From: Steven Price <steven.price@arm.com> To: Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org Cc: "Steven Price" <steven.price@arm.com>, "Andy Lutomirski" <luto@kernel.org>, "Ard Biesheuvel" <ard.biesheuvel@linaro.org>, "Arnd Bergmann" <arnd@arndb.de>, "Borislav Petkov" <bp@alien8.de>, "Catalin Marinas" <catalin.marinas@arm.com>, "Dave Hansen" <dave.hansen@linux.intel.com>, "Ingo Molnar" <mingo@redhat.com>, "James Morse" <james.morse@arm.com>, "Jérôme Glisse" <jglisse@redhat.com>, "Peter Zijlstra" <peterz@infradead.org>, "Thomas Gleixner" <tglx@linutronix.de>, "Will Deacon" <will@kernel.org>, x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, "Mark Rutland" <Mark.Rutland@arm.com>, "Liang, Kan" <kan.liang@linux.intel.com> Subject: [PATCH v16 13/25] mm: pagewalk: Don't lock PTEs for walk_page_range_novma() Date: Fri, 6 Dec 2019 13:53:04 +0000 [thread overview] Message-ID: <20191206135316.47703-14-steven.price@arm.com> (raw) In-Reply-To: <20191206135316.47703-1-steven.price@arm.com> walk_page_range_novma() can be used to walk page tables or the kernel or for firmware. These page tables may contain entries that are not backed by a struct page and so it isn't (in general) possible to take the PTE lock for the pte_entry() callback. So update walk_pte_range() to only take the lock when no_vma==false and add a comment explaining the difference to walk_page_range_novma(). Signed-off-by: Steven Price <steven.price@arm.com> --- mm/pagewalk.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/mm/pagewalk.c b/mm/pagewalk.c index efa464cf079b..1b9a3ba24c51 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -10,9 +10,10 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, pte_t *pte; int err = 0; const struct mm_walk_ops *ops = walk->ops; - spinlock_t *ptl; + spinlock_t *uninitialized_var(ptl); - pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); + pte = walk->no_vma ? pte_offset_map(pmd, addr) : + pte_offset_map_lock(walk->mm, pmd, addr, &ptl); for (;;) { err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk); if (err) @@ -23,7 +24,9 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, pte++; } - pte_unmap_unlock(pte, ptl); + if (!walk->no_vma) + spin_unlock(ptl); + pte_unmap(pte); return err; } @@ -383,6 +386,12 @@ int walk_page_range(struct mm_struct *mm, unsigned long start, return err; } +/* + * Similar to walk_page_range() but can walk any page tables even if they are + * not backed by VMAs. Because 'unusual' entries may be walked this function + * will also not lock the PTEs for the pte_entry() callback. This is useful for + * walking the kernel pages tables or page tables for firmware. + */ int walk_page_range_novma(struct mm_struct *mm, unsigned long start, unsigned long end, const struct mm_walk_ops *ops, void *private) -- 2.20.1
WARNING: multiple messages have this Message-ID (diff)
From: Steven Price <steven.price@arm.com> To: Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org Cc: "Mark Rutland" <Mark.Rutland@arm.com>, x86@kernel.org, "Arnd Bergmann" <arnd@arndb.de>, "Ard Biesheuvel" <ard.biesheuvel@linaro.org>, "Peter Zijlstra" <peterz@infradead.org>, "Catalin Marinas" <catalin.marinas@arm.com>, "Dave Hansen" <dave.hansen@linux.intel.com>, linux-kernel@vger.kernel.org, "Steven Price" <steven.price@arm.com>, "Jérôme Glisse" <jglisse@redhat.com>, "Ingo Molnar" <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>, "Andy Lutomirski" <luto@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>, "James Morse" <james.morse@arm.com>, "Thomas Gleixner" <tglx@linutronix.de>, "Will Deacon" <will@kernel.org>, linux-arm-kernel@lists.infradead.org, "Liang, Kan" <kan.liang@linux.intel.com> Subject: [PATCH v16 13/25] mm: pagewalk: Don't lock PTEs for walk_page_range_novma() Date: Fri, 6 Dec 2019 13:53:04 +0000 [thread overview] Message-ID: <20191206135316.47703-14-steven.price@arm.com> (raw) In-Reply-To: <20191206135316.47703-1-steven.price@arm.com> walk_page_range_novma() can be used to walk page tables or the kernel or for firmware. These page tables may contain entries that are not backed by a struct page and so it isn't (in general) possible to take the PTE lock for the pte_entry() callback. So update walk_pte_range() to only take the lock when no_vma==false and add a comment explaining the difference to walk_page_range_novma(). Signed-off-by: Steven Price <steven.price@arm.com> --- mm/pagewalk.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/mm/pagewalk.c b/mm/pagewalk.c index efa464cf079b..1b9a3ba24c51 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -10,9 +10,10 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, pte_t *pte; int err = 0; const struct mm_walk_ops *ops = walk->ops; - spinlock_t *ptl; + spinlock_t *uninitialized_var(ptl); - pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); + pte = walk->no_vma ? pte_offset_map(pmd, addr) : + pte_offset_map_lock(walk->mm, pmd, addr, &ptl); for (;;) { err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk); if (err) @@ -23,7 +24,9 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, pte++; } - pte_unmap_unlock(pte, ptl); + if (!walk->no_vma) + spin_unlock(ptl); + pte_unmap(pte); return err; } @@ -383,6 +386,12 @@ int walk_page_range(struct mm_struct *mm, unsigned long start, return err; } +/* + * Similar to walk_page_range() but can walk any page tables even if they are + * not backed by VMAs. Because 'unusual' entries may be walked this function + * will also not lock the PTEs for the pte_entry() callback. This is useful for + * walking the kernel pages tables or page tables for firmware. + */ int walk_page_range_novma(struct mm_struct *mm, unsigned long start, unsigned long end, const struct mm_walk_ops *ops, void *private) -- 2.20.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-12-06 13:55 UTC|newest] Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-12-06 13:52 [PATCH v16 00/25] Generic page walk and ptdump Steven Price 2019-12-06 13:52 ` Steven Price 2019-12-06 13:52 ` [PATCH v16 01/25] mm: Add generic p?d_leaf() macros Steven Price 2019-12-06 13:52 ` Steven Price 2019-12-06 13:52 ` [PATCH v16 02/25] arc: mm: Add p?d_leaf() definitions Steven Price 2019-12-06 13:52 ` Steven Price 2019-12-06 13:52 ` Steven Price 2019-12-06 13:52 ` [PATCH v16 03/25] arm: " Steven Price 2019-12-06 13:52 ` Steven Price 2019-12-06 13:52 ` [PATCH v16 04/25] arm64: " Steven Price 2019-12-06 13:52 ` Steven Price 2019-12-06 13:52 ` [PATCH v16 05/25] mips: " Steven Price 2019-12-06 13:52 ` Steven Price 2019-12-06 13:52 ` [PATCH v16 06/25] powerpc: " Steven Price 2019-12-06 13:52 ` Steven Price 2019-12-06 13:52 ` Steven Price 2019-12-06 13:52 ` Steven Price 2019-12-09 11:08 ` Michael Ellerman 2019-12-09 11:08 ` Michael Ellerman 2019-12-09 11:08 ` Michael Ellerman 2019-12-09 11:08 ` Michael Ellerman 2019-12-09 13:06 ` Steven Price 2019-12-09 13:06 ` Steven Price 2019-12-09 13:06 ` Steven Price 2019-12-09 13:06 ` Steven Price 2019-12-06 13:52 ` [PATCH v16 07/25] riscv: " Steven Price 2019-12-06 13:52 ` Steven Price 2019-12-06 13:52 ` Steven Price 2019-12-06 13:52 ` [PATCH v16 08/25] s390: " Steven Price 2019-12-06 13:52 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 09/25] sparc: " Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 10/25] x86: " Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 11/25] mm: pagewalk: Add p4d_entry() and pgd_entry() Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-12 11:23 ` Thomas Hellström (VMware) 2019-12-12 11:23 ` Thomas Hellström (VMware) 2019-12-12 11:33 ` Thomas Hellström (VMware) 2019-12-12 11:33 ` Thomas Hellström (VMware) 2019-12-12 13:15 ` Steven Price 2019-12-12 13:15 ` Steven Price 2019-12-12 14:04 ` Thomas Hellström (VMware) 2019-12-12 14:04 ` Thomas Hellström (VMware) 2019-12-12 15:18 ` Steven Price 2019-12-12 15:18 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 12/25] mm: pagewalk: Allow walking without vma Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` Steven Price [this message] 2019-12-06 13:53 ` [PATCH v16 13/25] mm: pagewalk: Don't lock PTEs for walk_page_range_novma() Steven Price 2019-12-10 11:23 ` kbuild test robot 2019-12-10 11:23 ` kbuild test robot 2019-12-10 11:23 ` kbuild test robot 2019-12-11 15:54 ` Steven Price 2019-12-11 15:54 ` Steven Price 2019-12-11 15:54 ` Steven Price 2019-12-11 17:12 ` Luc Van Oostenryck 2019-12-11 17:12 ` Luc Van Oostenryck 2019-12-11 17:19 ` Qian Cai 2019-12-11 17:19 ` Qian Cai 2019-12-06 13:53 ` [PATCH v16 14/25] mm: pagewalk: fix termination condition in walk_pte_range() Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 15/25] mm: pagewalk: Add test_p?d callbacks Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 16/25] mm: pagewalk: Add 'depth' parameter to pte_hole Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 17/25] x86: mm: Point to struct seq_file from struct pg_state Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 18/25] x86: mm+efi: Convert ptdump_walk_pgd_level() to take a mm_struct Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 19/25] x86: mm: Convert ptdump_walk_pgd_level_debugfs() to take an mm_struct Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 20/25] x86: mm: Convert ptdump_walk_pgd_level_core() " Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 21/25] mm: Add generic ptdump Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 22/25] x86: mm: Convert dump_pagetables to use walk_page_range Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 23/25] arm64: mm: Convert mm/dump.c to use walk_page_range() Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 24/25] arm64: mm: Display non-present entries in ptdump Steven Price 2019-12-06 13:53 ` Steven Price 2019-12-06 13:53 ` [PATCH v16 25/25] mm: ptdump: Reduce level numbers by 1 in note_page() Steven Price 2019-12-06 13:53 ` Steven Price
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