linux/arch/arm64/kernel/hibernate.c
Catalin Marinas 20794545c1 arm64: kasan: Revert "arm64: mte: reset the page tag in page->flags"
This reverts commit e5b8d92189.

Pages mapped in user-space with PROT_MTE have the allocation tags either
zeroed or copied/restored to some user values. In order for the kernel
to access such pages via page_address(), resetting the tag in
page->flags was necessary. This tag resetting was deferred to
set_pte_at() -> mte_sync_page_tags() but it can race with another CPU
reading the flags (via page_to_virt()):

P0 (mte_sync_page_tags):	P1 (memcpy from virt_to_page):
				  Rflags!=0xff
  Wflags=0xff
  DMB (doesn't help)
  Wtags=0
				  Rtags=0   // fault

Since now the post_alloc_hook() function resets the page->flags tag when
unpoisoning is skipped for user pages (including the __GFP_ZEROTAGS
case), revert the arm64 commit calling page_kasan_tag_reset().

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Peter Collingbourne <pcc@google.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20220610152141.2148929-5-catalin.marinas@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
2022-07-07 10:48:37 +01:00

479 lines
11 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*:
* Hibernate support specific for ARM64
*
* Derived from work on ARM hibernation support by:
*
* Ubuntu project, hibernation support for mach-dove
* Copyright (C) 2010 Nokia Corporation (Hiroshi Doyu)
* Copyright (C) 2010 Texas Instruments, Inc. (Teerth Reddy et al.)
* Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
*/
#define pr_fmt(x) "hibernate: " x
#include <linux/cpu.h>
#include <linux/kvm_host.h>
#include <linux/pm.h>
#include <linux/sched.h>
#include <linux/suspend.h>
#include <linux/utsname.h>
#include <asm/barrier.h>
#include <asm/cacheflush.h>
#include <asm/cputype.h>
#include <asm/daifflags.h>
#include <asm/irqflags.h>
#include <asm/kexec.h>
#include <asm/memory.h>
#include <asm/mmu_context.h>
#include <asm/mte.h>
#include <asm/sections.h>
#include <asm/smp.h>
#include <asm/smp_plat.h>
#include <asm/suspend.h>
#include <asm/sysreg.h>
#include <asm/trans_pgd.h>
#include <asm/virt.h>
/*
* Hibernate core relies on this value being 0 on resume, and marks it
* __nosavedata assuming it will keep the resume kernel's '0' value. This
* doesn't happen with either KASLR.
*
* defined as "__visible int in_suspend __nosavedata" in
* kernel/power/hibernate.c
*/
extern int in_suspend;
/* Do we need to reset el2? */
#define el2_reset_needed() (is_hyp_nvhe())
/* hyp-stub vectors, used to restore el2 during resume from hibernate. */
extern char __hyp_stub_vectors[];
/*
* The logical cpu number we should resume on, initialised to a non-cpu
* number.
*/
static int sleep_cpu = -EINVAL;
/*
* Values that may not change over hibernate/resume. We put the build number
* and date in here so that we guarantee not to resume with a different
* kernel.
*/
struct arch_hibernate_hdr_invariants {
char uts_version[__NEW_UTS_LEN + 1];
};
/* These values need to be know across a hibernate/restore. */
static struct arch_hibernate_hdr {
struct arch_hibernate_hdr_invariants invariants;
/* These are needed to find the relocated kernel if built with kaslr */
phys_addr_t ttbr1_el1;
void (*reenter_kernel)(void);
/*
* We need to know where the __hyp_stub_vectors are after restore to
* re-configure el2.
*/
phys_addr_t __hyp_stub_vectors;
u64 sleep_cpu_mpidr;
} resume_hdr;
static inline void arch_hdr_invariants(struct arch_hibernate_hdr_invariants *i)
{
memset(i, 0, sizeof(*i));
memcpy(i->uts_version, init_utsname()->version, sizeof(i->uts_version));
}
int pfn_is_nosave(unsigned long pfn)
{
unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn)) ||
crash_is_nosave(pfn);
}
void notrace save_processor_state(void)
{
WARN_ON(num_online_cpus() != 1);
}
void notrace restore_processor_state(void)
{
}
int arch_hibernation_header_save(void *addr, unsigned int max_size)
{
struct arch_hibernate_hdr *hdr = addr;
if (max_size < sizeof(*hdr))
return -EOVERFLOW;
arch_hdr_invariants(&hdr->invariants);
hdr->ttbr1_el1 = __pa_symbol(swapper_pg_dir);
hdr->reenter_kernel = _cpu_resume;
/* We can't use __hyp_get_vectors() because kvm may still be loaded */
if (el2_reset_needed())
hdr->__hyp_stub_vectors = __pa_symbol(__hyp_stub_vectors);
else
hdr->__hyp_stub_vectors = 0;
/* Save the mpidr of the cpu we called cpu_suspend() on... */
if (sleep_cpu < 0) {
pr_err("Failing to hibernate on an unknown CPU.\n");
return -ENODEV;
}
hdr->sleep_cpu_mpidr = cpu_logical_map(sleep_cpu);
pr_info("Hibernating on CPU %d [mpidr:0x%llx]\n", sleep_cpu,
hdr->sleep_cpu_mpidr);
return 0;
}
EXPORT_SYMBOL(arch_hibernation_header_save);
int arch_hibernation_header_restore(void *addr)
{
int ret;
struct arch_hibernate_hdr_invariants invariants;
struct arch_hibernate_hdr *hdr = addr;
arch_hdr_invariants(&invariants);
if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
pr_crit("Hibernate image not generated by this kernel!\n");
return -EINVAL;
}
sleep_cpu = get_logical_index(hdr->sleep_cpu_mpidr);
pr_info("Hibernated on CPU %d [mpidr:0x%llx]\n", sleep_cpu,
hdr->sleep_cpu_mpidr);
if (sleep_cpu < 0) {
pr_crit("Hibernated on a CPU not known to this kernel!\n");
sleep_cpu = -EINVAL;
return -EINVAL;
}
ret = bringup_hibernate_cpu(sleep_cpu);
if (ret) {
sleep_cpu = -EINVAL;
return ret;
}
resume_hdr = *hdr;
return 0;
}
EXPORT_SYMBOL(arch_hibernation_header_restore);
static void *hibernate_page_alloc(void *arg)
{
return (void *)get_safe_page((__force gfp_t)(unsigned long)arg);
}
/*
* Copies length bytes, starting at src_start into an new page,
* perform cache maintenance, then maps it at the specified address low
* address as executable.
*
* This is used by hibernate to copy the code it needs to execute when
* overwriting the kernel text. This function generates a new set of page
* tables, which it loads into ttbr0.
*
* Length is provided as we probably only want 4K of data, even on a 64K
* page system.
*/
static int create_safe_exec_page(void *src_start, size_t length,
phys_addr_t *phys_dst_addr)
{
struct trans_pgd_info trans_info = {
.trans_alloc_page = hibernate_page_alloc,
.trans_alloc_arg = (__force void *)GFP_ATOMIC,
};
void *page = (void *)get_safe_page(GFP_ATOMIC);
phys_addr_t trans_ttbr0;
unsigned long t0sz;
int rc;
if (!page)
return -ENOMEM;
memcpy(page, src_start, length);
caches_clean_inval_pou((unsigned long)page, (unsigned long)page + length);
rc = trans_pgd_idmap_page(&trans_info, &trans_ttbr0, &t0sz, page);
if (rc)
return rc;
cpu_install_ttbr0(trans_ttbr0, t0sz);
*phys_dst_addr = virt_to_phys(page);
return 0;
}
#ifdef CONFIG_ARM64_MTE
static DEFINE_XARRAY(mte_pages);
static int save_tags(struct page *page, unsigned long pfn)
{
void *tag_storage, *ret;
tag_storage = mte_allocate_tag_storage();
if (!tag_storage)
return -ENOMEM;
mte_save_page_tags(page_address(page), tag_storage);
ret = xa_store(&mte_pages, pfn, tag_storage, GFP_KERNEL);
if (WARN(xa_is_err(ret), "Failed to store MTE tags")) {
mte_free_tag_storage(tag_storage);
return xa_err(ret);
} else if (WARN(ret, "swsusp: %s: Duplicate entry", __func__)) {
mte_free_tag_storage(ret);
}
return 0;
}
static void swsusp_mte_free_storage(void)
{
XA_STATE(xa_state, &mte_pages, 0);
void *tags;
xa_lock(&mte_pages);
xas_for_each(&xa_state, tags, ULONG_MAX) {
mte_free_tag_storage(tags);
}
xa_unlock(&mte_pages);
xa_destroy(&mte_pages);
}
static int swsusp_mte_save_tags(void)
{
struct zone *zone;
unsigned long pfn, max_zone_pfn;
int ret = 0;
int n = 0;
if (!system_supports_mte())
return 0;
for_each_populated_zone(zone) {
max_zone_pfn = zone_end_pfn(zone);
for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
struct page *page = pfn_to_online_page(pfn);
if (!page)
continue;
if (!test_bit(PG_mte_tagged, &page->flags))
continue;
ret = save_tags(page, pfn);
if (ret) {
swsusp_mte_free_storage();
goto out;
}
n++;
}
}
pr_info("Saved %d MTE pages\n", n);
out:
return ret;
}
static void swsusp_mte_restore_tags(void)
{
XA_STATE(xa_state, &mte_pages, 0);
int n = 0;
void *tags;
xa_lock(&mte_pages);
xas_for_each(&xa_state, tags, ULONG_MAX) {
unsigned long pfn = xa_state.xa_index;
struct page *page = pfn_to_online_page(pfn);
mte_restore_page_tags(page_address(page), tags);
mte_free_tag_storage(tags);
n++;
}
xa_unlock(&mte_pages);
pr_info("Restored %d MTE pages\n", n);
xa_destroy(&mte_pages);
}
#else /* CONFIG_ARM64_MTE */
static int swsusp_mte_save_tags(void)
{
return 0;
}
static void swsusp_mte_restore_tags(void)
{
}
#endif /* CONFIG_ARM64_MTE */
int swsusp_arch_suspend(void)
{
int ret = 0;
unsigned long flags;
struct sleep_stack_data state;
if (cpus_are_stuck_in_kernel()) {
pr_err("Can't hibernate: no mechanism to offline secondary CPUs.\n");
return -EBUSY;
}
flags = local_daif_save();
if (__cpu_suspend_enter(&state)) {
/* make the crash dump kernel image visible/saveable */
crash_prepare_suspend();
ret = swsusp_mte_save_tags();
if (ret)
return ret;
sleep_cpu = smp_processor_id();
ret = swsusp_save();
} else {
/* Clean kernel core startup/idle code to PoC*/
dcache_clean_inval_poc((unsigned long)__mmuoff_data_start,
(unsigned long)__mmuoff_data_end);
dcache_clean_inval_poc((unsigned long)__idmap_text_start,
(unsigned long)__idmap_text_end);
/* Clean kvm setup code to PoC? */
if (el2_reset_needed()) {
dcache_clean_inval_poc(
(unsigned long)__hyp_idmap_text_start,
(unsigned long)__hyp_idmap_text_end);
dcache_clean_inval_poc((unsigned long)__hyp_text_start,
(unsigned long)__hyp_text_end);
}
swsusp_mte_restore_tags();
/* make the crash dump kernel image protected again */
crash_post_resume();
/*
* Tell the hibernation core that we've just restored
* the memory
*/
in_suspend = 0;
sleep_cpu = -EINVAL;
__cpu_suspend_exit();
/*
* Just in case the boot kernel did turn the SSBD
* mitigation off behind our back, let's set the state
* to what we expect it to be.
*/
spectre_v4_enable_mitigation(NULL);
}
local_daif_restore(flags);
return ret;
}
/*
* Setup then Resume from the hibernate image using swsusp_arch_suspend_exit().
*
* Memory allocated by get_safe_page() will be dealt with by the hibernate code,
* we don't need to free it here.
*/
int swsusp_arch_resume(void)
{
int rc;
void *zero_page;
size_t exit_size;
pgd_t *tmp_pg_dir;
phys_addr_t el2_vectors;
void __noreturn (*hibernate_exit)(phys_addr_t, phys_addr_t, void *,
void *, phys_addr_t, phys_addr_t);
struct trans_pgd_info trans_info = {
.trans_alloc_page = hibernate_page_alloc,
.trans_alloc_arg = (void *)GFP_ATOMIC,
};
/*
* Restoring the memory image will overwrite the ttbr1 page tables.
* Create a second copy of just the linear map, and use this when
* restoring.
*/
rc = trans_pgd_create_copy(&trans_info, &tmp_pg_dir, PAGE_OFFSET,
PAGE_END);
if (rc)
return rc;
/*
* We need a zero page that is zero before & after resume in order
* to break before make on the ttbr1 page tables.
*/
zero_page = (void *)get_safe_page(GFP_ATOMIC);
if (!zero_page) {
pr_err("Failed to allocate zero page.\n");
return -ENOMEM;
}
if (el2_reset_needed()) {
rc = trans_pgd_copy_el2_vectors(&trans_info, &el2_vectors);
if (rc) {
pr_err("Failed to setup el2 vectors\n");
return rc;
}
}
exit_size = __hibernate_exit_text_end - __hibernate_exit_text_start;
/*
* Copy swsusp_arch_suspend_exit() to a safe page. This will generate
* a new set of ttbr0 page tables and load them.
*/
rc = create_safe_exec_page(__hibernate_exit_text_start, exit_size,
(phys_addr_t *)&hibernate_exit);
if (rc) {
pr_err("Failed to create safe executable page for hibernate_exit code.\n");
return rc;
}
/*
* KASLR will cause the el2 vectors to be in a different location in
* the resumed kernel. Load hibernate's temporary copy into el2.
*
* We can skip this step if we booted at EL1, or are running with VHE.
*/
if (el2_reset_needed())
__hyp_set_vectors(el2_vectors);
hibernate_exit(virt_to_phys(tmp_pg_dir), resume_hdr.ttbr1_el1,
resume_hdr.reenter_kernel, restore_pblist,
resume_hdr.__hyp_stub_vectors, virt_to_phys(zero_page));
return 0;
}
int hibernate_resume_nonboot_cpu_disable(void)
{
if (sleep_cpu < 0) {
pr_err("Failing to resume from hibernate on an unknown CPU.\n");
return -ENODEV;
}
return freeze_secondary_cpus(sleep_cpu);
}