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Remove coherent stack usage from the cold boot path

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This patch reworks the cold boot path across the BL1, BL2, BL3-1 and BL3-2 boot
loader stages to not use stacks allocated in coherent memory for early platform
setup and enabling the MMU. Stacks allocated in normal memory are used instead.

Attributes for stack memory change from nGnRnE when the MMU is disabled to
Normal WBWA Inner-shareable when the MMU and data cache are enabled. It is
possible for the CPU to read stale stack memory after the MMU is enabled from
another CPUs cache. Hence, it is unsafe to turn on the MMU and data cache while
using normal stacks when multiple CPUs are a part of the same coherency
domain. It is safe to do so in the cold boot path as only the primary cpu
executes it. The secondary cpus are in a quiescent state.

This patch does not remove the allocation of coherent stack memory. That is done
in a subsequent patch.

Change-Id: I12c80b7c7ab23506d425c5b3a8a7de693498f830
This commit is contained in:
Achin Gupta 2014-06-25 19:26:22 +01:00
parent a1a441775f
commit 754a2b7a09
4 changed files with 26 additions and 47 deletions
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22
bl1/aarch64/bl1_entrypoint.S
View file

@ -130,14 +130,16 @@ func bl1_entrypoint
ldr x2, =__DATA_SIZE__
bl memcpy16
/* ---------------------------------------------
* Give ourselves a small coherent stack to
* ease the pain of initializing the MMU and
* CCI in assembler
* ---------------------------------------------
/* --------------------------------------------
* Allocate a stack whose memory will be marked
* as Normal-IS-WBWA when the MMU is enabled.
* There is no risk of reading stale stack
* memory after enabling the MMU as only the
* primary cpu is running at the moment.
* --------------------------------------------
*/
mrs x0, mpidr_el1
bl platform_set_coherent_stack
bl platform_set_stack
/* ---------------------------------------------
* Architectural init. can be generic e.g.
@ -150,14 +152,6 @@ func bl1_entrypoint
bl bl1_early_platform_setup
bl bl1_plat_arch_setup
/* ---------------------------------------------
* Give ourselves a stack allocated in Normal
* -IS-WBWA memory
* ---------------------------------------------
*/
mrs x0, mpidr_el1
bl platform_set_stack
/* --------------------------------------------------
* Initialize platform and jump to our c-entry point
* for this type of reset. Panic if it returns

17
bl2/aarch64/bl2_entrypoint.S
View file

@ -96,12 +96,15 @@ func bl2_entrypoint
bl zeromem16
/* --------------------------------------------
* Give ourselves a small coherent stack to
* ease the pain of initializing the MMU
* Allocate a stack whose memory will be marked
* as Normal-IS-WBWA when the MMU is enabled.
* There is no risk of reading stale stack
* memory after enabling the MMU as only the
* primary cpu is running at the moment.
* --------------------------------------------
*/
mrs x0, mpidr_el1
bl platform_set_coherent_stack
bl platform_set_stack
/* ---------------------------------------------
* Perform early platform setup & platform
@ -112,14 +115,6 @@ func bl2_entrypoint
bl bl2_early_platform_setup
bl bl2_plat_arch_setup
/* ---------------------------------------------
* Give ourselves a stack allocated in Normal
* -IS-WBWA memory
* ---------------------------------------------
*/
mrs x0, mpidr_el1
bl platform_set_stack
/* ---------------------------------------------
* Jump to main function.
* ---------------------------------------------

17
bl31/aarch64/bl31_entrypoint.S
View file

@ -152,12 +152,15 @@ func bl31_entrypoint
msr spsel, #0
/* --------------------------------------------
* Give ourselves a small coherent stack to
* ease the pain of initializing the MMU
* Allocate a stack whose memory will be marked
* as Normal-IS-WBWA when the MMU is enabled.
* There is no risk of reading stale stack
* memory after enabling the MMU as only the
* primary cpu is running at the moment.
* --------------------------------------------
*/
mrs x0, mpidr_el1
bl platform_set_coherent_stack
bl platform_set_stack
/* ---------------------------------------------
* Perform platform specific early arch. setup
@ -174,14 +177,6 @@ func bl31_entrypoint
bl bl31_early_platform_setup
bl bl31_plat_arch_setup
/* ---------------------------------------------
* Give ourselves a stack allocated in Normal
* -IS-WBWA memory
* ---------------------------------------------
*/
mrs x0, mpidr_el1
bl platform_set_stack
/* ---------------------------------------------
* Jump to main function.
* ---------------------------------------------

17
bl32/tsp/aarch64/tsp_entrypoint.S
View file

@ -111,12 +111,15 @@ func tsp_entrypoint
bl zeromem16
/* --------------------------------------------
* Give ourselves a small coherent stack to
* ease the pain of initializing the MMU
* Allocate a stack whose memory will be marked
* as Normal-IS-WBWA when the MMU is enabled.
* There is no risk of reading stale stack
* memory after enabling the MMU as only the
* primary cpu is running at the moment.
* --------------------------------------------
*/
mrs x0, mpidr_el1
bl platform_set_coherent_stack
bl platform_set_stack
/* ---------------------------------------------
* Perform early platform setup & platform
@ -126,14 +129,6 @@ func tsp_entrypoint
bl bl32_early_platform_setup
bl bl32_plat_arch_setup
/* ---------------------------------------------
* Give ourselves a stack allocated in Normal
* -IS-WBWA memory
* ---------------------------------------------
*/
mrs x0, mpidr_el1
bl platform_set_stack
/* ---------------------------------------------
* Jump to main function.
* ---------------------------------------------