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authorBrian Gerst <brgerst@gmail.com>2009-01-19 12:21:28 +0900
committerTejun Heo <tj@kernel.org>2009-01-20 12:29:20 +0900
commit947e76cdc34c782fc947313d4331380686eebbad (patch)
treede5d424c4760269fd7800bc745e48b060c725300 /arch/x86/kernel/head_64.S
parent8c7e58e690ae60ab4215b025f433ed4af261e103 (diff)
x86: move stack_canary into irq_stack
Impact: x86_64 percpu area layout change, irq_stack now at the beginning Now that the PDA is empty except for the stack canary, it can be removed. The irqstack is moved to the start of the per-cpu section. If the stack protector is enabled, the canary overlaps the bottom 48 bytes of the irqstack. tj: * updated subject * dropped asm relocation of irq_stack_ptr * updated comments a bit * rebased on top of stack canary changes Signed-off-by: Brian Gerst <brgerst@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'arch/x86/kernel/head_64.S')
-rw-r--r--arch/x86/kernel/head_64.S13
1 files changed, 5 insertions, 8 deletions
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 98ea26a2fca..a0a2b5ca9b7 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -242,13 +242,10 @@ ENTRY(secondary_startup_64)
/* Set up %gs.
*
- * On SMP, %gs should point to the per-cpu area. For initial
- * boot, make %gs point to the init data section. For a
- * secondary CPU,initial_gs should be set to its pda address
- * before the CPU runs this code.
- *
- * On UP, initial_gs points to PER_CPU_VAR(__pda) and doesn't
- * change.
+ * The base of %gs always points to the bottom of the irqstack
+ * union. If the stack protector canary is enabled, it is
+ * located at %gs:40. Note that, on SMP, the boot cpu uses
+ * init data section till per cpu areas are set up.
*/
movl $MSR_GS_BASE,%ecx
movq initial_gs(%rip),%rax
@@ -281,7 +278,7 @@ ENTRY(secondary_startup_64)
#ifdef CONFIG_SMP
.quad __per_cpu_load
#else
- .quad PER_CPU_VAR(__pda)
+ .quad PER_CPU_VAR(irq_stack_union)
#endif
__FINITDATA