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b5b4453e79
mirror_ubuntu-kernels/arch/powerpc/kernel
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Michael Ellerman b5b4453e79 powerpc/vdso64: Fix CLOCK_MONOTONIC inconsistencies across Y2038 
Jakub Drnec reported:
  Setting the realtime clock can sometimes make the monotonic clock go
  back by over a hundred years. Decreasing the realtime clock across
  the y2k38 threshold is one reliable way to reproduce. Allegedly this
  can also happen just by running ntpd, I have not managed to
  reproduce that other than booting with rtc at >2038 and then running
  ntp. When this happens, anything with timers (e.g. openjdk) breaks
  rather badly.

And included a test case (slightly edited for brevity):
  #define _POSIX_C_SOURCE 199309L
  #include <stdio.h>
  #include <time.h>
  #include <stdlib.h>
  #include <unistd.h>

  long get_time(void) {
    struct timespec tp;
    clock_gettime(CLOCK_MONOTONIC, &tp);
    return tp.tv_sec + tp.tv_nsec / 1000000000;
  }

  int main(void) {
    long last = get_time();
    while(1) {
      long now = get_time();
      if (now < last) {
        printf("clock went backwards by %ld seconds!\n", last - now);
      }
      last = now;
      sleep(1);
    }
    return 0;
  }

Which when run concurrently with:
 # date -s 2040-1-1
 # date -s 2037-1-1

Will detect the clock going backward.

The root cause is that wtom_clock_sec in struct vdso_data is only a
32-bit signed value, even though we set its value to be equal to
tk->wall_to_monotonic.tv_sec which is 64-bits.

Because the monotonic clock starts at zero when the system boots the
wall_to_montonic.tv_sec offset is negative for current and future
dates. Currently on a freshly booted system the offset will be in the
vicinity of negative 1.5 billion seconds.

However if the wall clock is set past the Y2038 boundary, the offset
from wall to monotonic becomes less than negative 2^31, and no longer
fits in 32-bits. When that value is assigned to wtom_clock_sec it is
truncated and becomes positive, causing the VDSO assembly code to
calculate CLOCK_MONOTONIC incorrectly.

That causes CLOCK_MONOTONIC to jump ahead by ~4 billion seconds which
it is not meant to do. Worse, if the time is then set back before the
Y2038 boundary CLOCK_MONOTONIC will jump backward.

We can fix it simply by storing the full 64-bit offset in the
vdso_data, and using that in the VDSO assembly code. We also shuffle
some of the fields in vdso_data to avoid creating a hole.

The original commit that added the CLOCK_MONOTONIC support to the VDSO
did actually use a 64-bit value for wtom_clock_sec, see commit
a7f290dad3 ("[PATCH] powerpc: Merge vdso's and add vdso support to
32 bits kernel") (Nov 2005). However just 3 days later it was
converted to 32-bits in commit 0c37ec2aa8 ("[PATCH] powerpc: vdso
fixes (take #2)"), and the bug has existed since then AFAICS.

Fixes: 0c37ec2aa8 ("[PATCH] powerpc: vdso fixes (take #2)")
Cc: stable@vger.kernel.org # v2.6.15+
Link: http://lkml.kernel.org/r/HaC.ZfES.62bwlnvAvMP.1STMMj@seznam.cz
Reported-by: Jakub Drnec <jaydee@email.cz>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-03-18 19:26:38 +11:00
..
syscalls powerpc updates for 5.1 2019-03-07 12:56:26 -08:00
trace powerpc/64: Replace CURRENT_THREAD_INFO with PACA_THREAD_INFO 2019-02-23 22:31:40 +11:00
vdso32 powerpc: Enable kcov 2019-02-23 21:04:32 +11:00
vdso64 powerpc/vdso64: Fix CLOCK_MONOTONIC inconsistencies across Y2038 2019-03-18 19:26:38 +11:00
.gitignore
align.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
asm-offsets.c powerpc/64: Replace CURRENT_THREAD_INFO with PACA_THREAD_INFO 2019-02-23 22:31:40 +11:00
audit.c
btext.c powerpc: Rework btext_find_display to use of_stdout and device_type helpers 2018-11-26 22:33:37 +11:00
cacheinfo.c powerpc: Use device_type helpers to access the node type 2018-11-26 22:33:37 +11:00
cacheinfo.h
compat_audit.c
cpu_setup_6xx.S powerpc/6xx: Store PGDIR physical address in a SPRG 2019-02-22 00:10:16 +11:00
cpu_setup_44x.S
cpu_setup_fsl_booke.S powerpc/mm: move platform specific mmu-xxx.h in platform directories 2018-12-04 19:45:01 +11:00
cpu_setup_pa6t.S
cpu_setup_power.S powerpc: Turn off CPU_FTR_P9_TM_HV_ASSIST in non-hypervisor mode 2018-10-09 16:04:27 +11:00
cpu_setup_ppc970.S
cputable.c powerpc/83xx: handle machine check caused by watchdog timer 2018-12-21 20:56:41 -06:00
crash_dump.c powerpc: don't use ioremap_prot() nor __ioremap() unless really needed. 2018-10-14 18:04:09 +11:00
crash.c powerpc: remove kdump.h from page.h 2018-07-30 22:47:53 +10:00
dbell.c
dma-iommu.c powerpc/dma: use the dma_direct mapping routines 2019-02-18 22:41:04 +11:00
dma-mask.c dma-mapping, powerpc: simplify the arch dma_set_mask override 2019-02-18 22:41:03 +11:00
dma-swiotlb.c powerpc/dma: use the generic direct mapping bypass 2019-02-18 22:41:04 +11:00
dt_cpu_ftrs.c treewide: add checks for the return value of memblock_alloc*() 2019-03-12 10:04:02 -07:00
eeh_cache.c powerpc/eeh_cache: Bump log level of eeh_addr_cache_print() 2019-02-22 00:10:14 +11:00
eeh_dev.c powerpc/eeh: Cleanup list_head field names 2018-10-13 22:21:25 +11:00
eeh_driver.c powerpc/eeh: Improve recovery of passed-through devices 2019-02-05 11:55:44 +11:00
eeh_event.c powerpc/eeh: Add eeh_force_recover to debugfs 2019-02-22 00:10:15 +11:00
eeh_pe.c powerpc/eeh: Add include_passed to eeh_pe_state_clear() 2019-02-05 11:55:43 +11:00
eeh_sysfs.c powerpc/eeh: Add include_passed to eeh_pe_state_clear() 2019-02-05 11:55:43 +11:00
eeh.c powerpc/eeh: Add eeh_force_recover to debugfs 2019-02-22 00:10:15 +11:00
entry_32.S powerpc/32: Clear on-stack exception marker upon exception return 2019-03-04 00:37:23 +11:00
entry_64.S powerpc/64: Replace CURRENT_THREAD_INFO with PACA_THREAD_INFO 2019-02-23 22:31:40 +11:00
epapr_hcalls.S powerpc/32: Remove CURRENT_THREAD_INFO and rename TI_CPU 2019-02-23 22:31:40 +11:00
epapr_paravirt.c
exceptions-64e.S powerpc/fsl: Fix the flush of branch predictor. 2019-02-27 22:52:38 +11:00
exceptions-64s.S powerpc/64s: Fix unrelocated interrupt trampoline address test 2019-03-02 00:25:47 +11:00
fadump.c powerpc/fadump: Do not allow hot-remove memory from fadump reserved area. 2018-12-21 11:32:49 +11:00
firmware.c
fpu.S powerpc: clean inclusions of asm/feature-fixups.h 2018-07-30 22:48:17 +10:00
fsl_booke_entry_mapping.S
head_8xx.S powerpc: Rename THREAD_INFO to TASK_STACK 2019-02-23 22:31:40 +11:00
head_32.S powerpc: 'current_set' is now a table of task_struct pointers 2019-02-23 22:31:40 +11:00
head_40x.S powerpc: Rename THREAD_INFO to TASK_STACK 2019-02-23 22:31:40 +11:00
head_44x.S powerpc: 'current_set' is now a table of task_struct pointers 2019-02-23 22:31:40 +11:00
head_64.S powerpc/64: Simplify __secondary_start paca->kstack handling 2019-02-23 22:31:39 +11:00
head_booke.h powerpc: Activate CONFIG_THREAD_INFO_IN_TASK 2019-02-23 22:31:40 +11:00
head_fsl_booke.S powerpc: remove dead code in head_fsl_booke.S 2019-03-05 16:38:45 +11:00
hw_breakpoint.c perf/arch/powerpc: Implement hw_breakpoint_arch_parse() 2018-06-26 09:07:55 +02:00
idle_6xx.S powerpc/32: Remove CURRENT_THREAD_INFO and rename TI_CPU 2019-02-23 22:31:40 +11:00
idle_book3e.S powerpc/64: Replace CURRENT_THREAD_INFO with PACA_THREAD_INFO 2019-02-23 22:31:40 +11:00
idle_book3s.S Merge branch 'fixes' into next 2018-08-13 15:59:06 +10:00
idle_e500.S powerpc/32: Remove CURRENT_THREAD_INFO and rename TI_CPU 2019-02-23 22:31:40 +11:00
idle_power4.S powerpc/64: Replace CURRENT_THREAD_INFO with PACA_THREAD_INFO 2019-02-23 22:31:40 +11:00
idle.c
ima_kexec.c
io-workarounds.c powerpc: handover page flags with a pgprot_t parameter 2018-10-14 18:04:09 +11:00
io.c
iomap.c powerpc: iomap.c: introduce io{read|write}64_{lo_hi|hi_lo} 2018-04-05 14:59:26 +10:00
iommu.c IOMMU Updates for Linux v4.21 2019-01-01 15:55:29 -08:00
irq.c powerpc: clean stack pointers naming 2019-02-23 22:31:40 +11:00
isa-bridge.c powerpc: Use device_type helpers to access the node type 2018-11-26 22:33:37 +11:00
jump_label.c jump_label: move 'asm goto' support test to Kconfig 2019-01-06 09:46:51 +09:00
kexec_elf_64.c kernel/kexec_file.c: allow archs to set purgatory load address 2018-04-13 17:10:28 -07:00
kgdb.c powerpc: Activate CONFIG_THREAD_INFO_IN_TASK 2019-02-23 22:31:40 +11:00
kprobes-ftrace.c bpf/error-inject/kprobes: Clear current_kprobe and enable preempt in kprobe 2018-06-21 12:33:19 +02:00
kprobes.c bpf/error-inject/kprobes: Clear current_kprobe and enable preempt in kprobe 2018-06-21 12:33:19 +02:00
kvm_emul.S powerpc: move ASM_CONST and stringify_in_c() into asm-const.h 2018-07-30 22:48:16 +10:00
kvm.c powerpc/kvm: Prefer fault_in_pages_readable function 2018-05-17 14:12:40 +10:00
l2cr_6xx.S powerpc: clean inclusions of asm/feature-fixups.h 2018-07-30 22:48:17 +10:00
legacy_serial.c powerpc: Use of_node_name_eq for node name comparisons 2018-12-22 21:29:50 +11:00
machine_kexec_32.c
machine_kexec_64.c powerpc: Activate CONFIG_THREAD_INFO_IN_TASK 2019-02-23 22:31:40 +11:00
machine_kexec_file_64.c powerpc, kexec_file: factor out memblock-based arch_kexec_walk_mem() 2018-12-06 14:38:50 +00:00
machine_kexec.c powerpc: remove kdump.h from page.h 2018-07-30 22:47:53 +10:00
Makefile powerpc: Enable kcov 2019-02-23 21:04:32 +11:00
mce_power.c powerpc/64s/hash: Do not use PPC_INVALIDATE_ERAT on CPUs before POWER9 2018-10-04 23:16:53 +10:00
mce.c powerpc/64s: Fix HV NMI vs HV interrupt recoverability test 2019-02-26 23:28:24 +11:00
misc_32.S powerpc/32: Remove CURRENT_THREAD_INFO and rename TI_CPU 2019-02-23 22:31:40 +11:00
misc_64.S powerpc: clean inclusions of asm/feature-fixups.h 2018-07-30 22:48:17 +10:00
misc.S powerpc/misc: merge reloc_offset() and add_reloc_offset() 2018-06-04 00:39:17 +10:00
module_32.c powerpc/sparse: Fix plain integer as NULL pointer warning 2018-05-25 12:04:38 +10:00
module_64.c powerpc/64/module: REL32 relocation range check 2018-10-20 13:26:47 +11:00
module.c powerpc64/module elfv1: Set opd addresses after module relocation 2018-10-20 13:26:47 +11:00
module.lds powerpc/modules: Fix alignment of .toc section in kernel modules 2017-12-11 13:03:35 +11:00
msi.c powerpc/msi: Fix NULL pointer access in teardown code 2018-11-29 23:49:11 +11:00
nvram_64.c powerpc: Adopt nvram module for PPC64 2019-01-22 10:21:45 +01:00
of_platform.c
optprobes_head.S powerpc/64: Rename soft_enabled to irq_soft_mask 2018-01-19 22:37:01 +11:00
optprobes.c
paca.c powerpc: use memblock functions returning virtual address 2019-03-12 10:04:01 -07:00
pci_32.c treewide: add checks for the return value of memblock_alloc*() 2019-03-12 10:04:02 -07:00
pci_64.c powerpc: handover page flags with a pgprot_t parameter 2018-10-14 18:04:09 +11:00
pci_dn.c powerpc/pci: Separate SR-IOV Calls 2017-12-11 13:03:35 +11:00
pci_of_scan.c powerpc: Use device_type helpers to access the node type 2018-11-26 22:33:37 +11:00
pci-common.c powerpc updates for 5.1 2019-03-07 12:56:26 -08:00
pci-hotplug.c powerpc/pci: Unroll two pass loop when scanning bridges 2017-12-18 23:05:52 -06:00
pmc.c powerpc: change CONFIG_6xx to CONFIG_PPC_BOOK3S_32 2018-11-26 22:33:37 +11:00
ppc32.h
ppc_save_regs.S powerpc: move ASM_CONST and stringify_in_c() into asm-const.h 2018-07-30 22:48:16 +10:00
proc_powerpc.c powerpc: Use octal numbers for file permissions 2018-01-22 05:48:33 +11:00
process.c powerpc: regain entire stack space 2019-02-23 22:31:40 +11:00
prom_init_check.sh powerpc: Check prom_init for disallowed sections 2018-10-19 00:56:17 +11:00
prom_init.c powerpc/prom_init: Generate "phandle" instead of "linux, phandle" 2018-10-19 00:56:17 +11:00
prom_parse.c
prom.c powerpc: use memblock functions returning virtual address 2019-03-12 10:04:01 -07:00
ptrace32.c
ptrace.c powerpc/ptrace: Simplify vr_get/set() to avoid GCC warning 2019-02-22 00:10:14 +11:00
reloc_32.S
reloc_64.S
rtas_flash.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
rtas_pci.c
rtas-proc.c powerpc updates for 4.18 2018-06-07 10:23:33 -07:00
rtas-rtc.c powerpc: use time64_t in read_persistent_clock 2018-06-03 20:43:33 +10:00
rtas.c memblock: drop memblock_alloc_base() 2019-03-12 10:04:01 -07:00
rtasd.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
security.c powerpc/fsl: Update Spectre v2 reporting 2018-12-20 22:59:03 +11:00
setup_32.c powerpc updates for 5.1 2019-03-07 12:56:26 -08:00
setup_64.c treewide: add checks for the return value of memblock_alloc*() 2019-03-12 10:04:02 -07:00
setup-common.c treewide: add checks for the return value of memblock_alloc*() 2019-03-12 10:04:02 -07:00
setup.h powerpc/tau: Synchronize function prototypes and body 2018-05-25 12:04:43 +10:00
signal_32.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
signal_64.c powerpc/tm: Limit TM code inside PPC_TRANSACTIONAL_MEM 2019-01-11 23:45:00 +11:00
signal.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
signal.h powerpc/syscalls: signal_{32, 64} - switch to SYSCALL_DEFINE 2018-05-10 23:25:13 +10:00
smp-tbsync.c
smp.c powerpc: 'current_set' is now a table of task_struct pointers 2019-02-23 22:31:40 +11:00
stacktrace.c powerpc: Remove export of save_stack_trace_tsk_reliable() 2019-03-02 14:43:05 +11:00
suspend.c
swsusp_32.S powerpc: clean inclusions of asm/feature-fixups.h 2018-07-30 22:48:17 +10:00
swsusp_64.c
swsusp_asm64.S powerpc/64s/hash: Simplify slb_flush_and_rebolt() 2018-10-14 18:04:09 +11:00
swsusp_booke.S
swsusp.c
sys_ppc32.c powerpc/syscalls: kill ppc32_select() 2018-05-10 23:25:15 +10:00
syscalls.c powerpc/64: Make sys_switch_endian() traceable 2019-02-22 00:10:15 +11:00
sysfs.c powerpc: change CONFIG_6xx to CONFIG_PPC_BOOK3S_32 2018-11-26 22:33:37 +11:00
systbl_chk.sh powerpc: Make it clearer that systbl check errors are errors 2018-05-10 23:25:16 +10:00
systbl.S powerpc: remove nargs from __SYSCALL 2019-03-02 14:43:05 +11:00
tau_6xx.c powerpc/tau: Make some function static 2018-05-25 12:04:44 +10:00
time.c powerpc/kernel/time: Remove duplicate header 2019-01-30 23:42:31 +11:00
tm.S Merge branch 'fixes' into next 2018-10-09 16:51:05 +11:00
traps.c powerpc/64s: Include <asm/nmi.h> header file to fix a warning 2019-03-13 15:03:13 +11:00
udbg_16550.c
udbg.c powerpc: use a CONSOLE_LOGLEVEL_DEBUG macro 2019-01-14 20:39:27 +11:00
uprobes.c
vdso.c powerpc/vdso: don't clear PG_reserved 2019-03-05 21:07:18 -08:00
vecemu.c powerpc: Add a missing include header 2018-05-25 12:04:46 +10:00
vector.S powerpc: move ASM_CONST and stringify_in_c() into asm-const.h 2018-07-30 22:48:16 +10:00
vmlinux.lds.S powerpc/kconfig: define CONFIG_DATA_SHIFT and CONFIG_ETEXT_SHIFT 2019-02-23 21:04:32 +11:00
watchdog.c powerpc: NMI IPI make NMI IPIs fully sychronous 2018-07-24 22:03:14 +10:00