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2b5548b681
Since the address of swapper_pg_dir is fixed for a given kernel image, it is an attractive target for manipulation via an arbitrary write. To mitigate this we'd like to make it read-only by moving it into the rodata section. We require that swapper_pg_dir is at a fixed offset from tramp_pg_dir and reserved_ttbr0, so these will also need to move into rodata. However, swapper_pg_dir is allocated along with some transient page tables used for boot which we do not want to move into rodata. As a step towards this, this patch separates the boot-time page tables into a new init_pg_dir, and reduces swapper_pg_dir to the single page it needs to be. This allows us to retain the relationship between swapper_pg_dir, tramp_pg_dir, and swapper_pg_dir, while cleanly separating these from the boot-time page tables. The init_pg_dir holds all of the pgd/pud/pmd/pte levels needed during boot, and all of these levels will be freed when we switch to the swapper_pg_dir, which is initialized by the existing code in paging_init(). Since we start off on the init_pg_dir, we no longer need to allocate a transient page table in paging_init() in order to ensure that swapper_pg_dir isn't live while we initialize it. There should be no functional change as a result of this patch. Signed-off-by: Jun Yao <yaojun8558363@gmail.com> Reviewed-by: James Morse <james.morse@arm.com> [Mark: place init_pg_dir after BSS, fold mm changes, commit message] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
103 lines
2.9 KiB
C
103 lines
2.9 KiB
C
/*
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __ASM_MMU_H
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#define __ASM_MMU_H
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#define MMCF_AARCH32 0x1 /* mm context flag for AArch32 executables */
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#define USER_ASID_BIT 48
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#define USER_ASID_FLAG (UL(1) << USER_ASID_BIT)
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#define TTBR_ASID_MASK (UL(0xffff) << 48)
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#define BP_HARDEN_EL2_SLOTS 4
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#ifndef __ASSEMBLY__
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typedef struct {
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atomic64_t id;
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void *vdso;
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unsigned long flags;
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} mm_context_t;
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/*
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* This macro is only used by the TLBI code, which cannot race with an
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* ASID change and therefore doesn't need to reload the counter using
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* atomic64_read.
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*/
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#define ASID(mm) ((mm)->context.id.counter & 0xffff)
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static inline bool arm64_kernel_unmapped_at_el0(void)
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{
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return IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0) &&
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cpus_have_const_cap(ARM64_UNMAP_KERNEL_AT_EL0);
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}
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typedef void (*bp_hardening_cb_t)(void);
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struct bp_hardening_data {
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int hyp_vectors_slot;
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bp_hardening_cb_t fn;
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};
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#if (defined(CONFIG_HARDEN_BRANCH_PREDICTOR) || \
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defined(CONFIG_HARDEN_EL2_VECTORS))
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extern char __bp_harden_hyp_vecs_start[], __bp_harden_hyp_vecs_end[];
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extern atomic_t arm64_el2_vector_last_slot;
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#endif /* CONFIG_HARDEN_BRANCH_PREDICTOR || CONFIG_HARDEN_EL2_VECTORS */
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#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
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DECLARE_PER_CPU_READ_MOSTLY(struct bp_hardening_data, bp_hardening_data);
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static inline struct bp_hardening_data *arm64_get_bp_hardening_data(void)
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{
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return this_cpu_ptr(&bp_hardening_data);
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}
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static inline void arm64_apply_bp_hardening(void)
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{
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struct bp_hardening_data *d;
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if (!cpus_have_const_cap(ARM64_HARDEN_BRANCH_PREDICTOR))
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return;
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d = arm64_get_bp_hardening_data();
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if (d->fn)
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d->fn();
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}
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#else
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static inline struct bp_hardening_data *arm64_get_bp_hardening_data(void)
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{
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return NULL;
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}
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static inline void arm64_apply_bp_hardening(void) { }
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#endif /* CONFIG_HARDEN_BRANCH_PREDICTOR */
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extern void paging_init(void);
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extern void bootmem_init(void);
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extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt);
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extern void init_mem_pgprot(void);
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extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
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unsigned long virt, phys_addr_t size,
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pgprot_t prot, bool page_mappings_only);
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extern void *fixmap_remap_fdt(phys_addr_t dt_phys);
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extern void mark_linear_text_alias_ro(void);
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#define INIT_MM_CONTEXT(name) \
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.pgd = init_pg_dir,
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#endif /* !__ASSEMBLY__ */
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#endif
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