Commit 94171b19 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Michael Ellerman
Browse files

powerpc/mm: Rename find_linux_pte_or_hugepte() 



Add newer helpers to make the function usage simpler. It is always
recommended to use find_current_mm_pte() for walking the page table.
If we cannot use find_current_mm_pte(), it should be documented why
the said usage of __find_linux_pte() is safe against a parallel THP
split.

For now we have KVM code using __find_linux_pte(). This is because kvm
code ends up calling __find_linux_pte() in real mode with MSR_EE=0 but
with PACA soft_enabled = 1. We may want to fix that later and make
sure we keep the MSR_EE and PACA soft_enabled in sync. When we do that
we can switch kvm to use find_linux_pte().

Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 520eccdf

arch/powerpc/include/asm/pgtable.h

+1 −9
Original line number Diff line number Diff line
@@ -66,16 +66,8 @@ extern int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr, 
#ifndef CONFIG_TRANSPARENT_HUGEPAGE

#define pmd_large(pmd)		0

#endif

pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,

				   bool *is_thp, unsigned *shift);

static inline pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,

					       bool *is_thp, unsigned *shift)

{

	VM_WARN(!arch_irqs_disabled(),

		"%s called with irq enabled\n", __func__);

	return __find_linux_pte_or_hugepte(pgdir, ea, is_thp, shift);

}



/* can we use this in kvm */

unsigned long vmalloc_to_phys(void *vmalloc_addr);



void pgtable_cache_add(unsigned shift, void (*ctor)(void *));

arch/powerpc/include/asm/pte-walk.h

0 → 100644
+35 −0
Original line number Diff line number Diff line 
#ifndef _ASM_POWERPC_PTE_WALK_H

#define _ASM_POWERPC_PTE_WALK_H



#include <linux/sched.h>



/* Don't use this directly */

extern pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,

			       bool *is_thp, unsigned *hshift);



static inline pte_t *find_linux_pte(pgd_t *pgdir, unsigned long ea,

				    bool *is_thp, unsigned *hshift)

{

	VM_WARN(!arch_irqs_disabled(), "%s called with irq enabled\n", __func__);

	return __find_linux_pte(pgdir, ea, is_thp, hshift);

}



static inline pte_t *find_init_mm_pte(unsigned long ea, unsigned *hshift)

{

	pgd_t *pgdir = init_mm.pgd;

	return __find_linux_pte(pgdir, ea, NULL, hshift);

}

/*

 * This is what we should always use. Any other lockless page table lookup needs

 * careful audit against THP split.

 */

static inline pte_t *find_current_mm_pte(pgd_t *pgdir, unsigned long ea,

					 bool *is_thp, unsigned *hshift)

{

	VM_WARN(!arch_irqs_disabled(), "%s called with irq enabled\n", __func__);

	VM_WARN(pgdir != current->mm->pgd,

		"%s lock less page table lookup called on wrong mm\n", __func__);

	return __find_linux_pte(pgdir, ea, is_thp, hshift);

}



#endif /* _ASM_POWERPC_PTE_WALK_H */

arch/powerpc/kernel/eeh.c

+2 −2
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ 
#include <asm/machdep.h>

#include <asm/ppc-pci.h>

#include <asm/rtas.h>

#include <asm/pte-walk.h>





/** Overview:
@@ -352,8 +353,7 @@ static inline unsigned long eeh_token_to_phys(unsigned long token) 
	 * worried about _PAGE_SPLITTING/collapse. Also we will not hit

	 * page table free, because of init_mm.

	 */

	ptep = __find_linux_pte_or_hugepte(init_mm.pgd, token,

					   NULL, &hugepage_shift);

	ptep = find_init_mm_pte(token, &hugepage_shift);

	if (!ptep)

		return token;

	WARN_ON(hugepage_shift);

arch/powerpc/kernel/io-workarounds.c

+3 −2
Original line number Diff line number Diff line
@@ -19,6 +19,8 @@ 
#include <asm/pgtable.h>

#include <asm/ppc-pci.h>

#include <asm/io-workarounds.h>

#include <asm/pte-walk.h>





#define IOWA_MAX_BUS	8
@@ -75,8 +77,7 @@ struct iowa_bus *iowa_mem_find_bus(const PCI_IO_ADDR addr) 
		 * We won't find huge pages here (iomem). Also can't hit

		 * a page table free due to init_mm

		 */

		ptep = __find_linux_pte_or_hugepte(init_mm.pgd, vaddr,

						   NULL, &hugepage_shift);

		ptep = find_init_mm_pte(vaddr, &hugepage_shift);

		if (ptep == NULL)

			paddr = 0;

		else {

arch/powerpc/kvm/book3s_64_mmu_hv.c

+3 −2
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ 
#include <asm/synch.h>

#include <asm/ppc-opcode.h>

#include <asm/cputable.h>

#include <asm/pte-walk.h>



#include "trace_hv.h"
@@ -597,7 +598,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, 
			 * hugepage split and collapse.

			 */

			local_irq_save(flags);

			ptep = find_linux_pte_or_hugepte(current->mm->pgd,

			ptep = find_current_mm_pte(current->mm->pgd,

						   hva, NULL, NULL);

			if (ptep) {

				pte = kvmppc_read_update_linux_pte(ptep, 1);

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