From 61b22cb930388510d057cdd79392529660fa4a8c Mon Sep 17 00:00:00 2001
From: Arthur Heymans <arthur@aheymans.xyz>
Date: Tue, 8 Jan 2019 23:25:04 +0100
Subject: drivers/intel/fsp1_1: Add stack guards
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This allows to check if stack overflows the car globals.
Change-Id: I369b2d846f35914facb3e69cc762f7e555271bec
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/30751
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
---
src/drivers/intel/fsp1_1/car.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
(limited to 'src')
diff --git a/src/drivers/intel/fsp1_1/car.c b/src/drivers/intel/fsp1_1/car.c
index 13161d66d5..63c5042776 100644
--- a/src/drivers/intel/fsp1_1/car.c
+++ b/src/drivers/intel/fsp1_1/car.c
@@ -35,6 +35,21 @@ static inline void set_fih_car(FSP_INFO_HEADER *fih)
asmlinkage void *cache_as_ram_main(struct cache_as_ram_params *car_params)
{
+ int i;
+ const int num_guards = 4;
+ const u32 stack_guard = 0xdeadbeef;
+ u32 *stack_base;
+ u32 size;
+
+ /* Size of unallocated CAR. */
+ size = _car_region_end - _car_relocatable_data_end;
+ size = ALIGN_DOWN(size, 16);
+
+ stack_base = (u32 *) (_car_region_end - size);
+
+ for (i = 0; i < num_guards; i++)
+ stack_base[i] = stack_guard;
+
/* Initialize timestamp book keeping only once. */
timestamp_init(car_params->tsc);
@@ -63,6 +78,13 @@ asmlinkage void *cache_as_ram_main(struct cache_as_ram_params *car_params)
set_fih_car(car_params->fih);
+ /* Check the stack. */
+ for (i = 0; i < num_guards; i++) {
+ if (stack_base[i] == stack_guard)
+ continue;
+ printk(BIOS_DEBUG, "Smashed stack detected in romstage!\n");
+ }
+
/* Return new stack value in RAM back to assembly stub. */
return cache_as_ram_stage_main(car_params->fih);
}
--
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