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ANDROID: 16K: Disable kernel APIs indexed by PFNs

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When emulating the userspace page size, /proc/*/pagemap
doesn't support PFNs since it is not guaranteed that
the PFNs of the virtually contiguous pages are also
contiguous physically and therefore cannot be collapsed
for purposes of the page size emulation.

On x86_64 16K devices, PFN bit of pagemap entries are
always zero, hence disable APIs that consume PFNs
from pagemap:
  - /proc/kpagecount
  - /proc/kpageflags
  - /proc/kpagecgroup
  - /sys/kernel/mm/page_idle/bitmap

Bug: 383389337
Bug: 385167611
Test: atest vts_ltp_test_x86_64:syscalls.msync04_64bit#syscalls.msync04_64bit
Test: atest vts_ltp_test_x86_64:syscalls.mmap12_64bit#syscalls.mmap12_64bit
Test: atest libmeminfo_test
Test: atest bionic-unit-tests:DlExtRelroSharingTest#VerifyMemorySaving
Note: bionic-unit-tests must be run as root (add require_root: true)
Change-Id: I214c8737c6f7385346436769f144c5ecd429a5b7
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
This commit is contained in:
Kalesh Singh
2025-01-28 21:06:27 +00:00
committed by Carlos Llamas
parent d684b3125e
commit 0d44e1eb0e
2 changed files with 8 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
fs/proc/page.c
View File

@@ -14,6 +14,7 @@
#include <linux/memcontrol.h>
#include <linux/mmu_notifier.h>
#include <linux/page_idle.h>
#include <linux/page_size_compat.h>
#include <linux/kernel-page-flags.h>
#include <linux/uaccess.h>
#include "internal.h"
@@ -328,6 +329,9 @@ static const struct proc_ops kpagecgroup_proc_ops = {
static int __init proc_page_init(void)
{
if (__PAGE_SIZE != PAGE_SIZE)
return 0;
proc_create("kpagecount", S_IRUSR, NULL, &kpagecount_proc_ops);
proc_create("kpageflags", S_IRUSR, NULL, &kpageflags_proc_ops);
#ifdef CONFIG_MEMCG

4
mm/page_idle.c
View File

@@ -8,6 +8,7 @@
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/pagemap.h>
#include <linux/page_size_compat.h>
#include <linux/rmap.h>
#include <linux/mmu_notifier.h>
#include <linux/page_ext.h>
@@ -211,6 +212,9 @@ static int __init page_idle_init(void)
{
int err;
if (__PAGE_SIZE != PAGE_SIZE)
return 0;
err = sysfs_create_group(mm_kobj, &page_idle_attr_group);
if (err) {
pr_err("page_idle: register sysfs failed\n");