linux-dev/arch/xtensa/mm, branch master

xtensa/mm: enable ARCH_HAS_VM_GET_PAGE_PROT

2022-07-18T00:14:39Z

This enables ARCH_HAS_VM_GET_PAGE_PROT on the platform and exports standard vm_get_page_prot() implementation via DECLARE_VM_GET_PAGE_PROT, which looks up a private and static protection_map[] array. Subsequently all __SXXX and __PXXX macros can be dropped which are no longer needed. Link: https://lkml.kernel.org/r/20220711070600.2378316-12-anshuman.khandual@arm.com Signed-off-by: Anshuman Khandual Cc: Chris Zankel Cc: Guo Ren Cc: Arnd Bergmann Cc: Brian Cain Cc: Catalin Marinas Cc: Christophe Leroy Cc: Christoph Hellwig Cc: Christoph Hellwig Cc: "David S. Miller" Cc: Dinh Nguyen Cc: Geert Uytterhoeven Cc: Heiko Carstens Cc: Huacai Chen Cc: Ingo Molnar Cc: "James E.J. Bottomley" Cc: Jeff Dike Cc: Jonas Bonn Cc: Michael Ellerman Cc: Michal Simek Cc: Nicholas Piggin Cc: Palmer Dabbelt Cc: Paul Mackerras Cc: Paul Walmsley Cc: Richard Henderson Cc: Rich Felker Cc: Russell King Cc: Sam Ravnborg Cc: Stafford Horne Cc: Thomas Bogendoerfer Cc: Thomas Gleixner Cc: Vasily Gorbik Cc: Vineet Gupta Cc: WANG Xuerui Cc: Will Deacon Cc: Yoshinori Sato Signed-off-by: Andrew Morton

mm: avoid unnecessary page fault retires on shared memory types

2022-06-17T02:48:27Z

I observed that for each of the shared file-backed page faults, we're very likely to retry one more time for the 1st write fault upon no page. It's because we'll need to release the mmap lock for dirty rate limit purpose with balance_dirty_pages_ratelimited() (in fault_dirty_shared_page()). Then after that throttling we return VM_FAULT_RETRY. We did that probably because VM_FAULT_RETRY is the only way we can return to the fault handler at that time telling it we've released the mmap lock. However that's not ideal because it's very likely the fault does not need to be retried at all since the pgtable was well installed before the throttling, so the next continuous fault (including taking mmap read lock, walk the pgtable, etc.) could be in most cases unnecessary. It's not only slowing down page faults for shared file-backed, but also add more mmap lock contention which is in most cases not needed at all. To observe this, one could try to write to some shmem page and look at "pgfault" value in /proc/vmstat, then we should expect 2 counts for each shmem write simply because we retried, and vm event "pgfault" will capture that. To make it more efficient, add a new VM_FAULT_COMPLETED return code just to show that we've completed the whole fault and released the lock. It's also a hint that we should very possibly not need another fault immediately on this page because we've just completed it. This patch provides a ~12% perf boost on my aarch64 test VM with a simple program sequentially dirtying 400MB shmem file being mmap()ed and these are the time it needs: Before: 650.980 ms (+-1.94%) After: 569.396 ms (+-1.38%) I believe it could help more than that. We need some special care on GUP and the s390 pgfault handler (for gmap code before returning from pgfault), the rest changes in the page fault handlers should be relatively straightforward. Another thing to mention is that mm_account_fault() does take this new fault as a generic fault to be accounted, unlike VM_FAULT_RETRY. I explicitly didn't touch hmm_vma_fault() and break_ksm() because they do not handle VM_FAULT_RETRY even with existing code, so I'm literally keeping them as-is. Link: https://lkml.kernel.org/r/20220530183450.42886-1-peterx@redhat.com Signed-off-by: Peter Xu Acked-by: Geert Uytterhoeven Acked-by: Peter Zijlstra (Intel) Acked-by: Johannes Weiner Acked-by: Vineet Gupta Acked-by: Guo Ren Acked-by: Max Filippov Acked-by: Christian Borntraeger Acked-by: Michael Ellerman (powerpc) Acked-by: Catalin Marinas Reviewed-by: Alistair Popple Reviewed-by: Ingo Molnar Acked-by: Russell King (Oracle) [arm part] Acked-by: Heiko Carstens Cc: Vasily Gorbik Cc: Stafford Horne Cc: David S. Miller Cc: Johannes Berg Cc: Brian Cain Cc: Richard Henderson Cc: Richard Weinberger Cc: Benjamin Herrenschmidt Cc: Thomas Gleixner Cc: Janosch Frank Cc: Albert Ou Cc: Anton Ivanov Cc: Dave Hansen Cc: Borislav Petkov Cc: Sven Schnelle Cc: Andrea Arcangeli Cc: James Bottomley Cc: Al Viro Cc: Alexander Gordeev Cc: Jonas Bonn Cc: Will Deacon Cc: Vlastimil Babka Cc: Michal Simek Cc: Matt Turner Cc: Paul Mackerras Cc: David Hildenbrand Cc: Nicholas Piggin Cc: Palmer Dabbelt Cc: Stefan Kristiansson Cc: Paul Walmsley Cc: Ivan Kokshaysky Cc: Chris Zankel Cc: Hugh Dickins Cc: Dinh Nguyen Cc: Rich Felker Cc: H. Peter Anvin Cc: Andy Lutomirski Cc: Thomas Bogendoerfer Cc: Helge Deller Cc: Yoshinori Sato Signed-off-by: Andrew Morton

xtensa: noMMU: allow handling protection faults

2022-05-02T02:51:21Z

Many xtensa CPU cores without full MMU still have memory protection features capable of raising exceptions for invalid instruction fetches/data access. Allow handling such exceptions. This improves behavior of processes that pass invalid memory pointers to syscalls in noMMU configs: in case of exception the kernel instead of killing the process is now able to return -EINVAL from a syscall. Introduce CONFIG_PFAULT that controls whether protection fault code is enabled and register handlers for common memory protection exceptions when it is enabled. Signed-off-by: Max Filippov

xtensa: extract vmalloc_fault code into a function

2022-05-02T02:51:21Z

Move full MMU-specific code into a separate function to isolate it from more generic do_page_fault code. No functional changes. Signed-off-by: Max Filippov

xtensa: move asid_cache from fault.c to mmu.c

2022-05-02T02:51:20Z

asid_cache is only useful with full MMU, but fault.c is also useful with MPU. Move asid_cache definition to MMU-specific source file. Signed-off-by: Max Filippov

xtensa: define update_mmu_tlb function

2022-03-22T16:45:09Z

Before the commit f9ce0be71d1f ("mm: Cleanup faultaround and finish_fault() codepaths") there was a call to update_mmu_cache in alloc_set_pte that used to invalidate TLB entry caching invalid PTE that caused a page fault. That commit removed that call so now invalid TLB entry survives causing repetitive page faults on the CPU that took the initial fault until that TLB entry is occasionally evicted. This issue is spotted by the xtensa TLB sanity checker. Fix this issue by defining update_mmu_tlb function that flushes TLB entry for the faulting address. Cc: stable@vger.kernel.org # 5.12+ Signed-off-by: Max Filippov

mm: remove redundant check about FAULT_FLAG_ALLOW_RETRY bit

2022-01-15T14:30:27Z

Since commit 4064b9827063 ("mm: allow VM_FAULT_RETRY for multiple times") allowed VM_FAULT_RETRY for multiple times, the FAULT_FLAG_ALLOW_RETRY bit of fault_flag will not be changed in the page fault path, so the following check is no longer needed: flags & FAULT_FLAG_ALLOW_RETRY So just remove it. [akpm@linux-foundation.org: coding style fixes] Link: https://lkml.kernel.org/r/20211110123358.36511-1-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng Cc: Peter Zijlstra Cc: Ingo Molnar Cc: David Hildenbrand Cc: Kirill Shutemov Cc: Peter Xu Cc: Muchun Song Cc: Chengming Zhou Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'exit-cleanups-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2021-11-11T00:15:54Z

Pull exit cleanups from Eric Biederman: "While looking at some issues related to the exit path in the kernel I found several instances where the code is not using the existing abstractions properly. This set of changes introduces force_fatal_sig a way of sending a signal and not allowing it to be caught, and corrects the misuse of the existing abstractions that I found. A lot of the misuse of the existing abstractions are silly things such as doing something after calling a no return function, rolling BUG by hand, doing more work than necessary to terminate a kernel thread, or calling do_exit(SIGKILL) instead of calling force_sig(SIGKILL). In the review a deficiency in force_fatal_sig and force_sig_seccomp where ptrace or sigaction could prevent the delivery of the signal was found. I have added a change that adds SA_IMMUTABLE to change that makes it impossible to interrupt the delivery of those signals, and allows backporting to fix force_sig_seccomp And Arnd found an issue where a function passed to kthread_run had the wrong prototype, and after my cleanup was failing to build." * 'exit-cleanups-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (23 commits) soc: ti: fix wkup_m3_rproc_boot_thread return type signal: Add SA_IMMUTABLE to ensure forced siganls do not get changed signal: Replace force_sigsegv(SIGSEGV) with force_fatal_sig(SIGSEGV) exit/r8188eu: Replace the macro thread_exit with a simple return 0 exit/rtl8712: Replace the macro thread_exit with a simple return 0 exit/rtl8723bs: Replace the macro thread_exit with a simple return 0 signal/x86: In emulate_vsyscall force a signal instead of calling do_exit signal/sparc32: In setup_rt_frame and setup_fram use force_fatal_sig signal/sparc32: Exit with a fatal signal when try_to_clear_window_buffer fails exit/syscall_user_dispatch: Send ordinary signals on failure signal: Implement force_fatal_sig exit/kthread: Have kernel threads return instead of calling do_exit signal/s390: Use force_sigsegv in default_trap_handler signal/vm86_32: Properly send SIGSEGV when the vm86 state cannot be saved. signal/vm86_32: Replace open coded BUG_ON with an actual BUG_ON signal/sparc: In setup_tsb_params convert open coded BUG into BUG signal/powerpc: On swapcontext failure force SIGSEGV signal/sh: Use force_sig(SIGKILL) instead of do_group_exit(SIGKILL) signal/mips: Update (_save|_restore)_fp_context to fail with -EFAULT signal/sparc32: Remove unreachable do_exit in do_sparc_fault ...

exit: Remove calls of do_exit after noreturn versions of die

2021-10-20T18:09:47Z

On nds32, openrisc, s390, sh, and xtensa the function die never returns. Mark die __noreturn so that no one expects die to return. Remove the do_exit calls after die as they will never be reached. Cc: Jonas Bonn Cc: Stefan Kristiansson Cc: Stafford Horne Cc: openrisc@lists.librecores.org Cc: Nick Hu Cc: Greentime Hu Cc: Vincent Chen Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Christian Borntraeger Cc: linux-s390@vger.kernel.org Cc: Yoshinori Sato Cc: Rich Felker Cc: linux-sh@vger.kernel.org Cc: linux-xtensa@linux-xtensa.org Cc: Chris Zankel Cc: Max Filippov Fixes: 2.3.16 Fixes: 2.3.99-pre8 Fixes: 3f65ce4d141e ("[PATCH] xtensa: Architecture support for Tensilica Xtensa Part 5") Fixes: 664eec400bf8 ("nds32: MMU fault handling and page table management") Fixes: 61e85e367535 ("OpenRISC: Memory management") Link: https://lkml.kernel.org/r/20211020174406.17889-2-ebiederm@xmission.com Signed-off-by: Eric W. Biederman

xtensa: use CONFIG_USE_OF instead of CONFIG_OF

2021-09-27T13:08:58Z

CONFIG_OF can be set by a randconfig or by a user -- without setting the early flattree option (OF_EARLY_FLATTREE). This causes build errors. However, if randconfig or a user sets USE_OF in the Xtensa config, the right kconfig symbols are set to fix the build. Fixes these build errors: ../arch/xtensa/kernel/setup.c:67:19: error: ‘__dtb_start’ undeclared here (not in a function); did you mean ‘dtb_start’? 67 | void *dtb_start = __dtb_start; | ^~~~~~~~~~~ ../arch/xtensa/kernel/setup.c: In function 'xtensa_dt_io_area': ../arch/xtensa/kernel/setup.c:201:14: error: implicit declaration of function 'of_flat_dt_is_compatible'; did you mean 'of_machine_is_compatible'? [-Werror=implicit-function-declaration] 201 | if (!of_flat_dt_is_compatible(node, "simple-bus")) ../arch/xtensa/kernel/setup.c:204:18: error: implicit declaration of function 'of_get_flat_dt_prop' [-Werror=implicit-function-declaration] 204 | ranges = of_get_flat_dt_prop(node, "ranges", &len); ../arch/xtensa/kernel/setup.c:204:16: error: assignment to 'const __be32 *' {aka 'const unsigned int *'} from 'int' makes pointer from integer without a cast [-Werror=int-conversion] 204 | ranges = of_get_flat_dt_prop(node, "ranges", &len); | ^ ../arch/xtensa/kernel/setup.c: In function 'early_init_devtree': ../arch/xtensa/kernel/setup.c:228:9: error: implicit declaration of function 'early_init_dt_scan'; did you mean 'early_init_devtree'? [-Werror=implicit-function-declaration] 228 | early_init_dt_scan(params); ../arch/xtensa/kernel/setup.c:229:9: error: implicit declaration of function 'of_scan_flat_dt' [-Werror=implicit-function-declaration] 229 | of_scan_flat_dt(xtensa_dt_io_area, NULL); xtensa-elf-ld: arch/xtensa/mm/mmu.o:(.text+0x0): undefined reference to `xtensa_kio_paddr' Fixes: da844a81779e ("xtensa: add device trees support") Fixes: 6cb971114f63 ("xtensa: remap io area defined in device tree") Signed-off-by: Randy Dunlap Signed-off-by: Max Filippov