ARC: [mm] Aliasing VIPT dcache support 2/4
This is the meat of the series which prevents any dcache alias creation
by always keeping the U and K mapping of a page congruent.
If a mapping already exists, and other tries to access the page, prev
one is flushed to physical page (wback+inv)
Essentially flush_dcache_page()/copy_user_highpage() create K-mapping
of a page, but try to defer flushing, unless U-mapping exist.
When page is actually mapped to userspace, update_mmu_cache() flushes
the K-mapping (in certain cases this can be optimised out)
Additonally flush_cache_mm(), flush_cache_range(), flush_cache_page()
handle the puring of stale userspace mappings on exit/munmap...
flush_anon_page() handles the existing U-mapping for anon page before
kernel reads it via the GUP path.
Note that while not complete, this is enough to boot a simple
dynamically linked Busybox based rootfs
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/include/asm/tlb.h b/arch/arc/include/asm/tlb.h
index fe91719..85b6df8 100644
--- a/arch/arc/include/asm/tlb.h
+++ b/arch/arc/include/asm/tlb.h
@@ -30,13 +30,20 @@
/*
* This pair is called at time of munmap/exit to flush cache and TLB entries
* for mappings being torn down.
- * 1) cache-flush part -implemented via tlb_start_vma( ) can be NOP (for now)
- * as we don't support aliasing configs in our VIPT D$.
+ * 1) cache-flush part -implemented via tlb_start_vma( ) for VIPT aliasing D$
* 2) tlb-flush part - implemted via tlb_end_vma( ) flushes the TLB range
*
* Note, read http://lkml.org/lkml/2004/1/15/6
*/
+#ifndef CONFIG_ARC_CACHE_VIPT_ALIASING
#define tlb_start_vma(tlb, vma)
+#else
+#define tlb_start_vma(tlb, vma) \
+do { \
+ if (!tlb->fullmm) \
+ flush_cache_range(vma, vma->vm_start, vma->vm_end); \
+} while(0)
+#endif
#define tlb_end_vma(tlb, vma) \
do { \