From d85a143b69abb4d7544227e26d12c4c7735ab27d Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Fri, 30 Jun 2023 18:24:49 -0700 Subject: xtensa: fix NOMMU build with lock_mm_and_find_vma() conversion MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit It turns out that xtensa has a really odd configuration situation: you can do a no-MMU config, but still have the page fault code enabled. Which doesn't sound all that sensible, but it turns out that xtensa can have protection faults even without the MMU, and we have this: config PFAULT bool "Handle protection faults" if EXPERT && !MMU default y help Handle protection faults. MMU configurations must enable it. noMMU configurations may disable it if used memory map never generates protection faults or faults are always fatal. If unsure, say Y. which completely violated my expectations of the page fault handling. End result: Guenter reports that the xtensa no-MMU builds all fail with arch/xtensa/mm/fault.c: In function ‘do_page_fault’: arch/xtensa/mm/fault.c:133:8: error: implicit declaration of function ‘lock_mm_and_find_vma’ because I never exposed the new lock_mm_and_find_vma() function for the no-MMU case. Doing so is simple enough, and fixes the problem. Reported-and-tested-by: Guenter Roeck Fixes: a050ba1e7422 ("mm/fault: convert remaining simple cases to lock_mm_and_find_vma()") Signed-off-by: Linus Torvalds --- include/linux/mm.h | 5 +++-- mm/nommu.c | 11 +++++++++++ 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 39aa409e84d5..4f2c33c273eb 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2323,6 +2323,9 @@ void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to); void truncate_pagecache_range(struct inode *inode, loff_t offset, loff_t end); int generic_error_remove_page(struct address_space *mapping, struct page *page); +struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm, + unsigned long address, struct pt_regs *regs); + #ifdef CONFIG_MMU extern vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address, unsigned int flags, @@ -2334,8 +2337,6 @@ void unmap_mapping_pages(struct address_space *mapping, pgoff_t start, pgoff_t nr, bool even_cows); void unmap_mapping_range(struct address_space *mapping, loff_t const holebegin, loff_t const holelen, int even_cows); -struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm, - unsigned long address, struct pt_regs *regs); #else static inline vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address, unsigned int flags, diff --git a/mm/nommu.c b/mm/nommu.c index 37d0b03143f1..fdc392735ec6 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -630,6 +630,17 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) } EXPORT_SYMBOL(find_vma); +/* + * At least xtensa ends up having protection faults even with no + * MMU.. No stack expansion, at least. + */ +struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm, + unsigned long addr, struct pt_regs *regs) +{ + mmap_read_lock(mm); + return vma_lookup(mm, addr); +} + /* * expand a stack to a given address * - not supported under NOMMU conditions -- cgit v1.2.3