commit 8bcd17411643beb9a601e032d0cf1016909a81d3
author David S. Miller <davem@sunset.davemloft.net> Thu Mar 02 18:12:27 2006 -0800
committer David S. Miller <davem@sunset.davemloft.net> Mon Mar 20 01:14:14 2006 -0800
tree fc71e788df4fada768247fa7c12e983d2f6f1a32
parent 45f791eb0f03e760183d30d3f1f18dc2b8e902fe

[SPARC64]: Do not allow mapping pages within 4GB of 64-bit VA hole.

The UltraSPARC T1 manual recommends this because the chip
could instruction prefetch into the VA hole, and this would
also make decoding  certain kinds of memory access traps
more difficult (because the chip sign extends certain pieces
of trap state).

Signed-off-by: David S. Miller <davem@davemloft.net>

include/asm-sparc64/page.h

diff --git a/include/asm-sparc64/page.h b/include/asm-sparc64/page.h
index 5426bb2..c277ac5 100644
--- a/include/asm-sparc64/page.h
+++ b/include/asm-sparc64/page.h
@@ -107,7 +107,8 @@
 #endif
 
 #define TASK_UNMAPPED_BASE	(test_thread_flag(TIF_32BIT) ? \
-				 (_AC(0x0000000070000000,UL)) : (PAGE_OFFSET))
+				 (_AC(0x0000000070000000,UL)) : \
+				 (_AC(0xfffff80000000000,UL) + (1UL << 32UL)))
 
 #endif /* !(__ASSEMBLY__) */