[PATCH] um: implement flush_cache_vmap/flush_cache_vunmap

[Johannes Berg]

From: Johannes Berg <johannes.berg at intel.com>

vmalloc() heavy workloads in UML are extremely slow, due to
flushing the entire kernel VM space (flush_tlb_kernel_vm())
on the first segfault.

Implement flush_cache_vmap() to avoid that, and while at it
also add flush_cache_vunmap() since it's trivial.

This speeds up my vmalloc() heavy test of copying files out
from /sys/kernel/debug/gcov/ by 30x (from 30s to 1s.)

Signed-off-by: Johannes Berg <johannes.berg at intel.com>
---
 arch/um/include/asm/cacheflush.h | 9 +++++++++
 arch/um/include/asm/tlb.h        | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)
 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 000000000000..4c9858cd36ec
--- /dev/null
+++ b/arch/um/include/asm/cacheflush.h
@@ -0,0 +1,9 @@
+#ifndef __UM_ASM_CACHEFLUSH_H
+#define __UM_ASM_CACHEFLUSH_H
+
+#include <asm/tlbflush.h>
+#define flush_cache_vmap flush_tlb_kernel_range
+#define flush_cache_vunmap flush_tlb_kernel_range
+
+#include <asm-generic/cacheflush.h>
+#endif /* __UM_ASM_CACHEFLUSH_H */
diff --git a/arch/um/include/asm/tlb.h b/arch/um/include/asm/tlb.h
index ff9c62828962..0422467bda5b 100644
--- a/arch/um/include/asm/tlb.h
+++ b/arch/um/include/asm/tlb.h
@@ -5,7 +5,7 @@
 #include <linux/mm.h>
 
 #include <asm/tlbflush.h>
-#include <asm-generic/cacheflush.h>
+#include <asm/cacheflush.h>
 #include <asm-generic/tlb.h>
 
 #endif
-- 
2.30.2