8a2e028a6d
Lowmem is currently mapped with sections (1MB/2MB) whenever possible due to TLB performance boosts. Sections cannot easily be changed at runtime however which makes implementing certain features annoying. Add an option to map lowmem with 4K patches. This is intended to be used as a debugging feature and should NOT be used for performance testing. Change-Id: I9612a99b8e05a022f5ba7e568f21307cf66b5667 Signed-off-by: Laura Abbott <lauraa@codeaurora.org> Signed-off-by: Susheel Khiani <skhiani@codeaurora.org>
97 lines
2.3 KiB
C
97 lines
2.3 KiB
C
/*
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* Copyright (c) 2014, The Linux Foundation. All rights reserved.
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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 and
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* only version 2 as 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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#include <linux/mm.h>
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#include <linux/module.h>
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#include <asm/pgtable.h>
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#include <asm/tlbflush.h>
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struct page_change_data {
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pgprot_t set_mask;
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pgprot_t clear_mask;
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};
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static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr,
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void *data)
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{
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struct page_change_data *cdata = data;
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pte_t pte = *ptep;
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pte = clear_pte_bit(pte, cdata->clear_mask);
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pte = set_pte_bit(pte, cdata->set_mask);
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set_pte_ext(ptep, pte, 0);
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return 0;
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}
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static int change_memory_common(unsigned long addr, int numpages,
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pgprot_t set_mask, pgprot_t clear_mask)
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{
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unsigned long start = addr;
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unsigned long size = PAGE_SIZE*numpages;
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unsigned long end = start + size;
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int ret;
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struct page_change_data data;
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if (!IS_ALIGNED(addr, PAGE_SIZE)) {
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start &= PAGE_MASK;
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end = start + size;
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WARN_ON_ONCE(1);
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}
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if (!IS_ENABLED(CONFIG_FORCE_PAGES)) {
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if (start < MODULES_VADDR || start >= MODULES_END)
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return -EINVAL;
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if (end < MODULES_VADDR || start >= MODULES_END)
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return -EINVAL;
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}
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data.set_mask = set_mask;
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data.clear_mask = clear_mask;
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ret = apply_to_page_range(&init_mm, start, size, change_page_range,
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&data);
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flush_tlb_kernel_range(start, end);
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return ret;
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}
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int set_memory_ro(unsigned long addr, int numpages)
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{
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return change_memory_common(addr, numpages,
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__pgprot(L_PTE_RDONLY),
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__pgprot(0));
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}
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int set_memory_rw(unsigned long addr, int numpages)
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{
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return change_memory_common(addr, numpages,
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__pgprot(0),
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__pgprot(L_PTE_RDONLY));
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}
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int set_memory_nx(unsigned long addr, int numpages)
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{
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return change_memory_common(addr, numpages,
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__pgprot(L_PTE_XN),
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__pgprot(0));
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}
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int set_memory_x(unsigned long addr, int numpages)
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{
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return change_memory_common(addr, numpages,
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__pgprot(0),
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__pgprot(L_PTE_XN));
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}
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