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| author |   Tejun Heo <tj@kernel.org> | 2009-01-13 20:41:35 +0900 |
|---|---|---|
| committer |   Ingo Molnar <mingo@elte.hu> | 2009-01-16 14:19:46 +0100 |
| commit | 1a51e3a0aed18767cf2762e95456ecfeb0bca5e6 (patch) | |
| tree | 2d930218ef1072a59f7dac0f97bb03aa02796c8c /arch/x86/kernel/vmlinux_64.lds.S | |
| parent | x86: use static _cpu_pda array (diff) | |
| download | linux-dev-1a51e3a0aed18767cf2762e95456ecfeb0bca5e6.tar.xz linux-dev-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/vmlinux_64.lds.S')
| -rw-r--r-- | arch/x86/kernel/vmlinux_64.lds.S | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/x86/kernel/vmlinux_64.lds.S b/arch/x86/kernel/vmlinux_64.lds.S index f50280db0dfe..962f21f1d4d7 100644 --- a/arch/x86/kernel/vmlinux_64.lds.S +++ b/arch/x86/kernel/vmlinux_64.lds.S @@ -5,6 +5,7 @@ #define LOAD_OFFSET __START_KERNEL_map #include <asm-generic/vmlinux.lds.h> +#include <asm/asm-offsets.h> #include <asm/page.h> #undef i386 /* in case the preprocessor is a 32bit one */ @@ -215,10 +216,11 @@ SECTIONS /* * percpu offsets are zero-based on SMP. PERCPU_VADDR() changes the * output PHDR, so the next output section - __data_nosave - should - * switch it back to data.init. + * switch it back to data.init. Also, pda should be at the head of + * percpu area. Preallocate it. */ . = ALIGN(PAGE_SIZE); - PERCPU_VADDR(0, :percpu) + PERCPU_VADDR_PREALLOC(0, :percpu, pda_size) #else PERCPU(PAGE_SIZE) #endif |