[PATCH kselftest v2 4/4] selftests: vDSO: unconditionally build chacha test

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

Rather than using symlinks to find the vgetrandom-chacha.S file for each
arch, store this in a file that uses the compiler to determine
architecture, and then make use of weak symbols to skip the test on
architectures that don't provide the code.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 tools/arch/arm64/vdso                            |  1 -
 tools/arch/loongarch/vdso                        |  1 -
 tools/arch/powerpc/vdso                          |  1 -
 tools/arch/s390/vdso                             |  1 -
 tools/arch/x86/vdso                              |  1 -
 tools/testing/selftests/vDSO/Makefile            |  6 +-----
 tools/testing/selftests/vDSO/vdso_test_chacha.c  |  6 ++++++
 .../selftests/vDSO/vgetrandom-chacha-finder.S    | 16 ++++++++++++++++
 8 files changed, 23 insertions(+), 10 deletions(-)
 delete mode 120000 tools/arch/arm64/vdso
 delete mode 120000 tools/arch/loongarch/vdso
 delete mode 120000 tools/arch/powerpc/vdso
 delete mode 120000 tools/arch/s390/vdso
 delete mode 120000 tools/arch/x86/vdso
 create mode 100644 tools/testing/selftests/vDSO/vgetrandom-chacha-finder.S

diff --git a/tools/arch/arm64/vdso b/tools/arch/arm64/vdso
deleted file mode 120000
index 233c7a26f6e5..000000000000
--- a/tools/arch/arm64/vdso
+++ /dev/null
@@ -1 +0,0 @@
-../../../arch/arm64/kernel/vdso
\ No newline at end of file
diff --git a/tools/arch/loongarch/vdso b/tools/arch/loongarch/vdso
deleted file mode 120000
index ebda43a82db7..000000000000
--- a/tools/arch/loongarch/vdso
+++ /dev/null
@@ -1 +0,0 @@
-../../../arch/loongarch/vdso
\ No newline at end of file
diff --git a/tools/arch/powerpc/vdso b/tools/arch/powerpc/vdso
deleted file mode 120000
index 4e676d1d1cb4..000000000000
--- a/tools/arch/powerpc/vdso
+++ /dev/null
@@ -1 +0,0 @@
-../../../arch/powerpc/kernel/vdso
\ No newline at end of file
diff --git a/tools/arch/s390/vdso b/tools/arch/s390/vdso
deleted file mode 120000
index 6cf4c1cebdcd..000000000000
--- a/tools/arch/s390/vdso
+++ /dev/null
@@ -1 +0,0 @@
-../../../arch/s390/kernel/vdso64
\ No newline at end of file
diff --git a/tools/arch/x86/vdso b/tools/arch/x86/vdso
deleted file mode 120000
index 7eb962fd3454..000000000000
--- a/tools/arch/x86/vdso
+++ /dev/null
@@ -1 +0,0 @@
-../../../arch/x86/entry/vdso/
\ No newline at end of file
diff --git a/tools/testing/selftests/vDSO/Makefile b/tools/testing/selftests/vDSO/Makefile
index 96b4f2a766e2..e453c178d97f 100644
--- a/tools/testing/selftests/vDSO/Makefile
+++ b/tools/testing/selftests/vDSO/Makefile
@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
 include ../../../scripts/Makefile.arch
-top_srcdir = $(realpath ../../../..)
 
 TEST_GEN_PROGS := vdso_test_gettimeofday
 TEST_GEN_PROGS += vdso_test_getcpu
@@ -11,15 +10,12 @@ TEST_GEN_PROGS += vdso_standalone_test_x86
 endif
 TEST_GEN_PROGS += vdso_test_correctness
 TEST_GEN_PROGS += vdso_test_getrandom
-ifneq ($(wildcard $(top_srcdir)/tools/arch/$(SRCARCH)/vdso/vgetrandom-chacha.S),)
 TEST_GEN_PROGS += vdso_test_chacha
-endif
 
 CFLAGS := -std=gnu99 -O2
 
 ifeq ($(CONFIG_X86_32),y)
 LDLIBS += -lgcc_s
-TEST_GEN_PROGS := $(filter-out vdso_test_chacha,$(TEST_GEN_PROGS))
 endif
 
 include ../lib.mk
@@ -39,7 +35,7 @@ $(OUTPUT)/vdso_test_getrandom: CFLAGS += -isystem $(top_srcdir)/tools/include \
                                          $(KHDR_INCLUDES) \
                                          -isystem $(top_srcdir)/include/uapi
 
-$(OUTPUT)/vdso_test_chacha: $(top_srcdir)/tools/arch/$(SRCARCH)/vdso/vgetrandom-chacha.S
+$(OUTPUT)/vdso_test_chacha: vgetrandom-chacha-finder.S
 $(OUTPUT)/vdso_test_chacha: CFLAGS += -idirafter $(top_srcdir)/tools/include \
                                       -idirafter $(top_srcdir)/tools/include/generated \
                                       -idirafter $(top_srcdir)/arch/$(SRCARCH)/include \
diff --git a/tools/testing/selftests/vDSO/vdso_test_chacha.c b/tools/testing/selftests/vDSO/vdso_test_chacha.c
index 60c5ea5cb925..e68f1cd4ebcf 100644
--- a/tools/testing/selftests/vDSO/vdso_test_chacha.c
+++ b/tools/testing/selftests/vDSO/vdso_test_chacha.c
@@ -78,6 +78,12 @@ typedef uint32_t u32;
 typedef uint64_t u64;
 #include <vdso/getrandom.h>
 
+__attribute__((weak))
+void __arch_chacha20_blocks_nostack(u8 *dst_bytes, const u32 *key, u32 *counter, size_t nblocks)
+{
+	ksft_exit_skip("Not implemented on architecture\n");
+}
+
 int main(int argc, char *argv[])
 {
 	enum { TRIALS = 1000, BLOCKS = 128, BLOCK_SIZE = 64 };
diff --git a/tools/testing/selftests/vDSO/vgetrandom-chacha-finder.S b/tools/testing/selftests/vDSO/vgetrandom-chacha-finder.S
new file mode 100644
index 000000000000..1ca240ddaab7
--- /dev/null
+++ b/tools/testing/selftests/vDSO/vgetrandom-chacha-finder.S
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#if defined(__aarch64__)
+#include "../../../../arch/arm64/kernel/vdso/vgetrandom-chacha.S"
+#elif defined(__loongarch__)
+#include "../../../../arch/loongarch/vdso/vgetrandom-chacha.S"
+#elif defined(__powerpc__) || defined(__powerpc64__)
+#include "../../../../arch/powerpc/kernel/vdso/vgetrandom-chacha.S"
+#elif defined(__s390x__)
+#include "../../../../arch/s390/kernel/vdso64/vgetrandom-chacha.S"
+#elif defined(__x86_64__)
+#include "../../../../arch/x86/entry/vdso/vgetrandom-chacha.S"
+#endif
-- 
2.46.0