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, 0 insertions, 51 deletions

diff --git a/arch/x86/include/asm/pgtable_32.h b/arch/x86/include/asm/pgtable_32.h
index 7c9c968a42ef..7d4ad8907297 100644
--- a/arch/x86/include/asm/pgtable_32.h
+++ b/arch/x86/include/asm/pgtable_32.h
@@ -48,15 +48,6 @@ 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 pagetables.
  * Enough space is reserved to allocate pagetables sufficient to cover all
  * of LOWMEM_PAGES, which is an upper bound on the size of the direct map of
diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_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 = (x).val })
 #define __swp_entry_to_pmd(x)		((pmd_t) { .pmd = (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 = ((long)addr) >> __VIRTUAL_MASK_SHIFT;
-	pgd_t *pgd;
-	p4d_t *p4d;
-	pud_t *pud;
-	pmd_t *pmd;
-	pte_t *pte;
-
-	if (above != 0 && above != -1UL)
-		return 0;
-
-	pgd = pgd_offset_k(addr);
-	if (pgd_none(*pgd))
-		return 0;
-
-	p4d = p4d_offset(pgd, addr);
-	if (!p4d_present(*p4d))
-		return 0;
-
-	pud = pud_offset(p4d, addr);
-	if (!pud_present(*pud))
-		return 0;
-
-	if (pud_large(*pud))
-		return pfn_valid(pud_pfn(*pud));
-
-	pmd = pmd_offset(pud, addr);
-	if (!pmd_present(*pmd))
-		return 0;
-
-	if (pmd_large(*pmd))
-		return pfn_valid(pmd_pfn(*pmd));
-
-	pte = 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 than