mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-28 11:18:45 +07:00
6bd33e1ece
The kernel runs in M-mode without using page tables, and thus can't run bare metal without help from additional firmware. Most of the patch is just stubbing out code not needed without page tables, but there is an interesting detail in the signals implementation: - The normal RISC-V syscall ABI only implements rt_sigreturn as VDSO entry point, but the ELF VDSO is not supported for nommu Linux. We instead copy the code to call the syscall onto the stack. In addition to enabling the nommu code a new defconfig for a small kernel image that can run in nommu mode on qemu is also provided, to run a kernel in qemu you can use the following command line: qemu-system-riscv64 -smp 2 -m 64 -machine virt -nographic \ -kernel arch/riscv/boot/loader \ -drive file=rootfs.ext2,format=raw,id=hd0 \ -device virtio-blk-device,drive=hd0 Contains contributions from Damien Le Moal <Damien.LeMoal@wdc.com>. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Anup Patel <anup@brainfault.org> [paul.walmsley@sifive.com: updated to apply; add CONFIG_MMU guards around PCI_IOBASE definition to fix build issues; fixed checkpatch issues; move the PCI_IO_* and VMEMMAP address space macros along with the others; resolve sparse warning] Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
88 lines
2.1 KiB
C
88 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2009 Chen Liqin <liqin.chen@sunplusct.com>
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* Copyright (C) 2012 Regents of the University of California
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*/
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#ifndef _ASM_RISCV_PGALLOC_H
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#define _ASM_RISCV_PGALLOC_H
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#include <linux/mm.h>
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#include <asm/tlb.h>
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#ifdef CONFIG_MMU
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#include <asm-generic/pgalloc.h> /* for pte_{alloc,free}_one */
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static inline void pmd_populate_kernel(struct mm_struct *mm,
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pmd_t *pmd, pte_t *pte)
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{
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unsigned long pfn = virt_to_pfn(pte);
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set_pmd(pmd, __pmd((pfn << _PAGE_PFN_SHIFT) | _PAGE_TABLE));
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}
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static inline void pmd_populate(struct mm_struct *mm,
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pmd_t *pmd, pgtable_t pte)
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{
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unsigned long pfn = virt_to_pfn(page_address(pte));
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set_pmd(pmd, __pmd((pfn << _PAGE_PFN_SHIFT) | _PAGE_TABLE));
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}
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#ifndef __PAGETABLE_PMD_FOLDED
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static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
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{
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unsigned long pfn = virt_to_pfn(pmd);
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set_pud(pud, __pud((pfn << _PAGE_PFN_SHIFT) | _PAGE_TABLE));
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}
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#endif /* __PAGETABLE_PMD_FOLDED */
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#define pmd_pgtable(pmd) pmd_page(pmd)
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static inline pgd_t *pgd_alloc(struct mm_struct *mm)
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{
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pgd_t *pgd;
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pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
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if (likely(pgd != NULL)) {
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memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
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/* Copy kernel mappings */
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memcpy(pgd + USER_PTRS_PER_PGD,
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init_mm.pgd + USER_PTRS_PER_PGD,
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(PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
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}
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return pgd;
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}
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static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
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{
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free_page((unsigned long)pgd);
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}
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#ifndef __PAGETABLE_PMD_FOLDED
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static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
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{
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return (pmd_t *)__get_free_page(
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GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_ZERO);
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}
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static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
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{
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free_page((unsigned long)pmd);
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}
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#define __pmd_free_tlb(tlb, pmd, addr) pmd_free((tlb)->mm, pmd)
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#endif /* __PAGETABLE_PMD_FOLDED */
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#define __pte_free_tlb(tlb, pte, buf) \
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do { \
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pgtable_pte_page_dtor(pte); \
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tlb_remove_page((tlb), pte); \
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} while (0)
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#endif /* CONFIG_MMU */
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#endif /* _ASM_RISCV_PGALLOC_H */
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