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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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bd00cd5f8c
Currently we place swapper_pg_dir and idmap_pg_dir below the kernel image, between PHYS_OFFSET and (PHYS_OFFSET + TEXT_OFFSET). However, bootloaders may use portions of this memory below the kernel and we do not parse the memory reservation list until after the MMU has been enabled. As such we may clobber some memory a bootloader wishes to have preserved. To enable the use of all of this memory by bootloaders (when the required memory reservations are communicated to the kernel) it is necessary to move our initial page tables elsewhere. As we currently have an effectively unbound requirement for memory at the end of the kernel image for .bss, we can place the page tables here. This patch moves the initial page table to the end of the kernel image, after the BSS. As they do not consist of any initialised data they will be stripped from the kernel Image as with the BSS. The BSS clearing routine is updated to stop at __bss_stop rather than _end so as to not clobber the page tables, and memory reservations made redundant by the new organisation are removed. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Laura Abbott <lauraa@codeaurora.org> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
77 lines
2.3 KiB
C
77 lines
2.3 KiB
C
/*
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* Based on arch/arm/include/asm/page.h
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*
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* Copyright (C) 1995-2003 Russell King
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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_PAGE_H
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#define __ASM_PAGE_H
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/* PAGE_SHIFT determines the page size */
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#ifdef CONFIG_ARM64_64K_PAGES
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#define PAGE_SHIFT 16
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#else
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#define PAGE_SHIFT 12
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#endif
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#define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT)
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#define PAGE_MASK (~(PAGE_SIZE-1))
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/* We do define AT_SYSINFO_EHDR but don't use the gate mechanism */
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#define __HAVE_ARCH_GATE_AREA 1
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/*
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* The idmap and swapper page tables need some space reserved in the kernel
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* image. The idmap only requires a pgd and a next level table to (section) map
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* the kernel, while the swapper also maps the FDT and requires an additional
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* table to map an early UART. See __create_page_tables for more information.
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*/
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#define SWAPPER_DIR_SIZE (3 * PAGE_SIZE)
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#define IDMAP_DIR_SIZE (2 * PAGE_SIZE)
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#ifndef __ASSEMBLY__
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#ifdef CONFIG_ARM64_64K_PAGES
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#include <asm/pgtable-2level-types.h>
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#else
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#include <asm/pgtable-3level-types.h>
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#endif
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extern void __cpu_clear_user_page(void *p, unsigned long user);
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extern void __cpu_copy_user_page(void *to, const void *from,
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unsigned long user);
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extern void copy_page(void *to, const void *from);
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extern void clear_page(void *to);
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#define clear_user_page(addr,vaddr,pg) __cpu_clear_user_page(addr, vaddr)
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#define copy_user_page(to,from,vaddr,pg) __cpu_copy_user_page(to, from, vaddr)
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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 \
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(((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0) | \
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VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
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#include <asm-generic/getorder.h>
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#endif
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