linux-toradex.git/arch/x86/include/asm, branch v3.14.37

x86/fpu: Drop_fpu() should not assume that tsk equals current

2015-03-26T14:06:58+00:00

commit f4c3686386393c120710dd34df2a74183ab805fd upstream.

drop_fpu() does clear_used_math() and usually this is correct
because tsk == current.

However switch_fpu_finish()->restore_fpu_checking() is called before
__switch_to() updates the "current_task" variable. If it fails,
we will wrongly clear the PF_USED_MATH flag of the previous task.

So use clear_stopped_child_used_math() instead.

Signed-off-by: Oleg Nesterov 
Signed-off-by: Borislav Petkov 
Reviewed-by: Rik van Riel 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Dave Hansen 
Cc: Fenghua Yu 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Pekka Riikonen 
Cc: Quentin Casasnovas 
Cc: Suresh Siddha 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20150309171041.GB11388@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

x86, tls: Interpret an all-zero struct user_desc as "no segment"

2015-01-30T01:40:49+00:00

commit 3669ef9fa7d35f573ec9c0e0341b29251c2734a7 upstream.

The Witcher 2 did something like this to allocate a TLS segment index:

        struct user_desc u_info;
        bzero(&u_info, sizeof(u_info));
        u_info.entry_number = (uint32_t)-1;

        syscall(SYS_set_thread_area, &u_info);

Strictly speaking, this code was never correct.  It should have set
read_exec_only and seg_not_present to 1 to indicate that it wanted
to find a free slot without putting anything there, or it should
have put something sensible in the TLS slot if it wanted to allocate
a TLS entry for real.  The actual effect of this code was to
allocate a bogus segment that could be used to exploit espfix.

The set_thread_area hardening patches changed the behavior, causing
set_thread_area to return -EINVAL and crashing the game.

This changes set_thread_area to interpret this as a request to find
a free slot and to leave it empty, which isn't *quite* what the game
expects but should be close enough to keep it working.  In
particular, using the code above to allocate two segments will
allocate the same segment both times.

According to FrostbittenKing on Github, this fixes The Witcher 2.

If this somehow still causes problems, we could instead allocate
a limit==0 32-bit data segment, but that seems rather ugly to me.

Fixes: 41bdc78544b8 x86/tls: Validate TLS entries to protect espfix
Signed-off-by: Andy Lutomirski 
Cc: torvalds@linux-foundation.org
Link: http://lkml.kernel.org/r/0cb251abe1ff0958b8e468a9a9a905b80ae3a746.1421954363.git.luto@amacapital.net
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

x86, tls, ldt: Stop checking lm in LDT_empty

2015-01-30T01:40:49+00:00

commit e30ab185c490e9a9381385529e0fd32f0a399495 upstream.

32-bit programs don't have an lm bit in their ABI, so they can't
reliably cause LDT_empty to return true without resorting to memset.
They shouldn't need to do this.

This should fix a longstanding, if minor, issue in all 64-bit kernels
as well as a potential regression in the TLS hardening code.

Fixes: 41bdc78544b8 x86/tls: Validate TLS entries to protect espfix
Signed-off-by: Andy Lutomirski 
Cc: torvalds@linux-foundation.org
Link: http://lkml.kernel.org/r/72a059de55e86ad5e2935c80aa91880ddf19d07c.1421954363.git.luto@amacapital.net
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

x86, vdso: Use asm volatile in __getcpu

2015-01-16T14:59:31+00:00

commit 1ddf0b1b11aa8a90cef6706e935fc31c75c406ba upstream.

In Linux 3.18 and below, GCC hoists the lsl instructions in the
pvclock code all the way to the beginning of __vdso_clock_gettime,
slowing the non-paravirt case significantly.  For unknown reasons,
presumably related to the removal of a branch, the performance issue
is gone as of

e76b027e6408 x86,vdso: Use LSL unconditionally for vgetcpu

but I don't trust GCC enough to expect the problem to stay fixed.

There should be no correctness issue, because the __getcpu calls in
__vdso_vlock_gettime were never necessary in the first place.

Note to stable maintainers: In 3.18 and below, depending on
configuration, gcc 4.9.2 generates code like this:

     9c3:       44 0f 03 e8             lsl    %ax,%r13d
     9c7:       45 89 eb                mov    %r13d,%r11d
     9ca:       0f 03 d8                lsl    %ax,%ebx

This patch won't apply as is to any released kernel, but I'll send a
trivial backported version if needed.

[
 Backported by Andy Lutomirski.  Should apply to all affected
 versions.  This fixes a functionality bug as well as a performance
 bug: buggy kernels can infinite loop in __vdso_clock_gettime on
 affected compilers.  See, for exammple:

 https://bugzilla.redhat.com/show_bug.cgi?id=1178975
]

Fixes: 51c19b4f5927 x86: vdso: pvclock gettime support
Cc: Marcelo Tosatti 
Acked-by: Paolo Bonzini 
Signed-off-by: Andy Lutomirski 
Signed-off-by: Greg Kroah-Hartman

x86: kvm: use alternatives for VMCALL vs. VMMCALL if kernel text is read-only

2014-12-06T23:55:40+00:00

commit c1118b3602c2329671ad5ec8bdf8e374323d6343 upstream.

On x86_64, kernel text mappings are mapped read-only with CONFIG_DEBUG_RODATA.
In that case, KVM will fail to patch VMCALL instructions to VMMCALL
as required on AMD processors.

The failure mode is currently a divide-by-zero exception, which obviously
is a KVM bug that has to be fixed.  However, picking the right instruction
between VMCALL and VMMCALL will be faster and will help if you cannot upgrade
the hypervisor.

Reported-by: Chris Webb 
Tested-by: Chris Webb 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: x86@kernel.org
Acked-by: Borislav Petkov 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Chris J Arges 
Signed-off-by: Greg Kroah-Hartman

uprobes, x86: Fix _TIF_UPROBE vs _TIF_NOTIFY_RESUME

2014-12-06T23:55:33+00:00

commit 82975bc6a6df743b9a01810fb32cb65d0ec5d60b upstream.

x86 call do_notify_resume on paranoid returns if TIF_UPROBE is set but
not on non-paranoid returns.  I suspect that this is a mistake and that
the code only works because int3 is paranoid.

Setting _TIF_NOTIFY_RESUME in the uprobe code was probably a workaround
for the x86 bug.  With that bug fixed, we can remove _TIF_NOTIFY_RESUME
from the uprobes code.

Reported-by: Oleg Nesterov 
Acked-by: Srikar Dronamraju 
Acked-by: Borislav Petkov 
Signed-off-by: Andy Lutomirski 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

x86_64, traps: Stop using IST for #SS

2014-12-06T23:55:33+00:00

commit 6f442be2fb22be02cafa606f1769fa1e6f894441 upstream.

On a 32-bit kernel, this has no effect, since there are no IST stacks.

On a 64-bit kernel, #SS can only happen in user code, on a failed iret
to user space, a canonical violation on access via RSP or RBP, or a
genuine stack segment violation in 32-bit kernel code.  The first two
cases don't need IST, and the latter two cases are unlikely fatal bugs,
and promoting them to double faults would be fine.

This fixes a bug in which the espfix64 code mishandles a stack segment
violation.

This saves 4k of memory per CPU and a tiny bit of code.

Signed-off-by: Andy Lutomirski 
Reviewed-by: Thomas Gleixner 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

x86, iosf: Added Quark MBI identifiers

2014-11-14T17:00:00+00:00

commit 7ef1def800e907edd28ddb1a5c64bae6b8749cdd upstream.

Added all the MBI units below and their associated read/write
opcodes:
 - Host Bridge Arbiter
 - Host Bridge
 - Remote Management Unit
 - Memory Manager & eSRAM
 - SoC Unit

Signed-off-by: Ong Boon Leong 
Link: http://lkml.kernel.org/r/1399668248-24199-3-git-send-email-david.e.box@linux.intel.com
Signed-off-by: David E. Box 
Signed-off-by: H. Peter Anvin 
Signed-off-by: Chang Rebecca Swee Fun 
Signed-off-by: Greg Kroah-Hartman

x86, iosf: Make IOSF driver modular and usable by more drivers

2014-11-14T16:59:59+00:00

commit 6b8f0c8780c71d78624f736d7849645b64cc88b7 upstream.

Currently drivers that run on non-IOSF systems (Core/Xeon) can't use the IOSF
driver on SOC's without selecting it which forces an unnecessary and limiting
dependency. Provides dummy functions to allow these modules to conditionally
use the driver on IOSF equipped platforms without impacting their ability to
compile and load on non-IOSF platforms. Build default m to ensure availability
on x86 SOC's.

Signed-off-by: David E. Box 
Link: http://lkml.kernel.org/r/1399668248-24199-2-git-send-email-david.e.box@linux.intel.com
Signed-off-by: H. Peter Anvin 
Signed-off-by: Chang Rebecca Swee Fun 
Signed-off-by: Greg Kroah-Hartman

KVM: x86: Check non-canonical addresses upon WRMSR

2014-11-14T16:59:55+00:00

commit 854e8bb1aa06c578c2c9145fa6bfe3680ef63b23 upstream.

Upon WRMSR, the CPU should inject #GP if a non-canonical value (address) is
written to certain MSRs. The behavior is "almost" identical for AMD and Intel
(ignoring MSRs that are not implemented in either architecture since they would
anyhow #GP). However, IA32_SYSENTER_ESP and IA32_SYSENTER_EIP cause #GP if
non-canonical address is written on Intel but not on AMD (which ignores the top
32-bits).

Accordingly, this patch injects a #GP on the MSRs which behave identically on
Intel and AMD.  To eliminate the differences between the architecutres, the
value which is written to IA32_SYSENTER_ESP and IA32_SYSENTER_EIP is turned to
canonical value before writing instead of injecting a #GP.

Some references from Intel and AMD manuals:

According to Intel SDM description of WRMSR instruction #GP is expected on
WRMSR "If the source register contains a non-canonical address and ECX
specifies one of the following MSRs: IA32_DS_AREA, IA32_FS_BASE, IA32_GS_BASE,
IA32_KERNEL_GS_BASE, IA32_LSTAR, IA32_SYSENTER_EIP, IA32_SYSENTER_ESP."

According to AMD manual instruction manual:
LSTAR/CSTAR (SYSCALL): "The WRMSR instruction loads the target RIP into the
LSTAR and CSTAR registers.  If an RIP written by WRMSR is not in canonical
form, a general-protection exception (#GP) occurs."
IA32_GS_BASE and IA32_FS_BASE (WRFSBASE/WRGSBASE): "The address written to the
base field must be in canonical form or a #GP fault will occur."
IA32_KERNEL_GS_BASE (SWAPGS): "The address stored in the KernelGSbase MSR must
be in canonical form."

This patch fixes CVE-2014-3610.

Signed-off-by: Nadav Amit 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman