From: Benjamin Gray bgray@linux.ibm.com
commit 1abce0580b89464546ae06abd5891ebec43c9470 upstream.
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: b11931e9adc1 ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/include/asm/book3s/64/tlbflush.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
--- a/arch/powerpc/include/asm/book3s/64/tlbflush.h +++ b/arch/powerpc/include/asm/book3s/64/tlbflush.h @@ -163,6 +163,11 @@ static inline void flush_tlb_fix_spuriou */ }
+static inline bool __pte_protnone(unsigned long pte) +{ + return (pte & (pgprot_val(PAGE_NONE) | _PAGE_RWX)) == pgprot_val(PAGE_NONE); +} + static inline bool __pte_flags_need_flush(unsigned long oldval, unsigned long newval) { @@ -179,8 +184,8 @@ static inline bool __pte_flags_need_flus /* * We do not expect kernel mappings or non-PTEs or not-present PTEs. */ - VM_WARN_ON_ONCE(oldval & _PAGE_PRIVILEGED); - VM_WARN_ON_ONCE(newval & _PAGE_PRIVILEGED); + VM_WARN_ON_ONCE(!__pte_protnone(oldval) && oldval & _PAGE_PRIVILEGED); + VM_WARN_ON_ONCE(!__pte_protnone(newval) && newval & _PAGE_PRIVILEGED); VM_WARN_ON_ONCE(!(oldval & _PAGE_PTE)); VM_WARN_ON_ONCE(!(newval & _PAGE_PTE)); VM_WARN_ON_ONCE(!(oldval & _PAGE_PRESENT));