From 94171b19c3f1f4d9d4c0e3aaa1aa161def1ec7ea Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Thu, 27 Jul 2017 11:54:53 +0530 Subject: 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: Aneesh Kumar K.V Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/pte-walk.h | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 arch/powerpc/include/asm/pte-walk.h (limited to 'arch/powerpc/include/asm/pte-walk.h') diff --git a/arch/powerpc/include/asm/pte-walk.h b/arch/powerpc/include/asm/pte-walk.h new file mode 100644 index 000000000000..2d633e9d686c --- /dev/null +++ b/arch/powerpc/include/asm/pte-walk.h @@ -0,0 +1,35 @@ +#ifndef _ASM_POWERPC_PTE_WALK_H +#define _ASM_POWERPC_PTE_WALK_H + +#include + +/* 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 */ -- cgit v1.2.3-59-g8ed1b