kernel.git/arch/arm64/mm, branch linux-4.5.y

arm64: Implement ptep_set_access_flags() for hardware AF/DBM

2016-06-01T19:16:56Z

commit 66dbd6e61a526ae7d11a208238ae2c17e5cacb6b upstream. When hardware updates of the access and dirty states are enabled, the default ptep_set_access_flags() implementation based on calling set_pte_at() directly is potentially racy. This triggers the "racy dirty state clearing" warning in set_pte_at() because an existing writable PTE is overridden with a clean entry. There are two main scenarios for this situation: 1. The CPU getting an access fault does not support hardware updates of the access/dirty flags. However, a different agent in the system (e.g. SMMU) can do this, therefore overriding a writable entry with a clean one could potentially lose the automatically updated dirty status 2. A more complex situation is possible when all CPUs support hardware AF/DBM: a) Initial state: shareable + writable vma and pte_none(pte) b) Read fault taken by two threads of the same process on different CPUs c) CPU0 takes the mmap_sem and proceeds to handling the fault. It eventually reaches do_set_pte() which sets a writable + clean pte. CPU0 releases the mmap_sem d) CPU1 acquires the mmap_sem and proceeds to handle_pte_fault(). The pte entry it reads is present, writable and clean and it continues to pte_mkyoung() e) CPU1 calls ptep_set_access_flags() If between (d) and (e) the hardware (another CPU) updates the dirty state (clears PTE_RDONLY), CPU1 will override the PTR_RDONLY bit marking the entry clean again. This patch implements an arm64-specific ptep_set_access_flags() function to perform an atomic update of the PTE flags. Fixes: 2f4b829c625e ("arm64: Add support for hardware updates of the access and dirty pte bits") Signed-off-by: Catalin Marinas Reported-by: Ming Lei Tested-by: Julien Grall Cc: Will Deacon [will: reworded comment] Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman

arm64: hugetlb: partial revert of 66b3923a1a0f

2016-03-09T15:29:29Z

Commit 66b3923a1a0f ("arm64: hugetlb: add support for PTE contiguous bit") introduced support for huge pages using the contiguous bit in the PTE as opposed to block mappings, which may be slightly unwieldy (512M) in 64k page configurations. Unfortunately, this support has resulted in some late regressions when running the libhugetlbfs test suite with 64k pages and CONFIG_DEBUG_VM as a result of a BUG: | readback (2M: 64): ------------[ cut here ]------------ | kernel BUG at fs/hugetlbfs/inode.c:446! | Internal error: Oops - BUG: 0 [#1] SMP | Modules linked in: | CPU: 7 PID: 1448 Comm: readback Not tainted 4.5.0-rc7 #148 | Hardware name: linux,dummy-virt (DT) | task: fffffe0040964b00 ti: fffffe00c2668000 task.ti: fffffe00c2668000 | PC is at remove_inode_hugepages+0x44c/0x480 | LR is at remove_inode_hugepages+0x264/0x480 Rather than revert the entire patch, simply avoid advertising the contiguous huge page sizes for now while people are actively working on a fix. This patch can then be reverted once things have been sorted out. Cc: David Woods Reported-by: Steve Capper Signed-off-by: Will Deacon

Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2016-03-05T01:43:40Z

Pull arm64 fix from Will Deacon: "Arm64 fix for -rc7. Without it, our struct page array can overflow the vmemmap region on systems with a large PHYS_OFFSET. Nothing else on the radar at the moment, so hopefully that's it for 4.5 from us. Summary: Ensure struct page array fits within vmemmap area" * tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: arm64: vmemmap: use virtual projection of linear region

mm: ASLR: use get_random_long()

2016-02-27T18:28:52Z

Replace calls to get_random_int() followed by a cast to (unsigned long) with calls to get_random_long(). Also address shifting bug which, in case of x86 removed entropy mask for mmap_rnd_bits values > 31 bits. Signed-off-by: Daniel Cashman Acked-by: Kees Cook Cc: "Theodore Ts'o" Cc: Arnd Bergmann Cc: Greg Kroah-Hartman Cc: Catalin Marinas Cc: Will Deacon Cc: Ralf Baechle Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Cc: David S. Miller Cc: Thomas Gleixner Cc: Ingo Molnar Cc: H. Peter Anvin Cc: Al Viro Cc: Nick Kralevich Cc: Jeff Vander Stoep Cc: Mark Salyzyn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

arm64: vmemmap: use virtual projection of linear region

2016-02-26T17:59:04Z

Commit dd006da21646 ("arm64: mm: increase VA range of identity map") made some changes to the memory mapping code to allow physical memory to reside at an offset that exceeds the size of the virtual mapping. However, since the size of the vmemmap area is proportional to the size of the VA area, but it is populated relative to the physical space, we may end up with the struct page array being mapped outside of the vmemmap region. For instance, on my Seattle A0 box, I can see the following output in the dmesg log. vmemmap : 0xffffffbdc0000000 - 0xffffffbfc0000000 ( 8 GB maximum) 0xffffffbfc0000000 - 0xffffffbfd0000000 ( 256 MB actual) We can fix this by deciding that the vmemmap region is not a projection of the physical space, but of the virtual space above PAGE_OFFSET, i.e., the linear region. This way, we are guaranteed that the vmemmap region is of sufficient size, and we can even reduce the size by half. Cc: Signed-off-by: Ard Biesheuvel Signed-off-by: Will Deacon

arm64: mm: allow the kernel to handle alignment faults on user accesses

2016-02-19T12:20:37Z

Although we don't expect to take alignment faults on access to normal memory, misbehaving (i.e. buggy) user code can pass MMIO pointers into system calls, leading to things like get_user accessing device memory. Rather than OOPS the kernel, allow any exception fixups to run and return something like -EFAULT back to userspace. This makes the behaviour more consistent with userspace, even though applications with access to device mappings can easily cause other issues if they try hard enough. Acked-by: Catalin Marinas Signed-off-by: Eun Taik Lee [will: dropped __kprobes annotation and rewrote commit mesage] Signed-off-by: Will Deacon

arm64: dma-mapping: fix handling of devices registered before arch_initcall

2016-02-17T11:48:01Z

This patch ensures that devices, which got registered before arch_initcall will be handled correctly by IOMMU-based DMA-mapping code. Cc: Fixes: 13b8629f6511 ("arm64: Add IOMMU dma_ops") Acked-by: Robin Murphy Signed-off-by: Marek Szyprowski Signed-off-by: Will Deacon

arm64: allow vmalloc regions to be set with set_memory_*

2016-02-02T15:42:15Z

The range of set_memory_* is currently restricted to the module address range because of difficulties in breaking down larger block sizes. vmalloc maps PAGE_SIZE pages so it is safe to use as well. Update the function ranges and add a comment explaining why the range is restricted the way it is. Suggested-by: Laura Abbott Acked-by: Mark Rutland Signed-off-by: Ard Biesheuvel Signed-off-by: Will Deacon

arm64: mm: avoid calling apply_to_page_range on empty range

2016-01-26T15:56:44Z

Calling apply_to_page_range with an empty range results in a BUG_ON from the core code. This can be triggered by trying to load the st_drv module with CONFIG_DEBUG_SET_MODULE_RONX enabled: kernel BUG at mm/memory.c:1874! Internal error: Oops - BUG: 0 [#1] PREEMPT SMP Modules linked in: CPU: 3 PID: 1764 Comm: insmod Not tainted 4.5.0-rc1+ #2 Hardware name: ARM Juno development board (r0) (DT) task: ffffffc9763b8000 ti: ffffffc975af8000 task.ti: ffffffc975af8000 PC is at apply_to_page_range+0x2cc/0x2d0 LR is at change_memory_common+0x80/0x108 This patch fixes the issue by making change_memory_common (called by the set_memory_* functions) a NOP when numpages == 0, therefore avoiding the erroneous call to apply_to_page_range and bringing us into line with x86 and s390. Cc: Reviewed-by: Laura Abbott Acked-by: David Rientjes Signed-off-by: Mika Penttilä Signed-off-by: Will Deacon

arm64: Fix an enum typo in mm/dump.c

2016-01-25T11:53:03Z

This patch fixes a typo in mm/dump.c: "MODUELS_END_NR" should be "MODULES_END_NR". Signed-off-by: Masanari Iida Signed-off-by: Will Deacon