From c683c37cd13246941924c48f6c6a9863425e0cec Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 4 Dec 2018 13:37:06 -0800 Subject: generic/pgtable: Make {pmd, pud}_same() unconditionally available In preparation for {pmd,pud}_same() to be used outside of transparent huge page code paths, make them unconditionally available. This enables them to be used in the definition of a new family of set_{pte,pmd,pud,p4d,pgd}_safe() helpers. Signed-off-by: Dan Williams Acked-by: Kirill A. Shutemov Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Rik van Riel Cc: Sebastian Andrzej Siewior Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/154395942644.32119.10238934183949418128.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Ingo Molnar --- include/asm-generic/pgtable.h | 14 -------------- 1 file changed, 14 deletions(-) (limited to 'include/asm-generic') diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 359fb935ded6..eea50ef8b8cd 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -375,7 +375,6 @@ static inline int pte_unused(pte_t pte) #endif #ifndef __HAVE_ARCH_PMD_SAME -#ifdef CONFIG_TRANSPARENT_HUGEPAGE static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b) { return pmd_val(pmd_a) == pmd_val(pmd_b); @@ -385,19 +384,6 @@ static inline int pud_same(pud_t pud_a, pud_t pud_b) { return pud_val(pud_a) == pud_val(pud_b); } -#else /* CONFIG_TRANSPARENT_HUGEPAGE */ -static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b) -{ - BUILD_BUG(); - return 0; -} - -static inline int pud_same(pud_t pud_a, pud_t pud_b) -{ - BUILD_BUG(); - return 0; -} -#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ #endif #ifndef __HAVE_ARCH_DO_SWAP_PAGE -- cgit From 0cebbb60f759a709dabb3c87b9704f9844878850 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 4 Dec 2018 13:37:11 -0800 Subject: generic/pgtable: Introduce {p4d,pgd}_same() In preparation for introducing '_safe' versions of page table entry 'set' helpers, introduce generic versions of p4d_same() and pgd_same(). Signed-off-by: Dan Williams Acked-by: Kirill A. Shutemov Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Rik van Riel Cc: Sebastian Andrzej Siewior Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/154395943153.32119.1733586547359626311.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Ingo Molnar --- include/asm-generic/pgtable.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'include/asm-generic') diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index eea50ef8b8cd..dae7f98babed 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -386,6 +386,20 @@ static inline int pud_same(pud_t pud_a, pud_t pud_b) } #endif +#ifndef __HAVE_ARCH_P4D_SAME +static inline int p4d_same(p4d_t p4d_a, p4d_t p4d_b) +{ + return p4d_val(p4d_a) == p4d_val(p4d_b); +} +#endif + +#ifndef __HAVE_ARCH_PGD_SAME +static inline int pgd_same(pgd_t pgd_a, pgd_t pgd_b) +{ + return pgd_val(pgd_a) == pgd_val(pgd_b); +} +#endif + #ifndef __HAVE_ARCH_DO_SWAP_PAGE /* * Some architectures support metadata associated with a page. When a -- cgit From 4369deaa2f022ef92da45a0e7eec8a4a52e8e8a4 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 4 Dec 2018 13:37:16 -0800 Subject: generic/pgtable: Introduce set_pte_safe() Commit: f77084d96355 "x86/mm/pat: Disable preemption around __flush_tlb_all()" introduced a warning to capture cases __flush_tlb_all() is called without pre-emption disabled. It triggers a false positive warning in the memory hotplug path. On investigation it was found that the __flush_tlb_all() calls are not necessary. However, they are only "not necessary" in practice provided the ptes are being initially populated from the !present state. Introduce set_pte_safe() as a sanity check that the pte is being updated in a way that does not require a TLB flush. Forgive the macro, the availability of the various of set_pte() levels is hit and miss across architectures. [ mingo: Minor readability edits. ] Suggested-by: Peter Zijlstra Suggested-by: Dave Hansen Signed-off-by: Dan Williams Acked-by: Peter Zijlstra (Intel) Acked-by: Kirill A. Shutemov Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Rik van Riel Cc: Sebastian Andrzej Siewior Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/279dadae-9148-465c-7ec6-3f37e026c6c9@intel.com Signed-off-by: Ingo Molnar --- include/asm-generic/pgtable.h | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) (limited to 'include/asm-generic') diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index dae7f98babed..a9cac82e9a7a 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -400,6 +400,44 @@ static inline int pgd_same(pgd_t pgd_a, pgd_t pgd_b) } #endif +/* + * Use set_p*_safe(), and elide TLB flushing, when confident that *no* + * TLB flush will be required as a result of the "set". For example, use + * in scenarios where it is known ahead of time that the routine is + * setting non-present entries, or re-setting an existing entry to the + * same value. Otherwise, use the typical "set" helpers and flush the + * TLB. + */ +#define set_pte_safe(ptep, pte) \ +({ \ + WARN_ON_ONCE(pte_present(*ptep) && !pte_same(*ptep, pte)); \ + set_pte(ptep, pte); \ +}) + +#define set_pmd_safe(pmdp, pmd) \ +({ \ + WARN_ON_ONCE(pmd_present(*pmdp) && !pmd_same(*pmdp, pmd)); \ + set_pmd(pmdp, pmd); \ +}) + +#define set_pud_safe(pudp, pud) \ +({ \ + WARN_ON_ONCE(pud_present(*pudp) && !pud_same(*pudp, pud)); \ + set_pud(pudp, pud); \ +}) + +#define set_p4d_safe(p4dp, p4d) \ +({ \ + WARN_ON_ONCE(p4d_present(*p4dp) && !p4d_same(*p4dp, p4d)); \ + set_p4d(p4dp, p4d); \ +}) + +#define set_pgd_safe(pgdp, pgd) \ +({ \ + WARN_ON_ONCE(pgd_present(*pgdp) && !pgd_same(*pgdp, pgd)); \ + set_pgd(pgdp, pgd); \ +}) + #ifndef __HAVE_ARCH_DO_SWAP_PAGE /* * Some architectures support metadata associated with a page. When a -- cgit From 0a9fe8ca844d43f3f547f0e166122b6048121c8f Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 4 Dec 2018 13:37:21 -0800 Subject: x86/mm: Validate kernel_physical_mapping_init() PTE population The usage of __flush_tlb_all() in the kernel_physical_mapping_init() path is not necessary. In general flushing the TLB is not required when updating an entry from the !present state. However, to give confidence in the future removal of TLB flushing in this path, use the new set_pte_safe() family of helpers to assert that the !present assumption is true in this path. [ mingo: Minor readability edits. ] Suggested-by: Peter Zijlstra Suggested-by: Dave Hansen Signed-off-by: Dan Williams Acked-by: Kirill A. Shutemov Acked-by: Peter Zijlstra (Intel) Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Rik van Riel Cc: Sebastian Andrzej Siewior Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/154395944177.32119.8524957429632012270.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Ingo Molnar --- include/asm-generic/5level-fixup.h | 1 + include/asm-generic/pgtable-nop4d-hack.h | 1 + include/asm-generic/pgtable-nop4d.h | 1 + include/asm-generic/pgtable-nopud.h | 1 + 4 files changed, 4 insertions(+) (limited to 'include/asm-generic') diff --git a/include/asm-generic/5level-fixup.h b/include/asm-generic/5level-fixup.h index 73474bb52344..bb6cb347018c 100644 --- a/include/asm-generic/5level-fixup.h +++ b/include/asm-generic/5level-fixup.h @@ -26,6 +26,7 @@ #define p4d_clear(p4d) pgd_clear(p4d) #define p4d_val(p4d) pgd_val(p4d) #define p4d_populate(mm, p4d, pud) pgd_populate(mm, p4d, pud) +#define p4d_populate_safe(mm, p4d, pud) pgd_populate(mm, p4d, pud) #define p4d_page(p4d) pgd_page(p4d) #define p4d_page_vaddr(p4d) pgd_page_vaddr(p4d) diff --git a/include/asm-generic/pgtable-nop4d-hack.h b/include/asm-generic/pgtable-nop4d-hack.h index 1d6dd38c0e5e..829bdb0d6327 100644 --- a/include/asm-generic/pgtable-nop4d-hack.h +++ b/include/asm-generic/pgtable-nop4d-hack.h @@ -31,6 +31,7 @@ static inline void pgd_clear(pgd_t *pgd) { } #define pud_ERROR(pud) (pgd_ERROR((pud).pgd)) #define pgd_populate(mm, pgd, pud) do { } while (0) +#define pgd_populate_safe(mm, pgd, pud) do { } while (0) /* * (puds are folded into pgds so this doesn't get actually called, * but the define is needed for a generic inline function.) diff --git a/include/asm-generic/pgtable-nop4d.h b/include/asm-generic/pgtable-nop4d.h index 04cb913797bc..aebab905e6cd 100644 --- a/include/asm-generic/pgtable-nop4d.h +++ b/include/asm-generic/pgtable-nop4d.h @@ -26,6 +26,7 @@ static inline void pgd_clear(pgd_t *pgd) { } #define p4d_ERROR(p4d) (pgd_ERROR((p4d).pgd)) #define pgd_populate(mm, pgd, p4d) do { } while (0) +#define pgd_populate_safe(mm, pgd, p4d) do { } while (0) /* * (p4ds are folded into pgds so this doesn't get actually called, * but the define is needed for a generic inline function.) diff --git a/include/asm-generic/pgtable-nopud.h b/include/asm-generic/pgtable-nopud.h index 9bef475db6fe..c77a1d301155 100644 --- a/include/asm-generic/pgtable-nopud.h +++ b/include/asm-generic/pgtable-nopud.h @@ -35,6 +35,7 @@ static inline void p4d_clear(p4d_t *p4d) { } #define pud_ERROR(pud) (p4d_ERROR((pud).p4d)) #define p4d_populate(mm, p4d, pud) do { } while (0) +#define p4d_populate_safe(mm, p4d, pud) do { } while (0) /* * (puds are folded into p4ds so this doesn't get actually called, * but the define is needed for a generic inline function.) -- cgit