xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

s390: lowcore stack pointer offsets

Browse Source 
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>
This commit is contained in:
Martin Schwidefsky
2013-04-24 10:20:43 +02:00
parent b8668fd0a7
commit dc7ee00d47
4 changed files with 46 additions and 48 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
arch/s390/kernel/smp.c
View File

@@ -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);