Commit 5b323367 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Linus Torvalds
Browse files

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
bd5050e3 ("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@linux.ibm.com


Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 04a86453

arch/powerpc/include/asm/book3s/64/pgtable.h

+18 −0
Original line number Diff line number Diff line
@@ -1306,6 +1306,24 @@ 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_ */

arch/powerpc/include/asm/book3s/64/radix.h

+4 −0
Original line number Diff line number Diff line
@@ -127,6 +127,10 @@ extern void radix__ptep_set_access_flags(struct vm_area_struct *vma, pte_t *ptep 
					 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)

{

arch/powerpc/mm/pgtable-book3s64.c

+25 −0
Original line number Diff line number Diff line
@@ -401,6 +401,31 @@ void arch_report_meminfo(struct seq_file *m) 
}

#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);

}



/*

 * For hash translation mode, we use the deposited table to store hash slot

 * information and they are stored at PTRS_PER_PMD offset from related pmd

arch/powerpc/mm/pgtable-radix.c

+18 −0
Original line number Diff line number Diff line
@@ -1063,3 +1063,21 @@ void radix__ptep_set_access_flags(struct vm_area_struct *vma, pte_t *ptep, 
	}

	/* 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);

}

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