[v13,2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs
Commit Message
This IOCTL, PAGEMAP_SCAN on pagemap file can be used to get and/or clear
the info about page table entries. The following operations are supported
in this ioctl:
- Get the information if the pages have been written-to (PAGE_IS_WRITTEN),
file mapped (PAGE_IS_FILE), present (PAGE_IS_PRESENT) or swapped
(PAGE_IS_SWAPPED).
- Find pages which have been written-to and write protect the pages
(atomic PAGE_IS_WRITTEN + PAGEMAP_WP_ENGAGE)
This IOCTL can be extended to get information about more PTE bits.
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
---
Changes in v13:
- Review updates
- mmap_read_lock_killable() instead of mmap_read_lock()
- Replace uffd_wp_range() with helpers which increases performance
drastically for OP_WP operations by reducing the number of tlb
flushing etc
- Add MMU_NOTIFY_PROTECTION_VMA notification for the memory range
Changes in v12:
- Add hugetlb support to cover all memory types
- Merge "userfaultfd: Define dummy uffd_wp_range()" with this patch
- Review updates to the code
Changes in v11:
- Find written pages in a better way
- Fix a corner case (thanks Paul)
- Improve the code/comments
- remove ENGAGE_WP + ! GET operation
- shorten the commit message in favour of moving documentation to
pagemap.rst
Changes in v10:
- move changes in tools/include/uapi/linux/fs.h to separate patch
- update commit message
Change in v8:
- Correct is_pte_uffd_wp()
- Improve readability and error checks
- Remove some un-needed code
Changes in v7:
- Rebase on top of latest next
- Fix some corner cases
- Base soft-dirty on the uffd wp async
- Update the terminologies
- Optimize the memory usage inside the ioctl
Changes in v6:
- Rename variables and update comments
- Make IOCTL independent of soft_dirty config
- Change masks and bitmap type to _u64
- Improve code quality
Changes in v5:
- Remove tlb flushing even for clear operation
Changes in v4:
- Update the interface and implementation
Changes in v3:
- Tighten the user-kernel interface by using explicit types and add more
error checking
Changes in v2:
- Convert the interface from syscall to ioctl
- Remove pidfd support as it doesn't make sense in ioctl
task_mmu
task_mmu
task_mmu.c
---
fs/proc/task_mmu.c | 478 ++++++++++++++++++++++++++++++++++++++++
include/uapi/linux/fs.h | 53 +++++
2 files changed, 531 insertions(+)
Comments
Hi Muhammad,
kernel test robot noticed the following build warnings:
[auto build test WARNING on akpm-mm/mm-everything]
[cannot apply to linus/master v6.3-rc7]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Muhammad-Usama-Anjum/userfaultfd-UFFD_FEATURE_WP_ASYNC/20230417-210005
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20230417125630.1146906-3-usama.anjum%40collabora.com
patch subject: [PATCH v13 2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs
config: i386-randconfig-a003-20230417 (https://download.01.org/0day-ci/archive/20230417/202304172319.CjlksY4s-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
reproduce (this is a W=1 build):
# https://github.com/intel-lab-lkp/linux/commit/2e7e6f5bd3b9c28493f9871282fe8f14e2263962
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Muhammad-Usama-Anjum/userfaultfd-UFFD_FEATURE_WP_ASYNC/20230417-210005
git checkout 2e7e6f5bd3b9c28493f9871282fe8f14e2263962
# save the config file
mkdir build_dir && cp config build_dir/.config
make W=1 O=build_dir ARCH=i386 olddefconfig
make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash fs/proc/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304172319.CjlksY4s-lkp@intel.com/
All warnings (new ones prefixed by >>):
fs/proc/task_mmu.c: In function 'pagemap_scan_pte_hole':
fs/proc/task_mmu.c:2059:14: error: invalid use of undefined type 'struct pagemap_scan_private'
2059 | if (p->max_pages && p->found_pages + n_pages > p->max_pages)
| ^~
fs/proc/task_mmu.c:2059:30: error: invalid use of undefined type 'struct pagemap_scan_private'
2059 | if (p->max_pages && p->found_pages + n_pages > p->max_pages)
| ^~
fs/proc/task_mmu.c:2059:57: error: invalid use of undefined type 'struct pagemap_scan_private'
2059 | if (p->max_pages && p->found_pages + n_pages > p->max_pages)
| ^~
fs/proc/task_mmu.c:2060:28: error: invalid use of undefined type 'struct pagemap_scan_private'
2060 | n_pages = p->max_pages - p->found_pages;
| ^~
fs/proc/task_mmu.c:2060:43: error: invalid use of undefined type 'struct pagemap_scan_private'
2060 | n_pages = p->max_pages - p->found_pages;
| ^~
fs/proc/task_mmu.c:2062:15: error: implicit declaration of function 'pagemap_scan_output' [-Werror=implicit-function-declaration]
2062 | ret = pagemap_scan_output(false, vma->vm_file, false, false, p, addr,
| ^~~~~~~~~~~~~~~~~~~
fs/proc/task_mmu.c: At top level:
fs/proc/task_mmu.c:2068:22: error: 'pagemap_scan_test_walk' undeclared here (not in a function); did you mean 'pagemap_scan_pte_hole'?
2068 | .test_walk = pagemap_scan_test_walk,
| ^~~~~~~~~~~~~~~~~~~~~~
| pagemap_scan_pte_hole
fs/proc/task_mmu.c:2069:22: error: 'pagemap_scan_pmd_entry' undeclared here (not in a function); did you mean 'pagemap_scan_pte_hole'?
2069 | .pmd_entry = pagemap_scan_pmd_entry,
| ^~~~~~~~~~~~~~~~~~~~~~
| pagemap_scan_pte_hole
fs/proc/task_mmu.c: In function 'pagemap_scan_args_valid':
fs/proc/task_mmu.c:2080:27: error: 'PM_SCAN_OPS' undeclared (first use in this function); did you mean 'PM_SCAN_OP_WP'?
2080 | if (arg->flags & ~PM_SCAN_OPS)
| ^~~~~~~~~~~
| PM_SCAN_OP_WP
fs/proc/task_mmu.c:2080:27: note: each undeclared identifier is reported only once for each function it appears in
fs/proc/task_mmu.c:2085:35: error: 'PM_SCAN_BITS_ALL' undeclared (first use in this function); did you mean 'CPU_BITS_ALL'?
2085 | arg->return_mask) & ~PM_SCAN_BITS_ALL)
| ^~~~~~~~~~~~~~~~
| CPU_BITS_ALL
fs/proc/task_mmu.c:2106:14: error: implicit declaration of function 'PM_SCAN_DO_UFFD_WP'; did you mean 'PM_SCAN_OP_WP'? [-Werror=implicit-function-declaration]
2106 | if (!PM_SCAN_DO_UFFD_WP(arg))
| ^~~~~~~~~~~~~~~~~~
| PM_SCAN_OP_WP
fs/proc/task_mmu.c: In function 'do_pagemap_scan':
fs/proc/task_mmu.c:2123:37: error: storage size of 'p' isn't known
2123 | struct pagemap_scan_private p;
| ^
fs/proc/task_mmu.c:2148:21: error: 'PAGEMAP_WALK_SIZE' undeclared (first use in this function); did you mean 'PAGE_TABLE_SIZE'?
2148 | p.vec_len = PAGEMAP_WALK_SIZE >> PAGE_SHIFT;
| ^~~~~~~~~~~~~~~~~
| PAGE_TABLE_SIZE
In file included from include/linux/kernel.h:27,
from arch/x86/include/asm/percpu.h:27,
from arch/x86/include/asm/preempt.h:6,
from include/linux/preempt.h:78,
from include/linux/spinlock.h:56,
from include/linux/mmzone.h:8,
from include/linux/gfp.h:7,
from include/linux/mm.h:7,
from include/linux/pagewalk.h:5,
from fs/proc/task_mmu.c:2:
include/linux/minmax.h:36:9: error: first argument to '__builtin_choose_expr' not a constant
36 | __builtin_choose_expr(__safe_cmp(x, y), \
| ^~~~~~~~~~~~~~~~~~~~~
include/linux/minmax.h:67:25: note: in expansion of macro '__careful_cmp'
67 | #define min(x, y) __careful_cmp(x, y, <)
| ^~~~~~~~~~~~~
fs/proc/task_mmu.c:2173:29: note: in expansion of macro 'min'
2173 | p.vec_len = min(p.vec_len, empty_slots);
| ^~~
fs/proc/task_mmu.c:2175:63: error: 'PAGEMAP_WALK_MASK' undeclared (first use in this function)
2175 | walk_end = (walk_start + PAGEMAP_WALK_SIZE) & PAGEMAP_WALK_MASK;
| ^~~~~~~~~~~~~~~~~
fs/proc/task_mmu.c:2186:53: error: 'PM_SCAN_FOUND_MAX_PAGES' undeclared (first use in this function)
2186 | if (ret && ret != -ENOSPC && ret != PM_SCAN_FOUND_MAX_PAGES)
| ^~~~~~~~~~~~~~~~~~~~~~~
>> fs/proc/task_mmu.c:2123:37: warning: unused variable 'p' [-Wunused-variable]
2123 | struct pagemap_scan_private p;
| ^
fs/proc/task_mmu.c: At top level:
fs/proc/task_mmu.c:2240:27: error: 'pagemap_read' undeclared here (not in a function); did you mean 'filemap_read'?
2240 | .read = pagemap_read,
| ^~~~~~~~~~~~
| filemap_read
fs/proc/task_mmu.c:2241:27: error: 'pagemap_open' undeclared here (not in a function); did you mean 'pid_maps_open'?
2241 | .open = pagemap_open,
| ^~~~~~~~~~~~
| pid_maps_open
fs/proc/task_mmu.c:2242:27: error: 'pagemap_release' undeclared here (not in a function); did you mean 'proc_map_release'?
2242 | .release = pagemap_release,
| ^~~~~~~~~~~~~~~
| proc_map_release
fs/proc/task_mmu.c:2246:2: error: #endif without #if
2246 | #endif /* CONFIG_PROC_PAGE_MONITOR */
| ^~~~~
cc1: some warnings being treated as errors
vim +/p +2123 fs/proc/task_mmu.c
2115
2116 static long do_pagemap_scan(struct mm_struct *mm,
2117 struct pm_scan_arg __user *uarg)
2118 {
2119 unsigned long start, end, walk_start, walk_end;
2120 unsigned long empty_slots, vec_index = 0;
2121 struct mmu_notifier_range range;
2122 struct page_region __user *vec;
> 2123 struct pagemap_scan_private p;
2124 struct pm_scan_arg arg;
2125 int ret = 0;
2126
2127 if (copy_from_user(&arg, uarg, sizeof(arg)))
2128 return -EFAULT;
2129
2130 start = untagged_addr((unsigned long)arg.start);
2131 vec = (struct page_region *)untagged_addr((unsigned long)arg.vec);
2132
2133 ret = pagemap_scan_args_valid(&arg, start, vec);
2134 if (ret)
2135 return ret;
2136
2137 end = start + arg.len;
2138 p.max_pages = arg.max_pages;
2139 p.found_pages = 0;
2140 p.flags = arg.flags;
2141 p.required_mask = arg.required_mask;
2142 p.anyof_mask = arg.anyof_mask;
2143 p.excluded_mask = arg.excluded_mask;
2144 p.return_mask = arg.return_mask;
2145 p.cur.len = 0;
2146 p.cur.start = 0;
2147 p.vec = NULL;
2148 p.vec_len = PAGEMAP_WALK_SIZE >> PAGE_SHIFT;
2149
2150 /*
2151 * Allocate smaller buffer to get output from inside the page walk
2152 * functions and walk page range in PAGEMAP_WALK_SIZE size chunks. As
2153 * we want to return output to user in compact form where no two
2154 * consecutive regions should be continuous and have the same flags.
2155 * So store the latest element in p.cur between different walks and
2156 * store the p.cur at the end of the walk to the user buffer.
2157 */
2158 p.vec = kmalloc_array(p.vec_len, sizeof(*p.vec), GFP_KERNEL);
2159 if (!p.vec)
2160 return -ENOMEM;
2161
2162 if (p.flags & PM_SCAN_OP_WP) {
2163 mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_VMA, 0,
2164 vma->vm_mm, start, end);
2165 mmu_notifier_invalidate_range_start(&range);
2166 }
2167
2168 walk_start = walk_end = start;
2169 while (walk_end < end && !ret) {
2170 p.vec_index = 0;
2171
2172 empty_slots = arg.vec_len - vec_index;
2173 p.vec_len = min(p.vec_len, empty_slots);
2174
2175 walk_end = (walk_start + PAGEMAP_WALK_SIZE) & PAGEMAP_WALK_MASK;
2176 if (walk_end > end)
2177 walk_end = end;
2178
2179 ret = mmap_read_lock_killable(mm);
2180 if (ret)
2181 goto free_data;
2182 ret = walk_page_range(mm, walk_start, walk_end,
2183 &pagemap_scan_ops, &p);
2184 mmap_read_unlock(mm);
2185
2186 if (ret && ret != -ENOSPC && ret != PM_SCAN_FOUND_MAX_PAGES)
2187 goto free_data;
2188
2189 walk_start = walk_end;
2190 if (p.vec_index) {
2191 if (copy_to_user(&vec[vec_index], p.vec,
2192 p.vec_index * sizeof(*p.vec))) {
2193 /*
2194 * Return error even though the OP succeeded
2195 */
2196 ret = -EFAULT;
2197 goto free_data;
2198 }
2199 vec_index += p.vec_index;
2200 }
2201 }
2202
2203 if (p.flags & PM_SCAN_OP_WP) {
2204 mmu_notifier_invalidate_range_end(&range);
2205 flush_tlb_mm_range(mm, start, end, PAGE_SHIFT, false);
2206 }
2207
2208 if (p.cur.len) {
2209 if (copy_to_user(&vec[vec_index], &p.cur, sizeof(*p.vec))) {
2210 ret = -EFAULT;
2211 goto free_data;
2212 }
2213 vec_index++;
2214 }
2215
2216 ret = vec_index;
2217
2218 free_data:
2219 kfree(p.vec);
2220 return ret;
2221 }
2222
Hi Muhammad,
kernel test robot noticed the following build errors:
[auto build test ERROR on akpm-mm/mm-everything]
[cannot apply to linus/master v6.3-rc7]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Muhammad-Usama-Anjum/userfaultfd-UFFD_FEATURE_WP_ASYNC/20230417-210005
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20230417125630.1146906-3-usama.anjum%40collabora.com
patch subject: [PATCH v13 2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs
config: i386-randconfig-a003-20230417 (https://download.01.org/0day-ci/archive/20230418/202304180050.anuTGBfy-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
reproduce (this is a W=1 build):
# https://github.com/intel-lab-lkp/linux/commit/2e7e6f5bd3b9c28493f9871282fe8f14e2263962
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Muhammad-Usama-Anjum/userfaultfd-UFFD_FEATURE_WP_ASYNC/20230417-210005
git checkout 2e7e6f5bd3b9c28493f9871282fe8f14e2263962
# save the config file
mkdir build_dir && cp config build_dir/.config
make W=1 O=build_dir ARCH=i386 olddefconfig
make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash fs/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304180050.anuTGBfy-lkp@intel.com/
All errors (new ones prefixed by >>):
fs/proc/task_mmu.c: In function 'pagemap_scan_pte_hole':
>> fs/proc/task_mmu.c:2059:14: error: invalid use of undefined type 'struct pagemap_scan_private'
2059 | if (p->max_pages && p->found_pages + n_pages > p->max_pages)
| ^~
fs/proc/task_mmu.c:2059:30: error: invalid use of undefined type 'struct pagemap_scan_private'
2059 | if (p->max_pages && p->found_pages + n_pages > p->max_pages)
| ^~
fs/proc/task_mmu.c:2059:57: error: invalid use of undefined type 'struct pagemap_scan_private'
2059 | if (p->max_pages && p->found_pages + n_pages > p->max_pages)
| ^~
fs/proc/task_mmu.c:2060:28: error: invalid use of undefined type 'struct pagemap_scan_private'
2060 | n_pages = p->max_pages - p->found_pages;
| ^~
fs/proc/task_mmu.c:2060:43: error: invalid use of undefined type 'struct pagemap_scan_private'
2060 | n_pages = p->max_pages - p->found_pages;
| ^~
>> fs/proc/task_mmu.c:2062:15: error: implicit declaration of function 'pagemap_scan_output' [-Werror=implicit-function-declaration]
2062 | ret = pagemap_scan_output(false, vma->vm_file, false, false, p, addr,
| ^~~~~~~~~~~~~~~~~~~
fs/proc/task_mmu.c: At top level:
>> fs/proc/task_mmu.c:2068:22: error: 'pagemap_scan_test_walk' undeclared here (not in a function); did you mean 'pagemap_scan_pte_hole'?
2068 | .test_walk = pagemap_scan_test_walk,
| ^~~~~~~~~~~~~~~~~~~~~~
| pagemap_scan_pte_hole
>> fs/proc/task_mmu.c:2069:22: error: 'pagemap_scan_pmd_entry' undeclared here (not in a function); did you mean 'pagemap_scan_pte_hole'?
2069 | .pmd_entry = pagemap_scan_pmd_entry,
| ^~~~~~~~~~~~~~~~~~~~~~
| pagemap_scan_pte_hole
fs/proc/task_mmu.c: In function 'pagemap_scan_args_valid':
>> fs/proc/task_mmu.c:2080:27: error: 'PM_SCAN_OPS' undeclared (first use in this function); did you mean 'PM_SCAN_OP_WP'?
2080 | if (arg->flags & ~PM_SCAN_OPS)
| ^~~~~~~~~~~
| PM_SCAN_OP_WP
fs/proc/task_mmu.c:2080:27: note: each undeclared identifier is reported only once for each function it appears in
>> fs/proc/task_mmu.c:2085:35: error: 'PM_SCAN_BITS_ALL' undeclared (first use in this function); did you mean 'CPU_BITS_ALL'?
2085 | arg->return_mask) & ~PM_SCAN_BITS_ALL)
| ^~~~~~~~~~~~~~~~
| CPU_BITS_ALL
>> fs/proc/task_mmu.c:2106:14: error: implicit declaration of function 'PM_SCAN_DO_UFFD_WP'; did you mean 'PM_SCAN_OP_WP'? [-Werror=implicit-function-declaration]
2106 | if (!PM_SCAN_DO_UFFD_WP(arg))
| ^~~~~~~~~~~~~~~~~~
| PM_SCAN_OP_WP
fs/proc/task_mmu.c: In function 'do_pagemap_scan':
>> fs/proc/task_mmu.c:2123:37: error: storage size of 'p' isn't known
2123 | struct pagemap_scan_private p;
| ^
>> fs/proc/task_mmu.c:2148:21: error: 'PAGEMAP_WALK_SIZE' undeclared (first use in this function); did you mean 'PAGE_TABLE_SIZE'?
2148 | p.vec_len = PAGEMAP_WALK_SIZE >> PAGE_SHIFT;
| ^~~~~~~~~~~~~~~~~
| PAGE_TABLE_SIZE
In file included from include/linux/kernel.h:27,
from arch/x86/include/asm/percpu.h:27,
from arch/x86/include/asm/preempt.h:6,
from include/linux/preempt.h:78,
from include/linux/spinlock.h:56,
from include/linux/mmzone.h:8,
from include/linux/gfp.h:7,
from include/linux/mm.h:7,
from include/linux/pagewalk.h:5,
from fs/proc/task_mmu.c:2:
>> include/linux/minmax.h:36:9: error: first argument to '__builtin_choose_expr' not a constant
36 | __builtin_choose_expr(__safe_cmp(x, y), \
| ^~~~~~~~~~~~~~~~~~~~~
include/linux/minmax.h:67:25: note: in expansion of macro '__careful_cmp'
67 | #define min(x, y) __careful_cmp(x, y, <)
| ^~~~~~~~~~~~~
fs/proc/task_mmu.c:2173:29: note: in expansion of macro 'min'
2173 | p.vec_len = min(p.vec_len, empty_slots);
| ^~~
>> fs/proc/task_mmu.c:2175:63: error: 'PAGEMAP_WALK_MASK' undeclared (first use in this function)
2175 | walk_end = (walk_start + PAGEMAP_WALK_SIZE) & PAGEMAP_WALK_MASK;
| ^~~~~~~~~~~~~~~~~
>> fs/proc/task_mmu.c:2186:53: error: 'PM_SCAN_FOUND_MAX_PAGES' undeclared (first use in this function)
2186 | if (ret && ret != -ENOSPC && ret != PM_SCAN_FOUND_MAX_PAGES)
| ^~~~~~~~~~~~~~~~~~~~~~~
fs/proc/task_mmu.c:2123:37: warning: unused variable 'p' [-Wunused-variable]
2123 | struct pagemap_scan_private p;
| ^
fs/proc/task_mmu.c: At top level:
>> fs/proc/task_mmu.c:2240:27: error: 'pagemap_read' undeclared here (not in a function); did you mean 'filemap_read'?
2240 | .read = pagemap_read,
| ^~~~~~~~~~~~
| filemap_read
>> fs/proc/task_mmu.c:2241:27: error: 'pagemap_open' undeclared here (not in a function); did you mean 'pid_maps_open'?
2241 | .open = pagemap_open,
| ^~~~~~~~~~~~
| pid_maps_open
>> fs/proc/task_mmu.c:2242:27: error: 'pagemap_release' undeclared here (not in a function); did you mean 'proc_map_release'?
2242 | .release = pagemap_release,
| ^~~~~~~~~~~~~~~
| proc_map_release
fs/proc/task_mmu.c:2246:2: error: #endif without #if
2246 | #endif /* CONFIG_PROC_PAGE_MONITOR */
| ^~~~~
cc1: some warnings being treated as errors
vim +2059 fs/proc/task_mmu.c
2047
2048 static int pagemap_scan_pte_hole(unsigned long addr, unsigned long end,
2049 int depth, struct mm_walk *walk)
2050 {
2051 unsigned long n_pages = (end - addr)/PAGE_SIZE;
2052 struct pagemap_scan_private *p = walk->private;
2053 struct vm_area_struct *vma = walk->vma;
2054 int ret = 0;
2055
2056 if (!vma)
2057 return 0;
2058
> 2059 if (p->max_pages && p->found_pages + n_pages > p->max_pages)
> 2060 n_pages = p->max_pages - p->found_pages;
2061
> 2062 ret = pagemap_scan_output(false, vma->vm_file, false, false, p, addr,
2063 n_pages);
2064 return ret;
2065 }
2066
2067 static const struct mm_walk_ops pagemap_scan_ops = {
> 2068 .test_walk = pagemap_scan_test_walk,
> 2069 .pmd_entry = pagemap_scan_pmd_entry,
2070 .pte_hole = pagemap_scan_pte_hole,
2071 .hugetlb_entry = pagemap_scan_hugetlb_entry,
2072 };
2073
2074 static int pagemap_scan_args_valid(struct pm_scan_arg *arg, unsigned long start,
2075 struct page_region __user *vec)
2076 {
2077 /* Detect illegal size, flags, len and masks */
2078 if (arg->size != sizeof(struct pm_scan_arg))
2079 return -EINVAL;
> 2080 if (arg->flags & ~PM_SCAN_OPS)
2081 return -EINVAL;
2082 if (!arg->len)
2083 return -EINVAL;
2084 if ((arg->required_mask | arg->anyof_mask | arg->excluded_mask |
> 2085 arg->return_mask) & ~PM_SCAN_BITS_ALL)
2086 return -EINVAL;
2087 if (!arg->required_mask && !arg->anyof_mask &&
2088 !arg->excluded_mask)
2089 return -EINVAL;
2090 if (!arg->return_mask)
2091 return -EINVAL;
2092
2093 /* Validate memory ranges */
2094 if (!(arg->flags & PM_SCAN_OP_GET))
2095 return -EINVAL;
2096 if (!arg->vec)
2097 return -EINVAL;
2098 if (arg->vec_len == 0)
2099 return -EINVAL;
2100
2101 if (!IS_ALIGNED(start, PAGE_SIZE))
2102 return -EINVAL;
2103 if (!access_ok((void __user *)start, arg->len))
2104 return -EFAULT;
2105
> 2106 if (!PM_SCAN_DO_UFFD_WP(arg))
2107 return 0;
2108
2109 if ((arg->required_mask | arg->anyof_mask | arg->excluded_mask) &
2110 ~PAGE_IS_WRITTEN)
2111 return -EINVAL;
2112
2113 return 0;
2114 }
2115
2116 static long do_pagemap_scan(struct mm_struct *mm,
2117 struct pm_scan_arg __user *uarg)
2118 {
2119 unsigned long start, end, walk_start, walk_end;
2120 unsigned long empty_slots, vec_index = 0;
2121 struct mmu_notifier_range range;
2122 struct page_region __user *vec;
> 2123 struct pagemap_scan_private p;
2124 struct pm_scan_arg arg;
2125 int ret = 0;
2126
2127 if (copy_from_user(&arg, uarg, sizeof(arg)))
2128 return -EFAULT;
2129
2130 start = untagged_addr((unsigned long)arg.start);
2131 vec = (struct page_region *)untagged_addr((unsigned long)arg.vec);
2132
2133 ret = pagemap_scan_args_valid(&arg, start, vec);
2134 if (ret)
2135 return ret;
2136
2137 end = start + arg.len;
2138 p.max_pages = arg.max_pages;
2139 p.found_pages = 0;
2140 p.flags = arg.flags;
2141 p.required_mask = arg.required_mask;
2142 p.anyof_mask = arg.anyof_mask;
2143 p.excluded_mask = arg.excluded_mask;
2144 p.return_mask = arg.return_mask;
2145 p.cur.len = 0;
2146 p.cur.start = 0;
2147 p.vec = NULL;
> 2148 p.vec_len = PAGEMAP_WALK_SIZE >> PAGE_SHIFT;
2149
2150 /*
2151 * Allocate smaller buffer to get output from inside the page walk
2152 * functions and walk page range in PAGEMAP_WALK_SIZE size chunks. As
2153 * we want to return output to user in compact form where no two
2154 * consecutive regions should be continuous and have the same flags.
2155 * So store the latest element in p.cur between different walks and
2156 * store the p.cur at the end of the walk to the user buffer.
2157 */
2158 p.vec = kmalloc_array(p.vec_len, sizeof(*p.vec), GFP_KERNEL);
2159 if (!p.vec)
2160 return -ENOMEM;
2161
2162 if (p.flags & PM_SCAN_OP_WP) {
2163 mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_VMA, 0,
2164 vma->vm_mm, start, end);
2165 mmu_notifier_invalidate_range_start(&range);
2166 }
2167
2168 walk_start = walk_end = start;
2169 while (walk_end < end && !ret) {
2170 p.vec_index = 0;
2171
2172 empty_slots = arg.vec_len - vec_index;
> 2173 p.vec_len = min(p.vec_len, empty_slots);
2174
> 2175 walk_end = (walk_start + PAGEMAP_WALK_SIZE) & PAGEMAP_WALK_MASK;
2176 if (walk_end > end)
2177 walk_end = end;
2178
2179 ret = mmap_read_lock_killable(mm);
2180 if (ret)
2181 goto free_data;
2182 ret = walk_page_range(mm, walk_start, walk_end,
2183 &pagemap_scan_ops, &p);
2184 mmap_read_unlock(mm);
2185
> 2186 if (ret && ret != -ENOSPC && ret != PM_SCAN_FOUND_MAX_PAGES)
2187 goto free_data;
2188
2189 walk_start = walk_end;
2190 if (p.vec_index) {
2191 if (copy_to_user(&vec[vec_index], p.vec,
2192 p.vec_index * sizeof(*p.vec))) {
2193 /*
2194 * Return error even though the OP succeeded
2195 */
2196 ret = -EFAULT;
2197 goto free_data;
2198 }
2199 vec_index += p.vec_index;
2200 }
2201 }
2202
2203 if (p.flags & PM_SCAN_OP_WP) {
2204 mmu_notifier_invalidate_range_end(&range);
2205 flush_tlb_mm_range(mm, start, end, PAGE_SHIFT, false);
2206 }
2207
2208 if (p.cur.len) {
2209 if (copy_to_user(&vec[vec_index], &p.cur, sizeof(*p.vec))) {
2210 ret = -EFAULT;
2211 goto free_data;
2212 }
2213 vec_index++;
2214 }
2215
2216 ret = vec_index;
2217
2218 free_data:
2219 kfree(p.vec);
2220 return ret;
2221 }
2222
2223 static long do_pagemap_cmd(struct file *file, unsigned int cmd,
2224 unsigned long arg)
2225 {
2226 struct pm_scan_arg __user *uarg = (struct pm_scan_arg __user *)arg;
2227 struct mm_struct *mm = file->private_data;
2228
2229 switch (cmd) {
2230 case PAGEMAP_SCAN:
2231 return do_pagemap_scan(mm, uarg);
2232
2233 default:
2234 return -EINVAL;
2235 }
2236 }
2237
2238 const struct file_operations proc_pagemap_operations = {
2239 .llseek = mem_lseek, /* borrow this */
> 2240 .read = pagemap_read,
> 2241 .open = pagemap_open,
> 2242 .release = pagemap_release,
2243 .unlocked_ioctl = do_pagemap_cmd,
2244 .compat_ioctl = do_pagemap_cmd,
2245 };
2246 #endif /* CONFIG_PROC_PAGE_MONITOR */
2247
Muhammad,
On Mon, Apr 17, 2023 at 05:56:27PM +0500, Muhammad Usama Anjum wrote:
> +static int pagemap_scan_pmd_entry(pmd_t *pmd, unsigned long start,
> + unsigned long end, struct mm_walk *walk)
> +{
> + struct pagemap_scan_private *p = walk->private;
> + struct vm_area_struct *vma = walk->vma;
> + unsigned long addr = end;
> + pte_t *pte, *orig_pte;
> + spinlock_t *ptl;
> + bool is_written;
> + int ret = 0;
> +
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> + ptl = pmd_trans_huge_lock(pmd, vma);
> + if (ptl) {
> + unsigned long n_pages = (end - start)/PAGE_SIZE;
> +
> + if (p->max_pages && n_pages > p->max_pages - p->found_pages)
> + n_pages = p->max_pages - p->found_pages;
> +
> + is_written = !is_pmd_uffd_wp(*pmd);
> +
> + /*
> + * Break huge page into small pages if the WP operation need to
> + * be performed is on a portion of the huge page.
> + */
> + if (is_written && PM_SCAN_DO_UFFD_WP(p) &&
> + n_pages < HPAGE_SIZE/PAGE_SIZE) {
> + spin_unlock(ptl);
> + split_huge_pmd(vma, pmd, start);
> + goto process_smaller_pages;
> + }
> +
> + ret = pagemap_scan_output(is_written, vma->vm_file,
> + pmd_present(*pmd), is_swap_pmd(*pmd),
> + p, start, n_pages);
> +
> + if (ret >= 0 && is_written && PM_SCAN_DO_UFFD_WP(p))
> + make_uffd_wp_pmd(vma, addr, pmd);
> +
> + spin_unlock(ptl);
> + return ret;
> + }
> +process_smaller_pages:
> + if (pmd_trans_unstable(pmd))
> + return 0;
> +#endif
> +
> + pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
> + for (addr = start; addr < end && !ret; pte++, addr += PAGE_SIZE) {
> + is_written = !is_pte_uffd_wp(*pte);
> +
> + ret = pagemap_scan_output(is_written, vma->vm_file,
> + pte_present(*pte), is_swap_pte(*pte),
> + p, addr, 1);
> +
> + if (ret >= 0 && is_written && PM_SCAN_DO_UFFD_WP(p))
> + make_uffd_wp_pte(vma, addr, pte);
> + }
> + pte_unmap_unlock(orig_pte, ptl);
IIUC tlb flushes, mmu notifications are still missing here, am I right?
Thanks,
> +
> + cond_resched();
> + return ret;
> +}
@@ -19,6 +19,7 @@
#include <linux/shmem_fs.h>
#include <linux/uaccess.h>
#include <linux/pkeys.h>
+#include <linux/minmax.h>
#include <asm/elf.h>
#include <asm/tlb.h>
@@ -1767,11 +1768,488 @@ static int pagemap_release(struct inode *inode, struct file *file)
return 0;
}
+#define PM_SCAN_FOUND_MAX_PAGES (1)
+#define PM_SCAN_BITS_ALL (PAGE_IS_WRITTEN | PAGE_IS_FILE | \
+ PAGE_IS_PRESENT | PAGE_IS_SWAPPED)
+#define PM_SCAN_OPS (PM_SCAN_OP_GET | PM_SCAN_OP_WP)
+#define PM_SCAN_DO_UFFD_WP(a) (a->flags & PM_SCAN_OP_WP)
+#define PM_SCAN_BITMAP(wt, file, present, swap) \
+ ((wt) | ((file) << 1) | ((present) << 2) | ((swap) << 3))
+
+struct pagemap_scan_private {
+ struct page_region *vec;
+ struct page_region cur;
+ unsigned long vec_len, vec_index;
+ unsigned int max_pages, found_pages, flags;
+ unsigned long required_mask, anyof_mask, excluded_mask, return_mask;
+};
+
+static inline bool is_pte_uffd_wp(pte_t pte)
+{
+ return (pte_present(pte) && pte_uffd_wp(pte)) ||
+ pte_swp_uffd_wp_any(pte);
+}
+
+static inline void make_uffd_wp_pte(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *pte)
+{
+ pte_t ptent = *pte;
+
+ if (pte_present(ptent)) {
+ pte_t old_pte;
+
+ old_pte = ptep_modify_prot_start(vma, addr, pte);
+ ptent = pte_mkuffd_wp(ptent);
+ ptep_modify_prot_commit(vma, addr, pte, old_pte, ptent);
+ } else if (is_swap_pte(ptent)) {
+ ptent = pte_swp_mkuffd_wp(ptent);
+ set_pte_at(vma->vm_mm, addr, pte, ptent);
+ }
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline bool is_pmd_uffd_wp(pmd_t pmd)
+{
+ return (pmd_present(pmd) && pmd_uffd_wp(pmd)) ||
+ (is_swap_pmd(pmd) && pmd_swp_uffd_wp(pmd));
+}
+
+static inline void make_uffd_wp_pmd(struct vm_area_struct *vma,
+ unsigned long addr, pmd_t *pmdp)
+{
+ pmd_t old, pmd = *pmdp;
+
+ if (pmd_present(pmd)) {
+ old = pmdp_invalidate_ad(vma, addr, pmdp);
+ pmd = pmd_mkuffd_wp(old);
+ set_pmd_at(vma->vm_mm, addr, pmdp, pmd);
+ } else if (is_migration_entry(pmd_to_swp_entry(pmd))) {
+ pmd = pmd_swp_mkuffd_wp(pmd);
+ set_pmd_at(vma->vm_mm, addr, pmdp, pmd);
+ }
+}
+#endif
+
+#ifdef CONFIG_HUGETLB_PAGE
+static inline bool is_huge_pte_uffd_wp(pte_t pte)
+{
+ return ((pte_present(pte) && huge_pte_uffd_wp(pte)) ||
+ pte_swp_uffd_wp_any(pte));
+}
+
+static inline void make_uffd_wp_huge_pte(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep,
+ pte_t ptent)
+{
+ pte_t old_pte;
+
+ if (!huge_pte_none(ptent)) {
+ old_pte = huge_ptep_modify_prot_start(vma, addr, ptep);
+ ptent = huge_pte_mkuffd_wp(old_pte);
+ ptep_modify_prot_commit(vma, addr, ptep, old_pte, ptent);
+ } else {
+ set_huge_pte_at(vma->vm_mm, addr, ptep,
+ make_pte_marker(PTE_MARKER_UFFD_WP));
+ }
+}
+#endif
+
+static inline bool pagemap_scan_check_page_written(struct pagemap_scan_private *p)
+{
+ return (p->required_mask | p->anyof_mask | p->excluded_mask) &
+ PAGE_IS_WRITTEN;
+}
+
+static int pagemap_scan_test_walk(unsigned long start, unsigned long end,
+ struct mm_walk *walk)
+{
+ struct pagemap_scan_private *p = walk->private;
+ struct vm_area_struct *vma = walk->vma;
+
+ if (pagemap_scan_check_page_written(p) && (!userfaultfd_wp(vma) ||
+ !userfaultfd_wp_async(vma)))
+ return -EPERM;
+
+ if (vma->vm_flags & VM_PFNMAP)
+ return 1;
+
+ return 0;
+}
+
+static int pagemap_scan_output(bool wt, bool file, bool pres, bool swap,
+ struct pagemap_scan_private *p,
+ unsigned long addr, unsigned int n_pages)
+{
+ unsigned long bitmap = PM_SCAN_BITMAP(wt, file, pres, swap);
+ struct page_region *cur = &p->cur;
+
+ if (!n_pages)
+ return -EINVAL;
+
+ if ((p->required_mask & bitmap) != p->required_mask)
+ return 0;
+ if (p->anyof_mask && !(p->anyof_mask & bitmap))
+ return 0;
+ if (p->excluded_mask & bitmap)
+ return 0;
+
+ bitmap &= p->return_mask;
+ if (!bitmap)
+ return 0;
+
+ if (cur->bitmap == bitmap &&
+ cur->start + cur->len * PAGE_SIZE == addr) {
+ cur->len += n_pages;
+ p->found_pages += n_pages;
+
+ if (p->max_pages && (p->found_pages == p->max_pages))
+ return PM_SCAN_FOUND_MAX_PAGES;
+
+ return 0;
+ }
+
+ /*
+ * All data is copied to cur first. When more data is found, we push
+ * cur to vec and copy new data to cur. The vec_index represents the
+ * current index of vec array. We add 1 to the vec_index while
+ * performing checks to account for data in cur.
+ */
+ if (p->vec_index && (p->vec_index + 1) >= p->vec_len)
+ return -ENOSPC;
+
+ if (cur->len) {
+ memcpy(&p->vec[p->vec_index], cur, sizeof(*p->vec));
+ p->vec_index++;
+ }
+
+ cur->start = addr;
+ cur->len = n_pages;
+ cur->bitmap = bitmap;
+ p->found_pages += n_pages;
+
+ if (p->max_pages && (p->found_pages == p->max_pages))
+ return PM_SCAN_FOUND_MAX_PAGES;
+
+ return 0;
+}
+
+static int pagemap_scan_pmd_entry(pmd_t *pmd, unsigned long start,
+ unsigned long end, struct mm_walk *walk)
+{
+ struct pagemap_scan_private *p = walk->private;
+ struct vm_area_struct *vma = walk->vma;
+ unsigned long addr = end;
+ pte_t *pte, *orig_pte;
+ spinlock_t *ptl;
+ bool is_written;
+ int ret = 0;
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ ptl = pmd_trans_huge_lock(pmd, vma);
+ if (ptl) {
+ unsigned long n_pages = (end - start)/PAGE_SIZE;
+
+ if (p->max_pages && n_pages > p->max_pages - p->found_pages)
+ n_pages = p->max_pages - p->found_pages;
+
+ is_written = !is_pmd_uffd_wp(*pmd);
+
+ /*
+ * Break huge page into small pages if the WP operation need to
+ * be performed is on a portion of the huge page.
+ */
+ if (is_written && PM_SCAN_DO_UFFD_WP(p) &&
+ n_pages < HPAGE_SIZE/PAGE_SIZE) {
+ spin_unlock(ptl);
+ split_huge_pmd(vma, pmd, start);
+ goto process_smaller_pages;
+ }
+
+ ret = pagemap_scan_output(is_written, vma->vm_file,
+ pmd_present(*pmd), is_swap_pmd(*pmd),
+ p, start, n_pages);
+
+ if (ret >= 0 && is_written && PM_SCAN_DO_UFFD_WP(p))
+ make_uffd_wp_pmd(vma, addr, pmd);
+
+ spin_unlock(ptl);
+ return ret;
+ }
+process_smaller_pages:
+ if (pmd_trans_unstable(pmd))
+ return 0;
+#endif
+
+ pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
+ for (addr = start; addr < end && !ret; pte++, addr += PAGE_SIZE) {
+ is_written = !is_pte_uffd_wp(*pte);
+
+ ret = pagemap_scan_output(is_written, vma->vm_file,
+ pte_present(*pte), is_swap_pte(*pte),
+ p, addr, 1);
+
+ if (ret >= 0 && is_written && PM_SCAN_DO_UFFD_WP(p))
+ make_uffd_wp_pte(vma, addr, pte);
+ }
+ pte_unmap_unlock(orig_pte, ptl);
+
+ cond_resched();
+ return ret;
+}
+
+#ifdef CONFIG_HUGETLB_PAGE
+static int pagemap_scan_hugetlb_entry(pte_t *ptep, unsigned long hmask,
+ unsigned long start, unsigned long end,
+ struct mm_walk *walk)
+{
+ unsigned long n_pages = (end - start)/PAGE_SIZE;
+ struct pagemap_scan_private *p = walk->private;
+ struct vm_area_struct *vma = walk->vma;
+ struct hstate *h = hstate_vma(vma);
+ int ret = -EPERM;
+ spinlock_t *ptl;
+ bool is_written;
+ pte_t pte;
+
+ if (p->max_pages && n_pages > p->max_pages - p->found_pages)
+ n_pages = p->max_pages - p->found_pages;
+
+ if (PM_SCAN_DO_UFFD_WP(p)) {
+ i_mmap_lock_write(vma->vm_file->f_mapping);
+ ptl = huge_pte_lock(h, vma->vm_mm, ptep);
+ }
+
+ pte = huge_ptep_get(ptep);
+ is_written = !is_huge_pte_uffd_wp(pte);
+
+ /*
+ * Partial hugetlb page clear isn't supported
+ */
+ if (is_written && PM_SCAN_DO_UFFD_WP(p) &&
+ n_pages < HPAGE_SIZE/PAGE_SIZE)
+ goto unlock_and_return;
+
+ ret = pagemap_scan_output(is_written, vma->vm_file, pte_present(pte),
+ is_swap_pte(pte), p, start, n_pages);
+ if (ret < 0)
+ goto unlock_and_return;
+
+ if (is_written && PM_SCAN_DO_UFFD_WP(p)) {
+ make_uffd_wp_huge_pte(vma, start, ptep, pte);
+#define __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE
+ flush_hugetlb_tlb_range(vma, start, end);
+#endif
+ }
+
+unlock_and_return:
+ if (PM_SCAN_DO_UFFD_WP(p)) {
+ spin_unlock(ptl);
+ i_mmap_unlock_write(vma->vm_file->f_mapping);
+ }
+
+ return ret;
+}
+#else
+#define pagemap_scan_hugetlb_entry NULL
+#endif
+
+static int pagemap_scan_pte_hole(unsigned long addr, unsigned long end,
+ int depth, struct mm_walk *walk)
+{
+ unsigned long n_pages = (end - addr)/PAGE_SIZE;
+ struct pagemap_scan_private *p = walk->private;
+ struct vm_area_struct *vma = walk->vma;
+ int ret = 0;
+
+ if (!vma)
+ return 0;
+
+ if (p->max_pages && p->found_pages + n_pages > p->max_pages)
+ n_pages = p->max_pages - p->found_pages;
+
+ ret = pagemap_scan_output(false, vma->vm_file, false, false, p, addr,
+ n_pages);
+ return ret;
+}
+
+static const struct mm_walk_ops pagemap_scan_ops = {
+ .test_walk = pagemap_scan_test_walk,
+ .pmd_entry = pagemap_scan_pmd_entry,
+ .pte_hole = pagemap_scan_pte_hole,
+ .hugetlb_entry = pagemap_scan_hugetlb_entry,
+};
+
+static int pagemap_scan_args_valid(struct pm_scan_arg *arg, unsigned long start,
+ struct page_region __user *vec)
+{
+ /* Detect illegal size, flags, len and masks */
+ if (arg->size != sizeof(struct pm_scan_arg))
+ return -EINVAL;
+ if (arg->flags & ~PM_SCAN_OPS)
+ return -EINVAL;
+ if (!arg->len)
+ return -EINVAL;
+ if ((arg->required_mask | arg->anyof_mask | arg->excluded_mask |
+ arg->return_mask) & ~PM_SCAN_BITS_ALL)
+ return -EINVAL;
+ if (!arg->required_mask && !arg->anyof_mask &&
+ !arg->excluded_mask)
+ return -EINVAL;
+ if (!arg->return_mask)
+ return -EINVAL;
+
+ /* Validate memory ranges */
+ if (!(arg->flags & PM_SCAN_OP_GET))
+ return -EINVAL;
+ if (!arg->vec)
+ return -EINVAL;
+ if (arg->vec_len == 0)
+ return -EINVAL;
+
+ if (!IS_ALIGNED(start, PAGE_SIZE))
+ return -EINVAL;
+ if (!access_ok((void __user *)start, arg->len))
+ return -EFAULT;
+
+ if (!PM_SCAN_DO_UFFD_WP(arg))
+ return 0;
+
+ if ((arg->required_mask | arg->anyof_mask | arg->excluded_mask) &
+ ~PAGE_IS_WRITTEN)
+ return -EINVAL;
+
+ return 0;
+}
+
+static long do_pagemap_scan(struct mm_struct *mm,
+ struct pm_scan_arg __user *uarg)
+{
+ unsigned long start, end, walk_start, walk_end;
+ unsigned long empty_slots, vec_index = 0;
+ struct mmu_notifier_range range;
+ struct page_region __user *vec;
+ struct pagemap_scan_private p;
+ struct pm_scan_arg arg;
+ int ret = 0;
+
+ if (copy_from_user(&arg, uarg, sizeof(arg)))
+ return -EFAULT;
+
+ start = untagged_addr((unsigned long)arg.start);
+ vec = (struct page_region *)untagged_addr((unsigned long)arg.vec);
+
+ ret = pagemap_scan_args_valid(&arg, start, vec);
+ if (ret)
+ return ret;
+
+ end = start + arg.len;
+ p.max_pages = arg.max_pages;
+ p.found_pages = 0;
+ p.flags = arg.flags;
+ p.required_mask = arg.required_mask;
+ p.anyof_mask = arg.anyof_mask;
+ p.excluded_mask = arg.excluded_mask;
+ p.return_mask = arg.return_mask;
+ p.cur.len = 0;
+ p.cur.start = 0;
+ p.vec = NULL;
+ p.vec_len = PAGEMAP_WALK_SIZE >> PAGE_SHIFT;
+
+ /*
+ * Allocate smaller buffer to get output from inside the page walk
+ * functions and walk page range in PAGEMAP_WALK_SIZE size chunks. As
+ * we want to return output to user in compact form where no two
+ * consecutive regions should be continuous and have the same flags.
+ * So store the latest element in p.cur between different walks and
+ * store the p.cur at the end of the walk to the user buffer.
+ */
+ p.vec = kmalloc_array(p.vec_len, sizeof(*p.vec), GFP_KERNEL);
+ if (!p.vec)
+ return -ENOMEM;
+
+ if (p.flags & PM_SCAN_OP_WP) {
+ mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_VMA, 0,
+ vma->vm_mm, start, end);
+ mmu_notifier_invalidate_range_start(&range);
+ }
+
+ walk_start = walk_end = start;
+ while (walk_end < end && !ret) {
+ p.vec_index = 0;
+
+ empty_slots = arg.vec_len - vec_index;
+ p.vec_len = min(p.vec_len, empty_slots);
+
+ walk_end = (walk_start + PAGEMAP_WALK_SIZE) & PAGEMAP_WALK_MASK;
+ if (walk_end > end)
+ walk_end = end;
+
+ ret = mmap_read_lock_killable(mm);
+ if (ret)
+ goto free_data;
+ ret = walk_page_range(mm, walk_start, walk_end,
+ &pagemap_scan_ops, &p);
+ mmap_read_unlock(mm);
+
+ if (ret && ret != -ENOSPC && ret != PM_SCAN_FOUND_MAX_PAGES)
+ goto free_data;
+
+ walk_start = walk_end;
+ if (p.vec_index) {
+ if (copy_to_user(&vec[vec_index], p.vec,
+ p.vec_index * sizeof(*p.vec))) {
+ /*
+ * Return error even though the OP succeeded
+ */
+ ret = -EFAULT;
+ goto free_data;
+ }
+ vec_index += p.vec_index;
+ }
+ }
+
+ if (p.flags & PM_SCAN_OP_WP) {
+ mmu_notifier_invalidate_range_end(&range);
+ flush_tlb_mm_range(mm, start, end, PAGE_SHIFT, false);
+ }
+
+ if (p.cur.len) {
+ if (copy_to_user(&vec[vec_index], &p.cur, sizeof(*p.vec))) {
+ ret = -EFAULT;
+ goto free_data;
+ }
+ vec_index++;
+ }
+
+ ret = vec_index;
+
+free_data:
+ kfree(p.vec);
+ return ret;
+}
+
+static long do_pagemap_cmd(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ struct pm_scan_arg __user *uarg = (struct pm_scan_arg __user *)arg;
+ struct mm_struct *mm = file->private_data;
+
+ switch (cmd) {
+ case PAGEMAP_SCAN:
+ return do_pagemap_scan(mm, uarg);
+
+ default:
+ return -EINVAL;
+ }
+}
+
const struct file_operations proc_pagemap_operations = {
.llseek = mem_lseek, /* borrow this */
.read = pagemap_read,
.open = pagemap_open,
.release = pagemap_release,
+ .unlocked_ioctl = do_pagemap_cmd,
+ .compat_ioctl = do_pagemap_cmd,
};
#endif /* CONFIG_PROC_PAGE_MONITOR */
@@ -305,4 +305,57 @@ typedef int __bitwise __kernel_rwf_t;
#define RWF_SUPPORTED (RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_NOWAIT |\
RWF_APPEND)
+/* Pagemap ioctl */
+#define PAGEMAP_SCAN _IOWR('f', 16, struct pm_scan_arg)
+
+/* Bits are set in the bitmap of the page_region and masks in pm_scan_args */
+#define PAGE_IS_WRITTEN (1 << 0)
+#define PAGE_IS_FILE (1 << 1)
+#define PAGE_IS_PRESENT (1 << 2)
+#define PAGE_IS_SWAPPED (1 << 3)
+
+/*
+ * struct page_region - Page region with bitmap flags
+ * @start: Start of the region
+ * @len: Length of the region in pages
+ * bitmap: Bits sets for the region
+ */
+struct page_region {
+ __u64 start;
+ __u64 len;
+ __u64 bitmap;
+};
+
+/*
+ * struct pm_scan_arg - Pagemap ioctl argument
+ * @size: Size of the structure
+ * @flags: Flags for the IOCTL
+ * @start: Starting address of the region
+ * @len: Length of the region (All the pages in this length are included)
+ * @vec: Address of page_region struct array for output
+ * @vec_len: Length of the page_region struct array
+ * @max_pages: Optional max return pages
+ * @required_mask: Required mask - All of these bits have to be set in the PTE
+ * @anyof_mask: Any mask - Any of these bits are set in the PTE
+ * @excluded_mask: Exclude mask - None of these bits are set in the PTE
+ * @return_mask: Bits that are to be reported in page_region
+ */
+struct pm_scan_arg {
+ __u64 size;
+ __u64 flags;
+ __u64 start;
+ __u64 len;
+ __u64 vec;
+ __u64 vec_len;
+ __u64 max_pages;
+ __u64 required_mask;
+ __u64 anyof_mask;
+ __u64 excluded_mask;
+ __u64 return_mask;
+};
+
+/* Supported flags */
+#define PM_SCAN_OP_GET (1 << 0)
+#define PM_SCAN_OP_WP (1 << 1)
+
#endif /* _UAPI_LINUX_FS_H */