_high = ijb_address >> 16;
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ijb[i].pusha_instruction = IJB_PUSHA;
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ijb[i].mov_instruction = IJB_MOV_AL_IMM8;
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ijb[i].mov_value = i;
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ijb[i].jump_instruction = IJB_JMP_REL32;
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ijb[i].jump_destination = com32_irq_wrapper_phys -
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virt_to_phys ( &ijb[i + 1] );
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}
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/* Copy image to segment */
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buffer = phys_to_user ( COM32_START_PHYS );
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memcpy_user ( buffer, 0, image->data, 0, filesz );
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return 0;
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@ -13,50 +13,6 @@ FILE_LICENCE ( GPL2_OR_LATER );
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#include <setjmp.h>
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#include <ipxe/in.h>
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/** Descriptor in a 32-bit IDT */
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struct idt_descriptor {
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uint16_t offset_low;
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uint16_t selector;
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uint16_t flags;
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uint16_t offset_high;
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} __attribute__ (( packed ));
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/** Operand for the LIDT instruction */
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struct idt_register {
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uint16_t limit;
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uint32_t base;
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} __attribute__ (( packed ));
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/** Entry in the interrupt jump buffer */
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struct ijb_entry {
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uint8_t pusha_instruction;
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uint8_t mov_instruction;
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uint8_t mov_value;
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uint8_t jump_instruction;
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uint32_t jump_destination;
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} __attribute__ (( packed ));
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/** The x86 opcode for "pushal" */
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#define IJB_PUSHA 0x60
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/** The x86 opcode for "movb $imm8,%al" */
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#define IJB_MOV_AL_IMM8 0xB0
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/** The x86 opcode for "jmp rel32" */
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#define IJB_JMP_REL32 0xE9
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/** Flags that specify a 32-bit interrupt gate with DPL=0 */
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#define IDT_INTERRUPT_GATE_FLAGS 0x8E00
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/** Address of COM32 interrupt descriptor table */
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#define COM32_IDT 0x100000
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/** Number of entries in a fully populated IDT */
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#define COM32_NUM_IDT_ENTRIES 256
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/** Address of COM32 interrupt jump buffer */
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#define COM32_IJB 0x100800
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/** Segment used for COMBOOT PSP and image */
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#define COMBOOT_PSP_SEG 0x07C0
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@ -153,7 +109,6 @@ extern void unhook_comboot_interrupts ( );
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extern void com32_intcall_wrapper ( );
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extern void com32_farcall_wrapper ( );
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extern void com32_cfarcall_wrapper ( );
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extern void com32_irq_wrapper ( );
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/* Resolve a hostname to an (IPv4) address */
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extern int comboot_resolv ( const char *name, struct in_addr *address );
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@ -189,20 +189,3 @@ int __asmcall com32_cfarcall ( uint32_t proc, physaddr_t stack, size_t stacksz )
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return eax;
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}
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/**
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* IRQ handler
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*/
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void __asmcall com32_irq ( uint32_t vector ) {
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uint32_t *ivt_entry = phys_to_virt( vector * 4 );
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__asm__ __volatile__ (
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REAL_CODE ( "pushfw\n\t"
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"pushw %%cs\n\t"
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"pushw $com32_irq_return\n\t"
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"pushl %0\n\t"
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"lret\n"
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"com32_irq_return:\n\t" )
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: /* no outputs */
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: "r" ( *ivt_entry ) );
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}
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@ -23,26 +23,6 @@ FILE_LICENCE ( GPL2_OR_LATER )
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.arch i386
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.code32
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/*
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* This code is entered after running the following sequence out of
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* the interrupt jump buffer:
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*
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* pushal
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* movb $vector, %al
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* jmp com32_irq_wrapper
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*/
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.globl com32_irq_wrapper
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com32_irq_wrapper:
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movzbl %al,%eax
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pushl %eax
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movl $com32_irq, %eax
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call com32_wrapper
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popl %eax
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popal
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iret
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.globl com32_farcall_wrapper
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com32_farcall_wrapper:
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@ -69,9 +49,6 @@ com32_wrapper:
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/* Switch to internal virtual address space */
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call _phys_to_virt
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/* Switch to internal IDT (if we have one for debugging) */
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lidt com32_internal_idtr
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mov %eax, (com32_helper_function)
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/* Save external COM32 stack pointer */
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@ -99,9 +76,6 @@ com32_wrapper:
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movl %esp, (com32_internal_esp)
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movl (com32_external_esp), %esp
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/* Switch to com32 IDT */
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lidt com32_external_idtr
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/* Switch to external flat physical address space */
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call _virt_to_phys
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