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65ac2e9baa
linux/arch/x86/kernel
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Dave Hansen 65ac2e9baa x86/fpu: Correct and check XSAVE xstate size calculations 
Note: our xsaves support is currently broken and disabled.  This
patch does not fix it, but it is an incremental improvement.

This might be useful to someone backporting the entire set of
XSAVES patches at some point, but it should not be backported
alone.

Ingo said he wanted something like this (bullets 2 and 3):

  http://lkml.kernel.org/r/20150808091508.GB32641@gmail.com

There are currently two xsave buffer formats: standard and
compacted.  The standard format is waht 'XSAVE' and 'XSAVEOPT'
produce while 'XSAVES' and 'XSAVEC' produce a compacted-formet
buffer.  (The kernel never uses XSAVEC)

But, the XSAVES buffer *ALSO* contains "system state components"
which are never saved by a plain XSAVE.  So, XSAVES has two
things that might make its buffer differently-sized from an
XSAVE-produced one.

The current code assumes that an XSAVES buffer's size is simply
the sum of the sizes of the (user) states which are supported.
This seems to work in most cases, but it is not consistent with
what the SDM says, and it breaks if we 'align' a component in
the buffer.  The calculation is also unnecessary work since the
CPU *tells* us the size of the buffer directly.

This patch just reads the size of the buffer right out of the
CPUID leaf instead of trying to derive it.

But, blindly trusting the CPU like this is dangerous.  We add
a verification pass in do_extra_xstate_size_checks() to ensure
that the size we calculate matches with what we see from the
hardware.  When it comes down to it, we trust but verify the
CPU.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: dave@sr71.net
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20150902233130.234FE1EC@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-09-14 12:22:01 +02:00
..
acpi Power management and ACPI material for v4.3-rc1 2015-09-01 19:45:46 -07:00
apic Merge branch 'nmi' of git://ftp.arm.linux.org.uk/~rmk/linux-arm 2015-09-08 12:28:10 -07:00
cpu watchdog: rename watchdog_suspend() and watchdog_resume() 2015-09-04 16:54:41 -07:00
fpu x86/fpu: Correct and check XSAVE xstate size calculations 2015-09-14 12:22:01 +02:00
kprobes Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-04-14 14:37:47 -07:00
.gitignore
alternative.c Merge branch 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-06-22 17:59:09 -07:00
amd_gart_64.c
amd_nb.c x86/gart: Check for GART support before accessing GART registers 2015-05-06 11:15:53 +02:00
apb_timer.c x86/asm/tsc: Rename native_read_tsc() to rdtsc() 2015-07-06 15:23:28 +02:00
aperture_64.c x86/gart: Check for GART support before accessing GART registers 2015-05-06 11:15:53 +02:00
apm_32.c apm32: Fix cputime == jiffies assumption 2015-07-29 15:44:58 +02:00
asm-offsets_32.c x86: Remove unused TI_cpu 2015-05-05 20:48:02 +02:00
asm-offsets_64.c x86/asm/entry: (Re-)rename __NR_entry_INT80_compat_max to __NR_syscall_compat_max 2015-06-08 23:43:38 +02:00
asm-offsets.c x86: Merge common 32-bit values in asm-offsets.c 2015-05-05 20:48:02 +02:00
audit_64.c x86: hook up execveat system call 2014-12-13 12:42:51 -08:00
bootflag.c x86: don't use module_init for non-modular core bootflag code 2015-06-16 14:12:34 -04:00
check.c Linux 4.2-rc8 2015-08-25 09:59:19 +02:00
cpuid.c x86: Drop bogus __ref / __refdata annotations 2015-07-20 18:57:20 +02:00
crash_dump_32.c
crash_dump_64.c
crash.c x86/mm: Decouple <linux/vmalloc.h> from <asm/io.h> 2015-06-03 12:02:00 +02:00
devicetree.c Replace module_init with equivalent device_initcall in non modules. 2015-07-02 10:30:48 -07:00
doublefault.c
dumpstack_32.c Merge branch 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-04-13 13:23:34 -07:00
dumpstack_64.c x86/kernel: Use kstack_end() in dumpstack_64.c 2015-02-23 18:37:13 +01:00
dumpstack.c Merge branch 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-04-13 13:23:34 -07:00
e820.c The libnvdimm sub-system introduces, in addition to the libnvdimm-core, 2015-06-29 10:34:42 -07:00
early_printk.c x86/earlyprintk: Allow early_printk() to use console style parameters like '115200n8' 2015-07-06 17:33:47 +02:00
early-quirks.c Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux 2015-06-26 13:18:51 -07:00
espfix_64.c Merge branch 'x86/urgent' into x86/asm, before applying dependent patches 2015-07-31 10:23:35 +02:00
ftrace.c module: remove mod arg from module_free, rename module_memfree(). 2015-01-20 11:38:33 +10:30
head32.c x86: Store a per-cpu shadow copy of CR4 2015-02-04 12:10:42 +01:00
head64.c x86/kasan: Fix KASAN shadow region page tables 2015-07-06 14:53:13 +02:00
head_32.S Merge branch 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-06-22 17:59:09 -07:00
head_64.S x86/kasan: Fix KASAN shadow region page tables 2015-07-06 14:53:13 +02:00
head.c
hpet.c Merge branch 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 15:42:28 -07:00
hw_breakpoint.c perf/x86/hw_breakpoints: Fix check for kernel-space breakpoints 2015-08-04 10:16:55 +02:00
i386_ksyms_32.c preempt: Use preempt_schedule_context() as the official tracing preemption point 2015-06-07 15:57:42 +02:00
i8237.c
i8253.c clockevents/drivers/i8253: Migrate to new 'set-state' interface 2015-08-10 11:40:30 +02:00
i8259.c x86/asm/entry/irq: Clean up IRQn_VECTOR macros 2015-05-10 12:34:28 +02:00
io_delay.c
ioport.c x86/asm/entry: Rename 'init_tss' to 'cpu_tss' 2015-03-06 08:32:58 +01:00
irq_32.c x86/irq: Do not dereference irq descriptor before checking it 2015-08-28 10:30:15 +02:00
irq_64.c x86/irq: Store irq descriptor in vector array 2015-08-06 00:14:59 +02:00
irq_work.c x86: Consolidate irq entering inlines 2015-05-15 16:04:49 +02:00
irq.c Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 15:20:51 -07:00
irqinit.c x86/irq: Store irq descriptor in vector array 2015-08-06 00:14:59 +02:00
jump_label.c jump_label: Rename JUMP_LABEL_{EN,DIS}ABLE to JUMP_LABEL_{JMP,NOP} 2015-08-03 11:34:12 +02:00
kdebugfs.c
kexec-bzimage64.c Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2015-09-08 12:41:25 -07:00
kgdb.c Linux 4.0-rc7 2015-04-08 09:01:54 +02:00
ksysfs.c
kvm.c The bulk of the changes here is for x86. And for once it's not 2015-06-24 09:36:49 -07:00
kvmclock.c kexec: split kexec_load syscall from kexec core code 2015-09-10 13:29:01 -07:00
ldt.c x86/ldt: Make modify_ldt synchronous 2015-07-31 10:23:23 +02:00
livepatch.c livepatch: kernel: add support for live patching 2014-12-22 15:40:49 +01:00
machine_kexec_32.c x86, irq: Move IOAPIC related declarations from hw_irq.h into io_apic.h 2014-12-16 14:08:17 +01:00
machine_kexec_64.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching 2015-06-23 14:07:26 -07:00
Makefile kexec: split kexec_load syscall from kexec core code 2015-09-10 13:29:01 -07:00
mcount_64.S
mmconf-fam10h_64.c
module.c x86/mm/KASLR: Propagate KASLR status to kernel proper 2015-04-03 15:26:15 +02:00
mpparse.c x86: Cleanup irq_domain ops 2015-04-24 15:36:55 +02:00
msr.c
nmi_selftest.c
nmi.c Merge branch 'x86/urgent' into x86/asm, before applying dependent patches 2015-07-31 10:23:35 +02:00
paravirt_patch_32.c x86/asm/tsc, x86/paravirt: Remove read_tsc() and read_tscp() paravirt hooks 2015-07-06 15:23:26 +02:00
paravirt_patch_64.c Merge branch 'locking/core' into x86/core, to prepare for dependent patch 2015-06-03 10:07:35 +02:00
paravirt-spinlocks.c locking/pvqspinlock: Rename QUEUED_SPINLOCK to QUEUED_SPINLOCKS 2015-05-11 09:52:09 +02:00
paravirt.c x86/asm/tsc, x86/paravirt: Remove read_tsc() and read_tscp() paravirt hooks 2015-07-06 15:23:26 +02:00
pci-calgary_64.c
pci-dma.c dma-mapping: consolidate dma_set_mask 2015-09-10 13:29:01 -07:00
pci-iommu_table.c
pci-nommu.c
pci-swiotlb.c x86/swiotlb: Try coherent allocations with __GFP_NOWARN 2015-06-11 08:28:38 +02:00
pcspeaker.c
perf_regs.c perf/x86/64: Report regs_user->ax too in get_regs_user() 2015-04-11 13:08:53 +02:00
pmem.c libnvdimm, e820: make CONFIG_X86_PMEM_LEGACY a tristate option 2015-08-19 00:34:34 -04:00
probe_roms.c
process_32.c x86/vm86: Clean up vm86.h includes 2015-07-31 13:31:10 +02:00
process_64.c x86/ldt: Make modify_ldt() optional 2015-07-31 13:30:45 +02:00
process.c Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 08:40:25 -07:00
ptrace.c x86/entry: Move C entry and exit code to arch/x86/entry/common.c 2015-07-07 10:59:05 +02:00
pvclock.c x86: pvclock: Really remove the sched notifier for cross-cpu migrations 2015-04-27 15:49:30 +02:00
quirks.c
reboot_fixups_32.c
reboot.c kexec: split kexec_load syscall from kexec core code 2015-09-10 13:29:01 -07:00
relocate_kernel_32.S x86/asm: Optimize unnecessarily wide TEST instructions 2015-03-07 11:12:43 +01:00
relocate_kernel_64.S x86/asm: Replace "MOVQ $imm, %reg" with MOVL 2015-04-01 13:17:39 +02:00
resource.c
rtc.c kernel.h: remove ancient __FUNCTION__ hack 2015-02-12 18:54:13 -08:00
setup_percpu.c
setup.c kexec: split kexec_load syscall from kexec core code 2015-09-10 13:29:01 -07:00
signal_compat.c x86/compat: Move copy_siginfo_*_user32() to signal_compat.c 2015-07-06 15:28:55 +02:00
signal.c Merge branch 'x86/urgent' into x86/asm to fix up conflicts and to pick up fixes 2015-08-18 09:39:47 +02:00
smp.c x86/mce: Clear Local MCE opt-in before kexec 2015-08-13 10:12:52 +02:00
smpboot.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 09:33:26 -07:00
stacktrace.c
step.c Merge branch 'x86/urgent' into x86/asm to fix up conflicts and to pick up fixes 2015-08-18 09:39:47 +02:00
sys_x86_64.c x86/mm: Improve AMD Bulldozer ASLR workaround 2015-03-31 10:01:17 +02:00
sysfb_efi.c
sysfb_simplefb.c
sysfb.c
tboot.c
tce_64.c
test_nx.c
test_rodata.c treewide: Fix typo in printk messages 2015-03-06 23:05:39 +01:00
time.c x86/asm/entry: Change all 'user_mode_vm()' calls to 'user_mode()' 2015-03-23 11:14:17 +01:00
tls.c x86, tls: Interpret an all-zero struct user_desc as "no segment" 2015-01-22 21:45:07 +01:00
tls.h
topology.c x86: Drop bogus __ref / __refdata annotations 2015-07-20 18:57:20 +02:00
trace_clock.c x86/asm/tsc: Add rdtsc_ordered() and use it in trivial call sites 2015-07-06 15:23:29 +02:00
tracepoint.c
traps.c x86/fpu/mpx: Rework MPX 'xstate' types 2015-09-14 12:22:00 +02:00
tsc_msr.c
tsc_sync.c x86/asm/tsc/sync: Use rdtsc_ordered() in check_tsc_warp() and drop extra barriers 2015-07-06 15:23:29 +02:00
tsc.c Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-03 15:46:07 -07:00
uprobes.c uprobes/x86: Make arch_uretprobe_is_alive(RP_CHECK_CALL) more clever 2015-07-31 10:38:06 +02:00
verify_cpu.S
vm86_32.c x86/vm86: Rename vm86->v86flags and v86mask 2015-07-31 13:31:11 +02:00
vmlinux.lds.S kexec: split kexec_load syscall from kexec core code 2015-09-10 13:29:01 -07:00
vsmp_64.c x86: replace __init_or_module with __init in non-modular vsmp_64.c 2015-06-16 14:12:41 -04:00
x86_init.c PCI changes for the v4.2 merge window: 2015-06-23 13:41:24 -07:00
x8664_ksyms_64.c preempt: Use preempt_schedule_context() as the official tracing preemption point 2015-06-07 15:57:42 +02:00