cregit-Linux how code gets into the kernel

Release 4.17 arch/arm64/mm/pageattr.c

Directory: arch/arm64/mm
/*
 * Copyright (c) 2014, The Linux Foundation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/vmalloc.h>

#include <asm/pgtable.h>
#include <asm/set_memory.h>
#include <asm/tlbflush.h>


struct page_change_data {
	
pgprot_t set_mask;
	
pgprot_t clear_mask;
};


static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr, void *data) { struct page_change_data *cdata = data; pte_t pte = READ_ONCE(*ptep); pte = clear_pte_bit(pte, cdata->clear_mask); pte = set_pte_bit(pte, cdata->set_mask); set_pte(ptep, pte); return 0; }

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Laura Abbott6695.65%150.00%
Will Deacon34.35%150.00%
Total69100.00%2100.00%

/* * This function assumes that the range is mapped with PAGE_SIZE pages. */
static int __change_memory_common(unsigned long start, unsigned long size, pgprot_t set_mask, pgprot_t clear_mask) { struct page_change_data data; int ret; data.set_mask = set_mask; data.clear_mask = clear_mask; ret = apply_to_page_range(&init_mm, start, size, change_page_range, &data); flush_tlb_kernel_range(start, start + size); return ret; }

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Laura Abbott68100.00%1100.00%
Total68100.00%1100.00%


static int change_memory_common(unsigned long addr, int numpages, pgprot_t set_mask, pgprot_t clear_mask) { unsigned long start = addr; unsigned long size = PAGE_SIZE*numpages; unsigned long end = start + size; struct vm_struct *area; if (!PAGE_ALIGNED(addr)) { start &= PAGE_MASK; end = start + size; WARN_ON_ONCE(1); } /* * Kernel VA mappings are always live, and splitting live section * mappings into page mappings may cause TLB conflicts. This means * we have to ensure that changing the permission bits of the range * we are operating on does not result in such splitting. * * Let's restrict ourselves to mappings created by vmalloc (or vmap). * Those are guaranteed to consist entirely of page mappings, and * splitting is never needed. * * So check whether the [addr, addr + size) interval is entirely * covered by precisely one VM area that has the VM_ALLOC flag set. */ area = find_vm_area((void *)addr); if (!area || end > (unsigned long)area->addr + area->size || !(area->flags & VM_ALLOC)) return -EINVAL; if (!numpages) return 0; return __change_memory_common(start, size, set_mask, clear_mask); }

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Laura Abbott8764.44%457.14%
Ard Biesheuvel3928.89%114.29%
Mika Penttilä85.93%114.29%
Alexander Kuleshov10.74%114.29%
Total135100.00%7100.00%


int set_memory_ro(unsigned long addr, int numpages) { return change_memory_common(addr, numpages, __pgprot(PTE_RDONLY), __pgprot(PTE_WRITE)); }

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Laura Abbott30100.00%1100.00%
Total30100.00%1100.00%


int set_memory_rw(unsigned long addr, int numpages) { return change_memory_common(addr, numpages, __pgprot(PTE_WRITE), __pgprot(PTE_RDONLY)); }

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Laura Abbott30100.00%1100.00%
Total30100.00%1100.00%


int set_memory_nx(unsigned long addr, int numpages) { return change_memory_common(addr, numpages, __pgprot(PTE_PXN), __pgprot(0)); }

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Laura Abbott30100.00%1100.00%
Total30100.00%1100.00%

EXPORT_SYMBOL_GPL(set_memory_nx);
int set_memory_x(unsigned long addr, int numpages) { return change_memory_common(addr, numpages, __pgprot(0), __pgprot(PTE_PXN)); }

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Laura Abbott30100.00%1100.00%
Total30100.00%1100.00%

EXPORT_SYMBOL_GPL(set_memory_x);
int set_memory_valid(unsigned long addr, int numpages, int enable) { if (enable) return __change_memory_common(addr, PAGE_SIZE * numpages, __pgprot(PTE_VALID), __pgprot(0)); else return __change_memory_common(addr, PAGE_SIZE * numpages, __pgprot(0), __pgprot(PTE_VALID)); }

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Laura Abbott5083.33%150.00%
AKASHI Takahiro1016.67%150.00%
Total60100.00%2100.00%

#ifdef CONFIG_DEBUG_PAGEALLOC
void __kernel_map_pages(struct page *page, int numpages, int enable) { set_memory_valid((unsigned long)page_address(page), numpages, enable); }

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AKASHI Takahiro3093.75%150.00%
Laura Abbott26.25%150.00%
Total32100.00%2100.00%

#ifdef CONFIG_HIBERNATION /* * When built with CONFIG_DEBUG_PAGEALLOC and CONFIG_HIBERNATION, this function * is used to determine if a linear map page has been marked as not-valid by * CONFIG_DEBUG_PAGEALLOC. Walk the page table and check the PTE_VALID bit. * This is based on kern_addr_valid(), which almost does what we need. * * Because this is only called on the kernel linear map, p?d_sect() implies * p?d_present(). When debug_pagealloc is enabled, sections mappings are * disabled. */
bool kernel_page_present(struct page *page) { pgd_t *pgdp; pud_t *pudp, pud; pmd_t *pmdp, pmd; pte_t *ptep; unsigned long addr = (unsigned long)page_address(page); pgdp = pgd_offset_k(addr); if (pgd_none(READ_ONCE(*pgdp))) return false; pudp = pud_offset(pgdp, addr); pud = READ_ONCE(*pudp); if (pud_none(pud)) return false; if (pud_sect(pud)) return true; pmdp = pmd_offset(pudp, addr); pmd = READ_ONCE(*pmdp); if (pmd_none(pmd)) return false; if (pmd_sect(pmd)) return true; ptep = pte_offset_kernel(pmdp, addr); return pte_valid(READ_ONCE(*ptep)); }

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James Morse12076.43%150.00%
Will Deacon3723.57%150.00%
Total157100.00%2100.00%

#endif /* CONFIG_HIBERNATION */ #endif /* CONFIG_DEBUG_PAGEALLOC */

Overall Contributors

PersonTokensPropCommitsCommitProp
Laura Abbott43962.62%545.45%
James Morse12818.26%19.09%
AKASHI Takahiro436.13%19.09%
Ard Biesheuvel425.99%19.09%
Will Deacon405.71%19.09%
Mika Penttilä81.14%19.09%
Alexander Kuleshov10.14%19.09%
Total701100.00%11100.00%
Directory: arch/arm64/mm
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