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f2b375756c
linux/arch/x86/kernel
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Andy Lutomirski f2b375756c x86/entry: Vastly simplify SYSENTER TF (single-step) handling 
Due to a blatant design error, SYSENTER doesn't clear TF (single-step).

As a result, if a user does SYSENTER with TF set, we will single-step
through the kernel until something clears TF.  There is absolutely
nothing we can do to prevent this short of turning off SYSENTER [1].

Simplify the handling considerably with two changes:

  1. We already sanitize EFLAGS in SYSENTER to clear NT and AC.  We can
     add TF to that list of flags to sanitize with no overhead whatsoever.

  2. Teach do_debug() to ignore single-step traps in the SYSENTER prologue.

That's all we need to do.

Don't get too excited -- our handling is still buggy on 32-bit
kernels.  There's nothing wrong with the SYSENTER code itself, but
the #DB prologue has a clever fixup for traps on the very first
instruction of entry_SYSENTER_32, and the fixup doesn't work quite
correctly.  The next two patches will fix that.

[1] We could probably prevent it by forcing BTF on at all times and
    making sure we clear TF before any branches in the SYSENTER
    code.  Needless to say, this is a bad idea.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.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: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a30d2ea06fe4b621fe6a9ef911b02c0f38feb6f2.1457578375.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-10 09:48:13 +01:00
..
acpi PM / sleep / x86: Fix crash on graph trace through x86 suspend 2016-03-03 02:28:28 +01:00
apic Merge branch 'x86/urgent' into x86/asm, to pick up fixes 2016-02-18 09:28:03 +01:00
cpu x86/entry/32: Introduce and use X86_BUG_ESPFIX instead of paravirt_enabled 2016-03-08 14:16:44 +01:00
fpu x86/fpu: Disable AVX when eagerfpu is off 2016-01-12 11:51:21 +01:00
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 x86/alternatives: Make optimize_nops() interrupt safe and synced 2015-09-03 21:27:47 +02:00
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/syscalls: Add syscall entry qualifiers 2016-01-29 09:46:38 +01:00
asm-offsets_64.c x86/syscalls: Add syscall entry qualifiers 2016-01-29 09:46:38 +01:00
asm-offsets.c x86/asm-offsets: Remove PARAVIRT_enabled 2016-03-08 14:16:44 +01:00
audit_64.c
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 new helpers: no_seek_end_llseek{,_size}() 2015-12-23 10:41:31 -05:00
crash_dump_32.c
crash_dump_64.c
crash.c perf, x86: Stop Intel PT before kdump starts 2015-11-23 09:58:26 +01:00
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
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 x86/cpufeature: Carve out X86_FEATURE_* 2016-01-30 11:22:17 +01:00
early_printk.c x86/early_printk: Set __iomem address space for IO 2015-10-13 21:45:56 +02:00
early-quirks.c Linux 4.4-rc2 2015-11-23 09:04:05 +01:00
espfix_64.c Merge branch 'x86/urgent' into x86/asm, before applying dependent patches 2015-07-31 10:23:35 +02:00
ftrace.c x86/ftrace, x86/asm: Kill ftrace_caller_end label 2016-02-17 08:47:22 +01:00
head32.c
head64.c x86/platform/intel-mid: Enable 64-bit build 2016-01-19 08:39:56 +01:00
head_32.S x86/cpufeature: Carve out X86_FEATURE_* 2016-01-30 11:22:17 +01:00
head_64.S x86/asm: Remove unused L3_PAGE_OFFSET 2016-01-27 11:37:49 +01:00
head.c
hpet.c x86/cpufeature: Carve out X86_FEATURE_* 2016-01-30 11:22:17 +01:00
hw_breakpoint.c x86/cpufeature: Remove unused and seldomly used cpu_has_xx macros 2015-12-19 11:49:55 +01:00
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/irq: Probe for PIC presence before allocating descs for legacy IRQs 2015-11-07 10:37:37 +01:00
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 genirq: Remove irq argument from irq flow handlers 2015-09-16 15:47:51 +02:00
irq_64.c x86/irq: Drop unlikely before IS_ERR_OR_NULL 2015-10-01 11:08:56 +02:00
irq_work.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
irq.c x86/irq: Call irq_force_move_complete with irq descriptor 2016-01-15 13:44:01 +01:00
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 x86/kgdb: Replace bool_int_array[NR_CPUS] with bitmap 2015-09-28 10:13:31 +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 x86/vdso: Remove pvclock fixmap machinery 2015-12-11 08:56:03 +01:00
ldt.c x86/ldt: Fix small LDT allocation for Xen 2015-09-14 12:10:50 +02:00
livepatch.c livepatch: Cleanup module page permission changes 2015-12-04 22:51:07 +01:00
machine_kexec_32.c
machine_kexec_64.c kexec: move some memembers and definitions within the scope of CONFIG_KEXEC_FILE 2016-01-20 17:09:18 -08:00
Makefile kexec: split kexec_load syscall from kexec core code 2015-09-10 13:29:01 -07:00
mcount_64.S x86/ftrace, x86/asm: Kill ftrace_caller_end label 2016-02-17 08:47:22 +01:00
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 x86/cpufeature: Carve out X86_FEATURE_* 2016-01-30 11:22:17 +01:00
nmi_selftest.c
nmi.c x86/nmi: Save regs in crash dump on external NMI 2015-12-19 11:07:01 +01:00
paravirt_patch_32.c x86/paravirt: Remove the unused irq_enable_sysexit pv op 2015-11-23 10:48:16 +01:00
paravirt_patch_64.c x86/entry, x86/paravirt: Remove the unused usergs_sysret32 PV op 2015-11-23 10:48:16 +01:00
paravirt-spinlocks.c locking/pvqspinlock: Rename QUEUED_SPINLOCK to QUEUED_SPINLOCKS 2015-05-11 09:52:09 +02:00
paravirt.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-01-11 16:26:03 -08:00
pci-calgary_64.c x86/platform/calgary: Constify cal_chipset_ops structures 2015-11-29 08:50:58 +01:00
pci-dma.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
pci-iommu_table.c
pci-nommu.c
pci-swiotlb.c x86/mm/64: Enable SWIOTLB if system has SRAT memory regions above MAX_DMA32_PFN 2015-12-06 12:46:31 +01:00
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: skip module loading when no type-12 2015-11-30 09:10:33 -08:00
probe_roms.c
process_32.c sched/core, sched/x86: Kill thread_info::saved_preempt_count 2015-10-06 17:08:18 +02:00
process_64.c x86/LDT: Print the real LDT base address 2015-12-29 12:34:38 +01:00
process.c x86/vm86: Set thread.vm86 to NULL on fork/clone 2015-10-31 09:50:25 +01:00
ptrace.c arch/x86/kernel/ptrace.c: Remove unused arg_offs_table 2015-12-29 11:35:34 +01:00
pvclock.c x86/vdso: Remove pvclock fixmap machinery 2015-12-11 08:56:03 +01:00
quirks.c timers/x86/hpet: Type adjustments 2015-10-21 11:17:32 +02:00
reboot_fixups_32.c
reboot.c x86/reboot/quirks: Add iMac10,1 to pci_reboot_dmi_table[] 2016-01-12 12:27:36 +01:00
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 x86/paravirt: Prevent rtc_cmos platform device init on PV guests 2015-12-19 21:35:13 +01:00
setup_percpu.c
setup.c Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-01-11 17:16:01 -08:00
signal_compat.c x86/compat: Move copy_siginfo_*_user32() to signal_compat.c 2015-07-06 15:28:55 +02:00
signal.c x86/signal/64: Re-add support for SS in the 64-bit signal context 2016-02-17 08:32:11 +01:00
smp.c x86/smp: Remove single IPI wrapper 2015-11-05 13:07:54 +01:00
smpboot.c x86/cpufeature: Remove unused and seldomly used cpu_has_xx macros 2015-12-19 11:49:55 +01:00
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
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/entry: Vastly simplify SYSENTER TF (single-step) handling 2016-03-10 09:48:13 +01:00
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 x86/tsc: Remove unused tsc_pre_init() hook 2015-11-19 11:03:13 +01:00
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 x86/cpufeature: Carve out X86_FEATURE_* 2016-01-30 11:22:17 +01:00
vm86_32.c x86/cpufeature: Replace the old static_cpu_has() with safe variant 2016-01-30 11:22:18 +01:00
vmlinux.lds.S x86/alternatives: Add an auxilary section 2016-01-30 11:22:20 +01:00
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 x86/tsc: Remove unused tsc_pre_init() hook 2015-11-19 11:03:13 +01:00
x8664_ksyms_64.c preempt: Use preempt_schedule_context() as the official tracing preemption point 2015-06-07 15:57:42 +02:00