diff options
| -rw-r--r-- | src/arch/i386/prefix/pxeprefix.S | 365 |
1 files changed, 179 insertions, 186 deletions
diff --git a/src/arch/i386/prefix/pxeprefix.S b/src/arch/i386/prefix/pxeprefix.S index 0e0b6c00..dea0b199 100644 --- a/src/arch/i386/prefix/pxeprefix.S +++ b/src/arch/i386/prefix/pxeprefix.S @@ -1,16 +1,9 @@ -/* Offsets of words containing ROM's CS and size (in 512 byte blocks) - * from start of floppy boot block at 0x7c00 - * Offsets must match those in etherboot.h - */ -#define FLOPPY_SEGMENT 0x7c0 - #define PXENV_UNDI_CLEANUP 0x02 #define PXENV_UNDI_SHUTDOWN 0x05 #define PXENV_STOP_UNDI 0x15 #define PXENV_UNLOAD_STACK 0x70 #define PXENV_STOP_BASE 0x76 -#define PUSHA_SIZE 16 #define PXE_STACK_MAGIC 0x57ac /* 'STac' */ .text @@ -22,21 +15,35 @@ * Entry point: set cs, ds, bp, print welcome message ***************************************************************************** */ -_prefix: - jmp $FLOPPY_SEGMENT, $code_start-_prefix + jmp $0x7c0, $code_start 10: .asciz "PXE->EB " code_start: - pusha /* Preserve all registers */ - push %ds - movw %sp, %bp /* %bp must be preserved, hence do - * this after the pusha */ - push $PXE_STACK_MAGIC /* PXE stack magic marker */ - - push %cs /* Set up data segment */ - pop %ds - mov $0x40, %cx /* Set up %fs for access to 40:13 */ - mov %cx, %fs - movw $10b-_prefix, %si /* Print welcome message */ + /* Preserve registers for return to PXE stack */ + pushfl + pushal + pushw %gs + pushw %fs + pushw %es + pushw %ds + pushw %ss + pushw %cs + pushw $PXE_STACK_MAGIC /* PXE stack magic marker */ + /* Set up stack just below 0x7c00 */ + pushw %ss + popw %es + movw %sp, %di + xorw %ax, %ax + movw %ax, %ss + movw $0x7c00, %sp + pushw %es /* Save old PXE stack pointer */ + pushw %di + /* Set up our other segment registers */ + pushw %cs + popw %ds + movw $0x40, %ax /* BIOS data segment access */ + movw %ax, %fs + /* Print welcome message */ + movw $10b, %si call print_message /***************************************************************************** @@ -44,12 +51,12 @@ code_start: ***************************************************************************** */ detect_pxe: - les 4+PUSHA_SIZE+2(%bp), %di /* !PXE structure */ + les %es:54(%di), %di /* !PXE structure */ cmpl $0x45585021, %es:(%di) /* '!PXE' signature */ je detected_pxe - mov $0x5650, %ax + movw $0x5650, %ax int $0x1a - cmp $0x564e, %ax + cmpw $0x564e, %ax jne detected_nothing cmpl $0x4e455850, %es:(%bx) /* 'PXEN' signature */ jne detected_nothing @@ -57,49 +64,45 @@ detect_pxe: je detected_pxenv detected_nothing: - movw $10f-_prefix, %si + movw $10f, %si call print_message jmp finished_with_error 10: .asciz "No PXE " detected_pxenv: /* es:bx points to PXENV+ structure */ - push %es - push %bx - push %es:0x24(%bx) /* UNDI code segment */ - push %es:0x26(%bx) /* UNDI code size */ - push %es:0x20(%bx) /* UNDI data segment */ - push %es:0x22(%bx) /* UNDI data size */ + pushw %es + pushw %bx + pushw %es:0x24(%bx) /* UNDI code segment */ + pushw %es:0x26(%bx) /* UNDI code size */ + pushw %es:0x20(%bx) /* UNDI data segment */ + pushw %es:0x22(%bx) /* UNDI data size */ les %es:0x0a(%bx), %di /* Entry point to %es:%di */ - movw $10f-_prefix, %si + movw $10f, %si jmp pxe_setup_done 10: .asciz "PXENV+ " detected_pxe: /* es:di points to !PXE structure */ - push %es - push %di - push %es:0x30(%di) /* UNDI code segment */ - push %es:0x36(%di) /* UNDI code size */ - push %es:0x28(%di) /* UNDI data segment */ - push %es:0x2e(%di) /* UNDI data size */ + pushw %es + pushw %di + pushw %es:0x30(%di) /* UNDI code segment */ + pushw %es:0x36(%di) /* UNDI code size */ + pushw %es:0x28(%di) /* UNDI data segment */ + pushw %es:0x2e(%di) /* UNDI data size */ les %es:0x10(%di), %di /* Entry point to %es:%di */ - movw $10f-_prefix, %si + movw $10f, %si jmp pxe_setup_done 10: .asciz "!PXE " pxe_setup_done: - mov %es, pxe_entry_segment - _prefix - mov %di, pxe_entry_offset - _prefix - pop %ax - mov %ax, undi_data_size - _prefix - pop %ax - mov %ax, undi_data_segment - _prefix - pop %ax - mov %ax, undi_code_size - _prefix - pop %ax - mov %ax, undi_code_segment - _prefix + movw %es, pxe_entry_segment + movw %di, pxe_entry_offset + popw undi_data_size + popw undi_data_segment + popw undi_code_size + popw undi_code_segment call print_message - pop %di - pop %es /* Exit with %es:%di containing structure address */ + popw %di + popw %es /* Exit with %es:%di containing structure address */ /***************************************************************************** * Print information about located structure @@ -107,11 +110,11 @@ pxe_setup_done: */ print_structure_information: call print_segoff /* %es:%di contains address of structure */ - les %ds:(pxe_entry_segoff - _prefix), %di + les pxe_entry_segoff, %di call print_segoff - les %ds:(undi_code_segoff - _prefix), %di + les undi_code_segoff, %di call print_segoff - les %ds:(undi_data_segoff - _prefix), %di + les undi_data_segoff, %di call print_segoff /***************************************************************************** @@ -119,17 +122,17 @@ print_structure_information: ***************************************************************************** */ #ifdef PXELOADER_KEEP_ALL - xor %ax, %ax /* Force zero flag to show success */ + xorw %ax, %ax /* Force zero flag to show success */ jmp do_not_free_base_mem /* Skip the unloading */ #endif /* PXELOADER_KEEP_ALL */ unload_pxe: - mov $PXENV_UNLOAD_STACK, %bx + movw $PXENV_UNLOAD_STACK, %bx call pxe_call - mov $PXENV_STOP_UNDI, %bx + movw $PXENV_STOP_UNDI, %bx call pxe_call pushfw /* Ignore PXENV_UNDI_CLEANUP errors */ - mov $PXENV_UNDI_CLEANUP, %bx + movw $PXENV_UNDI_CLEANUP, %bx call pxe_call popfw /* On exit, zero flag is set iff all calls were successful */ @@ -141,45 +144,45 @@ unload_pxe: free_base_mem: jnz do_not_free_base_mem /* Using zero flag from unload_pxe */ - mov undi_code_segment - _prefix, %bx - mov undi_data_segment - _prefix, %cx - mov undi_code_size - _prefix, %ax - cmp %bx, %cx + movw undi_code_segment, %bx + movw undi_data_segment, %cx + movw undi_code_size, %ax + cmpw %bx, %cx jb 1f - mov %cx, %bx - mov undi_data_size - _prefix, %ax -1: add $0x0f, %ax /* Round up to next segment */ - shr $4, %ax - add %bx, %ax /* Highest segment address into %ax */ - add $(1024 / 16 - 1), %ax /* Round up to next kb */ - shr $6, %ax /* New free basemem size in %ax */ - mov %fs:(0x13), %bx /* Old free base memory in %bx */ - mov %ax, %fs:(0x13) /* Store new free base memory size */ + movw %cx, %bx + movw undi_data_size, %ax +1: addw $0x0f, %ax /* Round up to next segment */ + shrw $4, %ax + addw %bx, %ax /* Highest segment address into %ax */ + addw $(1024 / 16 - 1), %ax /* Round up to next kb */ + shrw $6, %ax /* New free basemem size in %ax */ + movw %fs:(0x13), %bx /* Old free base memory in %bx */ + movw %ax, %fs:(0x13) /* Store new free base memory size */ /* Note that zero_mem_loop will also zero out our stack, so make * sure the stack is empty at this point. */ - mov %ax, %dx - sub %bx, %dx /* numberof kb to zero in %dx */ - shl $6, %bx /* Segment address into %bx */ + movw %ax, %dx + subw %bx, %dx /* numberof kb to zero in %dx */ + shlw $6, %bx /* Segment address into %bx */ zero_mem_loop: - mov %bx, %es /* kB boundary into %es:00 */ - xor %ax, %ax - xor %di, %di - mov $0x400, %cx + movw %bx, %es /* kB boundary into %es:00 */ + xorw %ax, %ax + xorw %di, %di + movw $0x400, %cx rep stosb /* fill kB with zeroes */ - add $(1024 / 16), %bx - dec %dx + addw $(1024 / 16), %bx + decw %dx jnz zero_mem_loop /* Will exit here with zero flag set, so no need to set it explicitly * in order to indicate success. */ do_not_free_base_mem: - pushf /* Save success (zero) flag status */ - mov %fs:(0x13), %ax /* Free base memory in %ax */ + pushfw /* Save success (zero) flag status */ + movw %fs:(0x13), %ax /* Free base memory in %ax */ call print_hex_word /* Print free base memory */ - popf /* Restore success (zero) flag */ + popfw /* Restore success (zero) flag */ /***************************************************************************** * Exit point @@ -188,92 +191,16 @@ do_not_free_base_mem: ***************************************************************************** */ finished: - movw $10f-_prefix, %si + movw $10f, %si jz 1f finished_with_error: - movw $20f-_prefix, %si + movw $20f, %si 1: call print_message - jmp 99f + jmp run_etherboot 10: .asciz " ok\n" 20: .asciz " err\n" - - /* We place a stack here. It doesn't get used until after all - * the above code is finished, so we can happily write all - * over it. Putting the stack here ensures that it doesn't - * accidentally go over the 512 byte threshold, which would - * cause problems when returning via start32's prefix - * relocation mechanism. - */ -_estack: -99: - -/***************************************************************************** - * Run Etherboot main code - ***************************************************************************** - */ -run_etherboot: - /* Very temporarily switch stacks to one internal to the - * prefix. Do this because the stack provided by the PXE ROM - * could be absolutely anywhere, including in an area of - * memory that the call to prelocate will vapourise... - */ - pushw %ss /* PXE stack pointer to ES:DI */ - popw %es - movw %sp, %di - pushw %ds /* Set up stack in "safe" area */ - popw %ss - movw $_estack-_prefix, %sp - pushw %es /* Record PXE stack pointer */ - pushw %di - /* Relocate payload and stack to claimed base memory */ - pushw $4 /* Preserve old PXE stack pointer */ - call prelocate - popw %ax /* Remove parameter */ - pushl $4 /* Preserve old PXE stack pointer */ - pushw $0 /* Indicate prefix exit mechanism */ - jmp _start /* Run Etherboot */ - - .section ".text16", "ax", @progbits -prefix_exit: - pushw %cs /* Set %ds, %bp for access to text */ - popw %ds - call 1f -1: popw %bp - popw %di /* Old PXE stack to %es:di */ - popw %es - cmpw $PXE_STACK_MAGIC, %es:0(%di) /* See if PXE stack intact */ - jne exit_via_int18 -exit_via_pxe: /* Stack OK, return to PXE */ - push %es /* Restore PXE stack pointer */ - pop %ss - mov %di, %sp - pop %ax /* Discard PXE_STACK_MAGIC marker */ - leaw (10f-1b)(%bp), %si - call print_exit_message - pop %ds /* Restore PXE's DS */ - popa /* Restore PXE's other registers */ - movw $0, %ax /* Return PXENV_STATUS_SUCCESS */ - lret /* Return control to PXE ROM */ -10: .asciz "EB->PXE\r\n" -exit_via_int18: /* Stack damaged, do int 18 */ - leaw (10f-1b)(%bp), %si - call print_exit_message - int $0x18 -10: .asciz "EB->BIOS\r\n" -print_exit_message: - movw $0x0007, %bx /* page 0, attribute 7 (normal) */ - movb $0x0e, %ah /* write char, tty mode */ -1: lodsb - testb %al, %al - je 2f - int $0x10 - jmp 1b -2: ret -prefix_exit_end: - .previous - /***************************************************************************** * Subroutine: print character in %al (with LF -> LF,CR translation) ***************************************************************************** @@ -305,17 +232,17 @@ print_message: ***************************************************************************** */ print_hex_word: - mov $4, %cx + movw $4, %cx 1: - push %ax - shr $12, %ax + pushw %ax + shrw $12, %ax /* Courtesy of Norbert Juffa <norbert.juffa@amd.com> */ - cmp $10, %al - sbb $0x69, %al + cmpb $10, %al + sbbb $0x69, %al das call print_character - pop %ax - shl $4, %ax + popw %ax + shlw $4, %ax loop 1b ret @@ -324,15 +251,15 @@ print_hex_word: ***************************************************************************** */ print_segoff: - push %di - push %es - pop %ax + pushw %di + pushw %es + popw %ax call print_hex_word movb $0x3a,%al /* ':' */ call print_character - pop %ax + popw %ax call print_hex_word - mov $0x20, %al /* ' ' */ + movb $0x20, %al /* ' ' */ call print_character ret @@ -346,24 +273,24 @@ print_segoff: */ pxe_call: /* Set up registers for PXENV+ API. %bx already set up */ - push %ds - pop %es - mov $pxe_parameter_structure - _prefix, %di + pushw %ds + popw %es + movw $pxe_parameter_structure, %di /* Set up stack for !PXE API */ pushw %cs pushw %di pushw %bx /* Make the API call */ - lcall *(pxe_entry_segoff - _prefix) + lcall *pxe_entry_segoff /* Reset the stack */ - add $6, %sp - mov pxe_parameter_structure - _prefix, %ax - push %ax + addw $6, %sp + movw pxe_parameter_structure, %ax + pushw %ax call print_hex_word - mov $0x20, %ax /* ' ' */ + movw $0x20, %ax /* ' ' */ call print_character - pop %bx - or %bx, pxe_overall_status - _prefix + popw %bx + orw %bx, pxe_overall_status ret /***************************************************************************** @@ -389,7 +316,73 @@ pxe_parameter_structure: .word 0 .word 0,0,0,0,0 -end_of_pxeloader: +/***************************************************************************** + * Run Etherboot main code + ***************************************************************************** + */ +run_etherboot: + /* Install Etherboot */ + call install + + /* Jump to .text16 segment with %ds pointing to .data16*/ + movw %bx, %ds + pushw %ax + pushw $1f + lret + .section ".text16", "ax", @progbits +1: + /* Original PXE stack pointer to es:di. We must hold it in + * registers, because our current stack may be vapourised by + * the time main() returns. (main() will still be able to + * return, because prot_call() transfers the return address to + * the internal stack and back again). + */ + popw %di + popw %es + + /* Run main program */ + pushl $main + pushw %cs + call prot_call + popl %eax /* discard */ + + /* If original PXE stack is intact, return via PXE, else via INT 18 */ + cmpw $PXE_STACK_MAGIC, %es:0(%di) + jne exit_via_int18 +exit_via_pxe: /* Stack OK, return to PXE */ + movw $exit_via_pxe_message, %si + call print_exit_message + pushw %es /* Restore original PXE stack */ + popw %ss + movw %di, %sp + popw %ax /* discard PXE_STACK_MAGIC */ + popw %ax /* discard %cs */ + popw %ax /* discard %ss */ + popw %ds + popw %es + popw %fs + popw %gs + popal + popfl + xorw %ax, %ax /* Return PXENV_STATUS_SUCCESS */ + lret +exit_via_int18: /* Stack damaged, do int 18 */ + movw $exit_via_int18_message, %si + call print_exit_message + int $0x18 + +print_exit_message: + movw $0x0007, %bx /* page 0, attribute 7 (normal) */ + movb $0x0e, %ah /* write char, tty mode */ +1: lodsb + testb %al, %al + je 2f + int $0x10 + jmp 1b +2: ret - .balign 16, 0 -payload: + .section ".data16", "aw", @progbits +exit_via_pxe_message: + .asciz "EB->PXE\r\n" +exit_via_int18_message: + .asciz "EB->BIOS\r\n" |