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ARM: bL_switcher: simplify stack isolation 

We now have a dedicated thread for each logical CPU.  That's plenty
of stack space for our needs.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
This commit is contained in:
Nicolas Pitre 2012-11-27 15:55:33 -05:00
parent 71ce1deeff
commit c052de2693
1 changed files with 8 additions and 15 deletions
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23
arch/arm/common/bL_switcher.c
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@ -53,12 +53,6 @@ static void bL_do_switch(void *_unused)
{
unsigned mpidr, cpuid, clusterid, ob_cluster, ib_cluster;
/*
* We now have a piece of stack borrowed from the init task's.
* Let's also switch to init_mm right away to match it.
*/
cpu_switch_mm(init_mm.pgd, &init_mm);
pr_debug("%s\n", __func__);
mpidr = read_mpidr();
@ -93,22 +87,21 @@ static void bL_do_switch(void *_unused)
}
/*
* Stack isolation. To ensure 'current' remains valid, we just borrow
* a slice of the init/idle task which should be fairly lightly used.
* The borrowed area starts just above the thread_info structure located
* at the very bottom of the stack, aligned to a cache line.
* Stack isolation. To ensure 'current' remains valid, we just use another
* piece of our thread's stack space which should be fairly lightly used.
* The selected area starts just above the thread_info structure located
* at the very bottom of the stack, aligned to a cache line, and indexed
* with the cluster number.
*/
#define STACK_SIZE 256
#define STACK_SIZE 512
extern void call_with_stack(void (*fn)(void *), void *arg, void *sp);
static int bL_switchpoint(unsigned long _arg)
{
unsigned int mpidr = read_mpidr();
unsigned int cpuid = MPIDR_AFFINITY_LEVEL(mpidr, 0);
unsigned int clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1);
unsigned int cpu_index = cpuid + clusterid * MAX_CPUS_PER_CLUSTER;
void *stack = &init_thread_info + 1;
void *stack = current_thread_info() + 1;
stack = PTR_ALIGN(stack, L1_CACHE_BYTES);
stack += cpu_index * STACK_SIZE + STACK_SIZE;
stack += clusterid * STACK_SIZE + STACK_SIZE;
call_with_stack(bL_do_switch, (void *)_arg, stack);
BUG();
}