mirror of https://github.com/ipxe/ipxe.git
Since we now always unload the base code stack (even if we keep UNDI),
we can never return to the PXE stack and must always use INT 18.pull/1/head
Michael Brown
parent
f2f492a536
commit
697bcc9d24
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@ -3,8 +3,6 @@
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#define PXENV_STOP_UNDI 0x0015
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#define PXENV_UNLOAD_STACK 0x0070
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#define PXE_STACK_MAGIC 0x57ac /* 'STac' */
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.text
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.arch i386
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.org 0
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@ -17,31 +15,22 @@
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*****************************************************************************
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*/
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.section ".prefix"
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/* Set up our non-stack segment registers */
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jmp $0x7c0, $1f
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1: /* Preserve registers for return to PXE stack */
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pushfl
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pushal
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pushw %gs
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pushw %fs
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pushw %es
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pushw %ds
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pushw %ss
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pushw %cs
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pushw $PXE_STACK_MAGIC /* PXE stack magic marker */
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1: movw %cs, %ax
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movw %ax, %ds
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movw $0x40, %ax /* BIOS data segment access */
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movw %ax, %fs
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/* Record PXENV+ and !PXE nominal addresses */
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movw %es, %ax /* PXENV+ address */
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movw %ax, pxenv_segment
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movw %bx, pxenv_offset
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popl %eax /* Discard return address */
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popl ppxe_segoff /* !PXE address */
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/* Set up stack just below 0x7c00 */
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pushw %ss
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popw %gs
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movw %sp, %bp /* %gs:%bp points to old PXE stack */
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xorw %ax, %ax
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movw %ax, %ss
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movw $0x7c00, %sp
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pushw %gs /* Save old PXE stack pointer */
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pushw %bp
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/* Set up our other segment registers */
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pushw %cs
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popw %ds
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movw $0x40, %ax /* BIOS data segment access */
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movw %ax, %fs
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/* Clear direction flag, for the sake of sanity */
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cld
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/* Print welcome message */
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@ -57,21 +46,19 @@
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*/
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detect_pxenv:
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/* Signature check */
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cmpl $0x4e455850, %es:(%bx) /* 'PXEN' signature */
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les pxenv_segoff, %di
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cmpl $0x4e455850, %es:(%di) /* 'PXEN' signature */
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jne 99f
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cmpw $0x2b56, %es:4(%bx) /* 'V+' signature */
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cmpw $0x2b56, %es:4(%di) /* 'V+' signature */
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jne 99f
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/* Record structure address, entry point, and UNDI segments */
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pushw %es
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popw pxenv_segment
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movw %bx, pxenv_offset
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pushl %es:0x0a(%bx) /* Entry point */
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/* Record entry point and UNDI segments */
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pushl %es:0x0a(%di) /* Entry point */
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popl entry_segoff
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pushw %es:0x24(%bx) /* UNDI code segment */
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pushw %es:0x26(%bx) /* UNDI code size */
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pushw %es:0x24(%di) /* UNDI code segment */
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pushw %es:0x26(%di) /* UNDI code size */
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popl undi_code_segoff
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pushw %es:0x20(%bx) /* UNDI data segment */
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pushw %es:0x22(%bx) /* UNDI data size */
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pushw %es:0x20(%di) /* UNDI data segment */
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pushw %es:0x22(%di) /* UNDI data size */
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popl undi_data_segoff
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/* Print "PXENV+ at <address>" */
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movw $10f, %si
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@ -91,7 +78,7 @@ detect_pxenv:
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*/
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detect_ppxe:
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/* Signature check */
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les %gs:54(%bp), %di /* !PXE structure */
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les ppxe_segoff, %di
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cmpl $0x45585021, %es:(%di) /* '!PXE' signature */
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jne 99f
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/* Record structure address, entry point, and UNDI segments */
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@ -700,65 +687,19 @@ run_etherboot:
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rep movsb
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#endif
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/* Jump to .text16 segment with %ds pointing to .data16*/
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/* Jump to .text16 segment with %ds pointing to .data16 */
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movw %bx, %ds
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pushw %ax
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pushw $1f
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lret
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.section ".text16", "ax", @progbits
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1:
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/* Original PXE stack pointer to es:di. We must hold it in
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* registers, because our current stack may be vapourised by
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* the time main() returns. (main() will still be able to
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* return, because prot_call() transfers the return address to
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* the internal stack and back again).
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*/
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popw %di
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popw %es
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/* Run main program */
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pushl $main
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pushw %cs
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call prot_call
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popl %eax /* discard */
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/* If original PXE stack is intact, return via PXE, else via INT 18 */
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cmpw $PXE_STACK_MAGIC, %es:0(%di)
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jne exit_via_int18
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exit_via_pxe: /* Stack OK, return to PXE */
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movw $exit_via_pxe_message, %si
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call print_exit_message
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pushw %es /* Restore original PXE stack */
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popw %ss
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movw %di, %sp
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popw %ax /* discard PXE_STACK_MAGIC */
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popw %ax /* discard %cs */
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popw %ax /* discard %ss */
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popw %ds
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popw %es
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popw %fs
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popw %gs
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popal
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popfl
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xorw %ax, %ax /* Return PXENV_STATUS_SUCCESS */
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lret
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exit_via_int18: /* Stack damaged, do int 18 */
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movw $exit_via_int18_message, %si
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call print_exit_message
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/* Boot next device */
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int $0x18
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print_exit_message:
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movw $0x0007, %bx /* page 0, attribute 7 (normal) */
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movb $0x0e, %ah /* write char, tty mode */
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1: lodsb
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testb %al, %al
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je 2f
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int $0x10
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jmp 1b
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2: ret
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.section ".data16", "aw", @progbits
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exit_via_pxe_message:
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.asciz "EB->PXE\r\n"
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exit_via_int18_message:
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.asciz "EB->BIOS\r\n"
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.previous
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