[PATCH v2] selftests: vDSO: fix cross build for getrandom and chacha tests

["Jason A. Donenfeld" <Jason@zx2c4.com>]

From: Mark Brown <broonie@kernel.org>

Unlike the check for the standalone x86 test, the check for building the
vDSO getrandom and chacaha tests looks at the architecture for the host
rather than the architecture for the target when deciding if they should
be built. Since the chacha test includes some assembler code this means
that cross building with x86 as either the target or host is broken. Use
a check for ARCH instead.

This also handles s a small complication in conditionalizing on x86_64
but not x86, which requires defining the standard SRCARCH variable and
being careful about which uname-m substitutions are done.

Fixes: 4920a2590e91 ("selftests/vDSO: add tests for vgetrandom")
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
Mark - is this okay with you? I fixed the issue I mentioned.

 tools/testing/selftests/vDSO/Makefile | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/vDSO/Makefile b/tools/testing/selftests/vDSO/Makefile
index e21e78aae24d..5ead6b1f0478 100644
--- a/tools/testing/selftests/vDSO/Makefile
+++ b/tools/testing/selftests/vDSO/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
-uname_M := $(shell uname -m 2>/dev/null || echo not)
-ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/x86/ -e s/x86_64/x86/)
+ARCH ?= $(shell uname -m | sed -e s/i.86/x86/)
+SRCARCH := $(subst x86_64,x86,$(ARCH))
 
 TEST_GEN_PROGS := vdso_test_gettimeofday
 TEST_GEN_PROGS += vdso_test_getcpu
@@ -10,7 +10,7 @@ ifeq ($(ARCH),$(filter $(ARCH),x86 x86_64))
 TEST_GEN_PROGS += vdso_standalone_test_x86
 endif
 TEST_GEN_PROGS += vdso_test_correctness
-ifeq ($(uname_M),x86_64)
+ifeq ($(ARCH),$(filter $(ARCH),x86_64))
 TEST_GEN_PROGS += vdso_test_getrandom
 TEST_GEN_PROGS += vdso_test_chacha
 endif
@@ -38,8 +38,8 @@ $(OUTPUT)/vdso_test_getrandom: CFLAGS += -isystem $(top_srcdir)/tools/include \
                                          $(KHDR_INCLUDES) \
                                          -isystem $(top_srcdir)/include/uapi
 
-$(OUTPUT)/vdso_test_chacha: $(top_srcdir)/tools/arch/$(ARCH)/vdso/vgetrandom-chacha.S
+$(OUTPUT)/vdso_test_chacha: $(top_srcdir)/tools/arch/$(SRCARCH)/vdso/vgetrandom-chacha.S
 $(OUTPUT)/vdso_test_chacha: CFLAGS += -idirafter $(top_srcdir)/tools/include \
-                                      -idirafter $(top_srcdir)/arch/$(ARCH)/include \
+                                      -idirafter $(top_srcdir)/arch/$(SRCARCH)/include \
                                       -idirafter $(top_srcdir)/include \
                                       -D__ASSEMBLY__ -Wa,--noexecstack
-- 
2.46.0