New patch to review for coreboot: bd76048 arm: Prevent compilation of old, experimental SMP support

[Stefan Reinauer]

Stefan Reinauer ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/9222

-gerrit

commit bd7604841b4f7eedd733ede19d5358dbc03e6095
Author: Julius Werner 
Date:   Tue Sep 23 20:53:20 2014 -0700

arm: Prevent compilation of old, experimental SMP support

The ARM SMP feature was added a long time ago and has never really been
    used by anyone since. We are still always compiling cpu_info() even
    though we don't use it, and it makes some dangerous assumptions about
    stack alignment that are not guaranteed anywhere.

I'm planning to change the way the stack boundaries are defined. Rather
    than trying to work that into this unsafe, unused and hard to test
    feature, I think we should just seal it off with police tape and make
    sure that if anyone ever tries to use it again (which currently seems
    unlikely), they get forced to do their due diligence on making sure it
    works as intended.

BUG=None
    TEST=Compiled Veyron_Pinky.

Change-Id: Id25545cab88f29200c7672ef02c7804f0ac26399
    Signed-off-by: Stefan Reinauer 
    Original-Commit-Id: 5b517fc46b030a6e50ef2f5e4d4a449b98ce16c6
    Original-Change-Id: I8a60bd30e8b27a22bb3da68ca84daea99424dee9
    Original-Signed-off-by: Julius Werner 
    Original-Reviewed-on: https://chromium-review.googlesource.com/219680
    Original-Reviewed-by: Aaron Durbin 
    Original-Reviewed-by: David Hendricks 
---
 src/arch/arm/Makefile.inc | 2 +-
 src/arch/arm/cpu.c        | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/arch/arm/Makefile.inc b/src/arch/arm/Makefile.inc
index 25f764c..e739d0b 100644
--- a/src/arch/arm/Makefile.inc
+++ b/src/arch/arm/Makefile.inc
@@ -117,7 +117,7 @@ ifeq ($(CONFIG_ARCH_RAMSTAGE_ARM),y)

ramstage-y += stages.c
 ramstage-y += div0.c
-ramstage-y += cpu.c
+ramstage-$(CONFIG_COOP_MULTITASKING) += cpu.c
 ramstage-y += eabi_compat.c
 ramstage-y += boot.c
 ramstage-y += tables.c
diff --git a/src/arch/arm/cpu.c b/src/arch/arm/cpu.c
index f90c759..e02fed3 100644
--- a/src/arch/arm/cpu.c
+++ b/src/arch/arm/cpu.c
@@ -34,6 +34,11 @@
  */
 struct cpu_info *cpu_info(void)
 {
+#error "This is BROKEN! ARM stacks are currently not guaranteed to be " \
+       "STACK_SIZE-aligned in any way. If you ever plan to revive this " \
+       "feature, make sure you add the proper assertions " \
+       "(and maybe consider revising the whole thing to work closer to what " \
+       "arm64 is doing now)."
    uintptr_t addr = ALIGN((uintptr_t)__builtin_frame_address(0),
    	CONFIG_STACK_SIZE);
    addr -= sizeof(struct cpu_info);