+ mm-debug_vm_pgtable-drop-protection_map-usage.patch added to -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

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

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Anshuman Khandual <anshuman.khandual@arm.com>
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@arm.com/

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@arm.com
Link: https://lkml.kernel.org/r/1645425519-9034-2-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chris Zankel <chris@zankel.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Nick Hu <nickhu@andestech.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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@arm.com 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