The patch titled
Subject: arch/powerpc/mm: Nest MMU workaround for mprotect RW upgrade
has been added to the -mm tree. Its filename is
arch-powerpc-mm-nest-mmu-workaround-for-mprotect-rw-upgrade.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/arch-powerpc-mm-nest-mmu-workaround-for-mprotect-rw-upgrade.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/arch-powerpc-mm-nest-mmu-workaround-for-mprotect-rw-upgrade.patch
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------------------------------------------------------
From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx>
Subject: arch/powerpc/mm: Nest MMU workaround for mprotect RW upgrade
NestMMU requires us to mark the pte invalid and flush the tlb when we do a
RW upgrade of pte. We fixed a variant of this in the fault path in
bd5050e38aec ("powerpc/mm/radix: Change pte relax sequence to handle nest
MMU hang").
Do the same for mprotect upgrades.
Hugetlb is handled in the next patch.
Link: http://lkml.kernel.org/r/20190116085035.29729-4-aneesh.kumar@xxxxxxxxxxxxx
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/include/asm/book3s/64/pgtable.h | 18 ++++++++++++
arch/powerpc/include/asm/book3s/64/radix.h | 4 ++
arch/powerpc/mm/pgtable-book3s64.c | 25 +++++++++++++++++
arch/powerpc/mm/pgtable-radix.c | 18 ++++++++++++
4 files changed, 65 insertions(+)
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h~arch-powerpc-mm-nest-mmu-workaround-for-mprotect-rw-upgrade
+++ a/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -1314,6 +1314,24 @@ static inline int pud_pfn(pud_t pud)
BUILD_BUG();
return 0;
}
+#define __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION
+pte_t ptep_modify_prot_start(struct vm_area_struct *, unsigned long, pte_t *);
+void ptep_modify_prot_commit(struct vm_area_struct *, unsigned long,
+ pte_t *, pte_t, pte_t);
+
+/*
+ * Returns true for a R -> RW upgrade of pte
+ */
+static inline bool is_pte_rw_upgrade(unsigned long old_val, unsigned long new_val)
+{
+ if (!(old_val & _PAGE_READ))
+ return false;
+
+ if ((!(old_val & _PAGE_WRITE)) && (new_val & _PAGE_WRITE))
+ return true;
+
+ return false;
+}
#endif /* __ASSEMBLY__ */
#endif /* _ASM_POWERPC_BOOK3S_64_PGTABLE_H_ */
--- a/arch/powerpc/include/asm/book3s/64/radix.h~arch-powerpc-mm-nest-mmu-workaround-for-mprotect-rw-upgrade
+++ a/arch/powerpc/include/asm/book3s/64/radix.h
@@ -127,6 +127,10 @@ extern void radix__ptep_set_access_flags
pte_t entry, unsigned long address,
int psize);
+extern void radix__ptep_modify_prot_commit(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep,
+ pte_t old_pte, pte_t pte);
+
static inline unsigned long __radix_pte_update(pte_t *ptep, unsigned long clr,
unsigned long set)
{
--- a/arch/powerpc/mm/pgtable-book3s64.c~arch-powerpc-mm-nest-mmu-workaround-for-mprotect-rw-upgrade
+++ a/arch/powerpc/mm/pgtable-book3s64.c
@@ -397,3 +397,28 @@ void arch_report_meminfo(struct seq_file
atomic_long_read(&direct_pages_count[MMU_PAGE_1G]) << 20);
}
#endif /* CONFIG_PROC_FS */
+
+pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr,
+ pte_t *ptep)
+{
+ unsigned long pte_val;
+
+ /*
+ * Clear the _PAGE_PRESENT so that no hardware parallel update is
+ * possible. Also keep the pte_present true so that we don't take
+ * wrong fault.
+ */
+ pte_val = pte_update(vma->vm_mm, addr, ptep, _PAGE_PRESENT, _PAGE_INVALID, 0);
+
+ return __pte(pte_val);
+
+}
+
+void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr,
+ pte_t *ptep, pte_t old_pte, pte_t pte)
+{
+ if (radix_enabled())
+ return radix__ptep_modify_prot_commit(vma, addr,
+ ptep, old_pte, pte);
+ set_pte_at(vma->vm_mm, addr, ptep, pte);
+}
--- a/arch/powerpc/mm/pgtable-radix.c~arch-powerpc-mm-nest-mmu-workaround-for-mprotect-rw-upgrade
+++ a/arch/powerpc/mm/pgtable-radix.c
@@ -1052,3 +1052,21 @@ void radix__ptep_set_access_flags(struct
}
/* See ptesync comment in radix__set_pte_at */
}
+
+void radix__ptep_modify_prot_commit(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep,
+ pte_t old_pte, pte_t pte)
+{
+ struct mm_struct *mm = vma->vm_mm;
+
+ /*
+ * To avoid NMMU hang while relaxing access we need to flush the tlb before
+ * we set the new value. We need to do this only for radix, because hash
+ * translation does flush when updating the linux pte.
+ */
+ if (is_pte_rw_upgrade(pte_val(old_pte), pte_val(pte)) &&
+ (atomic_read(&mm->context.copros) > 0))
+ radix__flush_tlb_page(vma, addr);
+
+ set_pte_at(mm, addr, ptep, pte);
+}
_
Patches currently in -mm which might be from aneesh.kumar@xxxxxxxxxxxxx are
mm-update-ptep_modify_prot_start-commit-to-take-vm_area_struct-as-arg.patch
mm-update-ptep_modify_prot_commit-to-take-old-pte-value-as-arg.patch
arch-powerpc-mm-nest-mmu-workaround-for-mprotect-rw-upgrade.patch
mm-hugetlb-add-prot_modify_start-commit-sequence-for-hugetlb-update.patch
arch-powerpc-mm-hugetlb-nestmmu-workaround-for-hugetlb-mprotect-rw-upgrade.patch
