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a1c510d0ad
Wire up the generic support for managing task stack allocations via vmalloc, and implement the entry code that detects whether we faulted because of a stack overrun (or future stack overrun caused by pushing the pt_regs array) While this adds a fair amount of tricky entry asm code, it should be noted that it only adds a TST + branch to the svc_entry path. The code implementing the non-trivial handling of the overflow stack is emitted out-of-line into the .text section. Since on ARM, we rely on do_translation_fault() to keep PMD level page table entries that cover the vmalloc region up to date, we need to ensure that we don't hit such a stale PMD entry when accessing the stack. So we do a dummy read from the new stack while still running from the old one on the context switch path, and bump the vmalloc_seq counter when PMD level entries in the vmalloc range are modified, so that the MM switch fetches the latest version of the entries. Note that we need to increase the per-mode stack by 1 word, to gain some space to stash a GPR until we know it is safe to touch the stack. However, due to the cacheline alignment of the struct, this does not actually increase the memory footprint of the struct stack array at all. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Keith Packard <keithpac@amazon.com> Tested-by: Marc Zyngier <maz@kernel.org> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
172 lines
3.5 KiB
C
172 lines
3.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* arch/arm/include/asm/page.h
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*
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* Copyright (C) 1995-2003 Russell King
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*/
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#ifndef _ASMARM_PAGE_H
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#define _ASMARM_PAGE_H
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/* PAGE_SHIFT determines the page size */
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#define PAGE_SHIFT 12
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#define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT)
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#define PAGE_MASK (~((1 << PAGE_SHIFT) - 1))
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#ifndef __ASSEMBLY__
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#ifndef CONFIG_MMU
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#include <asm/page-nommu.h>
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#else
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#include <asm/glue.h>
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/*
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* User Space Model
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* ================
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*
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* This section selects the correct set of functions for dealing with
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* page-based copying and clearing for user space for the particular
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* processor(s) we're building for.
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*
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* We have the following to choose from:
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* v4wt - ARMv4 with writethrough cache, without minicache
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* v4wb - ARMv4 with writeback cache, without minicache
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* v4_mc - ARMv4 with minicache
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* xscale - Xscale
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* xsc3 - XScalev3
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*/
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#undef _USER
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#undef MULTI_USER
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#ifdef CONFIG_CPU_COPY_V4WT
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# ifdef _USER
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# define MULTI_USER 1
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# else
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# define _USER v4wt
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# endif
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#endif
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#ifdef CONFIG_CPU_COPY_V4WB
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# ifdef _USER
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# define MULTI_USER 1
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# else
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# define _USER v4wb
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# endif
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#endif
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#ifdef CONFIG_CPU_COPY_FEROCEON
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# ifdef _USER
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# define MULTI_USER 1
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# else
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# define _USER feroceon
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# endif
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#endif
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#ifdef CONFIG_CPU_COPY_FA
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# ifdef _USER
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# define MULTI_USER 1
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# else
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# define _USER fa
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# endif
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#endif
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#ifdef CONFIG_CPU_SA1100
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# ifdef _USER
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# define MULTI_USER 1
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# else
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# define _USER v4_mc
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# endif
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#endif
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#ifdef CONFIG_CPU_XSCALE
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# ifdef _USER
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# define MULTI_USER 1
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# else
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# define _USER xscale_mc
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# endif
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#endif
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#ifdef CONFIG_CPU_XSC3
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# ifdef _USER
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# define MULTI_USER 1
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# else
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# define _USER xsc3_mc
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# endif
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#endif
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#ifdef CONFIG_CPU_COPY_V6
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# define MULTI_USER 1
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#endif
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#if !defined(_USER) && !defined(MULTI_USER)
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#error Unknown user operations model
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#endif
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struct page;
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struct vm_area_struct;
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struct cpu_user_fns {
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void (*cpu_clear_user_highpage)(struct page *page, unsigned long vaddr);
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void (*cpu_copy_user_highpage)(struct page *to, struct page *from,
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unsigned long vaddr, struct vm_area_struct *vma);
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};
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#ifdef MULTI_USER
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extern struct cpu_user_fns cpu_user;
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#define __cpu_clear_user_highpage cpu_user.cpu_clear_user_highpage
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#define __cpu_copy_user_highpage cpu_user.cpu_copy_user_highpage
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#else
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#define __cpu_clear_user_highpage __glue(_USER,_clear_user_highpage)
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#define __cpu_copy_user_highpage __glue(_USER,_copy_user_highpage)
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extern void __cpu_clear_user_highpage(struct page *page, unsigned long vaddr);
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extern void __cpu_copy_user_highpage(struct page *to, struct page *from,
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unsigned long vaddr, struct vm_area_struct *vma);
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#endif
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#define clear_user_highpage(page,vaddr) \
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__cpu_clear_user_highpage(page, vaddr)
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#define __HAVE_ARCH_COPY_USER_HIGHPAGE
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#define copy_user_highpage(to,from,vaddr,vma) \
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__cpu_copy_user_highpage(to, from, vaddr, vma)
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#define clear_page(page) memset((void *)(page), 0, PAGE_SIZE)
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extern void copy_page(void *to, const void *from);
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#ifdef CONFIG_KUSER_HELPERS
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#define __HAVE_ARCH_GATE_AREA 1
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#endif
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#ifdef CONFIG_ARM_LPAE
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#include <asm/pgtable-3level-types.h>
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#else
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#include <asm/pgtable-2level-types.h>
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#endif
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#ifdef CONFIG_VMAP_STACK
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#define ARCH_PAGE_TABLE_SYNC_MASK PGTBL_PMD_MODIFIED
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#endif
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#endif /* CONFIG_MMU */
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typedef struct page *pgtable_t;
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#ifdef CONFIG_HAVE_ARCH_PFN_VALID
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extern int pfn_valid(unsigned long);
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#endif
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#include <asm/memory.h>
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#endif /* !__ASSEMBLY__ */
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#define VM_DATA_DEFAULT_FLAGS VM_DATA_FLAGS_TSK_EXEC
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#include <asm-generic/getorder.h>
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#endif
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