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731bd6a93a
linux/arch/x86/kernel
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Suresh Siddha 731bd6a93a x86, fpu: Check tsk_used_math() in kernel_fpu_end() for eager FPU 
For non-eager fpu mode, thread's fpu state is allocated during the first
fpu usage (in the context of device not available exception). This
(math_state_restore()) can be a blocking call and hence we enable
interrupts (which were originally disabled when the exception happened),
allocate memory and disable interrupts etc.

But the eager-fpu mode, call's the same math_state_restore() from
kernel_fpu_end(). The assumption being that tsk_used_math() is always
set for the eager-fpu mode and thus avoid the code path of enabling
interrupts, allocating fpu state using blocking call and disable
interrupts etc.

But the below issue was noticed by Maarten Baert, Nate Eldredge and
few others:

If a user process dumps core on an ecrypt fs while aesni-intel is loaded,
we get a BUG() in __find_get_block() complaining that it was called with
interrupts disabled; then all further accesses to our ecrypt fs hang
and we have to reboot.

The aesni-intel code (encrypting the core file that we are writing) needs
the FPU and quite properly wraps its code in kernel_fpu_{begin,end}(),
the latter of which calls math_state_restore(). So after kernel_fpu_end(),
interrupts may be disabled, which nobody seems to expect, and they stay
that way until we eventually get to __find_get_block() which barfs.

For eager fpu, most the time, tsk_used_math() is true. At few instances
during thread exit, signal return handling etc, tsk_used_math() might
be false.

In kernel_fpu_end(), for eager-fpu, call math_state_restore()
only if tsk_used_math() is set. Otherwise, don't bother. Kernel code
path which cleared tsk_used_math() knows what needs to be done
with the fpu state.

Reported-by: Maarten Baert <maarten-baert@hotmail.com>
Reported-by: Nate Eldredge <nate@thatsmathematics.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Suresh Siddha <sbsiddha@gmail.com>
Link: http://lkml.kernel.org/r/1391410583.3801.6.camel@europa
Cc: George Spelvin <linux@horizon.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-03-11 12:32:52 -07:00
..
acpi ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
apic Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-01-31 08:59:46 -08:00
cpu perf/x86: Fix event scheduling 2014-02-27 12:38:02 +01:00
kprobes Merge branch 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-09-04 08:42:44 -07:00
.gitignore
alternative.c lockdep, x86/alternatives: Drop ancient lockdep fixup message 2013-09-28 10:09:41 +02:00
amd_gart_64.c x86, mm: use pfn_range_is_mapped() with gart 2012-11-17 11:59:10 -08:00
amd_nb.c x86/AMD/NB: Fix amd_set_subcaches() parameter type 2014-01-25 08:50:09 +01:00
apb_timer.c intel_mid: Renamed *mrst* to *intel_mid* 2013-10-17 16:40:47 -07:00
aperture_64.c x86/mm/gart: Drop unnecessary check 2013-04-16 10:54:40 +02:00
apm_32.c x86, asmlinkage, apm: Make APM data structure used from assembler visible 2013-08-06 14:20:20 -07:00
asm-offsets_32.c x86: Get rid of ->hard_math and all the FPU asm fu 2013-06-06 14:32:04 -07:00
asm-offsets_64.c x86, gdt, hibernate: Store/load GDT for hibernate path. 2013-05-02 11:27:35 -07:00
asm-offsets.c sched, x86: Provide a per-cpu preempt_count implementation 2013-09-25 14:07:57 +02:00
audit_64.c
bootflag.c
check.c x86/mm: memblock: switch to use NUMA_NO_NODE 2014-01-21 16:19:47 -08:00
cpuid.c x86: delete __cpuinit usage from all x86 files 2013-07-14 19:36:56 -04:00
crash_dump_32.c
crash_dump_64.c
crash.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
devicetree.c Merge remote-tracking branch 'grant/devicetree/next' into for-next 2013-11-07 10:34:46 -06:00
doublefault.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
dumpstack_32.c dump_stack: unify debug information printed by show_regs() 2013-04-30 17:04:02 -07:00
dumpstack_64.c dump_stack: unify debug information printed by show_regs() 2013-04-30 17:04:02 -07:00
dumpstack.c x86/dumpstack: Fix printk_address for direct addresses 2013-11-12 21:06:06 +01:00
e820.c x86/mm: memblock: switch to use NUMA_NO_NODE 2014-01-21 16:19:47 -08:00
early_printk.c Merge branch 'x86-intel-mid-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-11-12 11:12:22 +09:00
early-quirks.c x86/early quirk: use gen6 stolen detection for VLV 2013-11-14 09:32:11 +01:00
entry_32.S ftrace/x86: Load ftrace_ops in parameter not the variable holding it 2014-01-09 13:24:29 -08:00
entry_64.S ftrace/x86: Load ftrace_ops in parameter not the variable holding it 2014-01-09 13:24:29 -08:00
ftrace.c ftrace/x86: Use breakpoints for converting function graph caller 2014-02-11 20:19:44 -05:00
head32.c intel_mid: Renamed *mrst* to *intel_mid* 2013-10-17 16:40:47 -07:00
head64.c x86, trace: Register exception handler to trace IDT 2013-11-08 14:15:45 -08:00
head_32.S x86: fix compile error due to X86_TRAP_NMI use in asm files 2014-03-07 18:58:40 -08:00
head_64.S x86: fix compile error due to X86_TRAP_NMI use in asm files 2014-03-07 18:58:40 -08:00
head.c x86: Make sure we can boot in the case the BDA contains pure garbage 2013-02-27 13:38:57 -08:00
hpet.c x86, hpet: Introduce x86_msi_ops.setup_hpet_msi 2013-01-28 10:48:30 +01:00
hw_breakpoint.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
i386_ksyms_32.c sched, x86: Optimize the preempt_schedule() call 2013-09-25 14:23:07 +02:00
i387.c x86, fpu: Check tsk_used_math() in kernel_fpu_end() for eager FPU 2014-03-11 12:32:52 -07:00
i8237.c
i8253.c
i8259.c x86/irq: Correct comment about i8259 initialization 2013-09-04 07:46:04 +02:00
io_delay.c
ioport.c x86: get rid of pt_regs argument of iopl(2) 2013-02-03 18:16:24 -05:00
iosf_mbi.c arch: x86: New MailBox support driver for Intel SOC's 2014-01-08 14:36:29 -08:00
irq_32.c Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-11-12 10:20:12 +09:00
irq_64.c irq: Consolidate do_softirq() arch overriden implementations 2013-10-01 12:53:25 +02:00
irq_work.c x86, asmlinkage: Make all interrupt handlers asmlinkage / __visible 2013-08-06 14:18:23 -07:00
irq.c x86, cpu hotplug: Fix stack frame warning in check_irq_vectors_for_cpu_disable() 2014-01-30 16:40:13 -08:00
irqinit.c x86/irq: Fix do_IRQ() interrupt warning for cpu hotplug retriggered irqs 2014-01-12 13:13:02 +01:00
jump_label.c x86/jump_label: expect default_nop if static_key gets enabled on boot-up 2013-10-19 19:45:35 -04:00
kdebugfs.c
kgdb.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
ksysfs.c x86: ksysfs.c build fix 2014-01-03 14:37:13 +00:00
kvm.c Second batch of KVM updates. Some minor x86 fixes, 2014-01-31 08:37:32 -08:00
kvmclock.c pvclock: detect watchdog reset at pvclock read 2013-11-06 09:48:43 +02:00
ldt.c
machine_kexec_32.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
machine_kexec_64.c x86, kaslr: export offset in VMCOREINFO ELF notes 2014-02-25 16:57:47 -08:00
Makefile Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-01-20 12:09:31 -08:00
mmconf-fam10h_64.c x86: delete __cpuinit usage from all x86 files 2013-07-14 19:36:56 -04:00
module.c mm/arch: use NUMA_NO_NODE 2013-11-13 12:09:05 +09:00
mpparse.c
msr.c x86, msr: Use file_inode(), not f_mapping->host 2013-10-08 12:01:29 -07:00
nmi_selftest.c
nmi.c perf/x86: Fix NMI measurements 2013-10-29 12:01:20 +01:00
paravirt_patch_32.c
paravirt_patch_64.c
paravirt-spinlocks.c x86, ticketlock: Add slowpath logic 2013-08-09 07:54:00 -07:00
paravirt.c x86, paravirt: Remove duplicate definition for DEF_NATIVE 2013-09-04 09:46:43 -07:00
pci-calgary_64.c
pci-dma.c x86: dma-mapping: fix GFP_ATOMIC macro usage 2014-02-11 09:40:15 +01:00
pci-iommu_table.c
pci-nommu.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
pci-swiotlb.c
pcspeaker.c
perf_regs.c perf: Fix off by one test in perf_reg_value() 2012-09-19 17:08:40 +02:00
preempt.S sched, x86: Optimize the preempt_schedule() call 2013-09-25 14:23:07 +02:00
probe_roms.c
process_32.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
process_64.c Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-11-14 16:55:56 +09:00
process.c sched, idle: Fix the idle polling state logic 2013-09-25 13:53:10 +02:00
ptrace.c ptrace/x86: cleanup ptrace_set_debugreg() 2013-07-09 10:33:26 -07:00
pvclock.c hung_task: add method to reset detector 2013-11-06 09:49:02 +02:00
quirks.c x86/quirks: Add workaround for AMD F16h Erratum792 2014-01-25 08:44:19 +01:00
reboot_fixups_32.c
reboot.c x86/apic, doc: Justification for disabling IO APIC before Local APIC 2013-12-04 19:33:21 -08:00
relocate_kernel_32.S x86, asm, cleanup: Replace open-coded control register values with symbolic 2013-06-25 16:26:06 -07:00
relocate_kernel_64.S x86, reloc: Use xorl instead of xorq in relocate_kernel_64.S 2013-06-20 21:30:04 -07:00
resource.c
rtc.c Merge branch 'x86-intel-mid-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-11-12 11:12:22 +09:00
setup_percpu.c
setup.c x86/efi: Quirk out SGI UV 2014-03-04 23:43:33 +00:00
signal.c Merge branch 'x86-smap-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-09-04 11:08:32 -07:00
smp.c x86, asmlinkage: Make all interrupt handlers asmlinkage / __visible 2013-08-06 14:18:23 -07:00
smpboot.c Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-01-20 12:11:41 -08:00
stacktrace.c
step.c ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL 2013-01-22 10:08:00 -08:00
sys_x86_64.c x86 get_unmapped_area: Access mmap_legacy_base through mm_struct member 2013-08-22 10:19:35 -07:00
syscall_32.c x86, asmlinkage: Make syscall tables visible 2013-08-06 14:20:18 -07:00
syscall_64.c x86, asmlinkage: Make syscall tables visible 2013-08-06 14:20:18 -07:00
sysfb_efi.c x86: sysfb: move EFI quirks from efifb to sysfb 2013-08-02 16:17:47 -07:00
sysfb_simplefb.c x86/simplefb: Mark framebuffer mem-resources as IORESOURCE_BUSY to avoid bootup warning 2013-10-03 07:51:11 +02:00
sysfb.c x86: sysfb: move EFI quirks from efifb to sysfb 2013-08-02 16:17:47 -07:00
tboot.c x86 / tboot / ACPI: Fail extended mode reduced hardware sleep 2013-07-31 14:25:51 +02:00
tce_64.c
test_nx.c
test_rodata.c
time.c
tls.c make SYSCALL_DEFINE<n>-generated wrappers do asmlinkage_protect 2013-03-03 22:58:33 -05:00
tls.h
topology.c hotplug, powerpc, x86: Remove cpu_hotplug_driver_lock() 2013-09-30 19:55:51 +02:00
trace_clock.c tracing,x86: Add a TSC trace_clock 2012-11-13 15:48:27 -05:00
tracepoint.c x86: Make sure IDT is page aligned 2013-07-16 15:14:48 -07:00
traps.c x86/traps: Clean up error exception handler definitions 2013-12-12 14:46:42 +01:00
tsc_msr.c x86: tsc: Add missing Baytrail frequency to the table 2014-02-19 17:12:24 +01:00
tsc_sync.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
tsc.c x86, tsc: Fallback to normal calibration if fast MSR calibration fails 2014-02-19 17:12:24 +01:00
uprobes.c uretprobes/x86: Hijack return address 2013-04-13 15:31:55 +02:00
verify_cpu.S
vm86_32.c x86, vm86: fix VM86 syscalls: use SYSCALL_DEFINEx(...) 2013-05-02 20:36:32 -04:00
vmlinux.lds.S x86: intel-mid: Add section for sfi device table 2013-10-17 16:41:04 -07:00
vsmp_64.c x86, asmlinkage, paravirt: Make paravirt thunks global 2014-01-29 22:17:17 -08:00
vsyscall_64.c x86: delete __cpuinit usage from all x86 files 2013-07-14 19:36:56 -04:00
vsyscall_emu_64.S
vsyscall_trace.h
x86_init.c PCI: Drop "irq" param from *_restore_msi_irqs() 2013-12-13 08:44:30 -07:00
x8664_ksyms_64.c sched, x86: Optimize the preempt_schedule() call 2013-09-25 14:23:07 +02:00
xsave.c x86, xsave: Support eager-only xsave features, add MPX support 2013-12-06 17:17:42 -08:00