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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 /arch/x86_64/kernel/ptrace.c
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 'arch/x86_64/kernel/ptrace.c')
-rw-r--r--arch/x86_64/kernel/ptrace.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/x86_64/kernel/ptrace.c b/arch/x86_64/kernel/ptrace.c
index 2d50024c9f30..d35ec1bc696a 100644
--- a/arch/x86_64/kernel/ptrace.c
+++ b/arch/x86_64/kernel/ptrace.c
@@ -420,9 +420,13 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
if ((0x5554 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
break;
if (i == 4) {
- child->thread.debugreg7 = data;
+ child->thread.debugreg7 = data;
+ if (data)
+ set_tsk_thread_flag(child, TIF_DEBUG);
+ else
+ clear_tsk_thread_flag(child, TIF_DEBUG);
ret = 0;
- }
+ }
break;
}
break;