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| author | Tejun Heo <tj@kernel.org> | 2009-01-13 12:41:35 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-01-16 14:19:46 +0100 |
| commit | 1a51e3a0aed18767cf2762e95456ecfeb0bca5e6 (patch) | |
| tree | 2d930218ef1072a59f7dac0f97bb03aa02796c8c /arch/x86/kernel/head64.c | |
| parent | x86: use static _cpu_pda array (diff) | |
| download | linux-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/kernel/head64.c')
| -rw-r--r-- | arch/x86/kernel/head64.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 462d0beccb6b..1a311293f733 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -26,12 +26,18 @@ #include <asm/bios_ebda.h> #include <asm/trampoline.h> -/* boot cpu pda, referenced by head_64.S to initialize %gs for boot CPU */ +#ifndef CONFIG_SMP +/* boot cpu pda, referenced by head_64.S to initialize %gs on UP */ struct x8664_pda _boot_cpu_pda; +#endif void __init x86_64_init_pda(void) { +#ifdef CONFIG_SMP + cpu_pda(0) = (void *)__per_cpu_load; +#else cpu_pda(0) = &_boot_cpu_pda; +#endif cpu_pda(0)->data_offset = (unsigned long)(__per_cpu_load - __per_cpu_start); pda_init(0); |