mm: remove kern_addr_valid() completely

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 as there is no need for kern_addr_valid(), let's
remove it.

Link: https://lkml.kernel.org/r/20221018074014.185687-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>	[m68k]
Acked-by: Heiko Carstens <hca@linux.ibm.com>		[s390]
Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: Helge Deller <deller@gmx.de>			[parisc]
Acked-by: Michael Ellerman <mpe@ellerman.id.au>		[powerpc]
Acked-by: Guo Ren <guoren@kernel.org>			[csky]
Acked-by: Catalin Marinas <catalin.marinas@arm.com>	[arm64]
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: <aou@eecs.berkeley.edu>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Chris Zankel <chris@zankel.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
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: Xuerui Wang <kernel@xen0n.name>
Cc: Yoshinori Sato <ysato@users.osdn.me>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

3 files changed, 1 insertions, 51 deletions

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.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 = arch_kasan_reset_tag(addr);
-	if ((((long)addr) >> VA_BITS) != -1UL)
-		return 0;
-
-	pgdp = pgd_offset_k(addr);
-	if (pgd_none(READ_ONCE(*pgdp)))
-		return 0;
-
-	p4dp = p4d_offset(pgdp, addr);
-	if (p4d_none(READ_ONCE(*p4dp)))
-		return 0;
-
-	pudp = pud_offset(p4dp, addr);
-	pud = READ_ONCE(*pudp);
-	if (pud_none(pud))
-		return 0;
-
-	if (pud_sect(pud))
-		return pfn_valid(pud_pfn(pud));
-
-	pmdp = pmd_offset(pudp, addr);
-	pmd = READ_ONCE(*pmdp);
-	if (pmd_none(pmd))
-		return 0;
-
-	if (pmd_sect(pmd))
-		return pfn_valid(pmd_pfn(pmd));
-
-	ptep = pte_offset_kernel(pmdp, addr);
-	pte = 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 numpages, int enable)
 
 /*
  * This function is used to determine if a linear map page has been marked 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() implies
  * p?d_present(). When debug_pagealloc is enabled, sections mappings are