+ set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled.patch added to -mm tree

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The patch titled
     Subject: set_memory: allow querying whether set_direct_map_*() is actually enabled
has been added to the -mm tree.  Its filename is
     set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled.patch

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------------------------------------------------------
From: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Subject: set_memory: allow querying whether set_direct_map_*() is actually enabled

On arm64, set_direct_map_*() functions may return 0 without actually
changing the linear map.  This behaviour can be controlled using kernel
parameters, so we need a way to determine at runtime whether calls to
set_direct_map_invalid_noflush() and set_direct_map_default_noflush() have
any effect.

Extend set_memory API with can_set_direct_map() function that allows
checking if calling set_direct_map_*() will actually change the page
table, replace several occurrences of open coded checks in arm64 with the
new function and provide a generic stub for architectures that always
modify page tables upon calls to set_direct_map APIs.

[arnd@xxxxxxxx: arm64: kfence: fix header inclusion ]
Link: https://lkml.kernel.org/r/20210513184734.29317-5-rppt@xxxxxxxxxx
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Christopher Lameter <cl@xxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Elena Reshetova <elena.reshetova@xxxxxxxxx>
Cc: Hagen Paul Pfeifer <hagen@xxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
Cc: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Tycho Andersen <tycho@xxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 arch/arm64/include/asm/Kbuild       |    1 -
 arch/arm64/include/asm/cacheflush.h |    6 ------
 arch/arm64/include/asm/kfence.h     |    2 +-
 arch/arm64/include/asm/set_memory.h |   17 +++++++++++++++++
 arch/arm64/kernel/machine_kexec.c   |    1 +
 arch/arm64/mm/mmu.c                 |    6 +++---
 arch/arm64/mm/pageattr.c            |   13 +++++++++----
 include/linux/set_memory.h          |   12 ++++++++++++
 8 files changed, 43 insertions(+), 15 deletions(-)

--- a/arch/arm64/include/asm/cacheflush.h~set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled
+++ a/arch/arm64/include/asm/cacheflush.h
@@ -131,12 +131,6 @@ static __always_inline void __flush_icac
 	dsb(ish);
 }
 
-int set_memory_valid(unsigned long addr, int numpages, int enable);
-
-int set_direct_map_invalid_noflush(struct page *page, int numpages);
-int set_direct_map_default_noflush(struct page *page, int numpages);
-bool kernel_page_present(struct page *page);
-
 #include <asm-generic/cacheflush.h>
 
 #endif /* __ASM_CACHEFLUSH_H */
--- a/arch/arm64/include/asm/Kbuild~set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled
+++ a/arch/arm64/include/asm/Kbuild
@@ -3,7 +3,6 @@ generic-y += early_ioremap.h
 generic-y += mcs_spinlock.h
 generic-y += qrwlock.h
 generic-y += qspinlock.h
-generic-y += set_memory.h
 generic-y += user.h
 
 generated-y += cpucaps.h
--- a/arch/arm64/include/asm/kfence.h~set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled
+++ a/arch/arm64/include/asm/kfence.h
@@ -8,7 +8,7 @@
 #ifndef __ASM_KFENCE_H
 #define __ASM_KFENCE_H
 
-#include <asm/cacheflush.h>
+#include <asm/set_memory.h>
 
 static inline bool arch_kfence_init_pool(void) { return true; }
 
--- /dev/null
+++ a/arch/arm64/include/asm/set_memory.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef _ASM_ARM64_SET_MEMORY_H
+#define _ASM_ARM64_SET_MEMORY_H
+
+#include <asm-generic/set_memory.h>
+
+bool can_set_direct_map(void);
+#define can_set_direct_map can_set_direct_map
+
+int set_memory_valid(unsigned long addr, int numpages, int enable);
+
+int set_direct_map_invalid_noflush(struct page *page, int numpages);
+int set_direct_map_default_noflush(struct page *page, int numpages);
+bool kernel_page_present(struct page *page);
+
+#endif /* _ASM_ARM64_SET_MEMORY_H */
--- a/arch/arm64/kernel/machine_kexec.c~set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled
+++ a/arch/arm64/kernel/machine_kexec.c
@@ -11,6 +11,7 @@
 #include <linux/kernel.h>
 #include <linux/kexec.h>
 #include <linux/page-flags.h>
+#include <linux/set_memory.h>
 #include <linux/smp.h>
 
 #include <asm/cacheflush.h>
--- a/arch/arm64/mm/mmu.c~set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled
+++ a/arch/arm64/mm/mmu.c
@@ -22,6 +22,7 @@
 #include <linux/io.h>
 #include <linux/mm.h>
 #include <linux/vmalloc.h>
+#include <linux/set_memory.h>
 
 #include <asm/barrier.h>
 #include <asm/cputype.h>
@@ -515,7 +516,7 @@ static void __init map_mem(pgd_t *pgdp)
 	 */
 	BUILD_BUG_ON(pgd_index(direct_map_end - 1) == pgd_index(direct_map_end));
 
-	if (rodata_full || crash_mem_map || debug_pagealloc_enabled())
+	if (can_set_direct_map() || crash_mem_map)
 		flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
 
 	/*
@@ -1483,8 +1484,7 @@ int arch_add_memory(int nid, u64 start,
 	 * KFENCE requires linear map to be mapped at page granularity, so that
 	 * it is possible to protect/unprotect single pages in the KFENCE pool.
 	 */
-	if (rodata_full || debug_pagealloc_enabled() ||
-	    IS_ENABLED(CONFIG_KFENCE))
+	if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE))
 		flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
 
 	__create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),
--- a/arch/arm64/mm/pageattr.c~set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled
+++ a/arch/arm64/mm/pageattr.c
@@ -19,6 +19,11 @@ struct page_change_data {
 
 bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED);
 
+bool can_set_direct_map(void)
+{
+	return rodata_full || debug_pagealloc_enabled();
+}
+
 static int change_page_range(pte_t *ptep, unsigned long addr, void *data)
 {
 	struct page_change_data *cdata = data;
@@ -156,7 +161,7 @@ int set_direct_map_invalid_noflush(struc
 	};
 	unsigned long size = PAGE_SIZE * numpages;
 
-	if (!debug_pagealloc_enabled() && !rodata_full)
+	if (!can_set_direct_map())
 		return 0;
 
 	return apply_to_page_range(&init_mm,
@@ -172,7 +177,7 @@ int set_direct_map_default_noflush(struc
 	};
 	unsigned long size = PAGE_SIZE * numpages;
 
-	if (!debug_pagealloc_enabled() && !rodata_full)
+	if (!can_set_direct_map())
 		return 0;
 
 	return apply_to_page_range(&init_mm,
@@ -183,7 +188,7 @@ int set_direct_map_default_noflush(struc
 #ifdef CONFIG_DEBUG_PAGEALLOC
 void __kernel_map_pages(struct page *page, int numpages, int enable)
 {
-	if (!debug_pagealloc_enabled() && !rodata_full)
+	if (!can_set_direct_map())
 		return;
 
 	set_memory_valid((unsigned long)page_address(page), numpages, enable);
@@ -208,7 +213,7 @@ bool kernel_page_present(struct page *pa
 	pte_t *ptep;
 	unsigned long addr = (unsigned long)page_address(page);
 
-	if (!debug_pagealloc_enabled() && !rodata_full)
+	if (!can_set_direct_map())
 		return true;
 
 	pgdp = pgd_offset_k(addr);
--- a/include/linux/set_memory.h~set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled
+++ a/include/linux/set_memory.h
@@ -28,7 +28,19 @@ static inline bool kernel_page_present(s
 {
 	return true;
 }
+#else /* CONFIG_ARCH_HAS_SET_DIRECT_MAP */
+/*
+ * Some architectures, e.g. ARM64 can disable direct map modifications at
+ * boot time. Let them overrive this query.
+ */
+#ifndef can_set_direct_map
+static inline bool can_set_direct_map(void)
+{
+	return true;
+}
+#define can_set_direct_map can_set_direct_map
 #endif
+#endif /* CONFIG_ARCH_HAS_SET_DIRECT_MAP */
 
 #ifndef set_mce_nospec
 static inline int set_mce_nospec(unsigned long pfn, bool unmap)
_

Patches currently in -mm which might be from rppt@xxxxxxxxxxxxx are

mm-mmzoneh-simplify-is_highmem_idx.patch
docs-procrst-meminfo-briefly-describe-gaps-in-memory-accounting.patch
include-linux-mmzoneh-add-documentation-for-pfn_valid.patch
memblock-update-initialization-of-reserved-pages.patch
arm64-decouple-check-whether-pfn-is-in-linear-map-from-pfn_valid.patch
arm64-drop-pfn_valid_within-and-simplify-pfn_valid.patch
mmap-make-mlock_future_check-global.patch
riscv-kconfig-make-direct-map-manipulation-options-depend-on-mmu.patch
set_memory-allow-set_direct_map__noflush-for-multiple-pages.patch
set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled.patch
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas.patch
pm-hibernate-disable-when-there-are-active-secretmem-users.patch
arch-mm-wire-up-memfd_secret-system-call-where-relevant.patch
secretmem-test-add-basic-selftest-for-memfd_secret2.patch




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