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Commit e82a3b75 authored by Helge Deller's avatar Helge Deller Committed by Kyle McMartin
Browse files

parisc: ensure broadcast tlb purge runs single threaded 



The TLB flushing functions on hppa, which causes PxTLB broadcasts on the system
bus, needs to be protected by irq-safe spinlocks to avoid irq handlers to deadlock
the kernel. The deadlocks only happened during I/O intensive loads and triggered
pretty seldom, which is why this bug went so long unnoticed.

Signed-off-by: default avatarHelge Deller <deller@gmx.de>
[edited to use spin_lock_irqsave on UP as well since we'd been locking there
 all this time anyway, --kyle]
Signed-off-by: default avatarKyle McMartin <kyle@mcmartin.ca>
parent 84be31be

arch/parisc/include/asm/tlbflush.h

+7 −7
Original line number Diff line number Diff line
@@ -12,14 +12,12 @@ 
 * N class systems, only one PxTLB inter processor broadcast can be

 * active at any one time on the Merced bus.  This tlb purge

 * synchronisation is fairly lightweight and harmless so we activate

 * it on all SMP systems not just the N class.  We also need to have

 * preemption disabled on uniprocessor machines, and spin_lock does that

 * nicely.

 * it on all systems not just the N class.

 */

extern spinlock_t pa_tlb_lock;



#define purge_tlb_start(x) spin_lock(&pa_tlb_lock)

#define purge_tlb_end(x) spin_unlock(&pa_tlb_lock)

#define purge_tlb_start(flags)	spin_lock_irqsave(&pa_tlb_lock, flags)

#define purge_tlb_end(flags)	spin_unlock_irqrestore(&pa_tlb_lock, flags)



extern void flush_tlb_all(void);

extern void flush_tlb_all_local(void *);
@@ -63,14 +61,16 @@ static inline void flush_tlb_mm(struct mm_struct *mm) 
static inline void flush_tlb_page(struct vm_area_struct *vma,

	unsigned long addr)

{

	unsigned long flags;



	/* For one page, it's not worth testing the split_tlb variable */



	mb();

	mtsp(vma->vm_mm->context,1);

	purge_tlb_start();

	purge_tlb_start(flags);

	pdtlb(addr);

	pitlb(addr);

	purge_tlb_end();

	purge_tlb_end(flags);

}



void __flush_tlb_range(unsigned long sid,

arch/parisc/kernel/cache.c

+15 −8
Original line number Diff line number Diff line
@@ -397,12 +397,13 @@ EXPORT_SYMBOL(flush_kernel_icache_range_asm); 


void clear_user_page_asm(void *page, unsigned long vaddr)

{

	unsigned long flags;

	/* This function is implemented in assembly in pacache.S */

	extern void __clear_user_page_asm(void *page, unsigned long vaddr);



	purge_tlb_start();

	purge_tlb_start(flags);

	__clear_user_page_asm(page, vaddr);

	purge_tlb_end();

	purge_tlb_end(flags);

}



#define FLUSH_THRESHOLD 0x80000 /* 0.5MB */
@@ -443,20 +444,24 @@ extern void clear_user_page_asm(void *page, unsigned long vaddr); 


void clear_user_page(void *page, unsigned long vaddr, struct page *pg)

{

	unsigned long flags;



	purge_kernel_dcache_page((unsigned long)page);

	purge_tlb_start();

	purge_tlb_start(flags);

	pdtlb_kernel(page);

	purge_tlb_end();

	purge_tlb_end(flags);

	clear_user_page_asm(page, vaddr);

}

EXPORT_SYMBOL(clear_user_page);



void flush_kernel_dcache_page_addr(void *addr)

{

	unsigned long flags;



	flush_kernel_dcache_page_asm(addr);

	purge_tlb_start();

	purge_tlb_start(flags);

	pdtlb_kernel(addr);

	purge_tlb_end();

	purge_tlb_end(flags);

}

EXPORT_SYMBOL(flush_kernel_dcache_page_addr);
@@ -489,8 +494,10 @@ void __flush_tlb_range(unsigned long sid, unsigned long start, 
	if (npages >= 512)  /* 2MB of space: arbitrary, should be tuned */

		flush_tlb_all();

	else {

		unsigned long flags;



		mtsp(sid, 1);

		purge_tlb_start();

		purge_tlb_start(flags);

		if (split_tlb) {

			while (npages--) {

				pdtlb(start);
@@ -503,7 +510,7 @@ void __flush_tlb_range(unsigned long sid, unsigned long start, 
				start += PAGE_SIZE;

			}

		}

		purge_tlb_end();

		purge_tlb_end(flags);

	}

}

arch/parisc/kernel/pci-dma.c

+8 −4
Original line number Diff line number Diff line
@@ -90,12 +90,14 @@ static inline int map_pte_uncached(pte_t * pte, 
	if (end > PMD_SIZE)

		end = PMD_SIZE;

	do {

		unsigned long flags;



		if (!pte_none(*pte))

			printk(KERN_ERR "map_pte_uncached: page already exists\n");

		set_pte(pte, __mk_pte(*paddr_ptr, PAGE_KERNEL_UNC));

		purge_tlb_start();

		purge_tlb_start(flags);

		pdtlb_kernel(orig_vaddr);

		purge_tlb_end();

		purge_tlb_end(flags);

		vaddr += PAGE_SIZE;

		orig_vaddr += PAGE_SIZE;

		(*paddr_ptr) += PAGE_SIZE;
@@ -168,11 +170,13 @@ static inline void unmap_uncached_pte(pmd_t * pmd, unsigned long vaddr, 
	if (end > PMD_SIZE)

		end = PMD_SIZE;

	do {

		unsigned long flags;

		pte_t page = *pte;



		pte_clear(&init_mm, vaddr, pte);

		purge_tlb_start();

		purge_tlb_start(flags);

		pdtlb_kernel(orig_vaddr);

		purge_tlb_end();

		purge_tlb_end(flags);

		vaddr += PAGE_SIZE;

		orig_vaddr += PAGE_SIZE;

		pte++;