wireguard-linux/arch/xtensa/mm, branch jd/unified-crypt-queue

mm: allow VM_FAULT_RETRY for multiple times

2020-04-02T16:35:30Z

The idea comes from a discussion between Linus and Andrea [1]. Before this patch we only allow a page fault to retry once. We achieved this by clearing the FAULT_FLAG_ALLOW_RETRY flag when doing handle_mm_fault() the second time. This was majorly used to avoid unexpected starvation of the system by looping over forever to handle the page fault on a single page. However that should hardly happen, and after all for each code path to return a VM_FAULT_RETRY we'll first wait for a condition (during which time we should possibly yield the cpu) to happen before VM_FAULT_RETRY is really returned. This patch removes the restriction by keeping the FAULT_FLAG_ALLOW_RETRY flag when we receive VM_FAULT_RETRY. It means that the page fault handler now can retry the page fault for multiple times if necessary without the need to generate another page fault event. Meanwhile we still keep the FAULT_FLAG_TRIED flag so page fault handler can still identify whether a page fault is the first attempt or not. Then we'll have these combinations of fault flags (only considering ALLOW_RETRY flag and TRIED flag): - ALLOW_RETRY and !TRIED: this means the page fault allows to retry, and this is the first try - ALLOW_RETRY and TRIED: this means the page fault allows to retry, and this is not the first try - !ALLOW_RETRY and !TRIED: this means the page fault does not allow to retry at all - !ALLOW_RETRY and TRIED: this is forbidden and should never be used In existing code we have multiple places that has taken special care of the first condition above by checking against (fault_flags & FAULT_FLAG_ALLOW_RETRY). This patch introduces a simple helper to detect the first retry of a page fault by checking against both (fault_flags & FAULT_FLAG_ALLOW_RETRY) and !(fault_flag & FAULT_FLAG_TRIED) because now even the 2nd try will have the ALLOW_RETRY set, then use that helper in all existing special paths. One example is in __lock_page_or_retry(), now we'll drop the mmap_sem only in the first attempt of page fault and we'll keep it in follow up retries, so old locking behavior will be retained. This will be a nice enhancement for current code [2] at the same time a supporting material for the future userfaultfd-writeprotect work, since in that work there will always be an explicit userfault writeprotect retry for protected pages, and if that cannot resolve the page fault (e.g., when userfaultfd-writeprotect is used in conjunction with swapped pages) then we'll possibly need a 3rd retry of the page fault. It might also benefit other potential users who will have similar requirement like userfault write-protection. GUP code is not touched yet and will be covered in follow up patch. Please read the thread below for more information. [1] https://lore.kernel.org/lkml/20171102193644.GB22686@redhat.com/ [2] https://lore.kernel.org/lkml/20181230154648.GB9832@redhat.com/ Suggested-by: Linus Torvalds Suggested-by: Andrea Arcangeli Signed-off-by: Peter Xu Signed-off-by: Andrew Morton Tested-by: Brian Geffon Cc: Bobby Powers Cc: David Hildenbrand Cc: Denis Plotnikov Cc: "Dr . David Alan Gilbert" Cc: Hugh Dickins Cc: Jerome Glisse Cc: Johannes Weiner Cc: "Kirill A . Shutemov" Cc: Martin Cracauer Cc: Marty McFadden Cc: Matthew Wilcox Cc: Maya Gokhale Cc: Mel Gorman Cc: Mike Kravetz Cc: Mike Rapoport Cc: Pavel Emelyanov Link: http://lkml.kernel.org/r/20200220160246.9790-1-peterx@redhat.com Signed-off-by: Linus Torvalds

mm: introduce FAULT_FLAG_DEFAULT

2020-04-02T16:35:29Z

Although there're tons of arch-specific page fault handlers, most of them are still sharing the same initial value of the page fault flags. Say, merely all of the page fault handlers would allow the fault to be retried, and they also allow the fault to respond to SIGKILL. Let's define a default value for the fault flags to replace those initial page fault flags that were copied over. With this, it'll be far easier to introduce new fault flag that can be used by all the architectures instead of touching all the archs. Signed-off-by: Peter Xu Signed-off-by: Andrew Morton Tested-by: Brian Geffon Reviewed-by: David Hildenbrand Cc: Andrea Arcangeli Cc: Bobby Powers Cc: Denis Plotnikov Cc: "Dr . David Alan Gilbert" Cc: Hugh Dickins Cc: Jerome Glisse Cc: Johannes Weiner Cc: "Kirill A . Shutemov" Cc: Martin Cracauer Cc: Marty McFadden Cc: Matthew Wilcox Cc: Maya Gokhale Cc: Mel Gorman Cc: Mike Kravetz Cc: Mike Rapoport Cc: Pavel Emelyanov Link: http://lkml.kernel.org/r/20200220160238.9694-1-peterx@redhat.com Signed-off-by: Linus Torvalds

mm: introduce fault_signal_pending()

2020-04-02T16:35:29Z

For most architectures, we've got a quick path to detect fatal signal after a handle_mm_fault(). Introduce a helper for that quick path. It cleans the current codes a bit so we don't need to duplicate the same check across archs. More importantly, this will be an unified place that we handle the signal immediately right after an interrupted page fault, so it'll be much easier for us if we want to change the behavior of handling signals later on for all the archs. Note that currently only part of the archs are using this new helper, because some archs have their own way to handle signals. In the follow up patches, we'll try to apply this helper to all the rest of archs. Another note is that the "regs" parameter in the new helper is not used yet. It'll be used very soon. Now we kept it in this patch only to avoid touching all the archs again in the follow up patches. [peterx@redhat.com: fix sparse warnings] Link: http://lkml.kernel.org/r/20200311145921.GD479302@xz-x1 Signed-off-by: Peter Xu Signed-off-by: Andrew Morton Tested-by: Brian Geffon Cc: Andrea Arcangeli Cc: Bobby Powers Cc: David Hildenbrand Cc: Denis Plotnikov Cc: "Dr . David Alan Gilbert" Cc: Hugh Dickins Cc: Jerome Glisse Cc: Johannes Weiner Cc: "Kirill A . Shutemov" Cc: Martin Cracauer Cc: Marty McFadden Cc: Matthew Wilcox Cc: Maya Gokhale Cc: Mel Gorman Cc: Mike Kravetz Cc: Mike Rapoport Cc: Pavel Emelyanov Link: http://lkml.kernel.org/r/20200220155353.8676-4-peterx@redhat.com Signed-off-by: Linus Torvalds

xtensa: use MEMBLOCK_ALLOC_ANYWHERE for KASAN shadow map

2019-11-26T19:33:39Z

KASAN shadow map doesn't need to be accessible through the linear kernel mapping, allocate its pages with MEMBLOCK_ALLOC_ANYWHERE so that high memory can be used. This frees up to ~100MB of low memory on xtensa configurations with KASAN and high memory. Cc: stable@vger.kernel.org # v5.1+ Fixes: f240ec09bb8a ("memblock: replace memblock_alloc_base(ANYWHERE) with memblock_phys_alloc") Reviewed-by: Mike Rapoport Signed-off-by: Max Filippov

xtensa: fix TLB sanity checker

2019-11-26T19:33:39Z

Virtual and translated addresses retrieved by the xtensa TLB sanity checker must be consistent, i.e. correspond to the same state of the checked TLB entry. KASAN shadow memory is mapped dynamically using auto-refill TLB entries and thus may change TLB state between the virtual and translated address retrieval, resulting in false TLB insanity report. Move read_xtlb_translation close to read_xtlb_virtual to make sure that read values are consistent. Cc: stable@vger.kernel.org Fixes: a99e07ee5e88 ("xtensa: check TLB sanity on return to userspace") Signed-off-by: Max Filippov

xtensa: get rid of __ARCH_USE_5LEVEL_HACK

2019-11-26T19:33:39Z

xtensa has 2-level page tables and already uses pgtable-nopmd for page table folding. Add walks of p4d level where appropriate and drop usage of __ARCH_USE_5LEVEL_HACK. Signed-off-by: Mike Rapoport Message-Id: <1572964400-16542-3-git-send-email-rppt@kernel.org> Signed-off-by: Max Filippov [fix up arch/xtensa/include/asm/fixmap.h and arch/xtensa/mm/tlb.c]

xtensa: mm: fix PMD folding implementation

2019-11-26T19:33:39Z

There was a definition of pmd_offset() in arch/xtensa/include/asm/pgtable.h that shadowed the generic implementation defined in include/asm-generic/pgtable-nopmd.h. As the result, xtensa had shortcuts in page table traversal in several places instead of doing level unfolding. Remove local override for pmd_offset() and add page table unfolding where necessary. Signed-off-by: Mike Rapoport Message-Id: <1572964400-16542-2-git-send-email-rppt@kernel.org> Signed-off-by: Max Filippov

xtensa: use correct symbol for the end of .rodata

2019-10-21T06:48:29Z

Use correct symbol for the end of .rodata section when dumping virtual memory layout. This fixes odd rodata size with XIP kernel. Signed-off-by: Max Filippov

xtensa: remove free_initrd_mem

2019-08-27T01:19:04Z

The xtensa free_initrd_mem() verifies that initrd is mapped and then frees its memory using free_reserved_area(). The initrd is considered mapped when its memory was successfully reserved with mem_reserve(). Resetting initrd_start to 0 in case of mem_reserve() failure allows to switch to generic free_initrd_mem() implementation. Signed-off-by: Mike Rapoport Message-Id: <1563977432-8376-1-git-send-email-rppt@linux.ibm.com> Signed-off-by: Max Filippov

Merge tag 'xtensa-20190715' of git://github.com/jcmvbkbc/linux-xtensa

2019-07-16T19:17:07Z

Pull Xtensa updates from Max Filippov: - clean up PCI support code - add defconfig and DTS for the 'virt' board - abstract 'entry' and 'retw' uses in xtensa assembly in preparation for XEA3/NX pipeline support - random small cleanups * tag 'xtensa-20190715' of git://github.com/jcmvbkbc/linux-xtensa: xtensa: virt: add defconfig and DTS xtensa: abstract 'entry' and 'retw' in assembly code xtensa: One function call less in bootmem_init() xtensa: remove arch/xtensa/include/asm/types.h xtensa: use generic pcibios_set_master and pcibios_enable_device xtensa: drop dead PCI support code xtensa/PCI: Remove unused variable