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Message-ID: <157867915799.30329.10290582536970737315.tip-bot2@tip-bot2>
Date: Fri, 10 Jan 2020 17:59:17 -0000
From: "tip-bot2 for Ingo Molnar" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Borislav Petkov <bp@...en8.de>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Rik van Riel <riel@...hat.com>, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, x86 <x86@...nel.org>
Subject: [tip: x86/mm] mm, x86/mm: Untangle address space layout definitions
from basic pgtable type definitions
The following commit has been merged into the x86/mm branch of tip:
Commit-ID: 186525bd6b83efc592672e2d6185e4d7c810d2b4
Gitweb: https://git.kernel.org/tip/186525bd6b83efc592672e2d6185e4d7c810d2b4
Author: Ingo Molnar <mingo@...nel.org>
AuthorDate: Fri, 29 Nov 2019 08:17:25 +01:00
Committer: Ingo Molnar <mingo@...nel.org>
CommitterDate: Tue, 10 Dec 2019 10:12:55 +01:00
mm, x86/mm: Untangle address space layout definitions from basic pgtable type definitions
- Untangle the somewhat incestous way of how VMALLOC_START is used all across the
kernel, but is, on x86, defined deep inside one of the lowest level page table headers.
It doesn't help that vmalloc.h only includes a single asm header:
#include <asm/page.h> /* pgprot_t */
So there was no existing cross-arch way to decouple address layout
definitions from page.h details. I used this:
#ifndef VMALLOC_START
# include <asm/vmalloc.h>
#endif
This way every architecture that wants to simplify page.h can do so.
- Also on x86 we had a couple of LDT related inline functions that used
the late-stage address space layout positions - but these could be
uninlined without real trouble - the end result is cleaner this way as
well.
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
arch/x86/include/asm/cpu_entry_area.h | 10 +---
arch/x86/include/asm/mmu_context.h | 86 +-----------------------
arch/x86/include/asm/pgtable_32_areas.h | 53 +++++++++++++++-
arch/x86/include/asm/pgtable_32_types.h | 57 +----------------
arch/x86/include/asm/pgtable_areas.h | 16 ++++-
arch/x86/include/asm/vmalloc.h | 2 +-
arch/x86/kernel/ldt.c | 83 +++++++++++++++++++++++-
arch/x86/kernel/setup.c | 1 +-
arch/x86/mm/fault.c | 1 +-
arch/x86/mm/init_32.c | 1 +-
arch/x86/mm/pgtable_32.c | 1 +-
arch/x86/mm/physaddr.c | 1 +-
include/linux/mm.h | 15 +---
mm/highmem.c | 2 +-
mm/vmalloc.c | 8 ++-
15 files changed, 183 insertions(+), 154 deletions(-)
create mode 100644 arch/x86/include/asm/pgtable_32_areas.h
create mode 100644 arch/x86/include/asm/pgtable_areas.h
diff --git a/arch/x86/include/asm/cpu_entry_area.h b/arch/x86/include/asm/cpu_entry_area.h
index 8047340..02c0078 100644
--- a/arch/x86/include/asm/cpu_entry_area.h
+++ b/arch/x86/include/asm/cpu_entry_area.h
@@ -6,6 +6,7 @@
#include <linux/percpu-defs.h>
#include <asm/processor.h>
#include <asm/intel_ds.h>
+#include <asm/pgtable_areas.h>
#ifdef CONFIG_X86_64
@@ -134,15 +135,6 @@ DECLARE_PER_CPU(struct cea_exception_stacks *, cea_exception_stacks);
extern void setup_cpu_entry_areas(void);
extern void cea_set_pte(void *cea_vaddr, phys_addr_t pa, pgprot_t flags);
-/* Single page reserved for the readonly IDT mapping: */
-#define CPU_ENTRY_AREA_RO_IDT CPU_ENTRY_AREA_BASE
-#define CPU_ENTRY_AREA_PER_CPU (CPU_ENTRY_AREA_RO_IDT + PAGE_SIZE)
-
-#define CPU_ENTRY_AREA_RO_IDT_VADDR ((void *)CPU_ENTRY_AREA_RO_IDT)
-
-#define CPU_ENTRY_AREA_MAP_SIZE \
- (CPU_ENTRY_AREA_PER_CPU + CPU_ENTRY_AREA_ARRAY_SIZE - CPU_ENTRY_AREA_BASE)
-
extern struct cpu_entry_area *get_cpu_entry_area(int cpu);
static inline struct entry_stack *cpu_entry_stack(int cpu)
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 5f33924..b243234 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -69,14 +69,6 @@ struct ldt_struct {
int slot;
};
-/* This is a multiple of PAGE_SIZE. */
-#define LDT_SLOT_STRIDE (LDT_ENTRIES * LDT_ENTRY_SIZE)
-
-static inline void *ldt_slot_va(int slot)
-{
- return (void *)(LDT_BASE_ADDR + LDT_SLOT_STRIDE * slot);
-}
-
/*
* Used for LDT copy/destruction.
*/
@@ -99,87 +91,21 @@ static inline void destroy_context_ldt(struct mm_struct *mm) { }
static inline void ldt_arch_exit_mmap(struct mm_struct *mm) { }
#endif
-static inline void load_mm_ldt(struct mm_struct *mm)
-{
#ifdef CONFIG_MODIFY_LDT_SYSCALL
- struct ldt_struct *ldt;
-
- /* READ_ONCE synchronizes with smp_store_release */
- ldt = READ_ONCE(mm->context.ldt);
-
- /*
- * Any change to mm->context.ldt is followed by an IPI to all
- * CPUs with the mm active. The LDT will not be freed until
- * after the IPI is handled by all such CPUs. This means that,
- * if the ldt_struct changes before we return, the values we see
- * will be safe, and the new values will be loaded before we run
- * any user code.
- *
- * NB: don't try to convert this to use RCU without extreme care.
- * We would still need IRQs off, because we don't want to change
- * the local LDT after an IPI loaded a newer value than the one
- * that we can see.
- */
-
- if (unlikely(ldt)) {
- if (static_cpu_has(X86_FEATURE_PTI)) {
- if (WARN_ON_ONCE((unsigned long)ldt->slot > 1)) {
- /*
- * Whoops -- either the new LDT isn't mapped
- * (if slot == -1) or is mapped into a bogus
- * slot (if slot > 1).
- */
- clear_LDT();
- return;
- }
-
- /*
- * If page table isolation is enabled, ldt->entries
- * will not be mapped in the userspace pagetables.
- * Tell the CPU to access the LDT through the alias
- * at ldt_slot_va(ldt->slot).
- */
- set_ldt(ldt_slot_va(ldt->slot), ldt->nr_entries);
- } else {
- set_ldt(ldt->entries, ldt->nr_entries);
- }
- } else {
- clear_LDT();
- }
+extern void load_mm_ldt(struct mm_struct *mm);
+extern void switch_ldt(struct mm_struct *prev, struct mm_struct *next);
#else
+static inline void load_mm_ldt(struct mm_struct *mm)
+{
clear_LDT();
-#endif
}
-
static inline void switch_ldt(struct mm_struct *prev, struct mm_struct *next)
{
-#ifdef CONFIG_MODIFY_LDT_SYSCALL
- /*
- * Load the LDT if either the old or new mm had an LDT.
- *
- * An mm will never go from having an LDT to not having an LDT. Two
- * mms never share an LDT, so we don't gain anything by checking to
- * see whether the LDT changed. There's also no guarantee that
- * prev->context.ldt actually matches LDTR, but, if LDTR is non-NULL,
- * then prev->context.ldt will also be non-NULL.
- *
- * If we really cared, we could optimize the case where prev == next
- * and we're exiting lazy mode. Most of the time, if this happens,
- * we don't actually need to reload LDTR, but modify_ldt() is mostly
- * used by legacy code and emulators where we don't need this level of
- * performance.
- *
- * This uses | instead of || because it generates better code.
- */
- if (unlikely((unsigned long)prev->context.ldt |
- (unsigned long)next->context.ldt))
- load_mm_ldt(next);
-#endif
-
DEBUG_LOCKS_WARN_ON(preemptible());
}
+#endif
-void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk);
+extern void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk);
/*
* Init a new mm. Used on mm copies, like at fork()
diff --git a/arch/x86/include/asm/pgtable_32_areas.h b/arch/x86/include/asm/pgtable_32_areas.h
new file mode 100644
index 0000000..b635541
--- /dev/null
+++ b/arch/x86/include/asm/pgtable_32_areas.h
@@ -0,0 +1,53 @@
+#ifndef _ASM_X86_PGTABLE_32_AREAS_H
+#define _ASM_X86_PGTABLE_32_AREAS_H
+
+#include <asm/cpu_entry_area.h>
+
+/*
+ * Just any arbitrary offset to the start of the vmalloc VM area: the
+ * current 8MB value just means that there will be a 8MB "hole" after the
+ * physical memory until the kernel virtual memory starts. That means that
+ * any out-of-bounds memory accesses will hopefully be caught.
+ * The vmalloc() routines leaves a hole of 4kB between each vmalloced
+ * area for the same reason. ;)
+ */
+#define VMALLOC_OFFSET (8 * 1024 * 1024)
+
+#ifndef __ASSEMBLY__
+extern bool __vmalloc_start_set; /* set once high_memory is set */
+#endif
+
+#define VMALLOC_START ((unsigned long)high_memory + VMALLOC_OFFSET)
+#ifdef CONFIG_X86_PAE
+#define LAST_PKMAP 512
+#else
+#define LAST_PKMAP 1024
+#endif
+
+#define CPU_ENTRY_AREA_PAGES (NR_CPUS * DIV_ROUND_UP(sizeof(struct cpu_entry_area), PAGE_SIZE))
+
+/* The +1 is for the readonly IDT page: */
+#define CPU_ENTRY_AREA_BASE \
+ ((FIXADDR_TOT_START - PAGE_SIZE*(CPU_ENTRY_AREA_PAGES+1)) & PMD_MASK)
+
+#define LDT_BASE_ADDR \
+ ((CPU_ENTRY_AREA_BASE - PAGE_SIZE) & PMD_MASK)
+
+#define LDT_END_ADDR (LDT_BASE_ADDR + PMD_SIZE)
+
+#define PKMAP_BASE \
+ ((LDT_BASE_ADDR - PAGE_SIZE) & PMD_MASK)
+
+#ifdef CONFIG_HIGHMEM
+# define VMALLOC_END (PKMAP_BASE - 2 * PAGE_SIZE)
+#else
+# define VMALLOC_END (LDT_BASE_ADDR - 2 * PAGE_SIZE)
+#endif
+
+#define MODULES_VADDR VMALLOC_START
+#define MODULES_END VMALLOC_END
+#define MODULES_LEN (MODULES_VADDR - MODULES_END)
+
+#define MAXMEM (VMALLOC_END - PAGE_OFFSET - __VMALLOC_RESERVE)
+
+#endif /* _ASM_X86_PGTABLE_32_AREAS_H */
diff --git a/arch/x86/include/asm/pgtable_32_types.h b/arch/x86/include/asm/pgtable_32_types.h
index 0416d42..5356a46 100644
--- a/arch/x86/include/asm/pgtable_32_types.h
+++ b/arch/x86/include/asm/pgtable_32_types.h
@@ -1,6 +1,6 @@
/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_X86_PGTABLE_32_DEFS_H
-#define _ASM_X86_PGTABLE_32_DEFS_H
+#ifndef _ASM_X86_PGTABLE_32_TYPES_H
+#define _ASM_X86_PGTABLE_32_TYPES_H
/*
* The Linux x86 paging architecture is 'compile-time dual-mode', it
@@ -20,55 +20,4 @@
#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
#define PGDIR_MASK (~(PGDIR_SIZE - 1))
-/* Just any arbitrary offset to the start of the vmalloc VM area: the
- * current 8MB value just means that there will be a 8MB "hole" after the
- * physical memory until the kernel virtual memory starts. That means that
- * any out-of-bounds memory accesses will hopefully be caught.
- * The vmalloc() routines leaves a hole of 4kB between each vmalloced
- * area for the same reason. ;)
- */
-#define VMALLOC_OFFSET (8 * 1024 * 1024)
-
-#ifndef __ASSEMBLY__
-extern bool __vmalloc_start_set; /* set once high_memory is set */
-#endif
-
-#define VMALLOC_START ((unsigned long)high_memory + VMALLOC_OFFSET)
-#ifdef CONFIG_X86_PAE
-#define LAST_PKMAP 512
-#else
-#define LAST_PKMAP 1024
-#endif
-
-/*
- * This is an upper bound on sizeof(struct cpu_entry_area) / PAGE_SIZE.
- * Define this here and validate with BUILD_BUG_ON() in cpu_entry_area.c
- * to avoid include recursion hell.
- */
-#define CPU_ENTRY_AREA_PAGES (NR_CPUS * 43)
-
-/* The +1 is for the readonly IDT page: */
-#define CPU_ENTRY_AREA_BASE \
- ((FIXADDR_TOT_START - PAGE_SIZE*(CPU_ENTRY_AREA_PAGES+1)) & PMD_MASK)
-
-#define LDT_BASE_ADDR \
- ((CPU_ENTRY_AREA_BASE - PAGE_SIZE) & PMD_MASK)
-
-#define LDT_END_ADDR (LDT_BASE_ADDR + PMD_SIZE)
-
-#define PKMAP_BASE \
- ((LDT_BASE_ADDR - PAGE_SIZE) & PMD_MASK)
-
-#ifdef CONFIG_HIGHMEM
-# define VMALLOC_END (PKMAP_BASE - 2 * PAGE_SIZE)
-#else
-# define VMALLOC_END (LDT_BASE_ADDR - 2 * PAGE_SIZE)
-#endif
-
-#define MODULES_VADDR VMALLOC_START
-#define MODULES_END VMALLOC_END
-#define MODULES_LEN (MODULES_VADDR - MODULES_END)
-
-#define MAXMEM (VMALLOC_END - PAGE_OFFSET - __VMALLOC_RESERVE)
-
-#endif /* _ASM_X86_PGTABLE_32_DEFS_H */
+#endif /* _ASM_X86_PGTABLE_32_TYPES_H */
diff --git a/arch/x86/include/asm/pgtable_areas.h b/arch/x86/include/asm/pgtable_areas.h
new file mode 100644
index 0000000..d34cce1
--- /dev/null
+++ b/arch/x86/include/asm/pgtable_areas.h
@@ -0,0 +1,16 @@
+#ifndef _ASM_X86_PGTABLE_AREAS_H
+#define _ASM_X86_PGTABLE_AREAS_H
+
+#ifdef CONFIG_X86_32
+# include <asm/pgtable_32_areas.h>
+#endif
+
+/* Single page reserved for the readonly IDT mapping: */
+#define CPU_ENTRY_AREA_RO_IDT CPU_ENTRY_AREA_BASE
+#define CPU_ENTRY_AREA_PER_CPU (CPU_ENTRY_AREA_RO_IDT + PAGE_SIZE)
+
+#define CPU_ENTRY_AREA_RO_IDT_VADDR ((void *)CPU_ENTRY_AREA_RO_IDT)
+
+#define CPU_ENTRY_AREA_MAP_SIZE (CPU_ENTRY_AREA_PER_CPU + CPU_ENTRY_AREA_ARRAY_SIZE - CPU_ENTRY_AREA_BASE)
+
+#endif /* _ASM_X86_PGTABLE_AREAS_H */
diff --git a/arch/x86/include/asm/vmalloc.h b/arch/x86/include/asm/vmalloc.h
index ba6295f..2983774 100644
--- a/arch/x86/include/asm/vmalloc.h
+++ b/arch/x86/include/asm/vmalloc.h
@@ -1,4 +1,6 @@
#ifndef _ASM_X86_VMALLOC_H
#define _ASM_X86_VMALLOC_H
+#include <asm/pgtable_areas.h>
+
#endif /* _ASM_X86_VMALLOC_H */
diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c
index b2463fc..c57e1ca 100644
--- a/arch/x86/kernel/ldt.c
+++ b/arch/x86/kernel/ldt.c
@@ -28,6 +28,89 @@
#include <asm/desc.h>
#include <asm/mmu_context.h>
#include <asm/syscalls.h>
+#include <asm/pgtable_areas.h>
+
+/* This is a multiple of PAGE_SIZE. */
+#define LDT_SLOT_STRIDE (LDT_ENTRIES * LDT_ENTRY_SIZE)
+
+static inline void *ldt_slot_va(int slot)
+{
+ return (void *)(LDT_BASE_ADDR + LDT_SLOT_STRIDE * slot);
+}
+
+void load_mm_ldt(struct mm_struct *mm)
+{
+ struct ldt_struct *ldt;
+
+ /* READ_ONCE synchronizes with smp_store_release */
+ ldt = READ_ONCE(mm->context.ldt);
+
+ /*
+ * Any change to mm->context.ldt is followed by an IPI to all
+ * CPUs with the mm active. The LDT will not be freed until
+ * after the IPI is handled by all such CPUs. This means that,
+ * if the ldt_struct changes before we return, the values we see
+ * will be safe, and the new values will be loaded before we run
+ * any user code.
+ *
+ * NB: don't try to convert this to use RCU without extreme care.
+ * We would still need IRQs off, because we don't want to change
+ * the local LDT after an IPI loaded a newer value than the one
+ * that we can see.
+ */
+
+ if (unlikely(ldt)) {
+ if (static_cpu_has(X86_FEATURE_PTI)) {
+ if (WARN_ON_ONCE((unsigned long)ldt->slot > 1)) {
+ /*
+ * Whoops -- either the new LDT isn't mapped
+ * (if slot == -1) or is mapped into a bogus
+ * slot (if slot > 1).
+ */
+ clear_LDT();
+ return;
+ }
+
+ /*
+ * If page table isolation is enabled, ldt->entries
+ * will not be mapped in the userspace pagetables.
+ * Tell the CPU to access the LDT through the alias
+ * at ldt_slot_va(ldt->slot).
+ */
+ set_ldt(ldt_slot_va(ldt->slot), ldt->nr_entries);
+ } else {
+ set_ldt(ldt->entries, ldt->nr_entries);
+ }
+ } else {
+ clear_LDT();
+ }
+}
+
+void switch_ldt(struct mm_struct *prev, struct mm_struct *next)
+{
+ /*
+ * Load the LDT if either the old or new mm had an LDT.
+ *
+ * An mm will never go from having an LDT to not having an LDT. Two
+ * mms never share an LDT, so we don't gain anything by checking to
+ * see whether the LDT changed. There's also no guarantee that
+ * prev->context.ldt actually matches LDTR, but, if LDTR is non-NULL,
+ * then prev->context.ldt will also be non-NULL.
+ *
+ * If we really cared, we could optimize the case where prev == next
+ * and we're exiting lazy mode. Most of the time, if this happens,
+ * we don't actually need to reload LDTR, but modify_ldt() is mostly
+ * used by legacy code and emulators where we don't need this level of
+ * performance.
+ *
+ * This uses | instead of || because it generates better code.
+ */
+ if (unlikely((unsigned long)prev->context.ldt |
+ (unsigned long)next->context.ldt))
+ load_mm_ldt(next);
+
+ DEBUG_LOCKS_WARN_ON(preemptible());
+}
static void refresh_ldt_segments(void)
{
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index b5ac993..90296a0 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -41,6 +41,7 @@
#include <asm/proto.h>
#include <asm/unwind.h>
#include <asm/vsyscall.h>
+#include <linux/vmalloc.h>
/*
* max_low_pfn_mapped: highest directly mapped pfn < 4 GB
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 304d31d..c9c8523 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -29,6 +29,7 @@
#include <asm/efi.h> /* efi_recover_from_page_fault()*/
#include <asm/desc.h> /* store_idt(), ... */
#include <asm/cpu_entry_area.h> /* exception stack */
+#include <asm/pgtable_areas.h> /* VMALLOC_START, ... */
#define CREATE_TRACE_POINTS
#include <asm/trace/exceptions.h>
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 930edeb..16274a3 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -52,6 +52,7 @@
#include <asm/page_types.h>
#include <asm/cpu_entry_area.h>
#include <asm/init.h>
+#include <asm/pgtable_areas.h>
#include "mm_internal.h"
diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c
index 9bb7f0a..0e6700e 100644
--- a/arch/x86/mm/pgtable_32.c
+++ b/arch/x86/mm/pgtable_32.c
@@ -18,6 +18,7 @@
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/io.h>
+#include <linux/vmalloc.h>
unsigned int __VMALLOC_RESERVE = 128 << 20;
diff --git a/arch/x86/mm/physaddr.c b/arch/x86/mm/physaddr.c
index bdc9815..fc3f3d3 100644
--- a/arch/x86/mm/physaddr.c
+++ b/arch/x86/mm/physaddr.c
@@ -5,6 +5,7 @@
#include <linux/mm.h>
#include <asm/page.h>
+#include <linux/vmalloc.h>
#include "physaddr.h"
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c97ea3b..fb8f941 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -625,24 +625,19 @@ unsigned long vmalloc_to_pfn(const void *addr);
* On nommu, vmalloc/vfree wrap through kmalloc/kfree directly, so there
* is no special casing required.
*/
-static inline bool is_vmalloc_addr(const void *x)
-{
-#ifdef CONFIG_MMU
- unsigned long addr = (unsigned long)x;
-
- return addr >= VMALLOC_START && addr < VMALLOC_END;
-#else
- return false;
-#endif
-}
#ifndef is_ioremap_addr
#define is_ioremap_addr(x) is_vmalloc_addr(x)
#endif
#ifdef CONFIG_MMU
+extern bool is_vmalloc_addr(const void *x);
extern int is_vmalloc_or_module_addr(const void *x);
#else
+static inline bool is_vmalloc_addr(const void *x)
+{
+ return false;
+}
static inline int is_vmalloc_or_module_addr(const void *x)
{
return 0;
diff --git a/mm/highmem.c b/mm/highmem.c
index 107b10f..64d8dea 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -29,7 +29,7 @@
#include <linux/highmem.h>
#include <linux/kgdb.h>
#include <asm/tlbflush.h>
-
+#include <linux/vmalloc.h>
#if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)
DEFINE_PER_CPU(int, __kmap_atomic_idx);
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 4d3b3d6..19cdbb1 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -41,6 +41,14 @@
#include "internal.h"
+bool is_vmalloc_addr(const void *x)
+{
+ unsigned long addr = (unsigned long)x;
+
+ return addr >= VMALLOC_START && addr < VMALLOC_END;
+}
+EXPORT_SYMBOL(is_vmalloc_addr);
+
struct vfree_deferred {
struct llist_head list;
struct work_struct wq;
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