The patch titled
Subject: mm/debug_vm_pgtable: introduce struct vm_pgtable_debug
has been added to the -mm tree. Its filename is
mm-debug_vm_pgtable-introduce-struct-vm_pgtable_debug.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-debug_vm_pgtable-introduce-struct-vm_pgtable_debug.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-debug_vm_pgtable-introduce-struct-vm_pgtable_debug.patch
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------------------------------------------------------
From: Gavin Shan <gshan@xxxxxxxxxx>
Subject: mm/debug_vm_pgtable: introduce struct vm_pgtable_debug
Patch series "mm/debug_vm_pgtable: Enhancements".
There are couple of issues with current implementations and this series
tries to resolve the issues:
(a) All needed information are scattered in variables, passed to various
test functions. The code is organized in pretty much relaxed fashion.
(b) The page isn't allocated from buddy during page table entry modifying
tests. The page can be invalid, conflicting to the implementations
of set_{pud, pmd, pte}_at() on ARM64. The target page is accessed
so that the iCache can be flushed when execution permission is given
on ARM64. Besides, the target page can be unmapped and access to
it causes kernel crash.
"struct vm_pgtable_debug" is introduced to address issue (a). For issue
(b), the used page is allocated from buddy in page table entry modifying
tests. The corresponding tets will be skipped if we fail to allocate the
(huge) page. For other test cases, the original page around to kernel
symbol (@start_kernel) is still used.
This patch (of 12):
In debug_vm_pgtable(), there are many local variables introduced to track
the needed information and they are passed to the functions for various
test cases. It'd better to introduce a struct as place holder for these
information. With it, what the functions for various test cases need is
the struct, to simplify the code. It makes the code easier to be
maintained.
Besides, set_pte_at() could access the data on the corresponding pages.
So the test cases using set_pte_at() should have the pages allocated from
buddy. Otherwise, we're acceessing pages that aren't owned by us. This
causes issues like page flag corruption. So we need the allocated pages
for these tests where set_pte_at() is used. The struct is introduced so
that the old and new implementation can coexist so that the patches can be
organized in a easy way.
This introduces "struct vm_pgtable_debug" for above purposes. The struct
is initialized and destroyed, but the information in the struct isn't used
yet. They will be used in subsequent patches.
Link: https://lkml.kernel.org/r/20210706061748.161258-1-gshan@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20210706061748.161258-2-gshan@xxxxxxxxxx
Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Chunyu Hu <chuhu@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/debug_vm_pgtable.c | 210 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 209 insertions(+), 1 deletion(-)
--- a/mm/debug_vm_pgtable.c~mm-debug_vm_pgtable-introduce-struct-vm_pgtable_debug
+++ a/mm/debug_vm_pgtable.c
@@ -58,6 +58,36 @@
#define RANDOM_ORVALUE (GENMASK(BITS_PER_LONG - 1, 0) & ~ARCH_SKIP_MASK)
#define RANDOM_NZVALUE GENMASK(7, 0)
+struct vm_pgtable_debug {
+ struct mm_struct *mm;
+ struct vm_area_struct *vma;
+
+ pgd_t *pgdp;
+ p4d_t *p4dp;
+ pud_t *pudp;
+ pmd_t *pmdp;
+ pte_t *ptep;
+
+ p4d_t *start_p4dp;
+ pud_t *start_pudp;
+ pmd_t *start_pmdp;
+ pgtable_t start_ptep;
+
+ unsigned long vaddr;
+ pgprot_t page_prot;
+ pgprot_t page_prot_none;
+
+ unsigned long pud_pfn;
+ unsigned long pmd_pfn;
+ unsigned long pte_pfn;
+
+ unsigned long fixed_pgd_pfn;
+ unsigned long fixed_p4d_pfn;
+ unsigned long fixed_pud_pfn;
+ unsigned long fixed_pmd_pfn;
+ unsigned long fixed_pte_pfn;
+};
+
static void __init pte_basic_tests(unsigned long pfn, int idx)
{
pgprot_t prot = protection_map[idx];
@@ -955,8 +985,180 @@ static unsigned long __init get_random_v
return random_vaddr;
}
+static void __init free_mem(struct vm_pgtable_debug *debug)
+{
+ struct page *page = NULL;
+ int order = 0;
+
+ /* Free (huge) page */
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+ if (has_transparent_hugepage() &&
+ debug->pud_pfn != ULONG_MAX) {
+ page = pfn_to_page(debug->pud_pfn);
+ order = HPAGE_PUD_SHIFT - PAGE_SHIFT;
+ }
+#endif
+
+ if (has_transparent_hugepage() &&
+ debug->pmd_pfn != ULONG_MAX && !page) {
+ page = pfn_to_page(debug->pmd_pfn);
+ order = HPAGE_PMD_ORDER;
+ }
+#endif
+
+ if (debug->pte_pfn != ULONG_MAX && !page) {
+ page = pfn_to_page(debug->pte_pfn);
+ order = 0;
+ }
+
+ if (page)
+ __free_pages(page, order);
+
+ /* Free page table */
+ if (debug->start_ptep) {
+ pte_free(debug->mm, debug->start_ptep);
+ mm_dec_nr_ptes(debug->mm);
+ }
+
+ if (debug->start_pmdp) {
+ pmd_free(debug->mm, debug->start_pmdp);
+ mm_dec_nr_pmds(debug->mm);
+ }
+
+ if (debug->start_pudp) {
+ pud_free(debug->mm, debug->start_pudp);
+ mm_dec_nr_puds(debug->mm);
+ }
+
+ if (debug->start_p4dp)
+ p4d_free(debug->mm, debug->p4dp);
+
+ /* Free vma and mm struct */
+ if (debug->vma)
+ vm_area_free(debug->vma);
+ if (debug->mm)
+ mmdrop(debug->mm);
+}
+
+static int __init alloc_mem(struct vm_pgtable_debug *debug)
+{
+ struct page *page = NULL;
+ phys_addr_t phys;
+ int ret = 0;
+
+ /* Initialize the debugging data */
+ debug->mm = NULL;
+ debug->vma = NULL;
+ debug->pgdp = NULL;
+ debug->p4dp = NULL;
+ debug->pudp = NULL;
+ debug->pmdp = NULL;
+ debug->ptep = NULL;
+ debug->start_p4dp = NULL;
+ debug->start_pudp = NULL;
+ debug->start_pmdp = NULL;
+ debug->start_ptep = NULL;
+ debug->vaddr = 0UL;
+ debug->page_prot = vm_get_page_prot(VM_READ | VM_WRITE | VM_EXEC);
+ debug->page_prot_none = __P000;
+ debug->pud_pfn = ULONG_MAX;
+ debug->pmd_pfn = ULONG_MAX;
+ debug->pte_pfn = ULONG_MAX;
+ debug->fixed_pgd_pfn = ULONG_MAX;
+ debug->fixed_p4d_pfn = ULONG_MAX;
+ debug->fixed_pud_pfn = ULONG_MAX;
+ debug->fixed_pmd_pfn = ULONG_MAX;
+ debug->fixed_pte_pfn = ULONG_MAX;
+
+ /* Allocate mm and vma */
+ debug->mm = mm_alloc();
+ if (!debug->mm) {
+ pr_warn("Failed to allocate mm struct\n");
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ debug->vma = vm_area_alloc(debug->mm);
+ if (!debug->vma) {
+ pr_warn("Failed to allocate vma\n");
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ /* Figure out the virtual address and allocate page table entries */
+ debug->vaddr = get_random_vaddr();
+ debug->pgdp = pgd_offset(debug->mm, debug->vaddr);
+ debug->p4dp = p4d_alloc(debug->mm, debug->pgdp, debug->vaddr);
+ debug->pudp = debug->p4dp ?
+ pud_alloc(debug->mm, debug->p4dp, debug->vaddr) : NULL;
+ debug->pmdp = debug->pudp ?
+ pmd_alloc(debug->mm, debug->pudp, debug->vaddr) : NULL;
+ debug->ptep = debug->pmdp ?
+ pte_alloc_map(debug->mm, debug->pmdp, debug->vaddr) : NULL;
+ if (!debug->ptep) {
+ pr_warn("Failed to allocate page table\n");
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ /*
+ * The above page table entries will be modified. Lets save the
+ * page table entries so that they can be released when the tests
+ * are completed.
+ */
+ debug->start_p4dp = p4d_offset(debug->pgdp, 0UL);
+ debug->start_pudp = pud_offset(debug->p4dp, 0UL);
+ debug->start_pmdp = pmd_offset(debug->pudp, 0UL);
+ debug->start_ptep = pmd_pgtable(*(debug->pmdp));
+
+ /*
+ * Figure out the fixed addresses, which are all around the kernel
+ * symbol (@start_kernel). The corresponding PFNs might be invalid,
+ * but it's fine as the following tests won't access the pages.
+ */
+ phys = __pa_symbol(&start_kernel);
+ debug->fixed_pgd_pfn = __phys_to_pfn(phys & PGDIR_MASK);
+ debug->fixed_p4d_pfn = __phys_to_pfn(phys & P4D_MASK);
+ debug->fixed_pud_pfn = __phys_to_pfn(phys & PUD_MASK);
+ debug->fixed_pmd_pfn = __phys_to_pfn(phys & PMD_MASK);
+ debug->fixed_pte_pfn = __phys_to_pfn(phys & PAGE_MASK);
+
+ /*
+ * Allocate (huge) pages because some of the tests need to access
+ * the data in the pages. The corresponding tests will be skipped
+ * if we fail to allocate (huge) pages.
+ */
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+ if (has_transparent_hugepage()) {
+ page = alloc_pages(GFP_KERNEL, HPAGE_PUD_SHIFT - PAGE_SHIFT);
+ if (page)
+ debug->pud_pfn = page_to_pfn(page);
+ }
+#endif
+
+ if (has_transparent_hugepage()) {
+ page = page ? page : alloc_pages(GFP_KERNEL, HPAGE_PMD_ORDER);
+ if (page)
+ debug->pmd_pfn = page_to_pfn(page);
+ }
+#endif
+
+ page = page ? page : alloc_pages(GFP_KERNEL, 0);
+ if (page)
+ debug->pte_pfn = page_to_pfn(page);
+
+ return 0;
+
+error:
+ free_mem(debug);
+ return ret;
+}
+
static int __init debug_vm_pgtable(void)
{
+ struct vm_pgtable_debug debug;
struct vm_area_struct *vma;
struct mm_struct *mm;
pgd_t *pgdp;
@@ -970,9 +1172,13 @@ static int __init debug_vm_pgtable(void)
unsigned long vaddr, pte_aligned, pmd_aligned;
unsigned long pud_aligned, p4d_aligned, pgd_aligned;
spinlock_t *ptl = NULL;
- int idx;
+ int idx, ret;
pr_info("Validating architecture page table helpers\n");
+ ret = alloc_mem(&debug);
+ if (ret)
+ return ret;
+
prot = vm_get_page_prot(VMFLAGS);
vaddr = get_random_vaddr();
mm = mm_alloc();
@@ -1127,6 +1333,8 @@ static int __init debug_vm_pgtable(void)
mm_dec_nr_pmds(mm);
mm_dec_nr_ptes(mm);
mmdrop(mm);
+
+ free_mem(&debug);
return 0;
}
late_initcall(debug_vm_pgtable);
_
Patches currently in -mm which might be from gshan@xxxxxxxxxx are
mm-debug_vm_pgtable-introduce-struct-vm_pgtable_debug.patch
mm-debug_vm_pgtable-use-struct-vm_pgtable_debug-in-basic-tests.patch
mm-debug_vm_pgtable-use-struct-vm_pgtable_debug-in-leaf-and-savewrite-tests.patch
mm-debug_vm_pgtable-use-struct-vm_pgtable_debug-in-protnone-and-devmap-tests.patch
mm-vm_debug_pgtable-use-struct-vm_pgtable_debug-in-soft_dirty-and-swap-tests.patch
mm-debug_vm_pgtable-use-struct-vm_pgtable_debug-in-migration-and-thp-tests.patch
mm-debug_vm_pgtable-use-struct-vm_pgtable_debug-in-pte-modifying-tests.patch
mm-debug_vm_pgtable-use-struct-vm_pgtable_debug-in-pmd-modifying-tests.patch
mm-vm_debug_pgtable-use-struct-vm_pgtable_debug-in-pud-modifying-tests.patch
mm-debug_vm_pgtable-use-struct-vm_pgtable_debug-in-pgd-and-p4d-modifying-tests.patch
mm-debug_vm_pgtable-remove-unused-code.patch
mm-debug_vm_pgtable-fix-corrupted-page-flag.patch
