Files
system76-coreboot/src/arch/x86/exit_car.S
Aaron Durbin 028e18ff3c arch/x86: update assembly to ensure 16-byte alignment into C
When the C compiler expects 16-byte alignment of the stack it is
at the call instruction.  Correct existing call points from assembly
to ensure the stacks are aligned to 16 bytes at the call instruction.

Change-Id: Icadd7a1f9284e92aecd99c30cb2acb307823682c
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/20314
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
2017-06-29 14:58:59 +00:00

131 lines
2.9 KiB
ArmAsm

/*
* This file is part of the coreboot project.
*
* Copyright 2016 Google Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; version 2 of
* the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <cpu/x86/mtrr.h>
#include <cpu/x86/cr.h>
.section ".module_parameters", "aw", @progbits
/* stack_top indicates the stack to pull MTRR information from. */
.global post_car_stack_top
post_car_stack_top:
.long 0
.long 0
.text
.global _start
_start:
/* Assume stack alignment doesn't matter here as chipset_teardown_car
is expected to be implemented in assembly. */
/* chipset_teardown_car() is expected to disable cache-as-ram. */
call chipset_teardown_car
/* Enable caching if not already enabled. */
mov %cr0, %eax
and $(~(CR0_CD | CR0_NW)), %eax
mov %eax, %cr0
/* Ensure cache is clean. */
invd
/* Set up new stack. */
mov post_car_stack_top, %esp
/*
* Honor variable MTRR information pushed on the stack with the
* following layout:
*
* Offset: Value
* ...
* 0x14: MTRR mask 0 63:32
* 0x10: MTRR mask 0 31:0
* 0x0c: MTRR base 0 63:32
* 0x08: MTRR base 0 31:0
* 0x04: Number of variable MTRRs to set
* 0x00: Number of variable MTRRs to clear
*/
#if IS_ENABLED(CONFIG_SOC_SETS_MSRS)
mov %esp, %ebp
/* Need to align stack to 16 bytes at the call instruction. Therefore
account for the 1 push. */
andl $0xfffffff0, %esp
sub $12, %esp
push %ebp
call soc_set_mtrrs
/* Ignore fixing up %esp since we're setting it a new value. */
/* eax: new top_of_stack with setup_stack_and_mtrrs data removed */
movl %eax, %esp
/* Align stack to 16 bytes at call instruction. */
andl $0xfffffff0, %esp
call soc_enable_mtrrs
#else /* CONFIG_SOC_SETS_MSRS */
/* Clear variable MTRRs. */
pop %ebx /* Number to clear */
test %ebx, %ebx
jz 2f
xor %eax, %eax
xor %edx, %edx
mov $(MTRR_PHYS_BASE(0)), %ecx
1:
wrmsr
inc %ecx
wrmsr
inc %ecx
dec %ebx
jnz 1b
2:
/* Set Variable MTRRs based on stack contents. */
pop %ebx /* Number to set. */
test %ebx, %ebx
jz 2f
mov $(MTRR_PHYS_BASE(0)), %ecx
1:
/* Write MTRR base. */
pop %eax
pop %edx
wrmsr
inc %ecx
/* Write MTRR mask. */
pop %eax
pop %edx
wrmsr
inc %ecx
dec %ebx
jnz 1b
2:
/* Enable MTRR. */
mov $(MTRR_DEF_TYPE_MSR), %ecx
rdmsr
/* Make default type uncacheable. */
and $(~(MTRR_DEF_TYPE_MASK)), %eax
or $(MTRR_DEF_TYPE_EN), %eax
wrmsr
#endif /* CONFIG_SOC_SETS_MSRS */
/* Align stack to 16 bytes at call instruction. */
andl $0xfffffff0, %esp
/* Call into main for postcar. */
call main
/* Should never return. */
1:
jmp 1b