From d61e832e53029fd135c877514d3d2d38167aafd6 Mon Sep 17 00:00:00 2001 From: Marshall Dawson Date: Wed, 9 Aug 2017 19:59:20 -0600 Subject: soc/amd/stoneyridge: Revert CAR teardown wbinvd Change the cache-as-ram teardown to use invd instead of wbinvd. Save the return and recover the call's return address in chipset_teardown_car. CAR teardown had been modified to use wbinvd to send CAR contents to DRAM backing prior to teardown. This allowed CAR variables, stack, and local variables to be preserved while running the AMD_DISABLE_STACK macro. Using the wbinvd instruction has the side effect of sending all dirty cache contents to DRAM and not only our CAR data. This would likely cause corruption, e.g. during S3 resume. Stoney Ridge now uses a postcar stage and this is no longer a requirement. BUG=b:64768556 Change-Id: I8e6bcb3947f508b1db1a42fd0714bba70074837a Signed-off-by: Marshall Dawson Reviewed-on: https://review.coreboot.org/20967 Reviewed-by: Aaron Durbin Tested-by: build bot (Jenkins) --- src/soc/amd/common/block/cpu/Kconfig | 8 +++++--- src/soc/amd/common/block/cpu/car/exit_car.S | 3 ++- 2 files changed, 7 insertions(+), 4 deletions(-) (limited to 'src/soc/amd/common') diff --git a/src/soc/amd/common/block/cpu/Kconfig b/src/soc/amd/common/block/cpu/Kconfig index 86cc77194c..5941599df0 100644 --- a/src/soc/amd/common/block/cpu/Kconfig +++ b/src/soc/amd/common/block/cpu/Kconfig @@ -3,6 +3,8 @@ config SOC_AMD_COMMON_BLOCK_CAR default n help This option allows the SOC to use a standard AMD cache-as-ram (CAR) - implementation. CAR setup is built into bootblock and teardown in - romstage. If it is not used the system must implement these functions - separately. + implementation. CAR setup is built into bootblock and teardown is + in postcar. The teardown procedure does not preserve the stack so + it may not be appropriate for a romstage implementation without + additional consideration. If this option is not used, the SOC must + implement these functions separately. diff --git a/src/soc/amd/common/block/cpu/car/exit_car.S b/src/soc/amd/common/block/cpu/car/exit_car.S index ac36cb0e4f..f9d056e599 100644 --- a/src/soc/amd/common/block/cpu/car/exit_car.S +++ b/src/soc/amd/common/block/cpu/car/exit_car.S @@ -20,6 +20,7 @@ .globl chipset_teardown_car chipset_teardown_car: + pop %esp /* Disable cache */ movl %cr0, %eax @@ -33,4 +34,4 @@ chipset_teardown_car: andl $(~(CR0_CD | CR0_NW)), %eax movl %eax, %cr0 - ret + jmp *%esp -- cgit v1.2.3