d862613800
Patch series "mm: Get rid of vmalloc_sync_(un)mappings()", v3. After the recent issue with vmalloc and tracing code[1] on x86 and a long history of previous issues related to the vmalloc_sync_mappings() interface, I thought the time has come to remove it. Please see [2], [3], and [4] for some other issues in the past. The patches add tracking of page-table directory changes to the vmalloc and ioremap code. Depending on which page-table levels changes have been made, a new per-arch function is called: arch_sync_kernel_mappings(). On x86-64 with 4-level paging, this function will not be called more than 64 times in a systems runtime (because vmalloc-space takes 64 PGD entries which are only populated, but never cleared). As a side effect this also allows to get rid of vmalloc faults on x86, making it safe to touch vmalloc'ed memory in the page-fault handler. Note that this potentially includes per-cpu memory. This patch (of 7): Add page-table allocation functions which will keep track of changed directory entries. They are needed for new PGD, P4D, PUD, and PMD entries and will be used in vmalloc and ioremap code to decide whether any changes in the kernel mappings need to be synchronized between page-tables in the system. Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Andy Lutomirski <luto@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Christoph Hellwig <hch@lst.de> Link: http://lkml.kernel.org/r/20200515140023.25469-1-joro@8bytes.org Link: http://lkml.kernel.org/r/20200515140023.25469-2-joro@8bytes.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
60 lines
1.4 KiB
C
60 lines
1.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _5LEVEL_FIXUP_H
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#define _5LEVEL_FIXUP_H
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#define __ARCH_HAS_5LEVEL_HACK
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#define __PAGETABLE_P4D_FOLDED 1
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#define P4D_SHIFT PGDIR_SHIFT
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#define P4D_SIZE PGDIR_SIZE
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#define P4D_MASK PGDIR_MASK
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#define MAX_PTRS_PER_P4D 1
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#define PTRS_PER_P4D 1
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#define p4d_t pgd_t
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#define pud_alloc(mm, p4d, address) \
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((unlikely(pgd_none(*(p4d))) && __pud_alloc(mm, p4d, address)) ? \
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NULL : pud_offset(p4d, address))
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#define p4d_alloc(mm, pgd, address) (pgd)
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#define p4d_alloc_track(mm, pgd, address, mask) (pgd)
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#define p4d_offset(pgd, start) (pgd)
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#ifndef __ASSEMBLY__
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static inline int p4d_none(p4d_t p4d)
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{
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return 0;
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}
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static inline int p4d_bad(p4d_t p4d)
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{
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return 0;
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}
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static inline int p4d_present(p4d_t p4d)
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{
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return 1;
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}
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#endif
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#define p4d_ERROR(p4d) do { } while (0)
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#define p4d_clear(p4d) pgd_clear(p4d)
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#define p4d_val(p4d) pgd_val(p4d)
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#define p4d_populate(mm, p4d, pud) pgd_populate(mm, p4d, pud)
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#define p4d_populate_safe(mm, p4d, pud) pgd_populate(mm, p4d, pud)
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#define p4d_page(p4d) pgd_page(p4d)
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#define p4d_page_vaddr(p4d) pgd_page_vaddr(p4d)
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#define __p4d(x) __pgd(x)
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#define set_p4d(p4dp, p4d) set_pgd(p4dp, p4d)
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#undef p4d_free_tlb
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#define p4d_free_tlb(tlb, x, addr) do { } while (0)
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#define p4d_free(mm, x) do { } while (0)
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#undef p4d_addr_end
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#define p4d_addr_end(addr, end) (end)
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#endif
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