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authorPaul Mundt <lethal@linux-sh.org>2010-01-27 21:56:57 +0900
committerPaul Mundt <lethal@linux-sh.org>2010-01-27 21:56:57 +0900
commit08b36c4a02b5a9db609fc6d93b9c41d7fa75713c (patch)
tree3399d6e0ae71eecbf3cc348324becf536f0f1b99
parent485773f3e401fca31c112c1ff24797e42ff87afd (diff)
sh: Optimize runtime disabling of trapped I/O.
Presently trapped I/O is only registered if it's not explicitly disabled for the platforms that select it openly. From the fault path this runs through an address lookup before figuring out that nothing matches and falls back through the error path, but we can forego the lookup completely by testing if it's been explicitly disabled. This provides a measurable speedup for things like qemu that rely on runtime disabling. Signed-off-by: Paul Mundt <lethal@linux-sh.org>
-rw-r--r--arch/sh/kernel/io_trapped.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/sh/kernel/io_trapped.c b/arch/sh/kernel/io_trapped.c
index 16b83cc89a4..4a8bb4eeb8a 100644
--- a/arch/sh/kernel/io_trapped.c
+++ b/arch/sh/kernel/io_trapped.c
@@ -271,6 +271,8 @@ int handle_trapped_io(struct pt_regs *regs, unsigned long address)
insn_size_t instruction;
int tmp;
+ if (trapped_io_disable)
+ return 0;
if (!lookup_tiop(address))
return 0;