The patch titled
Subject: mm/debug_vm_pgtable: drop protection_map[] usage
has been added to the -mm tree. Its filename is
mm-debug_vm_pgtable-drop-protection_map-usage.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-debug_vm_pgtable-drop-protection_map-usage.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-debug_vm_pgtable-drop-protection_map-usage.patch
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From: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Subject: mm/debug_vm_pgtable: drop protection_map[] usage
Patch series "mm/mmap: Drop protection_map[] and platform's __SXXX/__PXXX requirements", v2.
protection_map[] is an array based construct that translates given
vm_flags combination. This array contains page protection map, which is
populated by the platform via [__S000 .. __S111] and [__P000 .. __P111]
exported macros. Primary usage for protection_map[] is for
vm_get_page_prot(), which is used to determine page protection value for a
given vm_flags. vm_get_page_prot() implementation, could again call
platform overrides arch_vm_get_page_prot() and arch_filter_pgprot(). Some
platforms override protection_map[] that was originally built with
__SXXX/__PXXX with different runtime values.
Currently there are multiple layers of abstraction i.e __SXXX/__PXXX
macros , protection_map[], arch_vm_get_page_prot() and
arch_filter_pgprot() built between the platform and generic MM, finally
defining vm_get_page_prot().
Hence this series proposes to drop all these abstraction levels and
instead just move the responsibility of defining vm_get_page_prot() to the
platform itself making it clean and simple.
This first introduces ARCH_HAS_VM_GET_PAGE_PROT which enables the
platforms to define custom vm_get_page_prot(). This starts converting
platforms that either change protection_map[] or define the overrides
arch_filter_pgprot() or arch_vm_get_page_prot() which enables for those
constructs to be dropped off completely. This series then converts
remaining platforms which enables for __SXXX/__PXXX constructs to be
dropped off completely. Finally it drops the generic vm_get_page_prot()
and then ARCH_HAS_VM_GET_PAGE_PROT as every platform now defines their own
vm_get_page_prot().
The series has been inspired from an earlier discuss with Christoph
Hellwig
https://lore.kernel.org/all/1632712920-8171-1-git-send-email-anshuman.khandual@xxxxxxx/
This series has been cross built for multiple platforms.
This patch (of 30):
Although protection_map[] contains the platform defined page protection
map for a given vm_flags combination, vm_get_page_prot() is the right
interface to use. This will also reduce dependency on protection_map[]
which is going to be dropped off completely later on.
Link: https://lkml.kernel.org/r/1645425519-9034-1-git-send-email-anshuman.khandual@xxxxxxx
Link: https://lkml.kernel.org/r/1645425519-9034-2-git-send-email-anshuman.khandual@xxxxxxx
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Brian Cain <bcain@xxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Chris Zankel <chris@xxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Dinh Nguyen <dinguyen@xxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Guo Ren <guoren@xxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "James E.J. Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Cc: Jeff Dike <jdike@xxxxxxxxxxx>
Cc: Jonas Bonn <jonas@xxxxxxxxxxxx>
Cc: Khalid Aziz <khalid.aziz@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Michal Simek <monstr@xxxxxxxxx>
Cc: Nick Hu <nickhu@xxxxxxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
Cc: Richard Henderson <rth@xxxxxxxxxxx>
Cc: Rich Felker <dalias@xxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Stafford Horne <shorne@xxxxxxxxx>
Cc: Sven Schnelle <svens@xxxxxxxxxxxxx>
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Vineet Gupta <vgupta@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/debug_vm_pgtable.c | 31 +++++++++++++++++++------------
1 file changed, 19 insertions(+), 12 deletions(-)
--- a/mm/debug_vm_pgtable.c~mm-debug_vm_pgtable-drop-protection_map-usage
+++ a/mm/debug_vm_pgtable.c
@@ -93,7 +93,7 @@ struct pgtable_debug_args {
static void __init pte_basic_tests(struct pgtable_debug_args *args, int idx)
{
- pgprot_t prot = protection_map[idx];
+ pgprot_t prot = vm_get_page_prot(idx);
pte_t pte = pfn_pte(args->fixed_pte_pfn, prot);
unsigned long val = idx, *ptr = &val;
@@ -101,7 +101,7 @@ static void __init pte_basic_tests(struc
/*
* This test needs to be executed after the given page table entry
- * is created with pfn_pte() to make sure that protection_map[idx]
+ * is created with pfn_pte() to make sure that vm_get_page_prot(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.
@@ -190,7 +190,7 @@ static void __init pte_savedwrite_tests(
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void __init pmd_basic_tests(struct pgtable_debug_args *args, int idx)
{
- pgprot_t prot = protection_map[idx];
+ pgprot_t prot = vm_get_page_prot(idx);
unsigned long val = idx, *ptr = &val;
pmd_t pmd;
@@ -202,7 +202,7 @@ static void __init pmd_basic_tests(struc
/*
* This test needs to be executed after the given page table entry
- * is created with pfn_pmd() to make sure that protection_map[idx]
+ * is created with pfn_pmd() to make sure that vm_get_page_prot(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.
@@ -325,7 +325,7 @@ static void __init pmd_savedwrite_tests(
#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
static void __init pud_basic_tests(struct pgtable_debug_args *args, int idx)
{
- pgprot_t prot = protection_map[idx];
+ pgprot_t prot = vm_get_page_prot(idx);
unsigned long val = idx, *ptr = &val;
pud_t pud;
@@ -337,7 +337,7 @@ static void __init pud_basic_tests(struc
/*
* This test needs to be executed after the given page table entry
- * is created with pfn_pud() to make sure that protection_map[idx]
+ * is created with pfn_pud() to make sure that vm_get_page_prot(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.
@@ -1106,14 +1106,14 @@ static int __init init_args(struct pgtab
/*
* Initialize the debugging data.
*
- * protection_map[0] (or even protection_map[8]) will help create
- * page table entries with PROT_NONE permission as required for
- * pxx_protnone_tests().
+ * vm_get_page_prot(VM_NONE) or vm_get_page_prot(VM_SHARED|VM_NONE)
+ * will help create page table entries with PROT_NONE permission as
+ * required for pxx_protnone_tests().
*/
memset(args, 0, sizeof(*args));
args->vaddr = get_random_vaddr();
args->page_prot = vm_get_page_prot(VMFLAGS);
- args->page_prot_none = protection_map[0];
+ args->page_prot_none = vm_get_page_prot(VM_NONE);
args->is_contiguous_page = false;
args->pud_pfn = ULONG_MAX;
args->pmd_pfn = ULONG_MAX;
@@ -1248,12 +1248,19 @@ static int __init debug_vm_pgtable(void)
return ret;
/*
- * Iterate over the protection_map[] to make sure that all
+ * Iterate over each possible vm_flags to make sure that all
* the basic page table transformation validations just hold
* true irrespective of the starting protection value for a
* given page table entry.
+ *
+ * Protection based vm_flags combinatins are always linear
+ * and increasing i.e starting from VM_NONE and going upto
+ * (VM_SHARED | READ | WRITE | EXEC).
*/
- for (idx = 0; idx < ARRAY_SIZE(protection_map); idx++) {
+#define VM_FLAGS_START (VM_NONE)
+#define VM_FLAGS_END (VM_SHARED | VM_EXEC | VM_WRITE | VM_READ)
+
+ for (idx = VM_FLAGS_START; idx <= VM_FLAGS_END; idx++) {
pte_basic_tests(&args, idx);
pmd_basic_tests(&args, idx);
pud_basic_tests(&args, idx);
_
Patches currently in -mm which might be from anshuman.khandual@xxxxxxx are
mm-generalize-arch_has_filter_pgprot.patch
mm-merge-pte_mkhuge-call-into-arch_make_huge_pte.patch
mm-debug_vm_pgtable-drop-protection_map-usage.patch
mm-mmap-clarify-protection_map-indices.patch
mm-mmap-add-new-config-arch_has_vm_get_page_prot.patch
powerpc-mm-enable-arch_has_vm_get_page_prot.patch
arm64-mm-enable-arch_has_vm_get_page_prot.patch
sparc-mm-enable-arch_has_vm_get_page_prot.patch
mips-mm-enable-arch_has_vm_get_page_prot.patch
m68k-mm-enable-arch_has_vm_get_page_prot.patch
arm-mm-enable-arch_has_vm_get_page_prot.patch
mm-mmap-drop-protection_map.patch
mm-mmap-drop-arch_filter_pgprot.patch
mm-mmap-drop-arch_vm_get_page_pgprot.patch
s390-mm-enable-arch_has_vm_get_page_prot.patch
riscv-mm-enable-arch_has_vm_get_page_prot.patch
alpha-mm-enable-arch_has_vm_get_page_prot.patch
sh-mm-enable-arch_has_vm_get_page_prot.patch
arc-mm-enable-arch_has_vm_get_page_prot.patch
csky-mm-enable-arch_has_vm_get_page_prot.patch
extensa-mm-enable-arch_has_vm_get_page_prot.patch
parisc-mm-enable-arch_has_vm_get_page_prot.patch
openrisc-mm-enable-arch_has_vm_get_page_prot.patch
um-mm-enable-arch_has_vm_get_page_prot.patch
microblaze-mm-enable-arch_has_vm_get_page_prot.patch
nios2-mm-enable-arch_has_vm_get_page_prot.patch
hexagon-mm-enable-arch_has_vm_get_page_prot.patch
nds32-mm-enable-arch_has_vm_get_page_prot.patch
ia64-mm-enable-arch_has_vm_get_page_prot.patch
mm-mmap-drop-generic-vm_get_page_prot.patch
mm-mmap-drop-arch_has_vm_get_page_prot.patch
mm-hugetlb-generalize-arch_want_general_hugetlb.patch
mm-migration-add-trace-events-for-thp-migrations.patch
mm-migration-add-trace-events-for-base-page-and-hugetlb-migrations.patch
