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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2013-04-24 10:20:43 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2013-04-26 09:07:01 +0200
commitdc7ee00d4771b3218b10e09e1071ee6eb176d381 (patch)
tree18eb16aa67cadf8d4bb880b8443563d2fb47cf43 /arch/s390/kernel/smp.c
parentb8668fd0a7e1b59ff4fd33b65e7f6d46b2d3cf1c (diff)
downloadlinux-linaro-stable-dc7ee00d4771b3218b10e09e1071ee6eb176d381.tar.gz
s390: lowcore stack pointer offsets
Store the stack pointers in the lowcore for the kernel stack, the async stack and the panic stack with the offset required for the first user. This avoids an unnecessary add instruction on the system call path. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/smp.c')
-rw-r--r--arch/s390/kernel/smp.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 549c9d173c0f..8bde89eafd88 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -181,8 +181,10 @@ static int __cpuinit pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu)
lc = pcpu->lowcore;
memcpy(lc, &S390_lowcore, 512);
memset((char *) lc + 512, 0, sizeof(*lc) - 512);
- lc->async_stack = pcpu->async_stack + ASYNC_SIZE;
- lc->panic_stack = pcpu->panic_stack + PAGE_SIZE;
+ lc->async_stack = pcpu->async_stack + ASYNC_SIZE
+ - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
+ lc->panic_stack = pcpu->panic_stack + PAGE_SIZE
+ - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
lc->cpu_nr = cpu;
#ifndef CONFIG_64BIT
if (MACHINE_HAS_IEEE) {
@@ -253,7 +255,8 @@ static void pcpu_attach_task(struct pcpu *pcpu, struct task_struct *tsk)
struct _lowcore *lc = pcpu->lowcore;
struct thread_info *ti = task_thread_info(tsk);
- lc->kernel_stack = (unsigned long) task_stack_page(tsk) + THREAD_SIZE;
+ lc->kernel_stack = (unsigned long) task_stack_page(tsk)
+ + THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
lc->thread_info = (unsigned long) task_thread_info(tsk);
lc->current_task = (unsigned long) tsk;
lc->user_timer = ti->user_timer;
@@ -810,8 +813,10 @@ void __init smp_prepare_boot_cpu(void)
pcpu->state = CPU_STATE_CONFIGURED;
pcpu->address = boot_cpu_address;
pcpu->lowcore = (struct _lowcore *)(unsigned long) store_prefix();
- pcpu->async_stack = S390_lowcore.async_stack - ASYNC_SIZE;
- pcpu->panic_stack = S390_lowcore.panic_stack - PAGE_SIZE;
+ pcpu->async_stack = S390_lowcore.async_stack - ASYNC_SIZE
+ + STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
+ pcpu->panic_stack = S390_lowcore.panic_stack - PAGE_SIZE
+ + STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
S390_lowcore.percpu_offset = __per_cpu_offset[0];
smp_cpu_set_polarization(0, POLARIZATION_UNKNOWN);
set_cpu_present(0, true);