Commit 63eca94c authored by Vineet Gupta's avatar Vineet Gupta
Browse files

ARC: [SMP] ASID allocation 



-Track a Per CPU ASID counter
-mm-per-cpu ASID (multiple threads, or mm migrated around)

Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent b6fe8e7c

arch/arc/include/asm/mmu.h

+1 −1
Original line number Diff line number Diff line
@@ -48,7 +48,7 @@ 
#ifndef __ASSEMBLY__



typedef struct {

	unsigned long asid;	/* 8 bit MMU PID + Generation cycle */

	unsigned long asid[NR_CPUS];	/* 8 bit MMU PID + Generation cycle */

} mm_context_t;



#ifdef CONFIG_ARC_DBG_TLB_PARANOIA

arch/arc/include/asm/mmu_context.h

+28 −16
Original line number Diff line number Diff line
@@ -30,13 +30,13 @@ 
 * "Fast Context Switch" i.e. no TLB flush on ctxt-switch

 *

 * Linux assigns each task a unique ASID. A simple round-robin allocation

 * of H/w ASID is done using software tracker @asid_cache.

 * of H/w ASID is done using software tracker @asid_cpu.

 * When it reaches max 255, the allocation cycle starts afresh by flushing

 * the entire TLB and wrapping ASID back to zero.

 *

 * A new allocation cycle, post rollover, could potentially reassign an ASID

 * to a different task. Thus the rule is to refresh the ASID in a new cycle.

 * The 32 bit @asid_cache (and mm->asid) have 8 bits MMU PID and rest 24 bits

 * The 32 bit @asid_cpu (and mm->asid) have 8 bits MMU PID and rest 24 bits

 * serve as cycle/generation indicator and natural 32 bit unsigned math

 * automagically increments the generation when lower 8 bits rollover.

 */
@@ -47,9 +47,11 @@ 
#define MM_CTXT_FIRST_CYCLE	(MM_CTXT_ASID_MASK + 1)

#define MM_CTXT_NO_ASID		0UL



#define hw_pid(mm)		(mm->context.asid & MM_CTXT_ASID_MASK)

#define asid_mm(mm, cpu)	mm->context.asid[cpu]

#define hw_pid(mm, cpu)		(asid_mm(mm, cpu) & MM_CTXT_ASID_MASK)



extern unsigned int asid_cache;

DECLARE_PER_CPU(unsigned int, asid_cache);

#define asid_cpu(cpu)		per_cpu(asid_cache, cpu)



/*

 * Get a new ASID if task doesn't have a valid one (unalloc or from prev cycle)
@@ -57,6 +59,7 @@ extern unsigned int asid_cache; 
 */

static inline void get_new_mmu_context(struct mm_struct *mm)

{

	const unsigned int cpu = smp_processor_id();

	unsigned long flags;



	local_irq_save(flags);
@@ -71,11 +74,11 @@ static inline void get_new_mmu_context(struct mm_struct *mm) 
	 * 	 first need to destroy the context, setting it to invalid

	 * 	 value.

	 */

	if (!((mm->context.asid ^ asid_cache) & MM_CTXT_CYCLE_MASK))

	if (!((asid_mm(mm, cpu) ^ asid_cpu(cpu)) & MM_CTXT_CYCLE_MASK))

		goto set_hw;



	/* move to new ASID and handle rollover */

	if (unlikely(!(++asid_cache & MM_CTXT_ASID_MASK))) {

	if (unlikely(!(++asid_cpu(cpu) & MM_CTXT_ASID_MASK))) {



		flush_tlb_all();
@@ -84,15 +87,15 @@ static inline void get_new_mmu_context(struct mm_struct *mm) 
		 * If the container itself wrapped around, set it to a non zero

		 * "generation" to distinguish from no context

		 */

		if (!asid_cache)

			asid_cache = MM_CTXT_FIRST_CYCLE;

		if (!asid_cpu(cpu))

			asid_cpu(cpu) = MM_CTXT_FIRST_CYCLE;

	}



	/* Assign new ASID to tsk */

	mm->context.asid = asid_cache;

	asid_mm(mm, cpu) = asid_cpu(cpu);



set_hw:

	write_aux_reg(ARC_REG_PID, hw_pid(mm) | MMU_ENABLE);

	write_aux_reg(ARC_REG_PID, hw_pid(mm, cpu) | MMU_ENABLE);



	local_irq_restore(flags);

}
@@ -104,10 +107,24 @@ static inline void get_new_mmu_context(struct mm_struct *mm) 
static inline int

init_new_context(struct task_struct *tsk, struct mm_struct *mm)

{

	mm->context.asid = MM_CTXT_NO_ASID;

	int i;



	for_each_possible_cpu(i)

		asid_mm(mm, i) = MM_CTXT_NO_ASID;



	return 0;

}



static inline void destroy_context(struct mm_struct *mm)

{

	unsigned long flags;



	/* Needed to elide CONFIG_DEBUG_PREEMPT warning */

	local_irq_save(flags);

	asid_mm(mm, smp_processor_id()) = MM_CTXT_NO_ASID;

	local_irq_restore(flags);

}



/* Prepare the MMU for task: setup PID reg with allocated ASID

    If task doesn't have an ASID (never alloc or stolen, get a new ASID)

*/
@@ -131,11 +148,6 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, 
 */

#define activate_mm(prev, next)		switch_mm(prev, next, NULL)



static inline void destroy_context(struct mm_struct *mm)

{

	mm->context.asid = MM_CTXT_NO_ASID;

}



/* it seemed that deactivate_mm( ) is a reasonable place to do book-keeping

 * for retiring-mm. However destroy_context( ) still needs to do that because

 * between mm_release( ) = >deactive_mm( ) and

arch/arc/mm/tlb.c

+8 −6
Original line number Diff line number Diff line
@@ -100,7 +100,7 @@ 




/* A copy of the ASID from the PID reg is kept in asid_cache */

unsigned int asid_cache = MM_CTXT_FIRST_CYCLE;

DEFINE_PER_CPU(unsigned int, asid_cache) = MM_CTXT_FIRST_CYCLE;



/*

 * Utility Routine to erase a J-TLB entry
@@ -274,6 +274,7 @@ noinline void local_flush_tlb_mm(struct mm_struct *mm) 
void local_flush_tlb_range(struct vm_area_struct *vma, unsigned long start,

			   unsigned long end)

{

	const unsigned int cpu = smp_processor_id();

	unsigned long flags;



	/* If range @start to @end is more than 32 TLB entries deep,
@@ -297,9 +298,9 @@ void local_flush_tlb_range(struct vm_area_struct *vma, unsigned long start, 


	local_irq_save(flags);



	if (vma->vm_mm->context.asid != MM_CTXT_NO_ASID) {

	if (asid_mm(vma->vm_mm, cpu) != MM_CTXT_NO_ASID) {

		while (start < end) {

			tlb_entry_erase(start | hw_pid(vma->vm_mm));

			tlb_entry_erase(start | hw_pid(vma->vm_mm, cpu));

			start += PAGE_SIZE;

		}

	}
@@ -346,6 +347,7 @@ void local_flush_tlb_kernel_range(unsigned long start, unsigned long end) 


void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)

{

	const unsigned int cpu = smp_processor_id();

	unsigned long flags;



	/* Note that it is critical that interrupts are DISABLED between
@@ -353,8 +355,8 @@ void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page) 
	 */

	local_irq_save(flags);



	if (vma->vm_mm->context.asid != MM_CTXT_NO_ASID) {

		tlb_entry_erase((page & PAGE_MASK) | hw_pid(vma->vm_mm));

	if (asid_mm(vma->vm_mm, cpu) != MM_CTXT_NO_ASID) {

		tlb_entry_erase((page & PAGE_MASK) | hw_pid(vma->vm_mm, cpu));

		utlb_invalidate();

	}
@@ -400,7 +402,7 @@ void create_tlb(struct vm_area_struct *vma, unsigned long address, pte_t *ptep) 


	local_irq_save(flags);



	tlb_paranoid_check(vma->vm_mm->context.asid, address);

	tlb_paranoid_check(asid_mm(vma->vm_mm, smp_processor_id()), address);



	address &= PAGE_MASK;