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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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a847b17009
Lots of functions in mm/highmem.c do not write to the given pointers and do not call functions that take non-const pointers and can therefore be constified. This includes functions like kunmap() which might be implemented in a way that writes to the pointer (e.g. to update reference counters or mapping fields), but currently are not. kmap() on the other hand cannot be made const because it calls set_page_address() which is non-const in some architectures/configurations. [akpm@linux-foundation.org: "fix" folio_page() build failure] Link: https://lkml.kernel.org/r/20250901205021.3573313-13-max.kellermann@ionos.com Signed-off-by: Max Kellermann <max.kellermann@ionos.com> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andreas Larsson <andreas@gaisler.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Borislav Betkov <bp@alien8.de> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Christian Brauner <brauner@kernel.org> Cc: Christian Zankel <chris@zankel.net> Cc: David Rientjes <rientjes@google.com> Cc: David S. Miller <davem@davemloft.net> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Bottomley <james.bottomley@HansenPartnership.com> Cc: Jan Kara <jack@suse.cz> Cc: Jocelyn Falempe <jfalempe@redhat.com> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Mark Brown <broonie@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Hocko <mhocko@suse.com> Cc: "Nysal Jan K.A" <nysal@linux.ibm.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Russel King <linux@armlinux.org.uk> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Thomas Gleinxer <tglx@linutronix.de> Cc: Thomas Huth <thuth@redhat.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Cc: Wei Xu <weixugc@google.com> Cc: Yuanchu Xie <yuanchu@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
79 lines
2.3 KiB
C
79 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_HIGHMEM_H
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#define _ASM_HIGHMEM_H
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#include <asm/cachetype.h>
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#include <asm/fixmap.h>
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#define PKMAP_BASE (PAGE_OFFSET - PMD_SIZE)
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#define LAST_PKMAP PTRS_PER_PTE
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#define LAST_PKMAP_MASK (LAST_PKMAP - 1)
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#define PKMAP_NR(virt) (((virt) - PKMAP_BASE) >> PAGE_SHIFT)
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#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
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#define flush_cache_kmaps() \
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do { \
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if (cache_is_vivt()) \
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flush_cache_all(); \
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} while (0)
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extern pte_t *pkmap_page_table;
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/*
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* The reason for kmap_high_get() is to ensure that the currently kmap'd
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* page usage count does not decrease to zero while we're using its
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* existing virtual mapping in an atomic context. With a VIVT cache this
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* is essential to do, but with a VIPT cache this is only an optimization
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* so not to pay the price of establishing a second mapping if an existing
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* one can be used. However, on platforms without hardware TLB maintenance
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* broadcast, we simply cannot use ARCH_NEEDS_KMAP_HIGH_GET at all since
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* the locking involved must also disable IRQs which is incompatible with
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* the IPI mechanism used by global TLB operations.
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*/
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#define ARCH_NEEDS_KMAP_HIGH_GET
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#if defined(CONFIG_SMP) && defined(CONFIG_CPU_TLB_V6)
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#undef ARCH_NEEDS_KMAP_HIGH_GET
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#if defined(CONFIG_HIGHMEM) && defined(CONFIG_CPU_CACHE_VIVT)
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#error "The sum of features in your kernel config cannot be supported together"
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#endif
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#endif
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/*
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* Needed to be able to broadcast the TLB invalidation for kmap.
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*/
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#ifdef CONFIG_ARM_ERRATA_798181
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#undef ARCH_NEEDS_KMAP_HIGH_GET
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#endif
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#ifdef ARCH_NEEDS_KMAP_HIGH_GET
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extern void *kmap_high_get(const struct page *page);
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static inline void *arch_kmap_local_high_get(const struct page *page)
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{
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if (IS_ENABLED(CONFIG_DEBUG_HIGHMEM) && !cache_is_vivt())
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return NULL;
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return kmap_high_get(page);
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}
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#define arch_kmap_local_high_get arch_kmap_local_high_get
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#else /* ARCH_NEEDS_KMAP_HIGH_GET */
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static inline void *kmap_high_get(const struct page *page)
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{
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return NULL;
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}
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#endif /* !ARCH_NEEDS_KMAP_HIGH_GET */
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#define arch_kmap_local_post_map(vaddr, pteval) \
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local_flush_tlb_kernel_page(vaddr)
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#define arch_kmap_local_pre_unmap(vaddr) \
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do { \
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if (cache_is_vivt()) \
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__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE); \
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} while (0)
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#define arch_kmap_local_post_unmap(vaddr) \
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local_flush_tlb_kernel_page(vaddr)
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#endif
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