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authorStephane Eranian <eranian@hpl.hp.com>2006-09-26 10:52:28 +0200
committerAndi Kleen <andi@basil.nowhere.org>2006-09-26 10:52:28 +0200
commitd3a4f48d4866b8623ca9adde8ce4e5fde979c132 (patch)
tree04413a1f18c6f49688d6008b583b20a287920a0f /include/asm-x86_64/thread_info.h
parent2f766d16062d0147edff91be15de4a950667ca42 (diff)
[PATCH] x86-64 TIF flags for debug regs and io bitmap in ctxsw
Hello, Following my discussion with Andi. Here is a patch that introduces two new TIF flags to simplify the context switch code in __switch_to(). The idea is to minimize the number of cache lines accessed in the common case, i.e., when neither the debug registers nor the I/O bitmap are used. This patch covers the x86-64 modifications. A patch for i386 follows. Changelog: - add TIF_DEBUG to track when debug registers are active - add TIF_IO_BITMAP to track when I/O bitmap is used - modify __switch_to() to use the new TIF flags <signed-off-by>: eranian@hpl.hp.com Signed-off-by: Andi Kleen <ak@suse.de>
Diffstat (limited to 'include/asm-x86_64/thread_info.h')
-rw-r--r--include/asm-x86_64/thread_info.h7
1 files changed, 7 insertions, 0 deletions
diff --git a/include/asm-x86_64/thread_info.h b/include/asm-x86_64/thread_info.h
index 790c512a436..787a08114b4 100644
--- a/include/asm-x86_64/thread_info.h
+++ b/include/asm-x86_64/thread_info.h
@@ -120,6 +120,8 @@ static inline struct thread_info *stack_thread_info(void)
#define TIF_FORK 18 /* ret_from_fork */
#define TIF_ABI_PENDING 19
#define TIF_MEMDIE 20
+#define TIF_DEBUG 21 /* uses debug registers */
+#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
@@ -133,6 +135,8 @@ static inline struct thread_info *stack_thread_info(void)
#define _TIF_IA32 (1<<TIF_IA32)
#define _TIF_FORK (1<<TIF_FORK)
#define _TIF_ABI_PENDING (1<<TIF_ABI_PENDING)
+#define _TIF_DEBUG (1<<TIF_DEBUG)
+#define _TIF_IO_BITMAP (1<<TIF_IO_BITMAP)
/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK \
@@ -140,6 +144,9 @@ static inline struct thread_info *stack_thread_info(void)
/* work to do on any return to user space */
#define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP)
+/* flags to check in __switch_to() */
+#define _TIF_WORK_CTXSW (_TIF_DEBUG|_TIF_IO_BITMAP)
+
#define PREEMPT_ACTIVE 0x10000000
/*