kernel.git/arch/s390/include/asm/pgtable.h, branch linux-5.5.y

s390/mm: fix panic in gup_fast on large pud

2020-03-12T06:18:35Z

commit 582b4e55403e053d8a48ff687a05174da9cc3fb0 upstream. On s390 there currently is no implementation of pud_write(). That was ok as long as we had our own implementation of get_user_pages_fast() which checked for pud protection by testing the bit directly w/o using pud_write(). The other callers of pud_write() are not reachable on s390. After commit 1a42010cdc26 ("s390/mm: convert to the generic get_user_pages_fast code") we use the generic get_user_pages_fast(), which does call pud_write() in pud_access_permitted() for FOLL_WRITE access on a large pud. Without an s390 specific pud_write(), the generic version is called, which contains a BUG() statement to remind us that we don't have a proper implementation. This results in a kernel panic. Fix this by providing an implementation of pud_write(). Cc: # 5.2+ Fixes: 1a42010cdc26 ("s390/mm: convert to the generic get_user_pages_fast code") Signed-off-by: Gerald Schaefer Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/mm: properly clear _PAGE_NOEXEC bit when it is not supported

2019-10-31T16:20:54Z

On older HW or under a hypervisor, w/o the instruction-execution- protection (IEP) facility, and also w/o EDAT-1, a translation-specification exception may be recognized when bit 55 of a pte is one (_PAGE_NOEXEC). The current code tries to prevent setting _PAGE_NOEXEC in such cases, by removing it within set_pte_at(). However, ptep_set_access_flags() will modify a pte directly, w/o using set_pte_at(). There is at least one scenario where this can result in an active pte with _PAGE_NOEXEC set, which would then lead to a panic due to a translation-specification exception (write to swapped out page): do_swap_page pte = mk_pte (with _PAGE_NOEXEC bit) set_pte_at (will remove _PAGE_NOEXEC bit in page table, but keep it in local variable pte) vmf->orig_pte = pte (pte still contains _PAGE_NOEXEC bit) do_wp_page wp_page_reuse entry = vmf->orig_pte (still with _PAGE_NOEXEC bit) ptep_set_access_flags (writes entry with _PAGE_NOEXEC bit) Fix this by clearing _PAGE_NOEXEC already in mk_pte_phys(), where the pgprot value is applied, so that no pte with _PAGE_NOEXEC will ever be visible, if it is not supported. The check in set_pte_at() can then also be removed. Cc: # 4.11+ Fixes: 57d7f939e7bd ("s390: add no-execute support") Signed-off-by: Gerald Schaefer Signed-off-by: Vasily Gorbik

s390/mm: simplify page table helpers for large entries

2019-10-31T16:20:53Z

For pmds and puds, there are a couple of page table helper functions that only make sense for large entries, like pxd_(mk)dirty/young/write etc. We currently explicitly check if the entries are large, but in practice those functions must never be used for normal entries, which point to lower level page tables, so the code can be simplified. This also fixes a theoretical bug, where common code could use one of the functions before actually marking a pmd large, like this: pmd = pmd_mkhuge(pmd_mkdirty(pmd)) With the current implementation, the resulting large pmd would not be dirty as requested. This could in theory result in the loss of dirty information, e.g. after collapsing into a transparent hugepage. Common code currently always marks an entry large before using one of the functions, but there is no hard requirement for this. The only requirement would be that it never uses the functions for normal entries pointing to lower level page tables, but they might be called before marking an entry large during its creation. In order to avoid issues with future common code, and to simplify the page table helpers, remove the checks for large entries and rely on common code never using them for normal entries. This was found by testing a patch from from Anshuman Khandual, which is currently discussed on LKML ("mm/debug: Add tests validating architecture page table helpers"). Signed-off-by: Gerald Schaefer Signed-off-by: Vasily Gorbik

s390/mm: make pmd/pud_bad() report large entries as bad

2019-10-31T16:20:53Z

The semantics of pmd/pud_bad() expect that large entries are reported as bad, but we also check large entries for sanity. There is currently no issue with this wrong behaviour, but let's conform to the semantics by reporting large pmd/pud entries as bad, in order to prevent future issues. This was found by testing a patch from from Anshuman Khandual, which is currently discussed on LKML ("mm/debug: Add tests validating architecture page table helpers"). Signed-off-by: Gerald Schaefer Signed-off-by: Vasily Gorbik

s390/mm: mark function(s) __always_inline

2019-10-04T14:37:33Z

Always inline asm inlines with variable operands for "i" constraints, since they won't compile if the compiler would decide to not inline them. Reported-by: Michal Kubecek Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/mm: fix -Wunused-but-set-variable warnings

2019-10-04T14:37:33Z

Convert two functions to static inline to get ride of W=1 GCC warnings like, mm/gup.c: In function 'gup_pte_range': mm/gup.c:1816:16: warning: variable 'ptem' set but not used [-Wunused-but-set-variable] pte_t *ptep, *ptem; ^~~~ mm/mmap.c: In function 'acct_stack_growth': mm/mmap.c:2322:16: warning: variable 'new_start' set but not used [-Wunused-but-set-variable] unsigned long new_start; ^~~~~~~~~ Signed-off-by: Qian Cai Link: https://lore.kernel.org/lkml/1570138596-11913-1-git-send-email-cai@lca.pw/ Signed-off-by: Christian Borntraeger Signed-off-by: Vasily Gorbik

mm: consolidate pgtable_cache_init() and pgd_cache_init()

2019-09-24T22:54:09Z

Both pgtable_cache_init() and pgd_cache_init() are used to initialize kmem cache for page table allocations on several architectures that do not use PAGE_SIZE tables for one or more levels of the page table hierarchy. Most architectures do not implement these functions and use __weak default NOP implementation of pgd_cache_init(). Since there is no such default for pgtable_cache_init(), its empty stub is duplicated among most architectures. Rename the definitions of pgd_cache_init() to pgtable_cache_init() and drop empty stubs of pgtable_cache_init(). Link: http://lkml.kernel.org/r/1566457046-22637-1-git-send-email-rppt@linux.ibm.com Signed-off-by: Mike Rapoport Acked-by: Will Deacon [arm64] Acked-by: Thomas Gleixner [x86] Cc: Catalin Marinas Cc: Ingo Molnar Cc: Borislav Petkov Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: remove quicklist page table caches

2019-09-24T22:54:09Z

Patch series "mm: remove quicklist page table caches". A while ago Nicholas proposed to remove quicklist page table caches [1]. I've rebased his patch on the curren upstream and switched ia64 and sh to use generic versions of PTE allocation. [1] https://lore.kernel.org/linux-mm/20190711030339.20892-1-npiggin@gmail.com This patch (of 3): Remove page table allocator "quicklists". These have been around for a long time, but have not got much traction in the last decade and are only used on ia64 and sh architectures. The numbers in the initial commit look interesting but probably don't apply anymore. If anybody wants to resurrect this it's in the git history, but it's unhelpful to have this code and divergent allocator behaviour for minor archs. Also it might be better to instead make more general improvements to page allocator if this is still so slow. Link: http://lkml.kernel.org/r/1565250728-21721-2-git-send-email-rppt@linux.ibm.com Signed-off-by: Nicholas Piggin Signed-off-by: Mike Rapoport Cc: Tony Luck Cc: Yoshinori Sato Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

s390: move vmalloc option parsing to startup code

2019-08-21T10:41:43Z

Few other crucial memory setup options are already handled in the startup code. Those values are needed by kaslr and kasan implementations. "vmalloc" is the last piece required for future improvements such as early decision on kernel page levels depth required for actual memory setup, as well as vmalloc memory area access monitoring in kasan. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

mm: simplify gup_fast_permitted

2019-07-12T18:05:44Z

Pass in the already calculated end value instead of recomputing it, and leave the end > start check in the callers instead of duplicating them in the arch code. Link: http://lkml.kernel.org/r/20190625143715.1689-3-hch@lst.de Signed-off-by: Christoph Hellwig Reviewed-by: Jason Gunthorpe Cc: Andrey Konovalov Cc: Benjamin Herrenschmidt Cc: David Miller Cc: James Hogan Cc: Khalid Aziz Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Paul Burton Cc: Paul Mackerras Cc: Ralf Baechle Cc: Rich Felker Cc: Yoshinori Sato Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds