[Buildroot] [PATCH] package/libnss: fix powerpc altivec build failure

[Giulio Benetti <giulio.benetti@benettiengineering.com>]

NSS doesn't provide a way to understand if PowerPC compiler supports
Altivec, and it would also be difficult to do with a simple Makefile.
So add patch to disable Altivec extension with variable
NSS_DISABLE_ALTIVEC, then pass NSS_DISABLE_ALTIVEC=1 if
BR2_POWERPC_CPU_HAS_ALTIVEC is not 'y'.

Fixes:
http://autobuild.buildroot.net/results/957/957cec911bcd68a18418ad02f13e7e3001521c59/
http://autobuild.buildroot.net/results/6a1/6a1578619a477e1605fe152070f004b662f1d839/

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
---
Pending upstream:
https://bugzilla.mozilla.org/show_bug.cgi?id=1608151
---
 ...1608151-Introduce-NSS_ENABLE_ALTIVEC.patch | 95 +++++++++++++++++++
 package/libnss/libnss.mk                      |  5 +
 2 files changed, 100 insertions(+)
 create mode 100644 package/libnss/0002-Bug-1608151-Introduce-NSS_ENABLE_ALTIVEC.patch

diff --git a/package/libnss/0002-Bug-1608151-Introduce-NSS_ENABLE_ALTIVEC.patch b/package/libnss/0002-Bug-1608151-Introduce-NSS_ENABLE_ALTIVEC.patch
new file mode 100644
index 0000000000..e492a63d6e
--- /dev/null
+++ b/package/libnss/0002-Bug-1608151-Introduce-NSS_ENABLE_ALTIVEC.patch
@@ -0,0 +1,95 @@
+From 7ce53f890e26630d2d9677ab579281b3708c2605 Mon Sep 17 00:00:00 2001
+From: Giulio Benetti <giulio.benetti@benettiengineering.com>
+Date: Tue, 14 Jan 2020 18:55:53 +0100
+Subject: [PATCH] Bug 1608151 - Introduce NSS_ENABLE_ALTIVEC
+
+Add NSS_ENABLE_ALTIVEC environment variable to enable/disable Altivec
+extension on PowerPC build. At the time NSS assumes that every PowerPC64
+architecture supports Altivec but it's not true and this leads to build
+failure.
+
+Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
+---
+ nss/coreconf/config.gypi  | 1 +
+ nss/coreconf/config.mk    | 5 +++++
+ nss/lib/freebl/Makefile   | 2 ++
+ nss/lib/freebl/freebl.gyp | 2 +-
+ nss/lib/freebl/gcm.h      | 2 ++
+ 5 files changed, 11 insertions(+), 1 deletion(-)
+
+diff --git a/nss/coreconf/config.gypi b/nss/coreconf/config.gypi
+index 2e6cc390e..fc113a6fc 100644
+--- a/nss/coreconf/config.gypi
++++ b/nss/coreconf/config.gypi
+@@ -102,6 +102,7 @@
+     'disable_dbm%': 1,
+     'disable_libpkix%': 1,
+     'disable_werror%': 0,
++    'disable_altivec': 1,
+     'mozilla_client%': 0,
+     'comm_client%': 0,
+     'moz_fold_libs%': 0,
+diff --git a/nss/coreconf/config.mk b/nss/coreconf/config.mk
+index 60a08411e..704e3fa83 100644
+--- a/nss/coreconf/config.mk
++++ b/nss/coreconf/config.mk
+@@ -196,6 +196,11 @@ DEFINES += -DPKIX_OBJECT_LEAK_TEST
+ endif
+ endif
+ 
++# Avoid building with PowerPC's Altivec acceleration
++ifdef NSS_DISABLE_ALTIVEC
++DEFINES += -DNSS_DISABLE_ALTIVEC
++endif
++
+ # This allows all library and tools code to use the util function
+ # implementations directly from libnssutil3, rather than the wrappers
+ # in libnss3 which are present for binary compatibility only
+diff --git a/nss/lib/freebl/Makefile b/nss/lib/freebl/Makefile
+index 00518d7f8..fc3e2099e 100644
+--- a/nss/lib/freebl/Makefile
++++ b/nss/lib/freebl/Makefile
+@@ -790,5 +790,7 @@ $(OBJDIR)/$(PROG_PREFIX)gcm-aarch64$(OBJ_SUFFIX): CFLAGS += -march=armv8-a+crypt
+ endif
+ 
+ ifeq ($(CPU_ARCH),ppc)
++ifndef NSS_DISABLE_ALTIVEC
+ $(OBJDIR)/$(PROG_PREFIX)gcm-ppc$(OBJ_SUFFIX): CFLAGS += -mcrypto -maltivec
+ endif
++endif
+diff --git a/nss/lib/freebl/freebl.gyp b/nss/lib/freebl/freebl.gyp
+index 5d247742d..f968c408a 100644
+--- a/nss/lib/freebl/freebl.gyp
++++ b/nss/lib/freebl/freebl.gyp
+@@ -238,7 +238,7 @@
+             'gcm-aes-aarch64_c_lib',
+           ],
+         }],
+-        [ 'target_arch=="ppc64le"', {
++        [ 'disable_altivec==0 and (target_arch=="ppc" or target_arch=="ppc64" or target_arch=="ppc64le")', {
+           'dependencies': [
+             'gcm-aes-ppc_c_lib',
+           ],
+diff --git a/nss/lib/freebl/gcm.h b/nss/lib/freebl/gcm.h
+index aa4dee824..64aac56b2 100644
+--- a/nss/lib/freebl/gcm.h
++++ b/nss/lib/freebl/gcm.h
+@@ -30,6 +30,7 @@
+ #include <arm_neon.h>
+ #endif
+ 
++#ifndef NSS_DISABLE_ALTIVEC
+ #ifdef __powerpc64__
+ #include "altivec-types.h"
+ 
+@@ -39,6 +40,7 @@
+ #undef vector
+ #undef bool
+ #endif
++#endif
+ 
+ /*
+  * PPC CRYPTO requires at least gcc 8 or clang. The LE check is purely
+-- 
+2.20.1
+
diff --git a/package/libnss/libnss.mk b/package/libnss/libnss.mk
index d7d3cda86b..b9dab44c11 100644
--- a/package/libnss/libnss.mk
+++ b/package/libnss/libnss.mk
@@ -50,6 +50,11 @@ LIBNSS_BUILD_VARS = \
 	OS_TEST=$(BR2_PACKAGE_LIBNSS_ARCH) \
 	NSS_ENABLE_WERROR=0
 
+ifeq ($(BR2_POWERPC_CPU_HAS_ALTIVEC),)
+# Disable Altivec if not supported
+LIBNSS_BUILD_VARS += NSS_DISABLE_ALTIVEC=1
+endif
+
 ifeq ($(BR2_ARCH_IS_64),y)
 # MIPS64 n32 is treated as a 32-bit architecture by libnss.
 # See: https://bugzilla.mozilla.org/show_bug.cgi?id=1010730
-- 
2.20.1