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authorLinus Torvalds <torvalds@linux-foundation.org>2023-07-01 04:24:49 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2023-07-01 07:08:05 +0300
commitd85a143b69abb4d7544227e26d12c4c7735ab27d (patch)
treea045ded33504b2274387b628a936bd6d1e2e5cee /mm
parentb25f62ccb490680a8cee755ac4528909395e0711 (diff)
downloadlinux-d85a143b69abb4d7544227e26d12c4c7735ab27d.tar.xz
xtensa: fix NOMMU build with lock_mm_and_find_vma() conversion
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 <linux@roeck-us.net> Fixes: a050ba1e7422 ("mm/fault: convert remaining simple cases to lock_mm_and_find_vma()") Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/nommu.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/mm/nommu.c b/mm/nommu.c
index 37d0b03143f1..fdc392735ec6 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -631,6 +631,17 @@ 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
*/