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authorTejun Heo <tj@kernel.org>2009-01-13 12:41:35 +0100
committerIngo Molnar <mingo@elte.hu>2009-01-16 14:19:46 +0100
commit1a51e3a0aed18767cf2762e95456ecfeb0bca5e6 (patch)
tree2d930218ef1072a59f7dac0f97bb03aa02796c8c /arch/x86/include/asm/percpu.h
parentx86: use static _cpu_pda array (diff)
downloadlinux-1a51e3a0aed18767cf2762e95456ecfeb0bca5e6.tar.xz
linux-1a51e3a0aed18767cf2762e95456ecfeb0bca5e6.zip
x86: fold pda into percpu area on SMP
[ Based on original patch from Christoph Lameter and Mike Travis. ] Currently pdas and percpu areas are allocated separately. %gs points to local pda and percpu area can be reached using pda->data_offset. This patch folds pda into percpu area. Due to strange gcc requirement, pda needs to be at the beginning of the percpu area so that pda->stack_canary is at %gs:40. To achieve this, a new percpu output section macro - PERCPU_VADDR_PREALLOC() - is added and used to reserve pda sized chunk at the start of the percpu area. After this change, for boot cpu, %gs first points to pda in the data.init area and later during setup_per_cpu_areas() gets updated to point to the actual pda. This means that setup_per_cpu_areas() need to reload %gs for CPU0 while clearing pda area for other cpus as cpu0 already has modified it when control reaches setup_per_cpu_areas(). This patch also removes now unnecessary get_local_pda() and its call sites. A lot of this patch is taken from Mike Travis' "x86_64: Fold pda into per cpu area" patch. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/include/asm/percpu.h')
-rw-r--r--arch/x86/include/asm/percpu.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index df644f3e53e6..0ed77cf33f76 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -1,6 +1,14 @@
#ifndef _ASM_X86_PERCPU_H
#define _ASM_X86_PERCPU_H
+#ifndef __ASSEMBLY__
+#ifdef CONFIG_X86_64
+extern void load_pda_offset(int cpu);
+#else
+static inline void load_pda_offset(int cpu) { }
+#endif
+#endif
+
#ifdef CONFIG_X86_64
#include <linux/compiler.h>