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Power management fixes for v4.7-rc7

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- Fix a recent performance regression on Power systems (powernv
    and pseries) introduced by a core cpuidle commit that decreased
    the precision of the last_residency conversion from nano- to
    microseconds, which should not matter in theory, but turned out
    to play not-so-well with the special "snooze" idle state on Power
    (Shreyas B Prabhu).
 
  - Fix a crash during resume from hibernation on x86-64 caused by
    possible corruption of the kernel text part of page tables in the
    last phase of image restoration exposed by a security-related
    change during the 4.3 development cycle (Rafael Wysocki).
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Merge tag 'pm-4.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management fixes from Rafael Wysocki:
 "One fix for a recent cpuidle core change that, against all odds,
  introduced a functional regression on Power systems and the fix for
  the crash during resume from hibernation on x86-64 that has been in
  the works for the last few weeks (it actually was ready last week, but
  I wanted to allow the reporters to test if for some more time).

  Specifics:

   - Fix a recent performance regression on Power systems (powernv and
     pseries) introduced by a core cpuidle commit that decreased the
     precision of the last_residency conversion from nano- to
     microseconds, which should not matter in theory, but turned out to
     play not-so-well with the special "snooze" idle state on Power
     (Shreyas B Prabhu).

   - Fix a crash during resume from hibernation on x86-64 caused by
     possible corruption of the kernel text part of page tables in the
     last phase of image restoration exposed by a security-related
     change during the 4.3 development cycle (Rafael Wysocki)"

* tag 'pm-4.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpuidle: Fix last_residency division
  x86/power/64: Fix kernel text mapping corruption during image restoration
This commit is contained in:
Linus Torvalds 2016-07-07 20:46:48 -07:00
commit c09230f308
3 changed files with 113 additions and 51 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

97
arch/x86/power/hibernate_64.c
View File

@ -19,6 +19,7 @@
#include <asm/mtrr.h>
#include <asm/sections.h>
#include <asm/suspend.h>
#include <asm/tlbflush.h>
/* Defined in hibernate_asm_64.S */
extern asmlinkage __visible int restore_image(void);
@ -28,6 +29,7 @@ extern asmlinkage __visible int restore_image(void);
* kernel's text (this value is passed in the image header).
*/
unsigned long restore_jump_address __visible;
unsigned long jump_address_phys;
/*
* Value of the cr3 register from before the hibernation (this value is passed
@ -37,7 +39,43 @@ unsigned long restore_cr3 __visible;
pgd_t *temp_level4_pgt __visible;
void *relocated_restore_code __visible;
unsigned long relocated_restore_code __visible;
static int set_up_temporary_text_mapping(void)
{
pmd_t *pmd;
pud_t *pud;
/*
* The new mapping only has to cover the page containing the image
* kernel's entry point (jump_address_phys), because the switch over to
* it is carried out by relocated code running from a page allocated
* specifically for this purpose and covered by the identity mapping, so
* the temporary kernel text mapping is only needed for the final jump.
* Moreover, in that mapping the virtual address of the image kernel's
* entry point must be the same as its virtual address in the image
* kernel (restore_jump_address), so the image kernel's
* restore_registers() code doesn't find itself in a different area of
* the virtual address space after switching over to the original page
* tables used by the image kernel.
*/
pud = (pud_t *)get_safe_page(GFP_ATOMIC);
if (!pud)
return -ENOMEM;
pmd = (pmd_t *)get_safe_page(GFP_ATOMIC);
if (!pmd)
return -ENOMEM;
set_pmd(pmd + pmd_index(restore_jump_address),
__pmd((jump_address_phys & PMD_MASK) | __PAGE_KERNEL_LARGE_EXEC));
set_pud(pud + pud_index(restore_jump_address),
__pud(__pa(pmd) | _KERNPG_TABLE));
set_pgd(temp_level4_pgt + pgd_index(restore_jump_address),
__pgd(__pa(pud) | _KERNPG_TABLE));
return 0;
}
static void *alloc_pgt_page(void *context)
{
@ -59,9 +97,10 @@ static int set_up_temporary_mappings(void)
if (!temp_level4_pgt)
return -ENOMEM;
/* It is safe to reuse the original kernel mapping */
set_pgd(temp_level4_pgt + pgd_index(__START_KERNEL_map),
init_level4_pgt[pgd_index(__START_KERNEL_map)]);
/* Prepare a temporary mapping for the kernel text */
result = set_up_temporary_text_mapping();
if (result)
return result;
/* Set up the direct mapping from scratch */
for (i = 0; i < nr_pfn_mapped; i++) {
@ -78,19 +117,50 @@ static int set_up_temporary_mappings(void)
return 0;
}
static int relocate_restore_code(void)
{
pgd_t *pgd;
pud_t *pud;
relocated_restore_code = get_safe_page(GFP_ATOMIC);
if (!relocated_restore_code)
return -ENOMEM;
memcpy((void *)relocated_restore_code, &core_restore_code, PAGE_SIZE);
/* Make the page containing the relocated code executable */
pgd = (pgd_t *)__va(read_cr3()) + pgd_index(relocated_restore_code);
pud = pud_offset(pgd, relocated_restore_code);
if (pud_large(*pud)) {
set_pud(pud, __pud(pud_val(*pud) & ~_PAGE_NX));
} else {
pmd_t *pmd = pmd_offset(pud, relocated_restore_code);
if (pmd_large(*pmd)) {
set_pmd(pmd, __pmd(pmd_val(*pmd) & ~_PAGE_NX));
} else {
pte_t *pte = pte_offset_kernel(pmd, relocated_restore_code);
set_pte(pte, __pte(pte_val(*pte) & ~_PAGE_NX));
}
}
__flush_tlb_all();
return 0;
}
int swsusp_arch_resume(void)
{
int error;
/* We have got enough memory and from now on we cannot recover */
if ((error = set_up_temporary_mappings()))
error = set_up_temporary_mappings();
if (error)
return error;
relocated_restore_code = (void *)get_safe_page(GFP_ATOMIC);
if (!relocated_restore_code)
return -ENOMEM;
memcpy(relocated_restore_code, &core_restore_code,
&restore_registers - &core_restore_code);
error = relocate_restore_code();
if (error)
return error;
restore_image();
return 0;
@ -109,11 +179,12 @@ int pfn_is_nosave(unsigned long pfn)
struct restore_data_record {
unsigned long jump_address;
unsigned long jump_address_phys;
unsigned long cr3;
unsigned long magic;
};
#define RESTORE_MAGIC 0x0123456789ABCDEFUL
#define RESTORE_MAGIC 0x123456789ABCDEF0UL
/**
* arch_hibernation_header_save - populate the architecture specific part
@ -126,7 +197,8 @@ int arch_hibernation_header_save(void *addr, unsigned int max_size)
if (max_size < sizeof(struct restore_data_record))
return -EOVERFLOW;
rdr->jump_address = restore_jump_address;
rdr->jump_address = (unsigned long)&restore_registers;
rdr->jump_address_phys = __pa_symbol(&restore_registers);
rdr->cr3 = restore_cr3;
rdr->magic = RESTORE_MAGIC;
return 0;
@ -142,6 +214,7 @@ int arch_hibernation_header_restore(void *addr)
struct restore_data_record *rdr = addr;
restore_jump_address = rdr->jump_address;
jump_address_phys = rdr->jump_address_phys;
restore_cr3 = rdr->cr3;
return (rdr->magic == RESTORE_MAGIC) ? 0 : -EINVAL;
}

55
arch/x86/power/hibernate_asm_64.S
View File

@ -44,9 +44,6 @@ ENTRY(swsusp_arch_suspend)
pushfq
popq pt_regs_flags(%rax)
/* save the address of restore_registers */
movq $restore_registers, %rax
movq %rax, restore_jump_address(%rip)
/* save cr3 */
movq %cr3, %rax
movq %rax, restore_cr3(%rip)
@ -57,31 +54,34 @@ ENTRY(swsusp_arch_suspend)
ENDPROC(swsusp_arch_suspend)
ENTRY(restore_image)
/* switch to temporary page tables */
movq $__PAGE_OFFSET, %rdx
movq temp_level4_pgt(%rip), %rax
subq %rdx, %rax
movq %rax, %cr3
/* Flush TLB */
movq mmu_cr4_features(%rip), %rax
movq %rax, %rdx
andq $~(X86_CR4_PGE), %rdx
movq %rdx, %cr4; # turn off PGE
movq %cr3, %rcx; # flush TLB
movq %rcx, %cr3;
movq %rax, %cr4; # turn PGE back on
/* prepare to jump to the image kernel */
movq restore_jump_address(%rip), %rax
movq restore_cr3(%rip), %rbx
movq restore_jump_address(%rip), %r8
movq restore_cr3(%rip), %r9
/* prepare to switch to temporary page tables */
movq temp_level4_pgt(%rip), %rax
movq mmu_cr4_features(%rip), %rbx
/* prepare to copy image data to their original locations */
movq restore_pblist(%rip), %rdx
/* jump to relocated restore code */
movq relocated_restore_code(%rip), %rcx
jmpq *%rcx
/* code below has been relocated to a safe page */
ENTRY(core_restore_code)
/* switch to temporary page tables */
movq $__PAGE_OFFSET, %rcx
subq %rcx, %rax
movq %rax, %cr3
/* flush TLB */
movq %rbx, %rcx
andq $~(X86_CR4_PGE), %rcx
movq %rcx, %cr4; # turn off PGE
movq %cr3, %rcx; # flush TLB
movq %rcx, %cr3;
movq %rbx, %cr4; # turn PGE back on
.Lloop:
testq %rdx, %rdx
jz .Ldone
@ -96,24 +96,17 @@ ENTRY(core_restore_code)
/* progress to the next pbe */
movq pbe_next(%rdx), %rdx
jmp .Lloop
.Ldone:
/* jump to the restore_registers address from the image header */
jmpq *%rax
/*
* NOTE: This assumes that the boot kernel's text mapping covers the
* image kernel's page containing restore_registers and the address of
* this page is the same as in the image kernel's text mapping (it
* should always be true, because the text mapping is linear, starting
* from 0, and is supposed to cover the entire kernel text for every
* kernel).
*
* code below belongs to the image kernel
*/
jmpq *%r8
/* code below belongs to the image kernel */
.align PAGE_SIZE
ENTRY(restore_registers)
FRAME_BEGIN
/* go back to the original page tables */
movq %rbx, %cr3
movq %r9, %cr3
/* Flush TLB, including "global" things (vmalloc) */
movq mmu_cr4_features(%rip), %rax

12
drivers/cpuidle/cpuidle.c
View File

@ -173,7 +173,7 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
struct cpuidle_state *target_state = &drv->states[index];
bool broadcast = !!(target_state->flags & CPUIDLE_FLAG_TIMER_STOP);
u64 time_start, time_end;
ktime_t time_start, time_end;
s64 diff;
/*
@ -195,13 +195,13 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
sched_idle_set_state(target_state);
trace_cpu_idle_rcuidle(index, dev->cpu);
time_start = local_clock();
time_start = ns_to_ktime(local_clock());
stop_critical_timings();
entered_state = target_state->enter(dev, drv, index);
start_critical_timings();
time_end = local_clock();
time_end = ns_to_ktime(local_clock());
trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
/* The cpu is no longer idle or about to enter idle. */
@ -217,11 +217,7 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
if (!cpuidle_state_is_coupled(drv, index))
local_irq_enable();
/*
* local_clock() returns the time in nanosecond, let's shift
* by 10 (divide by 1024) to have microsecond based time.
*/
diff = (time_end - time_start) >> 10;
diff = ktime_us_delta(time_end, time_start);
if (diff > INT_MAX)
diff = INT_MAX;