| From c0452fb9fb8f49c7d68ab9fa0ad092016be7b45f Mon Sep 17 00:00:00 2001 |
| From: John David Anglin <dave.anglin@bell.net> |
| Date: Thu, 24 Nov 2016 20:06:32 -0500 |
| Subject: parisc: Fix race in pci-dma.c |
| |
| From: John David Anglin <dave.anglin@bell.net> |
| |
| commit c0452fb9fb8f49c7d68ab9fa0ad092016be7b45f upstream. |
| |
| We are still troubled by occasional random segmentation faults and |
| memory memory corruption on SMP machines. The causes quite a few |
| package builds to fail on the Debian buildd machines for parisc. When |
| gcc-6 failed to build three times in a row, I looked again at the TLB |
| related code. I found a couple of issues. This is the first. |
| |
| In general, we need to ensure page table updates and corresponding TLB |
| purges are atomic. The attached patch fixes an instance in pci-dma.c |
| where the page table update was not guarded by the TLB lock. |
| |
| Tested on rp3440 and c8000. So far, no further random segmentation |
| faults have been observed. |
| |
| Signed-off-by: John David Anglin <dave.anglin@bell.net> |
| Signed-off-by: Helge Deller <deller@gmx.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/parisc/kernel/pci-dma.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/arch/parisc/kernel/pci-dma.c |
| +++ b/arch/parisc/kernel/pci-dma.c |
| @@ -95,8 +95,8 @@ static inline int map_pte_uncached(pte_t |
| |
| 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(flags); |
| + set_pte(pte, __mk_pte(*paddr_ptr, PAGE_KERNEL_UNC)); |
| pdtlb_kernel(orig_vaddr); |
| purge_tlb_end(flags); |
| vaddr += PAGE_SIZE; |