| From fc7092ad0e486be40ac838e74708ea542aada9ce Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Wed, 24 Feb 2021 12:01:32 -0800 |
| Subject: mm/debug_vm_pgtable/basic: add validation for dirtiness after write |
| protect |
| |
| From: Anshuman Khandual <anshuman.khandual@arm.com> |
| |
| [ Upstream commit bb5c47ced46797409f4791d0380db3116d93134c ] |
| |
| Patch series "mm/debug_vm_pgtable: Some minor updates", v3. |
| |
| This series contains some cleanups and new test suggestions from Catalin |
| from an earlier discussion. |
| |
| https://lore.kernel.org/linux-mm/20201123142237.GF17833@gaia/ |
| |
| This patch (of 2): |
| |
| This adds validation tests for dirtiness after write protect conversion |
| for each page table level. There are two new separate test types involved |
| here. |
| |
| The first test ensures that a given page table entry does not become dirty |
| after pxx_wrprotect(). This is important for platforms like arm64 which |
| transfers and drops the hardware dirty bit (!PTE_RDONLY) to the software |
| dirty bit while making it an write protected one. This test ensures that |
| no fresh page table entry could be created with hardware dirty bit set. |
| The second test ensures that a given page table entry always preserve the |
| dirty information across pxx_wrprotect(). |
| |
| This adds two previously missing PUD level basic tests and while here |
| fixes pxx_wrprotect() related typos in the documentation file. |
| |
| Link: https://lkml.kernel.org/r/1611137241-26220-1-git-send-email-anshuman.khandual@arm.com |
| Link: https://lkml.kernel.org/r/1611137241-26220-2-git-send-email-anshuman.khandual@arm.com |
| Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> |
| Suggested-by: Catalin Marinas <catalin.marinas@arm.com> |
| Tested-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390] |
| Cc: Christophe Leroy <christophe.leroy@csgroup.eu> |
| Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> |
| Cc: Vineet Gupta <vgupta@synopsys.com> |
| Cc: Paul Walmsley <paul.walmsley@sifive.com> |
| Cc: Steven Price <steven.price@arm.com> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| Documentation/vm/arch_pgtable_helpers.rst | 8 ++--- |
| mm/debug_vm_pgtable.c | 39 +++++++++++++++++++++++ |
| 2 files changed, 43 insertions(+), 4 deletions(-) |
| |
| diff --git a/Documentation/vm/arch_pgtable_helpers.rst b/Documentation/vm/arch_pgtable_helpers.rst |
| index f3591ee3aaa8..552567d863b8 100644 |
| --- a/Documentation/vm/arch_pgtable_helpers.rst |
| +++ b/Documentation/vm/arch_pgtable_helpers.rst |
| @@ -50,7 +50,7 @@ PTE Page Table Helpers |
| +---------------------------+--------------------------------------------------+ |
| | pte_mkwrite | Creates a writable PTE | |
| +---------------------------+--------------------------------------------------+ |
| -| pte_mkwrprotect | Creates a write protected PTE | |
| +| pte_wrprotect | Creates a write protected PTE | |
| +---------------------------+--------------------------------------------------+ |
| | pte_mkspecial | Creates a special PTE | |
| +---------------------------+--------------------------------------------------+ |
| @@ -120,7 +120,7 @@ PMD Page Table Helpers |
| +---------------------------+--------------------------------------------------+ |
| | pmd_mkwrite | Creates a writable PMD | |
| +---------------------------+--------------------------------------------------+ |
| -| pmd_mkwrprotect | Creates a write protected PMD | |
| +| pmd_wrprotect | Creates a write protected PMD | |
| +---------------------------+--------------------------------------------------+ |
| | pmd_mkspecial | Creates a special PMD | |
| +---------------------------+--------------------------------------------------+ |
| @@ -186,7 +186,7 @@ PUD Page Table Helpers |
| +---------------------------+--------------------------------------------------+ |
| | pud_mkwrite | Creates a writable PUD | |
| +---------------------------+--------------------------------------------------+ |
| -| pud_mkwrprotect | Creates a write protected PUD | |
| +| pud_wrprotect | Creates a write protected PUD | |
| +---------------------------+--------------------------------------------------+ |
| | pud_mkdevmap | Creates a ZONE_DEVICE mapped PUD | |
| +---------------------------+--------------------------------------------------+ |
| @@ -224,7 +224,7 @@ HugeTLB Page Table Helpers |
| +---------------------------+--------------------------------------------------+ |
| | huge_pte_mkwrite | Creates a writable HugeTLB | |
| +---------------------------+--------------------------------------------------+ |
| -| huge_pte_mkwrprotect | Creates a write protected HugeTLB | |
| +| huge_pte_wrprotect | Creates a write protected HugeTLB | |
| +---------------------------+--------------------------------------------------+ |
| | huge_ptep_get_and_clear | Clears a HugeTLB | |
| +---------------------------+--------------------------------------------------+ |
| diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c |
| index 750bfef26be3..79480fd18443 100644 |
| --- a/mm/debug_vm_pgtable.c |
| +++ b/mm/debug_vm_pgtable.c |
| @@ -63,6 +63,16 @@ static void __init pte_basic_tests(unsigned long pfn, pgprot_t prot) |
| pte_t pte = pfn_pte(pfn, prot); |
| |
| pr_debug("Validating PTE basic\n"); |
| + |
| + /* |
| + * This test needs to be executed after the given page table entry |
| + * is created with pfn_pte() to make sure that protection_map[idx] |
| + * does not have the dirty bit enabled from the beginning. This is |
| + * important for platforms like arm64 where (!PTE_RDONLY) indicate |
| + * dirty bit being set. |
| + */ |
| + WARN_ON(pte_dirty(pte_wrprotect(pte))); |
| + |
| WARN_ON(!pte_same(pte, pte)); |
| WARN_ON(!pte_young(pte_mkyoung(pte_mkold(pte)))); |
| WARN_ON(!pte_dirty(pte_mkdirty(pte_mkclean(pte)))); |
| @@ -70,6 +80,8 @@ static void __init pte_basic_tests(unsigned long pfn, pgprot_t prot) |
| WARN_ON(pte_young(pte_mkold(pte_mkyoung(pte)))); |
| WARN_ON(pte_dirty(pte_mkclean(pte_mkdirty(pte)))); |
| WARN_ON(pte_write(pte_wrprotect(pte_mkwrite(pte)))); |
| + WARN_ON(pte_dirty(pte_wrprotect(pte_mkclean(pte)))); |
| + WARN_ON(!pte_dirty(pte_wrprotect(pte_mkdirty(pte)))); |
| } |
| |
| static void __init pte_advanced_tests(struct mm_struct *mm, |
| @@ -137,6 +149,17 @@ static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot) |
| return; |
| |
| pr_debug("Validating PMD basic\n"); |
| + |
| + /* |
| + * This test needs to be executed after the given page table entry |
| + * is created with pfn_pmd() to make sure that protection_map[idx] |
| + * does not have the dirty bit enabled from the beginning. This is |
| + * important for platforms like arm64 where (!PTE_RDONLY) indicate |
| + * dirty bit being set. |
| + */ |
| + WARN_ON(pmd_dirty(pmd_wrprotect(pmd))); |
| + |
| + |
| WARN_ON(!pmd_same(pmd, pmd)); |
| WARN_ON(!pmd_young(pmd_mkyoung(pmd_mkold(pmd)))); |
| WARN_ON(!pmd_dirty(pmd_mkdirty(pmd_mkclean(pmd)))); |
| @@ -144,6 +167,8 @@ static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot) |
| WARN_ON(pmd_young(pmd_mkold(pmd_mkyoung(pmd)))); |
| WARN_ON(pmd_dirty(pmd_mkclean(pmd_mkdirty(pmd)))); |
| WARN_ON(pmd_write(pmd_wrprotect(pmd_mkwrite(pmd)))); |
| + WARN_ON(pmd_dirty(pmd_wrprotect(pmd_mkclean(pmd)))); |
| + WARN_ON(!pmd_dirty(pmd_wrprotect(pmd_mkdirty(pmd)))); |
| /* |
| * A huge page does not point to next level page table |
| * entry. Hence this must qualify as pmd_bad(). |
| @@ -257,11 +282,25 @@ static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot) |
| return; |
| |
| pr_debug("Validating PUD basic\n"); |
| + |
| + /* |
| + * This test needs to be executed after the given page table entry |
| + * is created with pfn_pud() to make sure that protection_map[idx] |
| + * does not have the dirty bit enabled from the beginning. This is |
| + * important for platforms like arm64 where (!PTE_RDONLY) indicate |
| + * dirty bit being set. |
| + */ |
| + WARN_ON(pud_dirty(pud_wrprotect(pud))); |
| + |
| WARN_ON(!pud_same(pud, pud)); |
| WARN_ON(!pud_young(pud_mkyoung(pud_mkold(pud)))); |
| + WARN_ON(!pud_dirty(pud_mkdirty(pud_mkclean(pud)))); |
| + WARN_ON(pud_dirty(pud_mkclean(pud_mkdirty(pud)))); |
| WARN_ON(!pud_write(pud_mkwrite(pud_wrprotect(pud)))); |
| WARN_ON(pud_write(pud_wrprotect(pud_mkwrite(pud)))); |
| WARN_ON(pud_young(pud_mkold(pud_mkyoung(pud)))); |
| + WARN_ON(pud_dirty(pud_wrprotect(pud_mkclean(pud)))); |
| + WARN_ON(!pud_dirty(pud_wrprotect(pud_mkdirty(pud)))); |
| |
| if (mm_pmd_folded(mm)) |
| return; |
| -- |
| 2.30.2 |
| |
