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UPSTREAM: libpayload: x86/head - implement argc/argv handling

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Implement the argc/argv passing as described in coreboots payload API:
http://www.coreboot.org/Payload_API

While at it, give the code some love by not needlessly trashing register
values.

BUG=none
BRANCH=none
TEST=none

Change-Id: If49874b1ac1c7359816f4ec02c5380c32101fa1a
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Original-Commit-Id: d2f16cac74
Original-Change-Id: Ib830f2c67b631b7216843203cefd55d9bb780d83
Original-Signed-off-by: Mathias Krause <minipli@googlemail.com>
Original-Reviewed-on: https://review.coreboot.org/18336
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Original-Tested-by: build bot (Jenkins)
Reviewed-on: https://chromium-review.googlesource.com/444817
This commit is contained in:
Mathias Krause 2017-02-11 22:47:04 +01:00 • committed by chrome-bot
parent 98efca1d93
commit c958bb42a0
1 changed files with 23 additions and 18 deletions
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37
payloads/libpayload/arch/x86/head.S
View file

@ -28,7 +28,7 @@
*/ */
.code32 .code32
.global _entry, _leave .global _entry
.text .text
.align 4 .align 4
@ -55,6 +55,11 @@ mb_header:
.long _end .long _end
.long _init .long _init
#define CB_MAGIC_VALUE 0x12345678
#define CB_MAGIC 0x04
#define CB_ARGV 0x08
#define CB_ARGC 0x10
/* /*
* This function saves off the previous stack and switches us to our * This function saves off the previous stack and switches us to our
* own execution environment. * own execution environment.
@ -63,34 +68,34 @@ _init:
/* No interrupts, please. */ /* No interrupts, please. */
cli cli
/* There is a bunch of stuff missing here to take arguments on the stack
* See http://www.coreboot.org/Payload_API and exec.S.
*/
/* Store current stack pointer. */
movl %esp, %esi
/* Store EAX and EBX */ /* Store EAX and EBX */
movl %eax, loader_eax movl %eax, loader_eax
movl %ebx, loader_ebx movl %ebx, loader_ebx
/* Setup new stack. */ /* Copy argv[] and argc as demanded by the Payload API,
movl $_stack, %ebx * see http://www.coreboot.org/Payload_API and exec.S.
*/
cmpl $CB_MAGIC_VALUE, CB_MAGIC(%esp)
jne 1f
movl %ebx, %esp movl CB_ARGV(%esp), %eax
movl %eax, main_argv
/* Save old stack pointer. */ movl CB_ARGC(%esp), %eax
pushl %esi movl %eax, main_argc
1:
/* Store current stack pointer and set up new stack. */
movl %esp, %eax
movl $_stack, %esp
pushl %eax
/* Let's rock. */ /* Let's rock. */
call start_main call start_main
/* %eax has the return value - pass it on unmolested */ /* %eax has the return value - pass it on unmolested */
_leave: _leave:
/* Get old stack pointer. */
popl %ebx
/* Restore old stack. */ /* Restore old stack. */
movl %ebx, %esp popl %esp
/* Return to the original context. */ /* Return to the original context. */
ret ret