[tip: x86/pti] arch/um: Add a dummy <asm/cacheflush.h> header

[tip-bot2 for Borislav Petkov]

The following commit has been merged into the x86/pti branch of tip:

Commit-ID:     e9c142f6f54db85c212ca64aefd4f2c232dac4ae
Gitweb:        https://git.kernel.org/tip/e9c142f6f54db85c212ca64aefd4f2c232dac4ae
Author:        Borislav Petkov <bp@xxxxxxx>
AuthorDate:    Tue, 22 Sep 2020 09:49:51 +02:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Tue, 22 Sep 2020 11:35:47 +02:00

arch/um: Add a dummy <asm/cacheflush.h> header

... in order to fix the defconfig build:

  ./arch/x86/include/asm/cacheflush.h: In function ‘l1d_flush_hw’:
  ./arch/x86/include/asm/cacheflush.h:15:6: error: implicit declaration of \
	  function ‘static_cpu_has’; did you mean ‘static_key_false’? [-Werror=implicit-function-declaration]

[ mingo: Changed the header guard to the existing nomenclature. ]

Fixes: a9210620ec36 ("x86/mm: Optionally flush L1D on context switch")
Reported-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20200922074951.2192-1-bp@xxxxxxxxx
---
 arch/um/include/asm/cacheflush.h |  9 +++++++++
 1 file changed, 9 insertions(+)
 create mode 100644 arch/um/include/asm/cacheflush.h

diff --git a/arch/um/include/asm/cacheflush.h b/arch/um/include/asm/cacheflush.h
new file mode 100644
index 0000000..f693cb9
--- /dev/null
+++ b/arch/um/include/asm/cacheflush.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_UM_CACHEFLUSH_H
+#define _ASM_UM_CACHEFLUSH_H
+
+#undef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
+#include <asm-generic/cacheflush.h>
+
+static inline int l1d_flush_hw(void) { return -EOPNOTSUPP; }
+#endif /* _ASM_UM_CACHEFLUSH_H */