page_64.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2#ifndef _ASM_X86_PAGE_64_H
  3#define _ASM_X86_PAGE_64_H
  4
  5#include <asm/page_64_types.h>
  6
  7#ifndef __ASSEMBLER__
  8#include <asm/cpufeatures.h>
  9#include <asm/alternative.h>
 10
 11#include <linux/kmsan-checks.h>
 12#include <linux/mmdebug.h>
 13
 14/* duplicated to the one in bootmem.h */
 15extern unsigned long max_pfn;
 16extern unsigned long phys_base;
 17
 18extern unsigned long page_offset_base;
 19extern unsigned long vmalloc_base;
 20extern unsigned long vmemmap_base;
 21extern unsigned long direct_map_physmem_end;
 22
 23static __always_inline unsigned long __phys_addr_nodebug(unsigned long x)
 24{
 25	unsigned long y = x - __START_KERNEL_map;
 26
 27	/* use the carry flag to determine if x was < __START_KERNEL_map */
 28	x = y + ((x > y) ? phys_base : (__START_KERNEL_map - PAGE_OFFSET));
 29
 30	return x;
 31}
 32
 33#ifdef CONFIG_DEBUG_VIRTUAL
 34extern unsigned long __phys_addr(unsigned long);
 35#else
 36#define __phys_addr(x)		__phys_addr_nodebug(x)
 37#endif
 38
 39static inline unsigned long __phys_addr_symbol(unsigned long x)
 40{
 41	unsigned long y = x - __START_KERNEL_map;
 42
 43	/* only check upper bounds since lower bounds will trigger carry */
 44	VIRTUAL_BUG_ON(y >= KERNEL_IMAGE_SIZE);
 45
 46	return y + phys_base;
 47}
 48
 49#define __phys_reloc_hide(x)	(x)
 50
 51void clear_page_orig(void *page);
 52void clear_page_rep(void *page);
 53void clear_page_erms(void *page);
 54KCFI_REFERENCE(clear_page_orig);
 55KCFI_REFERENCE(clear_page_rep);
 56KCFI_REFERENCE(clear_page_erms);
 57
 58static inline void clear_page(void *page)
 59{
 60	/*
 61	 * Clean up KMSAN metadata for the page being cleared. The assembly call
 62	 * below clobbers @page, so we perform unpoisoning before it.
 63	 */
 64	kmsan_unpoison_memory(page, PAGE_SIZE);
 65	alternative_call_2(clear_page_orig,
 66			   clear_page_rep, X86_FEATURE_REP_GOOD,
 67			   clear_page_erms, X86_FEATURE_ERMS,
 68			   "=D" (page),
 69			   "D" (page),
 70			   "cc", "memory", "rax", "rcx");
 71}
 72
 73void copy_page(void *to, void *from);
 74KCFI_REFERENCE(copy_page);
 75
 76/*
 77 * User space process size.  This is the first address outside the user range.
 78 * There are a few constraints that determine this:
 79 *
 80 * On Intel CPUs, if a SYSCALL instruction is at the highest canonical
 81 * address, then that syscall will enter the kernel with a
 82 * non-canonical return address, and SYSRET will explode dangerously.
 83 * We avoid this particular problem by preventing anything
 84 * from being mapped at the maximum canonical address.
 85 *
 86 * On AMD CPUs in the Ryzen family, there's a nasty bug in which the
 87 * CPUs malfunction if they execute code from the highest canonical page.
 88 * They'll speculate right off the end of the canonical space, and
 89 * bad things happen.  This is worked around in the same way as the
 90 * Intel problem.
 91 *
 92 * With page table isolation enabled, we map the LDT in ... [stay tuned]
 93 */
 94static __always_inline unsigned long task_size_max(void)
 95{
 96	unsigned long ret;
 97
 98	alternative_io("movq %[small],%0","movq %[large],%0",
 99			X86_FEATURE_LA57,
100			"=r" (ret),
101			[small] "i" ((1ul << 47)-PAGE_SIZE),
102			[large] "i" ((1ul << 56)-PAGE_SIZE));
103
104	return ret;
105}
106
107#endif	/* !__ASSEMBLER__ */
108
109#ifdef CONFIG_X86_VSYSCALL_EMULATION
110# define __HAVE_ARCH_GATE_AREA 1
111#endif
112
113#endif /* _ASM_X86_PAGE_64_H */