From 0adb24e03a124b79130c9499731936b11ce2677d Mon Sep 17 00:00:00 2001 From: John David Anglin Date: Tue, 27 Feb 2018 08:16:07 -0500 Subject: parisc: Fix ordering of cache and TLB flushes MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The change to flush_kernel_vmap_range() wasn't sufficient to avoid the SMP stalls.  The problem is some drivers call these routines with interrupts disabled.  Interrupts need to be enabled for flush_tlb_all() and flush_cache_all() to work.  This version adds checks to ensure interrupts are not disabled before calling routines that need IPI interrupts.  When interrupts are disabled, we now drop into slower code. The attached change fixes the ordering of cache and TLB flushes in several cases.  When we flush the cache using the existing PTE/TLB entries, we need to flush the TLB after doing the cache flush.  We don't need to do this when we flush the entire instruction and data caches as these flushes don't use the existing TLB entries.  The same is true for tmpalias region flushes. The flush_kernel_vmap_range() and invalidate_kernel_vmap_range() routines have been updated. Secondly, we added a new purge_kernel_dcache_range_asm() routine to pacache.S and use it in invalidate_kernel_vmap_range().  Nominally, purges are faster than flushes as the cache lines don't have to be written back to memory. Hopefully, this is sufficient to resolve the remaining problems due to cache speculation.  So far, testing indicates that this is the case.  I did work up a patch using tmpalias flushes, but there is a performance hit because we need the physical address for each page, and we also need to sequence access to the tmpalias flush code.  This increases the probability of stalls. Signed-off-by: John David Anglin  Cc: stable@vger.kernel.org # 4.9+ Signed-off-by: Helge Deller --- arch/parisc/kernel/cache.c | 57 +++++++++++++++++++++++++--------------------- 1 file changed, 31 insertions(+), 26 deletions(-) (limited to 'arch/parisc/kernel/cache.c') diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c index 19c0c141bc3f..79089778725b 100644 --- a/arch/parisc/kernel/cache.c +++ b/arch/parisc/kernel/cache.c @@ -465,10 +465,10 @@ EXPORT_SYMBOL(copy_user_page); int __flush_tlb_range(unsigned long sid, unsigned long start, unsigned long end) { - unsigned long flags, size; + unsigned long flags; - size = (end - start); - if (size >= parisc_tlb_flush_threshold) { + if ((!IS_ENABLED(CONFIG_SMP) || !arch_irqs_disabled()) && + end - start >= parisc_tlb_flush_threshold) { flush_tlb_all(); return 1; } @@ -539,13 +539,11 @@ void flush_cache_mm(struct mm_struct *mm) struct vm_area_struct *vma; pgd_t *pgd; - /* Flush the TLB to avoid speculation if coherency is required. */ - if (parisc_requires_coherency()) - flush_tlb_all(); - /* Flushing the whole cache on each cpu takes forever on rp3440, etc. So, avoid it if the mm isn't too big. */ - if (mm_total_size(mm) >= parisc_cache_flush_threshold) { + if ((!IS_ENABLED(CONFIG_SMP) || !arch_irqs_disabled()) && + mm_total_size(mm) >= parisc_cache_flush_threshold) { + flush_tlb_all(); flush_cache_all(); return; } @@ -553,9 +551,9 @@ void flush_cache_mm(struct mm_struct *mm) if (mm->context == mfsp(3)) { for (vma = mm->mmap; vma; vma = vma->vm_next) { flush_user_dcache_range_asm(vma->vm_start, vma->vm_end); - if ((vma->vm_flags & VM_EXEC) == 0) - continue; - flush_user_icache_range_asm(vma->vm_start, vma->vm_end); + if (vma->vm_flags & VM_EXEC) + flush_user_icache_range_asm(vma->vm_start, vma->vm_end); + flush_tlb_range(vma, vma->vm_start, vma->vm_end); } return; } @@ -581,14 +579,9 @@ void flush_cache_mm(struct mm_struct *mm) void flush_cache_range(struct vm_area_struct *vma, unsigned long start, unsigned long end) { - BUG_ON(!vma->vm_mm->context); - - /* Flush the TLB to avoid speculation if coherency is required. */ - if (parisc_requires_coherency()) + if ((!IS_ENABLED(CONFIG_SMP) || !arch_irqs_disabled()) && + end - start >= parisc_cache_flush_threshold) { flush_tlb_range(vma, start, end); - - if ((end - start) >= parisc_cache_flush_threshold - || vma->vm_mm->context != mfsp(3)) { flush_cache_all(); return; } @@ -596,6 +589,7 @@ void flush_cache_range(struct vm_area_struct *vma, flush_user_dcache_range_asm(start, end); if (vma->vm_flags & VM_EXEC) flush_user_icache_range_asm(start, end); + flush_tlb_range(vma, start, end); } void @@ -604,8 +598,7 @@ flush_cache_page(struct vm_area_struct *vma, unsigned long vmaddr, unsigned long BUG_ON(!vma->vm_mm->context); if (pfn_valid(pfn)) { - if (parisc_requires_coherency()) - flush_tlb_page(vma, vmaddr); + flush_tlb_page(vma, vmaddr); __flush_cache_page(vma, vmaddr, PFN_PHYS(pfn)); } } @@ -613,21 +606,33 @@ flush_cache_page(struct vm_area_struct *vma, unsigned long vmaddr, unsigned long void flush_kernel_vmap_range(void *vaddr, int size) { unsigned long start = (unsigned long)vaddr; + unsigned long end = start + size; - if ((unsigned long)size > parisc_cache_flush_threshold) + if ((!IS_ENABLED(CONFIG_SMP) || !arch_irqs_disabled()) && + (unsigned long)size >= parisc_cache_flush_threshold) { + flush_tlb_kernel_range(start, end); flush_data_cache(); - else - flush_kernel_dcache_range_asm(start, start + size); + return; + } + + flush_kernel_dcache_range_asm(start, end); + flush_tlb_kernel_range(start, end); } EXPORT_SYMBOL(flush_kernel_vmap_range); void invalidate_kernel_vmap_range(void *vaddr, int size) { unsigned long start = (unsigned long)vaddr; + unsigned long end = start + size; - if ((unsigned long)size > parisc_cache_flush_threshold) + if ((!IS_ENABLED(CONFIG_SMP) || !arch_irqs_disabled()) && + (unsigned long)size >= parisc_cache_flush_threshold) { + flush_tlb_kernel_range(start, end); flush_data_cache(); - else - flush_kernel_dcache_range_asm(start, start + size); + return; + } + + purge_kernel_dcache_range_asm(start, end); + flush_tlb_kernel_range(start, end); } EXPORT_SYMBOL(invalidate_kernel_vmap_range); -- cgit v1.2.2 From 9ef0f88fe5466c2ca1d2975549ba6be502c464c1 Mon Sep 17 00:00:00 2001 From: John David Anglin Date: Wed, 7 Mar 2018 08:18:05 -0500 Subject: parisc: Handle case where flush_cache_range is called with no context MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Just when I had decided that flush_cache_range() was always called with a valid context, Helge reported two cases where the "BUG_ON(!vma->vm_mm->context);" was hit on the phantom buildd: kernel BUG at /mnt/sdb6/linux/linux-4.15.4/arch/parisc/kernel/cache.c:587! CPU: 1 PID: 3254 Comm: kworker/1:2 Tainted: G D 4.15.0-1-parisc64-smp #1 Debian 4.15.4-1+b1 Workqueue: events free_ioctx   IAOQ[0]: flush_cache_range+0x164/0x168   IAOQ[1]: flush_cache_page+0x0/0x1c8   RP(r2): unmap_page_range+0xae8/0xb88 Backtrace:   [<00000000404a6980>] unmap_page_range+0xae8/0xb88   [<00000000404a6ae0>] unmap_single_vma+0xc0/0x188   [<00000000404a6cdc>] zap_page_range_single+0x134/0x1f8   [<00000000404a702c>] unmap_mapping_range+0x1cc/0x208   [<0000000040461518>] truncate_pagecache+0x98/0x108   [<0000000040461624>] truncate_setsize+0x9c/0xb8   [<00000000405d7f30>] put_aio_ring_file+0x80/0x100   [<00000000405d803c>] aio_free_ring+0x8c/0x290   [<00000000405d82c0>] free_ioctx+0x80/0x180   [<0000000040284e6c>] process_one_work+0x21c/0x668   [<00000000402854c4>] worker_thread+0x20c/0x778   [<0000000040291d44>] kthread+0x2d4/0x2e0   [<0000000040204020>] end_fault_vector+0x20/0xc0 This indicates that we need to handle the no context case in flush_cache_range() as we do in flush_cache_mm(). In thinking about this, I realized that we don't need to flush the TLB when there is no context. So, I added context checks to the large flush cases in flush_cache_mm() and flush_cache_range(). The large flush case occurs frequently in flush_cache_mm() and the change should improve fork performance. The v2 version of this change removes the BUG_ON from flush_cache_page() by skipping the TLB flush when there is no context.  I also added code to flush the TLB in flush_cache_mm() and flush_cache_range() when we have a context that's not current.  Now all three routines handle TLB flushes in a similar manner. Signed-off-by: John David Anglin Cc: stable@vger.kernel.org # 4.9+ Signed-off-by: Helge Deller --- arch/parisc/kernel/cache.c | 41 ++++++++++++++++++++++++++++++++--------- 1 file changed, 32 insertions(+), 9 deletions(-) (limited to 'arch/parisc/kernel/cache.c') diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c index 79089778725b..e3b45546d589 100644 --- a/arch/parisc/kernel/cache.c +++ b/arch/parisc/kernel/cache.c @@ -543,7 +543,8 @@ void flush_cache_mm(struct mm_struct *mm) rp3440, etc. So, avoid it if the mm isn't too big. */ if ((!IS_ENABLED(CONFIG_SMP) || !arch_irqs_disabled()) && mm_total_size(mm) >= parisc_cache_flush_threshold) { - flush_tlb_all(); + if (mm->context) + flush_tlb_all(); flush_cache_all(); return; } @@ -571,6 +572,8 @@ void flush_cache_mm(struct mm_struct *mm) pfn = pte_pfn(*ptep); if (!pfn_valid(pfn)) continue; + if (unlikely(mm->context)) + flush_tlb_page(vma, addr); __flush_cache_page(vma, addr, PFN_PHYS(pfn)); } } @@ -579,26 +582,46 @@ void flush_cache_mm(struct mm_struct *mm) void flush_cache_range(struct vm_area_struct *vma, unsigned long start, unsigned long end) { + pgd_t *pgd; + unsigned long addr; + if ((!IS_ENABLED(CONFIG_SMP) || !arch_irqs_disabled()) && end - start >= parisc_cache_flush_threshold) { - flush_tlb_range(vma, start, end); + if (vma->vm_mm->context) + flush_tlb_range(vma, start, end); flush_cache_all(); return; } - flush_user_dcache_range_asm(start, end); - if (vma->vm_flags & VM_EXEC) - flush_user_icache_range_asm(start, end); - flush_tlb_range(vma, start, end); + if (vma->vm_mm->context == mfsp(3)) { + flush_user_dcache_range_asm(start, end); + if (vma->vm_flags & VM_EXEC) + flush_user_icache_range_asm(start, end); + flush_tlb_range(vma, start, end); + return; + } + + pgd = vma->vm_mm->pgd; + for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) { + unsigned long pfn; + pte_t *ptep = get_ptep(pgd, addr); + if (!ptep) + continue; + pfn = pte_pfn(*ptep); + if (pfn_valid(pfn)) { + if (unlikely(vma->vm_mm->context)) + flush_tlb_page(vma, addr); + __flush_cache_page(vma, addr, PFN_PHYS(pfn)); + } + } } void flush_cache_page(struct vm_area_struct *vma, unsigned long vmaddr, unsigned long pfn) { - BUG_ON(!vma->vm_mm->context); - if (pfn_valid(pfn)) { - flush_tlb_page(vma, vmaddr); + if (likely(vma->vm_mm->context)) + flush_tlb_page(vma, vmaddr); __flush_cache_page(vma, vmaddr, PFN_PHYS(pfn)); } } -- cgit v1.2.2