| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20250623184321.927418-2-gerald.schaefer@linux.ibm.com>
Date: Mon, 23 Jun 2025 20:43:21 +0200
From: Gerald Schaefer <gerald.schaefer@...ux.ibm.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Anshuman Khandual <anshuman.khandual@....com>
Cc: Matthew Wilcox <willy@...radead.org>, David Hildenbrand <david@...hat.com>,
LKML <linux-kernel@...r.kernel.org>, linux-mm <linux-mm@...ck.org>
Subject: [RFC PATCH 1/1] mm/debug_vm_pgtable: Use a swp_entry_t input value for swap tests
The various __pte/pmd_to_swp_entry and __swp_entry_to_pte/pmd helper
functions are expected to operate on swapped PTE/PMD entries, not on
present and mapped entries.
Reflect this in the swap tests by using a swp_entry_t as input value,
similar to how it is already done in pte_swap_exclusive_tests().
Move the swap entry creation to init_args() and store it in args, so
it can also be used in other functions.
The pte/pmd_swap_tests() are also changed to compare entries instead of
pfn values, because pte/pmd_pfn() helpers are not expected to operate on
swapped entries. E.g. on s390, pmd_pfn() needs different shifts for leaf
(large) and non-leaf PMDs.
Also update documentation, to reflect that the helpers operate on
swapped and not mapped entries, and use correct names, i.e.
__swp_to_pte/pmd_entry -> __swp_entry_to_pte/pmd.
For consistency, also change pte/pmd_swap_soft_dirty_tests() to use
args->swp_entry instead of a present and mapped PTE/PMD.
Signed-off-by: Gerald Schaefer <gerald.schaefer@...ux.ibm.com>
---
Documentation/mm/arch_pgtable_helpers.rst | 8 ++--
mm/debug_vm_pgtable.c | 55 ++++++++++++++---------
2 files changed, 38 insertions(+), 25 deletions(-)
diff --git a/Documentation/mm/arch_pgtable_helpers.rst b/Documentation/mm/arch_pgtable_helpers.rst
index af245161d8e7..e2ac76202a85 100644
--- a/Documentation/mm/arch_pgtable_helpers.rst
+++ b/Documentation/mm/arch_pgtable_helpers.rst
@@ -242,13 +242,13 @@ SWAP Page Table Helpers
========================
+---------------------------+--------------------------------------------------+
-| __pte_to_swp_entry | Creates a swapped entry (arch) from a mapped PTE |
+| __pte_to_swp_entry | Creates a swap entry (arch) from a swapped PTE |
+---------------------------+--------------------------------------------------+
-| __swp_to_pte_entry | Creates a mapped PTE from a swapped entry (arch) |
+| __swp_entry_to_pte | Creates a swapped PTE from a swap entry (arch) |
+---------------------------+--------------------------------------------------+
-| __pmd_to_swp_entry | Creates a swapped entry (arch) from a mapped PMD |
+| __pmd_to_swp_entry | Creates a swap entry (arch) from a swapped PMD |
+---------------------------+--------------------------------------------------+
-| __swp_to_pmd_entry | Creates a mapped PMD from a swapped entry (arch) |
+| __swp_entry_to_pmd | Creates a swapped PMD from a swap entry (arch) |
+---------------------------+--------------------------------------------------+
| is_migration_entry | Tests a migration (read or write) swapped entry |
+-------------------------------+----------------------------------------------+
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 7731b238b534..3b0f83ed6c2e 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -73,6 +73,8 @@ struct pgtable_debug_args {
unsigned long fixed_pud_pfn;
unsigned long fixed_pmd_pfn;
unsigned long fixed_pte_pfn;
+
+ swp_entry_t swp_entry;
};
static void __init pte_basic_tests(struct pgtable_debug_args *args, int idx)
@@ -754,12 +756,15 @@ static void __init pte_soft_dirty_tests(struct pgtable_debug_args *args)
static void __init pte_swap_soft_dirty_tests(struct pgtable_debug_args *args)
{
- pte_t pte = pfn_pte(args->fixed_pte_pfn, args->page_prot);
+ pte_t pte;
if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY))
return;
pr_debug("Validating PTE swap soft dirty\n");
+ pte = swp_entry_to_pte(args->swp_entry);
+ WARN_ON(!is_swap_pte(pte));
+
WARN_ON(!pte_swp_soft_dirty(pte_swp_mksoft_dirty(pte)));
WARN_ON(pte_swp_soft_dirty(pte_swp_clear_soft_dirty(pte)));
}
@@ -793,7 +798,9 @@ static void __init pmd_swap_soft_dirty_tests(struct pgtable_debug_args *args)
return;
pr_debug("Validating PMD swap soft dirty\n");
- pmd = pfn_pmd(args->fixed_pmd_pfn, args->page_prot);
+ pmd = swp_entry_to_pmd(args->swp_entry);
+ WARN_ON(!is_swap_pmd(pmd));
+
WARN_ON(!pmd_swp_soft_dirty(pmd_swp_mksoft_dirty(pmd)));
WARN_ON(pmd_swp_soft_dirty(pmd_swp_clear_soft_dirty(pmd)));
}
@@ -804,17 +811,11 @@ static void __init pmd_swap_soft_dirty_tests(struct pgtable_debug_args *args) {
static void __init pte_swap_exclusive_tests(struct pgtable_debug_args *args)
{
- unsigned long max_swap_offset;
swp_entry_t entry, entry2;
pte_t pte;
pr_debug("Validating PTE swap exclusive\n");
-
- /* See generic_max_swapfile_size(): probe the maximum offset */
- max_swap_offset = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0, ~0UL))));
-
- /* Create a swp entry with all possible bits set */
- entry = swp_entry((1 << MAX_SWAPFILES_SHIFT) - 1, max_swap_offset);
+ entry = args->swp_entry;
pte = swp_entry_to_pte(entry);
WARN_ON(pte_swp_exclusive(pte));
@@ -838,30 +839,36 @@ static void __init pte_swap_exclusive_tests(struct pgtable_debug_args *args)
static void __init pte_swap_tests(struct pgtable_debug_args *args)
{
- swp_entry_t swp;
- pte_t pte;
+ swp_entry_t entry, arch_entry;
+ pte_t pte, pte2;
pr_debug("Validating PTE swap\n");
- pte = pfn_pte(args->fixed_pte_pfn, args->page_prot);
- swp = __pte_to_swp_entry(pte);
- pte = __swp_entry_to_pte(swp);
- WARN_ON(args->fixed_pte_pfn != pte_pfn(pte));
+ entry = args->swp_entry;
+
+ pte = swp_entry_to_pte(entry);
+ WARN_ON(!is_swap_pte(pte));
+ arch_entry = __pte_to_swp_entry(pte);
+ pte2 = __swp_entry_to_pte(arch_entry);
+ WARN_ON(memcmp(&pte, &pte2, sizeof(pte)));
}
#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
static void __init pmd_swap_tests(struct pgtable_debug_args *args)
{
- swp_entry_t swp;
- pmd_t pmd;
+ swp_entry_t entry, arch_entry;
+ pmd_t pmd, pmd2;
if (!has_transparent_hugepage())
return;
pr_debug("Validating PMD swap\n");
- pmd = pfn_pmd(args->fixed_pmd_pfn, args->page_prot);
- swp = __pmd_to_swp_entry(pmd);
- pmd = __swp_entry_to_pmd(swp);
- WARN_ON(args->fixed_pmd_pfn != pmd_pfn(pmd));
+ entry = args->swp_entry;
+ pmd = swp_entry_to_pmd(entry);
+ WARN_ON(!is_swap_pmd(pmd));
+
+ arch_entry = __pmd_to_swp_entry(pmd);
+ pmd2 = __swp_entry_to_pmd(arch_entry);
+ WARN_ON(memcmp(&pmd, &pmd2, sizeof(pmd)));
}
#else /* !CONFIG_ARCH_ENABLE_THP_MIGRATION */
static void __init pmd_swap_tests(struct pgtable_debug_args *args) { }
@@ -1166,6 +1173,7 @@ static void __init init_fixed_pfns(struct pgtable_debug_args *args)
static int __init init_args(struct pgtable_debug_args *args)
{
+ unsigned long max_swap_offset;
struct page *page = NULL;
int ret = 0;
@@ -1248,6 +1256,11 @@ static int __init init_args(struct pgtable_debug_args *args)
init_fixed_pfns(args);
+ /* See generic_max_swapfile_size(): probe the maximum offset */
+ max_swap_offset = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0, ~0UL))));
+ /* Create a swp entry with all possible bits set */
+ args->swp_entry = swp_entry((1 << MAX_SWAPFILES_SHIFT) - 1, max_swap_offset);
+
/*
* Allocate (huge) pages because some of the tests need to access
* the data in the pages. The corresponding tests will be skipped
--
2.48.1
Powered by blists - more mailing lists