[PATCH 2/2] ArmVirtPkg ARM: make relocatable PrePi users build with CLANG35


Ard Biesheuvel
 

The clang developers have made a backward incompatible change to the
command line arguments, and have replaced '-mllvm -arm-use-movt=0'
with '-mno-movt'. This does not matter for most ARM platforms, and
therefore it has been removed from the default CLANG35/ARM CC flags
in patch 1c63516075b3 ("BaseTools CLANG35: drop problematic use-movt
and save-temps options"), but as it turns out, the relocatable PrePi
implementation used by ArmVirtQemuKernel and ArmVirtXen will fail to
build if it contains MOVT/MOVW pairs, due to the fact that these are
not runtime relocatable under ELF.

Since they are runtime relocatable under PE/COFF, and GenFw does the
right thing when encountering them, selectively controlling their
use is more appropriate than disabling them altogether. Therefore,
this patch adds the -mno-movt argument only for the platforms that
use the relocatable PrePi, and only for the module types that may
be pulled into its build.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
ArmVirtPkg/ArmVirtQemuKernel.dsc | 8 ++++++++
ArmVirtPkg/ArmVirtXen.dsc | 9 +++++++++
2 files changed, 17 insertions(+)

diff --git a/ArmVirtPkg/ArmVirtQemuKernel.dsc b/ArmVirtPkg/ArmVirtQemuKernel.dsc
index 01a1d9b4613b..6c536d9bbd2d 100644
--- a/ArmVirtPkg/ArmVirtQemuKernel.dsc
+++ b/ArmVirtPkg/ArmVirtQemuKernel.dsc
@@ -45,6 +45,9 @@ [LibraryClasses.ARM]
ArmLib|ArmPkg/Library/ArmLib/ArmV7/ArmV7Lib.inf
ArmCpuLib|ArmPkg/Drivers/ArmCpuLib/ArmCortexA15Lib/ArmCortexA15Lib.inf

+[LibraryClasses.ARM.SEC]
+ ArmLib|ArmPkg/Library/ArmLib/ArmV7/ArmV7LibSec.inf
+
[LibraryClasses.common]
ArmMmuLib|ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf

@@ -77,6 +80,11 @@ [BuildOptions]
GCC:*_*_ARM_PLATFORM_FLAGS == -mcpu=cortex-a15 -I$(WORKSPACE)/ArmVirtPkg/Include
*_*_AARCH64_PLATFORM_FLAGS == -I$(WORKSPACE)/ArmVirtPkg/Include

+[BuildOptions.ARM.EDKII.SEC, BuildOptions.ARM.EDKII.BASE]
+ # Avoid MOVT/MOVW instruction pairs in code that may end up in the PIE
+ # executable we build for the relocatable PrePi. They are not runtime
+ # relocatable in ELF.
+ *_CLANG35_*_CC_FLAGS = -mno-movt

################################################################################
#
diff --git a/ArmVirtPkg/ArmVirtXen.dsc b/ArmVirtPkg/ArmVirtXen.dsc
index 5ad1bf630bda..4ebead5ba6e6 100644
--- a/ArmVirtPkg/ArmVirtXen.dsc
+++ b/ArmVirtPkg/ArmVirtXen.dsc
@@ -44,6 +44,9 @@ [LibraryClasses.ARM]
ArmLib|ArmPkg/Library/ArmLib/ArmV7/ArmV7Lib.inf
ArmCpuLib|ArmPkg/Drivers/ArmCpuLib/ArmCortexA15Lib/ArmCortexA15Lib.inf

+[LibraryClasses.ARM.SEC]
+ ArmLib|ArmPkg/Library/ArmLib/ArmV7/ArmV7LibSec.inf
+
[LibraryClasses.common]
ArmMmuLib|ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf

@@ -77,6 +80,12 @@ [BuildOptions]
GCC:*_*_ARM_PLATFORM_FLAGS == -mcpu=cortex-a15 -I$(WORKSPACE)/ArmVirtPkg/Include
GCC:*_*_AARCH64_PLATFORM_FLAGS == -I$(WORKSPACE)/ArmVirtPkg/Include

+[BuildOptions.ARM.EDKII.SEC, BuildOptions.ARM.EDKII.BASE]
+ # Avoid MOVT/MOVW instruction pairs in code that may end up in the PIE
+ # executable we build for the relocatable PrePi. They are not runtime
+ # relocatable in ELF.
+ *_CLANG35_*_CC_FLAGS = -mno-movt
+
################################################################################
#
# Pcd Section - list of all EDK II PCD Entries defined by this Platform
--
2.7.4

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