powerpc/64s: Fix __pte_needs_flush() false positive warning
Userspace PROT_NONE ptes set _PAGE_PRIVILEGED, triggering a false
positive debug assertion that __pte_flags_need_flush() is not called
on a kernel mapping.
Detect when it is a userspace PROT_NONE page by checking the required
bits of PAGE_NONE are set, and none of the RWX bits are set.
pte_protnone() is insufficient here because it always returns 0 when
CONFIG_NUMA_BALANCING=n.
Fixes: b11931e9ad
("powerpc/64s: add pte_needs_flush and huge_pmd_needs_flush")
Cc: stable@vger.kernel.org # v6.1+
Reported-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230302225947.81083-1-bgray@linux.ibm.com
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@ -148,6 +148,11 @@ static inline void flush_tlb_fix_spurious_fault(struct vm_area_struct *vma,
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*/
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}
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static inline bool __pte_protnone(unsigned long pte)
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{
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return (pte & (pgprot_val(PAGE_NONE) | _PAGE_RWX)) == pgprot_val(PAGE_NONE);
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}
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static inline bool __pte_flags_need_flush(unsigned long oldval,
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unsigned long newval)
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{
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@ -164,8 +169,8 @@ static inline bool __pte_flags_need_flush(unsigned long oldval,
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/*
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* We do not expect kernel mappings or non-PTEs or not-present PTEs.
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*/
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VM_WARN_ON_ONCE(oldval & _PAGE_PRIVILEGED);
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VM_WARN_ON_ONCE(newval & _PAGE_PRIVILEGED);
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VM_WARN_ON_ONCE(!__pte_protnone(oldval) && oldval & _PAGE_PRIVILEGED);
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VM_WARN_ON_ONCE(!__pte_protnone(newval) && newval & _PAGE_PRIVILEGED);
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VM_WARN_ON_ONCE(!(oldval & _PAGE_PTE));
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VM_WARN_ON_ONCE(!(newval & _PAGE_PTE));
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VM_WARN_ON_ONCE(!(oldval & _PAGE_PRESENT));
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