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Date:   Tue, 18 Oct 2022 10:32:06 +0200
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Subject: Re: [PATCH] mm: remove kern_addr_valid() completely
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To:     Kefeng Wang <wangkefeng.wang@huawei.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-snps-arc@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org,
        linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org,
        loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org,
        linux-mips@vger.kernel.org, openrisc@lists.librecores.org,
        linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org,
        linux-sh@vger.kernel.org, sparclinux@vger.kernel.org,
        linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org,
        linux-fsdevel@vger.kernel.org
Cc:     Richard Henderson <richard.henderson@linaro.org>,
        Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
        Matt Turner <mattst88@gmail.com>,
        Vineet Gupta <vgupta@kernel.org>,
        Russell King <linux@armlinux.org.uk>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>, Guo Ren <guoren@kernel.org>,
        Huacai Chen <chenhuacai@kernel.org>,
        WANG Xuerui <kernel@xen0n.name>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Greg Ungerer <gerg@linux-m68k.org>,
        Michal Simek <monstr@monstr.eu>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Dinh Nguyen <dinguyen@kernel.org>,
        Jonas Bonn <jonas@southpole.se>,
        Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
        Stafford Horne <shorne@gmail.com>,
        "James E . J . Bottomley" <James.Bottomley@HansenPartnership.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Nicholas Piggin <npiggin@gmail.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Sven Schnelle <svens@linux.ibm.com>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>,
        "David S . Miller" <davem@davemloft.net>,
        Richard Weinberger <richard@nod.at>,
        Anton Ivanov <anton.ivanov@cambridgegreys.com>,
        Johannes Berg <johannes@sipsolutions.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H . Peter Anvin" <hpa@zytor.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Chris Zankel <chris@zankel.net>,
        Max Filippov <jcmvbkbc@gmail.com>
References: <20221018074014.185687-1-wangkefeng.wang@huawei.com>
From:   Helge Deller <deller@gmx.de>
In-Reply-To: <20221018074014.185687-1-wangkefeng.wang@huawei.com>
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Precedence: bulk

On 10/18/22 09:40, Kefeng Wang wrote:
> Most architectures(except arm64/x86/sparc) simply return 1 for
> kern_addr_valid(), which is only used in read_kcore(), and it
> calls copy_from_kernel_nofault() which could check whether the
> address is a valid kernel address, so no need kern_addr_valid(),
> let's remove unneeded kern_addr_valid() completely.
>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Acked-by: Helge Deller <deller@gmx.de>  # parisc

Thanks!
Helge

> ---
>   arch/alpha/include/asm/pgtable.h          |  2 -
>   arch/arc/include/asm/pgtable-bits-arcv2.h |  2 -
>   arch/arm/include/asm/pgtable-nommu.h      |  2 -
>   arch/arm/include/asm/pgtable.h            |  4 --
>   arch/arm64/include/asm/pgtable.h          |  2 -
>   arch/arm64/mm/mmu.c                       | 47 -----------------------
>   arch/arm64/mm/pageattr.c                  |  3 +-
>   arch/csky/include/asm/pgtable.h           |  3 --
>   arch/hexagon/include/asm/page.h           |  7 ----
>   arch/ia64/include/asm/pgtable.h           | 16 --------
>   arch/loongarch/include/asm/pgtable.h      |  2 -
>   arch/m68k/include/asm/pgtable_mm.h        |  2 -
>   arch/m68k/include/asm/pgtable_no.h        |  1 -
>   arch/microblaze/include/asm/pgtable.h     |  3 --
>   arch/mips/include/asm/pgtable.h           |  2 -
>   arch/nios2/include/asm/pgtable.h          |  2 -
>   arch/openrisc/include/asm/pgtable.h       |  2 -
>   arch/parisc/include/asm/pgtable.h         | 15 --------
>   arch/powerpc/include/asm/pgtable.h        |  7 ----
>   arch/riscv/include/asm/pgtable.h          |  2 -
>   arch/s390/include/asm/pgtable.h           |  2 -
>   arch/sh/include/asm/pgtable.h             |  2 -
>   arch/sparc/include/asm/pgtable_32.h       |  6 ---
>   arch/sparc/mm/init_32.c                   |  3 +-
>   arch/sparc/mm/init_64.c                   |  1 -
>   arch/um/include/asm/pgtable.h             |  2 -
>   arch/x86/include/asm/pgtable_32.h         |  9 -----
>   arch/x86/include/asm/pgtable_64.h         |  1 -
>   arch/x86/mm/init_64.c                     | 41 --------------------
>   arch/xtensa/include/asm/pgtable.h         |  2 -
>   fs/proc/kcore.c                           | 26 +++++--------
>   31 files changed, 11 insertions(+), 210 deletions(-)
>
> diff --git a/arch/alpha/include/asm/pgtable.h b/arch/alpha/include/asm/p=
gtable.h
> index 3ea9661c09ff..9e45f6735d5d 100644
> --- a/arch/alpha/include/asm/pgtable.h
> +++ b/arch/alpha/include/asm/pgtable.h
> @@ -313,8 +313,6 @@ extern inline pte_t mk_swap_pte(unsigned long type, =
unsigned long offset)
>   #define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })
>   #define __swp_entry_to_pte(x)	((pte_t) { (x).val })
>
> -#define kern_addr_valid(addr)	(1)
> -
>   #define pte_ERROR(e) \
>   	printk("%s:%d: bad pte %016lx.\n", __FILE__, __LINE__, pte_val(e))
>   #define pmd_ERROR(e) \
> diff --git a/arch/arc/include/asm/pgtable-bits-arcv2.h b/arch/arc/includ=
e/asm/pgtable-bits-arcv2.h
> index b23be557403e..515e82db519f 100644
> --- a/arch/arc/include/asm/pgtable-bits-arcv2.h
> +++ b/arch/arc/include/asm/pgtable-bits-arcv2.h
> @@ -120,8 +120,6 @@ void update_mmu_cache(struct vm_area_struct *vma, un=
signed long address,
>   #define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val(pte) })
>   #define __swp_entry_to_pte(x)		((pte_t) { (x).val })
>
> -#define kern_addr_valid(addr)	(1)
> -
>   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>   #include <asm/hugepage.h>
>   #endif
> diff --git a/arch/arm/include/asm/pgtable-nommu.h b/arch/arm/include/asm=
/pgtable-nommu.h
> index d16aba48fa0a..25d8c7bb07e0 100644
> --- a/arch/arm/include/asm/pgtable-nommu.h
> +++ b/arch/arm/include/asm/pgtable-nommu.h
> @@ -21,8 +21,6 @@
>   #define pgd_none(pgd)		(0)
>   #define pgd_bad(pgd)		(0)
>   #define pgd_clear(pgdp)
> -#define kern_addr_valid(addr)	(1)
> -/* FIXME */
>   /*
>    * PMD_SHIFT determines the size of the area a second-level page table=
 can map
>    * PGDIR_SHIFT determines what a third-level page table entry can map
> diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtab=
le.h
> index 78a532068fec..00954ab1a039 100644
> --- a/arch/arm/include/asm/pgtable.h
> +++ b/arch/arm/include/asm/pgtable.h
> @@ -298,10 +298,6 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t =
newprot)
>    */
>   #define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > __SWP=
_TYPE_BITS)
>
> -/* Needs to be defined here and not in linux/mm.h, as it is arch depend=
ent */
> -/* FIXME: this is not correct */
> -#define kern_addr_valid(addr)	(1)
> -
>   /*
>    * We provide our own arch_get_unmapped_area to cope with VIPT caches.
>    */
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/p=
gtable.h
> index 71a1af42f0e8..4873c1d6e7d0 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -1021,8 +1021,6 @@ static inline pmd_t pmdp_establish(struct vm_area_=
struct *vma,
>    */
>   #define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > __SWP=
_TYPE_BITS)
>
> -extern int kern_addr_valid(unsigned long addr);
> -
>   #ifdef CONFIG_ARM64_MTE
>
>   #define __HAVE_ARCH_PREPARE_TO_SWAP
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 9a7c38965154..556154d821bf 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -814,53 +814,6 @@ void __init paging_init(void)
>   	create_idmap();
>   }
>
> -/*
> - * Check whether a kernel address is valid (derived from arch/x86/).
> - */
> -int kern_addr_valid(unsigned long addr)
> -{
> -	pgd_t *pgdp;
> -	p4d_t *p4dp;
> -	pud_t *pudp, pud;
> -	pmd_t *pmdp, pmd;
> -	pte_t *ptep, pte;
> -
> -	addr =3D arch_kasan_reset_tag(addr);
> -	if ((((long)addr) >> VA_BITS) !=3D -1UL)
> -		return 0;
> -
> -	pgdp =3D pgd_offset_k(addr);
> -	if (pgd_none(READ_ONCE(*pgdp)))
> -		return 0;
> -
> -	p4dp =3D p4d_offset(pgdp, addr);
> -	if (p4d_none(READ_ONCE(*p4dp)))
> -		return 0;
> -
> -	pudp =3D pud_offset(p4dp, addr);
> -	pud =3D READ_ONCE(*pudp);
> -	if (pud_none(pud))
> -		return 0;
> -
> -	if (pud_sect(pud))
> -		return pfn_valid(pud_pfn(pud));
> -
> -	pmdp =3D pmd_offset(pudp, addr);
> -	pmd =3D READ_ONCE(*pmdp);
> -	if (pmd_none(pmd))
> -		return 0;
> -
> -	if (pmd_sect(pmd))
> -		return pfn_valid(pmd_pfn(pmd));
> -
> -	ptep =3D pte_offset_kernel(pmdp, addr);
> -	pte =3D READ_ONCE(*ptep);
> -	if (pte_none(pte))
> -		return 0;
> -
> -	return pfn_valid(pte_pfn(pte));
> -}
> -
>   #ifdef CONFIG_MEMORY_HOTPLUG
>   static void free_hotplug_page_range(struct page *page, size_t size,
>   				    struct vmem_altmap *altmap)
> diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
> index d107c3d434e2..0a741a910a6a 100644
> --- a/arch/arm64/mm/pageattr.c
> +++ b/arch/arm64/mm/pageattr.c
> @@ -201,8 +201,7 @@ void __kernel_map_pages(struct page *page, int numpa=
ges, int enable)
>
>   /*
>    * This function is used to determine if a linear map page has been ma=
rked as
> - * not-valid. Walk the page table and check the PTE_VALID bit. This is =
based
> - * on kern_addr_valid(), which almost does what we need.
> + * not-valid. Walk the page table and check the PTE_VALID bit.
>    *
>    * Because this is only called on the kernel linear map,  p?d_sect() i=
mplies
>    * p?d_present(). When debug_pagealloc is enabled, sections mappings a=
re
> diff --git a/arch/csky/include/asm/pgtable.h b/arch/csky/include/asm/pgt=
able.h
> index c3d9b92cbe61..77bc6caff2d2 100644
> --- a/arch/csky/include/asm/pgtable.h
> +++ b/arch/csky/include/asm/pgtable.h
> @@ -249,9 +249,6 @@ extern void paging_init(void);
>   void update_mmu_cache(struct vm_area_struct *vma, unsigned long addres=
s,
>   		      pte_t *pte);
>
> -/* Needs to be defined here and not in linux/mm.h, as it is arch depend=
ent */
> -#define kern_addr_valid(addr)	(1)
> -
>   #define io_remap_pfn_range(vma, vaddr, pfn, size, prot) \
>   	remap_pfn_range(vma, vaddr, pfn, size, prot)
>
> diff --git a/arch/hexagon/include/asm/page.h b/arch/hexagon/include/asm/=
page.h
> index 7cbf719c578e..d7d4f9fca327 100644
> --- a/arch/hexagon/include/asm/page.h
> +++ b/arch/hexagon/include/asm/page.h
> @@ -131,13 +131,6 @@ static inline void clear_page(void *page)
>
>   #define page_to_virt(page)	__va(page_to_phys(page))
>
> -/*
> - * For port to Hexagon Virtual Machine, MAYBE we check for attempts
> - * to reference reserved HVM space, but in any case, the VM will be
> - * protected.
> - */
> -#define kern_addr_valid(addr)   (1)
> -
>   #include <asm/mem-layout.h>
>   #include <asm-generic/memory_model.h>
>   /* XXX Todo: implement assembly-optimized version of getorder. */
> diff --git a/arch/ia64/include/asm/pgtable.h b/arch/ia64/include/asm/pgt=
able.h
> index 6925e28ae61d..01517a5e6778 100644
> --- a/arch/ia64/include/asm/pgtable.h
> +++ b/arch/ia64/include/asm/pgtable.h
> @@ -181,22 +181,6 @@ ia64_phys_addr_valid (unsigned long addr)
>   	return (addr & (local_cpu_data->unimpl_pa_mask)) =3D=3D 0;
>   }
>
> -/*
> - * kern_addr_valid(ADDR) tests if ADDR is pointing to valid kernel
> - * memory.  For the return value to be meaningful, ADDR must be >=3D
> - * PAGE_OFFSET.  This operation can be relatively expensive (e.g.,
> - * require a hash-, or multi-level tree-lookup or something of that
> - * sort) but it guarantees to return TRUE only if accessing the page
> - * at that address does not cause an error.  Note that there may be
> - * addresses for which kern_addr_valid() returns FALSE even though an
> - * access would not cause an error (e.g., this is typically true for
> - * memory mapped I/O regions.
> - *
> - * XXX Need to implement this for IA-64.
> - */
> -#define kern_addr_valid(addr)	(1)
> -
> -
>   /*
>    * Now come the defines and routines to manage and access the three-le=
vel
>    * page table.
> diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/inclu=
de/asm/pgtable.h
> index 946704bee599..fc70b7041b76 100644
> --- a/arch/loongarch/include/asm/pgtable.h
> +++ b/arch/loongarch/include/asm/pgtable.h
> @@ -421,8 +421,6 @@ static inline void update_mmu_cache_pmd(struct vm_ar=
ea_struct *vma,
>   	__update_tlb(vma, address, (pte_t *)pmdp);
>   }
>
> -#define kern_addr_valid(addr)	(1)
> -
>   static inline unsigned long pmd_pfn(pmd_t pmd)
>   {
>   	return (pmd_val(pmd) & _PFN_MASK) >> _PFN_SHIFT;
> diff --git a/arch/m68k/include/asm/pgtable_mm.h b/arch/m68k/include/asm/=
pgtable_mm.h
> index 9b4e2fe2ac82..b93c41fe2067 100644
> --- a/arch/m68k/include/asm/pgtable_mm.h
> +++ b/arch/m68k/include/asm/pgtable_mm.h
> @@ -145,8 +145,6 @@ static inline void update_mmu_cache(struct vm_area_s=
truct *vma,
>
>   #endif /* !__ASSEMBLY__ */
>
> -#define kern_addr_valid(addr)	(1)
> -
>   /* MMU-specific headers */
>
>   #ifdef CONFIG_SUN3
> diff --git a/arch/m68k/include/asm/pgtable_no.h b/arch/m68k/include/asm/=
pgtable_no.h
> index bce5ca56c388..fed58da3a6b6 100644
> --- a/arch/m68k/include/asm/pgtable_no.h
> +++ b/arch/m68k/include/asm/pgtable_no.h
> @@ -20,7 +20,6 @@
>   #define pgd_none(pgd)		(0)
>   #define pgd_bad(pgd)		(0)
>   #define pgd_clear(pgdp)
> -#define kern_addr_valid(addr)	(1)
>   #define	pmd_offset(a, b)	((void *)0)
>
>   #define PAGE_NONE	__pgprot(0)
> diff --git a/arch/microblaze/include/asm/pgtable.h b/arch/microblaze/inc=
lude/asm/pgtable.h
> index ba348e997dbb..42f5988e998b 100644
> --- a/arch/microblaze/include/asm/pgtable.h
> +++ b/arch/microblaze/include/asm/pgtable.h
> @@ -416,9 +416,6 @@ extern unsigned long iopa(unsigned long addr);
>   #define	IOMAP_NOCACHE_NONSER	2
>   #define	IOMAP_NO_COPYBACK	3
>
> -/* Needs to be defined here and not in linux/mm.h, as it is arch depend=
ent */
> -#define kern_addr_valid(addr)	(1)
> -
>   void do_page_fault(struct pt_regs *regs, unsigned long address,
>   		   unsigned long error_code);
>
> diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgt=
able.h
> index 6caec386ad2f..364a06033105 100644
> --- a/arch/mips/include/asm/pgtable.h
> +++ b/arch/mips/include/asm/pgtable.h
> @@ -550,8 +550,6 @@ static inline void update_mmu_cache_pmd(struct vm_ar=
ea_struct *vma,
>   	__update_tlb(vma, address, pte);
>   }
>
> -#define kern_addr_valid(addr)	(1)
> -
>   /*
>    * Allow physical addresses to be fixed up to help 36-bit peripherals.
>    */
> diff --git a/arch/nios2/include/asm/pgtable.h b/arch/nios2/include/asm/p=
gtable.h
> index b3d45e815295..ab793bc517f5 100644
> --- a/arch/nios2/include/asm/pgtable.h
> +++ b/arch/nios2/include/asm/pgtable.h
> @@ -249,8 +249,6 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd=
)
>   #define __swp_entry_to_pte(swp)	((pte_t) { (swp).val })
>   #define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })
>
> -#define kern_addr_valid(addr)		(1)
> -
>   extern void __init paging_init(void);
>   extern void __init mmu_init(void);
>
> diff --git a/arch/openrisc/include/asm/pgtable.h b/arch/openrisc/include=
/asm/pgtable.h
> index dcae8aea132f..6477c17b3062 100644
> --- a/arch/openrisc/include/asm/pgtable.h
> +++ b/arch/openrisc/include/asm/pgtable.h
> @@ -395,8 +395,6 @@ static inline void update_mmu_cache(struct vm_area_s=
truct *vma,
>   #define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val(pte) })
>   #define __swp_entry_to_pte(x)		((pte_t) { (x).val })
>
> -#define kern_addr_valid(addr)           (1)
> -
>   typedef pte_t *pte_addr_t;
>
>   #endif /* __ASSEMBLY__ */
> diff --git a/arch/parisc/include/asm/pgtable.h b/arch/parisc/include/asm=
/pgtable.h
> index ecd028854469..bd09a44cfb2d 100644
> --- a/arch/parisc/include/asm/pgtable.h
> +++ b/arch/parisc/include/asm/pgtable.h
> @@ -23,21 +23,6 @@
>   #include <asm/processor.h>
>   #include <asm/cache.h>
>
> -/*
> - * kern_addr_valid(ADDR) tests if ADDR is pointing to valid kernel
> - * memory.  For the return value to be meaningful, ADDR must be >=3D
> - * PAGE_OFFSET.  This operation can be relatively expensive (e.g.,
> - * require a hash-, or multi-level tree-lookup or something of that
> - * sort) but it guarantees to return TRUE only if accessing the page
> - * at that address does not cause an error.  Note that there may be
> - * addresses for which kern_addr_valid() returns FALSE even though an
> - * access would not cause an error (e.g., this is typically true for
> - * memory mapped I/O regions.
> - *
> - * XXX Need to implement this for parisc.
> - */
> -#define kern_addr_valid(addr)	(1)
> -
>   /* This is for the serialization of PxTLB broadcasts. At least on the =
N class
>    * systems, only one PxTLB inter processor broadcast can be active at =
any one
>    * time on the Merced bus. */
> diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/a=
sm/pgtable.h
> index 283f40d05a4d..9972626ddaf6 100644
> --- a/arch/powerpc/include/asm/pgtable.h
> +++ b/arch/powerpc/include/asm/pgtable.h
> @@ -81,13 +81,6 @@ void poking_init(void);
>   extern unsigned long ioremap_bot;
>   extern const pgprot_t protection_map[16];
>
> -/*
> - * kern_addr_valid is intended to indicate whether an address is a vali=
d
> - * kernel address.  Most 32-bit archs define it as always true (like th=
is)
> - * but most 64-bit archs actually perform a test.  What should we do he=
re?
> - */
> -#define kern_addr_valid(addr)	(1)
> -
>   #ifndef CONFIG_TRANSPARENT_HUGEPAGE
>   #define pmd_large(pmd)		0
>   #endif
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/p=
gtable.h
> index 7ec936910a96..c7993bdf749f 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -801,8 +801,6 @@ static inline pmd_t pmdp_establish(struct vm_area_st=
ruct *vma,
>
>   #endif /* !CONFIG_MMU */
>
> -#define kern_addr_valid(addr)   (1) /* FIXME */
> -
>   extern char _start[];
>   extern void *_dtb_early_va;
>   extern uintptr_t _dtb_early_pa;
> diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgt=
able.h
> index f1cb9391190d..e1db07211818 100644
> --- a/arch/s390/include/asm/pgtable.h
> +++ b/arch/s390/include/asm/pgtable.h
> @@ -1773,8 +1773,6 @@ static inline swp_entry_t __swp_entry(unsigned lon=
g type, unsigned long offset)
>   #define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })
>   #define __swp_entry_to_pte(x)	((pte_t) { (x).val })
>
> -#define kern_addr_valid(addr)   (1)
> -
>   extern int vmem_add_mapping(unsigned long start, unsigned long size);
>   extern void vmem_remove_mapping(unsigned long start, unsigned long siz=
e);
>   extern int __vmem_map_4k_page(unsigned long addr, unsigned long phys, =
pgprot_t prot, bool alloc);
> diff --git a/arch/sh/include/asm/pgtable.h b/arch/sh/include/asm/pgtable=
.h
> index 6fb9ec54cf9b..3ce30becf6df 100644
> --- a/arch/sh/include/asm/pgtable.h
> +++ b/arch/sh/include/asm/pgtable.h
> @@ -92,8 +92,6 @@ static inline unsigned long phys_addr_mask(void)
>
>   typedef pte_t *pte_addr_t;
>
> -#define kern_addr_valid(addr)	(1)
> -
>   #define pte_pfn(x)		((unsigned long)(((x).pte_low >> PAGE_SHIFT)))
>
>   struct vm_area_struct;
> diff --git a/arch/sparc/include/asm/pgtable_32.h b/arch/sparc/include/as=
m/pgtable_32.h
> index 8ff549004fac..5acc05b572e6 100644
> --- a/arch/sparc/include/asm/pgtable_32.h
> +++ b/arch/sparc/include/asm/pgtable_32.h
> @@ -368,12 +368,6 @@ __get_iospace (unsigned long addr)
>   	}
>   }
>
> -extern unsigned long *sparc_valid_addr_bitmap;
> -
> -/* Needs to be defined here and not in linux/mm.h, as it is arch depend=
ent */
> -#define kern_addr_valid(addr) \
> -	(test_bit(__pa((unsigned long)(addr))>>20, sparc_valid_addr_bitmap))
> -
>   /*
>    * For sparc32&64, the pfn in io_remap_pfn_range() carries <iospace> i=
n
>    * its high 4 bits.  These macros/functions put it there or get it fro=
m there.
> diff --git a/arch/sparc/mm/init_32.c b/arch/sparc/mm/init_32.c
> index d88e774c8eb4..9c0ea457bdf0 100644
> --- a/arch/sparc/mm/init_32.c
> +++ b/arch/sparc/mm/init_32.c
> @@ -37,8 +37,7 @@
>
>   #include "mm_32.h"
>
> -unsigned long *sparc_valid_addr_bitmap;
> -EXPORT_SYMBOL(sparc_valid_addr_bitmap);
> +static unsigned long *sparc_valid_addr_bitmap;
>
>   unsigned long phys_base;
>   EXPORT_SYMBOL(phys_base);
> diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
> index d6faee23c77d..04f9db0c3111 100644
> --- a/arch/sparc/mm/init_64.c
> +++ b/arch/sparc/mm/init_64.c
> @@ -1667,7 +1667,6 @@ bool kern_addr_valid(unsigned long addr)
>
>   	return pfn_valid(pte_pfn(*pte));
>   }
> -EXPORT_SYMBOL(kern_addr_valid);
>
>   static unsigned long __ref kernel_map_hugepud(unsigned long vstart,
>   					      unsigned long vend,
> diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable=
.h
> index 66bc3f99d9be..4e3052f2671a 100644
> --- a/arch/um/include/asm/pgtable.h
> +++ b/arch/um/include/asm/pgtable.h
> @@ -298,8 +298,6 @@ extern pte_t *virt_to_pte(struct mm_struct *mm, unsi=
gned long addr);
>   	((swp_entry_t) { pte_val(pte_mkuptodate(pte)) })
>   #define __swp_entry_to_pte(x)		((pte_t) { (x).val })
>
> -#define kern_addr_valid(addr) (1)
> -
>   /* Clear a kernel PTE and flush it from the TLB */
>   #define kpte_clear_flush(ptep, vaddr)		\
>   do {						\
> diff --git a/arch/x86/include/asm/pgtable_32.h b/arch/x86/include/asm/pg=
table_32.h
> index 7c9c968a42ef..7d4ad8907297 100644
> --- a/arch/x86/include/asm/pgtable_32.h
> +++ b/arch/x86/include/asm/pgtable_32.h
> @@ -47,15 +47,6 @@ do {						\
>
>   #endif /* !__ASSEMBLY__ */
>
> -/*
> - * kern_addr_valid() is (1) for FLATMEM and (0) for SPARSEMEM
> - */
> -#ifdef CONFIG_FLATMEM
> -#define kern_addr_valid(addr)	(1)
> -#else
> -#define kern_addr_valid(kaddr)	(0)
> -#endif
> -
>   /*
>    * This is used to calculate the .brk reservation for initial pagetabl=
es.
>    * Enough space is reserved to allocate pagetables sufficient to cover=
 all
> diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pg=
table_64.h
> index e479491da8d5..7929327abe00 100644
> --- a/arch/x86/include/asm/pgtable_64.h
> +++ b/arch/x86/include/asm/pgtable_64.h
> @@ -240,7 +240,6 @@ static inline void native_pgd_clear(pgd_t *pgd)
>   #define __swp_entry_to_pte(x)		((pte_t) { .pte =3D (x).val })
>   #define __swp_entry_to_pmd(x)		((pmd_t) { .pmd =3D (x).val })
>
> -extern int kern_addr_valid(unsigned long addr);
>   extern void cleanup_highmap(void);
>
>   #define HAVE_ARCH_UNMAPPED_AREA
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 3f040c6e5d13..e8db4edd7cc9 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -1416,47 +1416,6 @@ void mark_rodata_ro(void)
>   	debug_checkwx();
>   }
>
> -int kern_addr_valid(unsigned long addr)
> -{
> -	unsigned long above =3D ((long)addr) >> __VIRTUAL_MASK_SHIFT;
> -	pgd_t *pgd;
> -	p4d_t *p4d;
> -	pud_t *pud;
> -	pmd_t *pmd;
> -	pte_t *pte;
> -
> -	if (above !=3D 0 && above !=3D -1UL)
> -		return 0;
> -
> -	pgd =3D pgd_offset_k(addr);
> -	if (pgd_none(*pgd))
> -		return 0;
> -
> -	p4d =3D p4d_offset(pgd, addr);
> -	if (!p4d_present(*p4d))
> -		return 0;
> -
> -	pud =3D pud_offset(p4d, addr);
> -	if (!pud_present(*pud))
> -		return 0;
> -
> -	if (pud_large(*pud))
> -		return pfn_valid(pud_pfn(*pud));
> -
> -	pmd =3D pmd_offset(pud, addr);
> -	if (!pmd_present(*pmd))
> -		return 0;
> -
> -	if (pmd_large(*pmd))
> -		return pfn_valid(pmd_pfn(*pmd));
> -
> -	pte =3D pte_offset_kernel(pmd, addr);
> -	if (pte_none(*pte))
> -		return 0;
> -
> -	return pfn_valid(pte_pfn(*pte));
> -}
> -
>   /*
>    * Block size is the minimum amount of memory which can be hotplugged =
or
>    * hotremoved. It must be power of two and must be equal or larger tha=
n
> diff --git a/arch/xtensa/include/asm/pgtable.h b/arch/xtensa/include/asm=
/pgtable.h
> index 54f577c13afa..5b5484d707b2 100644
> --- a/arch/xtensa/include/asm/pgtable.h
> +++ b/arch/xtensa/include/asm/pgtable.h
> @@ -386,8 +386,6 @@ ptep_set_wrprotect(struct mm_struct *mm, unsigned lo=
ng addr, pte_t *ptep)
>
>   #else
>
> -#define kern_addr_valid(addr)	(1)
> -
>   extern  void update_mmu_cache(struct vm_area_struct * vma,
>   			      unsigned long address, pte_t *ptep);
>
> diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
> index dff921f7ca33..590ecb79ad8b 100644
> --- a/fs/proc/kcore.c
> +++ b/fs/proc/kcore.c
> @@ -541,25 +541,17 @@ read_kcore(struct file *file, char __user *buffer,=
 size_t buflen, loff_t *fpos)
>   			fallthrough;
>   		case KCORE_VMEMMAP:
>   		case KCORE_TEXT:
> -			if (kern_addr_valid(start)) {
> -				/*
> -				 * Using bounce buffer to bypass the
> -				 * hardened user copy kernel text checks.
> -				 */
> -				if (copy_from_kernel_nofault(buf, (void *)start,
> -						tsz)) {
> -					if (clear_user(buffer, tsz)) {
> -						ret =3D -EFAULT;
> -						goto out;
> -					}
> -				} else {
> -					if (copy_to_user(buffer, buf, tsz)) {
> -						ret =3D -EFAULT;
> -						goto out;
> -					}
> +			/*
> +			 * Using bounce buffer to bypass the
> +			 * hardened user copy kernel text checks.
> +			 */
> +			if (copy_from_kernel_nofault(buf, (void *)start, tsz)) {
> +				if (clear_user(buffer, tsz)) {
> +					ret =3D -EFAULT;
> +					goto out;
>   				}
>   			} else {
> -				if (clear_user(buffer, tsz)) {
> +				if (copy_to_user(buffer, buf, tsz)) {
>   					ret =3D -EFAULT;
>   					goto out;
>   				}