Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   1) // SPDX-License-Identifier: GPL-2.0-or-later
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   3)  * Flexible mmap layout support
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   4)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   5)  * Based on code by Ingo Molnar and Andi Kleen, copyrighted
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   6)  * as follows:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   7)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   8)  * Copyright 2003-2009 Red Hat Inc.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   9)  * All Rights Reserved.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  10)  * Copyright 2005 Andi Kleen, SUSE Labs.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  11)  * Copyright 2007 Jiri Kosina, SUSE Labs.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  12)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  13) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  14) #include <linux/personality.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  15) #include <linux/mm.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  16) #include <linux/random.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  17) #include <linux/limits.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  18) #include <linux/sched/signal.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  19) #include <linux/sched/mm.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  20) #include <linux/compat.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  21) #include <linux/elf-randomize.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  22) #include <asm/elf.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  23) #include <asm/io.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  24) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  25) #include "physaddr.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  26) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  27) struct va_alignment __read_mostly va_align = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  28) 	.flags = -1,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  29) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  30) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  31) unsigned long task_size_32bit(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  32) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  33) 	return IA32_PAGE_OFFSET;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  34) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  35) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  36) unsigned long task_size_64bit(int full_addr_space)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  37) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  38) 	return full_addr_space ? TASK_SIZE_MAX : DEFAULT_MAP_WINDOW;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  39) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  40) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  41) static unsigned long stack_maxrandom_size(unsigned long task_size)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  42) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  43) 	unsigned long max = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  44) 	if (current->flags & PF_RANDOMIZE) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  45) 		max = (-1UL) & __STACK_RND_MASK(task_size == task_size_32bit());
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  46) 		max <<= PAGE_SHIFT;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  47) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  48) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  49) 	return max;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  50) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  51) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  52) #ifdef CONFIG_COMPAT
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  53) # define mmap32_rnd_bits  mmap_rnd_compat_bits
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  54) # define mmap64_rnd_bits  mmap_rnd_bits
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  55) #else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  56) # define mmap32_rnd_bits  mmap_rnd_bits
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  57) # define mmap64_rnd_bits  mmap_rnd_bits
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  58) #endif
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  59) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  60) #define SIZE_128M    (128 * 1024 * 1024UL)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  61) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  62) static int mmap_is_legacy(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  63) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  64) 	if (current->personality & ADDR_COMPAT_LAYOUT)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  65) 		return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  66) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  67) 	return sysctl_legacy_va_layout;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  68) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  69) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  70) static unsigned long arch_rnd(unsigned int rndbits)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  71) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  72) 	if (!(current->flags & PF_RANDOMIZE))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  73) 		return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  74) 	return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  75) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  76) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  77) unsigned long arch_mmap_rnd(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  78) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  79) 	return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  80) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  81) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  82) static unsigned long mmap_base(unsigned long rnd, unsigned long task_size,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  83) 			       struct rlimit *rlim_stack)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  84) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  85) 	unsigned long gap = rlim_stack->rlim_cur;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  86) 	unsigned long pad = stack_maxrandom_size(task_size) + stack_guard_gap;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  87) 	unsigned long gap_min, gap_max;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  88) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  89) 	/* Values close to RLIM_INFINITY can overflow. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  90) 	if (gap + pad > gap)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  91) 		gap += pad;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  92) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  93) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  94) 	 * Top of mmap area (just below the process stack).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  95) 	 * Leave an at least ~128 MB hole with possible stack randomization.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  96) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  97) 	gap_min = SIZE_128M;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  98) 	gap_max = (task_size / 6) * 5;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  99) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) 	if (gap < gap_min)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) 		gap = gap_min;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) 	else if (gap > gap_max)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) 		gap = gap_max;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) 	return PAGE_ALIGN(task_size - gap - rnd);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) static unsigned long mmap_legacy_base(unsigned long rnd,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) 				      unsigned long task_size)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) 	return __TASK_UNMAPPED_BASE(task_size) + rnd;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115)  * This function, called very early during the creation of a new
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116)  * process VM image, sets up which VM layout function to use:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) static void arch_pick_mmap_base(unsigned long *base, unsigned long *legacy_base,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) 		unsigned long random_factor, unsigned long task_size,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) 		struct rlimit *rlim_stack)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) 	*legacy_base = mmap_legacy_base(random_factor, task_size);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) 	if (mmap_is_legacy())
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) 		*base = *legacy_base;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) 	else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) 		*base = mmap_base(random_factor, task_size, rlim_stack);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) 	if (mmap_is_legacy())
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) 		mm->get_unmapped_area = arch_get_unmapped_area;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) 	else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) 		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) 	arch_pick_mmap_base(&mm->mmap_base, &mm->mmap_legacy_base,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) 			arch_rnd(mmap64_rnd_bits), task_size_64bit(0),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) 			rlim_stack);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) #ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) 	 * The mmap syscall mapping base decision depends solely on the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) 	 * syscall type (64-bit or compat). This applies for 64bit
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) 	 * applications and 32bit applications. The 64bit syscall uses
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) 	 * mmap_base, the compat syscall uses mmap_compat_base.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) 	arch_pick_mmap_base(&mm->mmap_compat_base, &mm->mmap_compat_legacy_base,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) 			arch_rnd(mmap32_rnd_bits), task_size_32bit(),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) 			rlim_stack);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) #endif
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) unsigned long get_mmap_base(int is_legacy)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) 	struct mm_struct *mm = current->mm;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) #ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) 	if (in_32bit_syscall()) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) 		return is_legacy ? mm->mmap_compat_legacy_base
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) 				 : mm->mmap_compat_base;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) #endif
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) 	return is_legacy ? mm->mmap_legacy_base : mm->mmap_base;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) const char *arch_vma_name(struct vm_area_struct *vma)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) 	return NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172)  * mmap_address_hint_valid - Validate the address hint of mmap
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173)  * @addr:	Address hint
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174)  * @len:	Mapping length
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176)  * Check whether @addr and @addr + @len result in a valid mapping.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178)  * On 32bit this only checks whether @addr + @len is <= TASK_SIZE.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180)  * On 64bit with 5-level page tables another sanity check is required
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181)  * because mappings requested by mmap(@addr, 0) which cross the 47-bit
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182)  * virtual address boundary can cause the following theoretical issue:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184)  *  An application calls mmap(addr, 0), i.e. without MAP_FIXED, where @addr
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185)  *  is below the border of the 47-bit address space and @addr + @len is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186)  *  above the border.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188)  *  With 4-level paging this request succeeds, but the resulting mapping
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189)  *  address will always be within the 47-bit virtual address space, because
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190)  *  the hint address does not result in a valid mapping and is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191)  *  ignored. Hence applications which are not prepared to handle virtual
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192)  *  addresses above 47-bit work correctly.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194)  *  With 5-level paging this request would be granted and result in a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195)  *  mapping which crosses the border of the 47-bit virtual address
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196)  *  space. If the application cannot handle addresses above 47-bit this
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197)  *  will lead to misbehaviour and hard to diagnose failures.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199)  * Therefore ignore address hints which would result in a mapping crossing
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200)  * the 47-bit virtual address boundary.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202)  * Note, that in the same scenario with MAP_FIXED the behaviour is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203)  * different. The request with @addr < 47-bit and @addr + @len > 47-bit
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204)  * fails on a 4-level paging machine but succeeds on a 5-level paging
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205)  * machine. It is reasonable to expect that an application does not rely on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206)  * the failure of such a fixed mapping request, so the restriction is not
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207)  * applied.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) bool mmap_address_hint_valid(unsigned long addr, unsigned long len)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) 	if (TASK_SIZE - len < addr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) 		return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) 	return (addr > DEFAULT_MAP_WINDOW) == (addr + len > DEFAULT_MAP_WINDOW);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217) /* Can we access it for direct reading/writing? Must be RAM: */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) int valid_phys_addr_range(phys_addr_t addr, size_t count)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) 	return addr + count - 1 <= __pa(high_memory - 1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) /* Can we access it through mmap? Must be a valid physical address: */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) int valid_mmap_phys_addr_range(unsigned long pfn, size_t count)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) 	phys_addr_t addr = (phys_addr_t)pfn << PAGE_SHIFT;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) 	return phys_addr_valid(addr + count - 1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232)  * Only allow root to set high MMIO mappings to PROT_NONE.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233)  * This prevents an unpriv. user to set them to PROT_NONE and invert
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234)  * them, then pointing to valid memory for L1TF speculation.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236)  * Note: for locked down kernels may want to disable the root override.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) bool pfn_modify_allowed(unsigned long pfn, pgprot_t prot)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240) 	if (!boot_cpu_has_bug(X86_BUG_L1TF))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241) 		return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) 	if (!__pte_needs_invert(pgprot_val(prot)))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243) 		return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244) 	/* If it's real memory always allow */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) 	if (pfn_valid(pfn))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246) 		return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247) 	if (pfn >= l1tf_pfn_limit() && !capable(CAP_SYS_ADMIN))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248) 		return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249) 	return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) }