8170e6bed4
Linear mode (CR0.PG = 0) is mutually exclusive with 64-bit mode; all
64-bit code has to use page tables. This makes it awkward before we
have first set up properly all-covering page tables to access objects
that are outside the static kernel range.
So far we have dealt with that simply by mapping a fixed amount of
low memory, but that fails in at least two upcoming use cases:
1. We will support load and run kernel, struct boot_params, ramdisk,
command line, etc. above the 4 GiB mark.
2. need to access ramdisk early to get microcode to update that as
early possible.
We could use early_iomap to access them too, but it will make code to
messy and hard to be unified with 32 bit.
Hence, set up a #PF table and use a fixed number of buffers to set up
page tables on demand. If the buffers fill up then we simply flush
them and start over. These buffers are all in __initdata, so it does
not increase RAM usage at runtime.
Thus, with the help of the #PF handler, we can set the final kernel
mapping from blank, and switch to init_level4_pgt later.
During the switchover in head_64.S, before #PF handler is available,
we use three pages to handle kernel crossing 1G, 512G boundaries with
sharing page by playing games with page aliasing: the same page is
mapped twice in the higher-level tables with appropriate wraparound.
The kernel region itself will be properly mapped; other mappings may
be spurious.
early_make_pgtable is using kernel high mapping address to access pages
to set page table.
-v4: Add phys_base offset to make kexec happy, and add
init_mapping_kernel() - Yinghai
-v5: fix compiling with xen, and add back ident level3 and level2 for xen
also move back init_level4_pgt from BSS to DATA again.
because we have to clear it anyway. - Yinghai
-v6: switch to init_level4_pgt in init_mem_mapping. - Yinghai
-v7: remove not needed clear_page for init_level4_page
it is with fill 512,8,0 already in head_64.S - Yinghai
-v8: we need to keep that handler alive until init_mem_mapping and don't
let early_trap_init to trash that early #PF handler.
So split early_trap_pf_init out and move it down. - Yinghai
-v9: switchover only cover kernel space instead of 1G so could avoid
touch possible mem holes. - Yinghai
-v11: change far jmp back to far return to initial_code, that is needed
to fix failure that is reported by Konrad on AMD systems. - Yinghai
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1359058816-7615-12-git-send-email-yinghai@kernel.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
68 lines
1.6 KiB
C
68 lines
1.6 KiB
C
#ifndef _ASM_X86_PGTABLE_64_DEFS_H
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#define _ASM_X86_PGTABLE_64_DEFS_H
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#include <asm/sparsemem.h>
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#ifndef __ASSEMBLY__
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#include <linux/types.h>
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/*
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* These are used to make use of C type-checking..
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*/
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typedef unsigned long pteval_t;
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typedef unsigned long pmdval_t;
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typedef unsigned long pudval_t;
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typedef unsigned long pgdval_t;
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typedef unsigned long pgprotval_t;
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typedef struct { pteval_t pte; } pte_t;
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#endif /* !__ASSEMBLY__ */
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#define SHARED_KERNEL_PMD 0
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#define PAGETABLE_LEVELS 4
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/*
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* PGDIR_SHIFT determines what a top-level page table entry can map
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*/
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#define PGDIR_SHIFT 39
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#define PTRS_PER_PGD 512
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/*
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* 3rd level page
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*/
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#define PUD_SHIFT 30
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#define PTRS_PER_PUD 512
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/*
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* PMD_SHIFT determines the size of the area a middle-level
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* page table can map
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*/
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#define PMD_SHIFT 21
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#define PTRS_PER_PMD 512
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/*
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* entries per page directory level
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*/
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#define PTRS_PER_PTE 512
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#define PMD_SIZE (_AC(1, UL) << PMD_SHIFT)
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#define PMD_MASK (~(PMD_SIZE - 1))
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#define PUD_SIZE (_AC(1, UL) << PUD_SHIFT)
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#define PUD_MASK (~(PUD_SIZE - 1))
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#define PGDIR_SIZE (_AC(1, UL) << PGDIR_SHIFT)
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#define PGDIR_MASK (~(PGDIR_SIZE - 1))
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/* See Documentation/x86/x86_64/mm.txt for a description of the memory map. */
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#define MAXMEM _AC(__AC(1, UL) << MAX_PHYSMEM_BITS, UL)
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#define VMALLOC_START _AC(0xffffc90000000000, UL)
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#define VMALLOC_END _AC(0xffffe8ffffffffff, UL)
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#define VMEMMAP_START _AC(0xffffea0000000000, UL)
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#define MODULES_VADDR _AC(0xffffffffa0000000, UL)
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#define MODULES_END _AC(0xffffffffff000000, UL)
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#define MODULES_LEN (MODULES_END - MODULES_VADDR)
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#define EARLY_DYNAMIC_PAGE_TABLES 64
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#endif /* _ASM_X86_PGTABLE_64_DEFS_H */
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