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arch/x86: Enforce CPU stack alignment

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When rmodule is loaded CPU stack alignment is only guaranteed
to 4kiB. Implementation of cpu_info() requires that each
CPU sees its stack aligned to CONFIG_STACK_SIZE.

Add one spare CPU for the stack reserve, such that alignment can
be enforced runtime.

Change-Id: Ie04956c64df0dc7bb156002d3d4f2629f92b340e
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/26302
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Kyösti Mälkki
2018-05-15 19:50:20 +03:00
committed by Patrick Georgi
parent b318be2218
commit 2fbb6773e3
3 changed files with 21 additions and 17 deletions
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7
src/arch/x86/c_start.S
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@ -19,9 +19,11 @@
.global _stack
.global _estack
/* Stack alignment is not enforced with rmodule loader, reserve one
* extra CPU such that alignment can be enforced on entry. */
.align CONFIG_STACK_SIZE
_stack:
.space CONFIG_MAX_CPUS*CONFIG_STACK_SIZE
.space (CONFIG_MAX_CPUS+1)*CONFIG_STACK_SIZE
_estack:
#if IS_ENABLED(CONFIG_COOP_MULTITASKING)
.global thread_stacks
@ -70,8 +72,9 @@ _start:
rep
stosl
/* set new stack */
/* Set new stack with enforced alignment. */
movl $_estack, %esp
andl $(~(CONFIG_STACK_SIZE-1)), %esp
#if IS_ENABLED(CONFIG_COOP_MULTITASKING)
/* Push the thread pointer. */