Commit Graph

318 Commits

Author SHA1 Message Date
Josh Poimboeuf 98990a33b7 x86/entry: Fix idtentry unwind hint
This fixes the following ORC warning in the 'int3' entry code:

  WARNING: can't dereference iret registers at ffff8801c5f17fe0 for ip ffffffff95f0d94b

The ORC metadata had the wrong stack offset for the iret registers.

Their location on the stack is dependent on whether the exception has an
error code.

Reported-and-tested-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 8c1f75587a ("x86/entry/64: Add unwind hint annotations")
Link: http://lkml.kernel.org/r/931d57f0551ed7979d5e7e05370d445c8e5137f8.1508516398.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-23 13:30:35 +02:00
Josh Poimboeuf 5c99b692cf x86/unwind: Use MSB for frame pointer encoding on 32-bit
On x86-32, Tetsuo Handa and Fengguang Wu reported unwinder warnings
like:

  WARNING: kernel stack regs at f60bb9c8 in swapper:1 has bad 'bp' value 0ba00000

And also there were some stack dumps with a bunch of unreliable '?'
symbols after an apic_timer_interrupt symbol, meaning the unwinder got
confused when it tried to read the regs.

The cause of those issues is that, with GCC 4.8 (and possibly older),
there are cases where GCC misaligns the stack pointer in a leaf function
for no apparent reason:

  c124a388 <acpi_rs_move_data>:
  c124a388:       55                      push   %ebp
  c124a389:       89 e5                   mov    %esp,%ebp
  c124a38b:       57                      push   %edi
  c124a38c:       56                      push   %esi
  c124a38d:       89 d6                   mov    %edx,%esi
  c124a38f:       53                      push   %ebx
  c124a390:       31 db                   xor    %ebx,%ebx
  c124a392:       83 ec 03                sub    $0x3,%esp
  ...
  c124a3e3:       83 c4 03                add    $0x3,%esp
  c124a3e6:       5b                      pop    %ebx
  c124a3e7:       5e                      pop    %esi
  c124a3e8:       5f                      pop    %edi
  c124a3e9:       5d                      pop    %ebp
  c124a3ea:       c3                      ret

If an interrupt occurs in such a function, the regs on the stack will be
unaligned, which breaks the frame pointer encoding assumption.  So on
32-bit, use the MSB instead of the LSB to encode the regs.

This isn't an issue on 64-bit, because interrupts align the stack before
writing to it.

Reported-and-tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-and-tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: LKP <lkp@01.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/279a26996a482ca716605c7dbc7f2db9d8d91e81.1507597785.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-10 12:49:48 +02:00
Linus Torvalds 24e700e291 Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 apic updates from Thomas Gleixner:
 "This update provides:

   - Cleanup of the IDT management including the removal of the extra
     tracing IDT. A first step to cleanup the vector management code.

   - The removal of the paravirt op adjust_exception_frame. This is a
     XEN specific issue, but merged through this branch to avoid nasty
     merge collisions

   - Prevent dmesg spam about the TSC DEADLINE bug, when the CPU has
     disabled the TSC DEADLINE timer in CPUID.

   - Adjust a debug message in the ioapic code to print out the
     information correctly"

* 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (51 commits)
  x86/idt: Fix the X86_TRAP_BP gate
  x86/xen: Get rid of paravirt op adjust_exception_frame
  x86/eisa: Add missing include
  x86/idt: Remove superfluous ALIGNment
  x86/apic: Silence "FW_BUG TSC_DEADLINE disabled due to Errata" on CPUs without the feature
  x86/idt: Remove the tracing IDT leftovers
  x86/idt: Hide set_intr_gate()
  x86/idt: Simplify alloc_intr_gate()
  x86/idt: Deinline setup functions
  x86/idt: Remove unused functions/inlines
  x86/idt: Move interrupt gate initialization to IDT code
  x86/idt: Move APIC gate initialization to tables
  x86/idt: Move regular trap init to tables
  x86/idt: Move IST stack based traps to table init
  x86/idt: Move debug stack init to table based
  x86/idt: Switch early trap init to IDT tables
  x86/idt: Prepare for table based init
  x86/idt: Move early IDT setup out of 32-bit asm
  x86/idt: Move early IDT handler setup to IDT code
  x86/idt: Consolidate IDT invalidation
  ...
2017-09-04 17:43:56 -07:00
Linus Torvalds 6c51e67b64 Merge branch 'x86-syscall-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull syscall updates from Ingo Molnar:
 "Improve the security of set_fs(): we now check the address limit on a
  number of key platforms (x86, arm, arm64) before returning to
  user-space - without adding overhead to the typical system call fast
  path"

* 'x86-syscall-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  arm64/syscalls: Check address limit on user-mode return
  arm/syscalls: Check address limit on user-mode return
  x86/syscalls: Check address limit on user-mode return
2017-09-04 11:18:17 -07:00
Linus Torvalds b0c79f49c3 Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm updates from Ingo Molnar:

 - Introduce the ORC unwinder, which can be enabled via
   CONFIG_ORC_UNWINDER=y.

   The ORC unwinder is a lightweight, Linux kernel specific debuginfo
   implementation, which aims to be DWARF done right for unwinding.
   Objtool is used to generate the ORC unwinder tables during build, so
   the data format is flexible and kernel internal: there's no
   dependency on debuginfo created by an external toolchain.

   The ORC unwinder is almost two orders of magnitude faster than the
   (out of tree) DWARF unwinder - which is important for perf call graph
   profiling. It is also significantly simpler and is coded defensively:
   there has not been a single ORC related kernel crash so far, even
   with early versions. (knock on wood!)

   But the main advantage is that enabling the ORC unwinder allows
   CONFIG_FRAME_POINTERS to be turned off - which speeds up the kernel
   measurably:

   With frame pointers disabled, GCC does not have to add frame pointer
   instrumentation code to every function in the kernel. The kernel's
   .text size decreases by about 3.2%, resulting in better cache
   utilization and fewer instructions executed, resulting in a broad
   kernel-wide speedup. Average speedup of system calls should be
   roughly in the 1-3% range - measurements by Mel Gorman [1] have shown
   a speedup of 5-10% for some function execution intense workloads.

   The main cost of the unwinder is that the unwinder data has to be
   stored in RAM: the memory cost is 2-4MB of RAM, depending on kernel
   config - which is a modest cost on modern x86 systems.

   Given how young the ORC unwinder code is it's not enabled by default
   - but given the performance advantages the plan is to eventually make
   it the default unwinder on x86.

   See Documentation/x86/orc-unwinder.txt for more details.

 - Remove lguest support: its intended role was that of a temporary
   proof of concept for virtualization, plus its removal will enable the
   reduction (removal) of the paravirt API as well, so Rusty agreed to
   its removal. (Juergen Gross)

 - Clean up and fix FSGS related functionality (Andy Lutomirski)

 - Clean up IO access APIs (Andy Shevchenko)

 - Enhance the symbol namespace (Jiri Slaby)

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (47 commits)
  objtool: Handle GCC stack pointer adjustment bug
  x86/entry/64: Use ENTRY() instead of ALIGN+GLOBAL for stub32_clone()
  x86/fpu/math-emu: Add ENDPROC to functions
  x86/boot/64: Extract efi_pe_entry() from startup_64()
  x86/boot/32: Extract efi_pe_entry() from startup_32()
  x86/lguest: Remove lguest support
  x86/paravirt/xen: Remove xen_patch()
  objtool: Fix objtool fallthrough detection with function padding
  x86/xen/64: Fix the reported SS and CS in SYSCALL
  objtool: Track DRAP separately from callee-saved registers
  objtool: Fix validate_branch() return codes
  x86: Clarify/fix no-op barriers for text_poke_bp()
  x86/switch_to/64: Rewrite FS/GS switching yet again to fix AMD CPUs
  selftests/x86/fsgsbase: Test selectors 1, 2, and 3
  x86/fsgsbase/64: Report FSBASE and GSBASE correctly in core dumps
  x86/fsgsbase/64: Fully initialize FS and GS state in start_thread_common
  x86/asm: Fix UNWIND_HINT_REGS macro for older binutils
  x86/asm/32: Fix regs_get_register() on segment registers
  x86/xen/64: Rearrange the SYSCALL entries
  x86/asm/32: Remove a bunch of '& 0xffff' from pt_regs segment reads
  ...
2017-09-04 09:52:57 -07:00
Juergen Gross 5878d5d6fd x86/xen: Get rid of paravirt op adjust_exception_frame
When running as Xen pv-guest the exception frame on the stack contains
%r11 and %rcx additional to the other data pushed by the processor.

Instead of having a paravirt op being called for each exception type
prepend the Xen specific code to each exception entry. When running as
Xen pv-guest just use the exception entry with prepended instructions,
otherwise use the entry without the Xen specific code.

[ tglx: Merged through tip to avoid ugly merge conflict ]

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: xen-devel@lists.xenproject.org
Cc: boris.ostrovsky@oracle.com
Cc: luto@amacapital.net
Link: http://lkml.kernel.org/r/20170831174249.26853-1-jg@pfupf.net
2017-08-31 21:35:10 +02:00
Jiri Slaby 499934898f x86/entry/64: Use ENTRY() instead of ALIGN+GLOBAL for stub32_clone()
ALIGN+GLOBAL is effectively what ENTRY() does, so use ENTRY() which is
dedicated for exactly this purpose -- global functions.

Note that stub32_clone() is a C-like leaf function -- it has a standard
call frame -- it only switches one argument and continues by jumping
into C. Since each ENTRY() should be balanced by some END*() marker, we
add a corresponding ENDPROC() to stub32_clone() too.

Besides that, x86's custom GLOBAL macro is going to die very soon.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Andy Lutomirski <luto@kernel.org>
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: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170824080624.7768-2-jslaby@suse.cz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 13:23:30 +02:00
Thomas Gleixner 38e9e81f4c x86/gdt: Use bitfields for initialization
The GDT entry related code uses two ways to access entries via
union fields:

 - bitfields

 - macros which initialize the two 16-bit parts of the entry
   by magic shift and mask operations.

Clean it up and only use the bitfields to initialize and access entries.

( The old access patterns were partly done due to GCC optimizing bitfield
  accesses in a horrible way - that's mostly fixed these days and clarity
  of code in such low level accessors is very important. )

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
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: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170828064958.197673367@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 12:07:25 +02:00
Thomas Gleixner 4b9a8dca0e x86/idt: Remove the tracing IDT completely
No more users of the tracing IDT. All exception tracepoints have been moved
into the regular handlers. Get rid of the mess which shouldn't have been
created in the first place.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170828064957.378851687@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 11:42:28 +02:00
Thomas Gleixner 11a7ffb017 x86/traps: Simplify pagefault tracing logic
Make use of the new irqvector tracing static key and remove the duplicated
trace_do_pagefault() implementation.

If irq vector tracing is disabled, then the overhead of this is a single
NOP5, which is a reasonable tradeoff to avoid duplicated code and the
unholy macro mess.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170828064956.672965407@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-29 11:42:23 +02:00
Ingo Molnar 93da8b221d Merge branch 'linus' into perf/core, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-24 10:12:33 +02:00
Masami Hiramatsu 229a718605 irq: Make the irqentry text section unconditional
Generate irqentry and softirqentry text sections without
any Kconfig dependencies. This will add extra sections, but
there should be no performace impact.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David S . Miller <davem@davemloft.net>
Cc: Francis Deslauriers <francis.deslauriers@efficios.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: linux-arch@vger.kernel.org
Cc: linux-cris-kernel@axis.com
Cc: mathieu.desnoyers@efficios.com
Link: http://lkml.kernel.org/r/150172789110.27216.3955739126693102122.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10 16:28:53 +02:00
Andy Lutomirski 8a9949bc71 x86/xen/64: Rearrange the SYSCALL entries
Xen's raw SYSCALL entries are much less weird than native.  Rather
than fudging them to look like native entries, use the Xen-provided
stack frame directly.

This lets us eliminate entry_SYSCALL_64_after_swapgs and two uses of
the SWAPGS_UNSAFE_STACK paravirt hook.  The SYSENTER code would
benefit from similar treatment.

This makes one change to the native code path: the compat
instruction that clears the high 32 bits of %rax is moved slightly
later.  I'd be surprised if this affects performance at all.

Tested-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/7c88ed36805d36841ab03ec3b48b4122c4418d71.1502164668.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10 13:14:32 +02:00
Ingo Molnar 1d0f49e140 Merge branch 'x86/urgent' into x86/asm, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10 13:14:15 +02:00
Andy Lutomirski e93c17301a x86/asm/64: Clear AC on NMI entries
This closes a hole in our SMAP implementation.

This patch comes from grsecurity. Good catch!

Signed-off-by: Andy Lutomirski <luto@kernel.org>
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: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/314cc9f294e8f14ed85485727556ad4f15bb1659.1502159503.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10 13:13:15 +02:00
Wincy Van 210f84b0ca x86: irq: Define a global vector for nested posted interrupts
We are using the same vector for nested/non-nested posted
interrupts delivery, this may cause interrupts latency in
L1 since we can't kick the L2 vcpu out of vmx-nonroot mode.

This patch introduces a new vector which is only for nested
posted interrupts to solve the problems above.

Signed-off-by: Wincy Van <fanwenyi0529@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-07-26 18:57:45 +02:00
Josh Poimboeuf 8c1f75587a x86/entry/64: Add unwind hint annotations
Add unwind hint annotations to entry_64.S.  This will enable the ORC
unwinder to unwind through any location in the entry code including
syscalls, interrupts, and exceptions.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
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: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/b9f6d478aadf68ba57c739dcfac34ec0dc021c4c.1499786555.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-18 10:57:44 +02:00
Andy Lutomirski 2995590964 x86/entry/64: Initialize the top of the IRQ stack before switching stacks
The OOPS unwinder wants the word at the top of the IRQ stack to
point back to the previous stack at all times when the IRQ stack
is in use.  There's currently a one-instruction window in ENTER_IRQ_STACK
during which this isn't the case.  Fix it by writing the old RSP to the
top of the IRQ stack before jumping.

This currently writes the pointer to the stack twice, which is a bit
ugly.  We could get rid of this by replacing irq_stack_ptr with
irq_stack_ptr_minus_eight (better name welcome).  OTOH, there may be
all kinds of odd microarchitectural considerations in play that
affect performance by a few cycles here.

Reported-by: Mike Galbraith <efault@gmx.de>
Reported-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
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: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/aae7e79e49914808440ad5310ace138ced2179ca.1499786555.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-18 10:56:23 +02:00
Andy Lutomirski 1d3e53e862 x86/entry/64: Refactor IRQ stacks and make them NMI-safe
This will allow IRQ stacks to nest inside NMIs or similar entries
that can happen during IRQ stack setup or teardown.

The new macros won't work correctly if they're invoked with IRQs on.
Add a check under CONFIG_DEBUG_ENTRY to detect that.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
[ Use %r10 instead of %r11 in xen_do_hypervisor_callback to make objtool
  and ORC unwinder's lives a little easier. ]
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
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: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/b0b2ff5fb97d2da2e1d7e1f380190c92545c8bb5.1499786555.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-18 10:56:22 +02:00
Linus Torvalds 09b56d5a41 Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm
Pull ARM updates from Russell King:

 - add support for ftrace-with-registers, which is needed for kgraft and
   other ftrace tools

 - support for mremap() for the sigpage/vDSO so that checkpoint/restore
   can work

 - add timestamps to each line of the register dump output

 - remove the unused KTHREAD_SIZE from nommu

 - align the ARM bitops APIs with the generic API (using unsigned long
   pointers rather than void pointers)

 - make the configuration of userspace Thumb support an expert option so
   that we can default it on, and avoid some hard to debug userspace
   crashes

* 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 8684/1: NOMMU: Remove unused KTHREAD_SIZE definition
  ARM: 8683/1: ARM32: Support mremap() for sigpage/vDSO
  ARM: 8679/1: bitops: Align prototypes to generic API
  ARM: 8678/1: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS
  ARM: make configuration of userspace Thumb support an expert option
  ARM: 8673/1: Fix __show_regs output timestamps
2017-07-08 12:17:25 -07:00
Thomas Garnier 5ea0727b16 x86/syscalls: Check address limit on user-mode return
Ensure the address limit is a user-mode segment before returning to
user-mode. Otherwise a process can corrupt kernel-mode memory and elevate
privileges [1].

The set_fs function sets the TIF_SETFS flag to force a slow path on
return. In the slow path, the address limit is checked to be USER_DS if
needed.

The addr_limit_user_check function is added as a cross-architecture
function to check the address limit.

[1] https://bugs.chromium.org/p/project-zero/issues/detail?id=990

Signed-off-by: Thomas Garnier <thgarnie@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: kernel-hardening@lists.openwall.com
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Pratyush Anand <panand@redhat.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Will Drewry <wad@chromium.org>
Cc: linux-api@vger.kernel.org
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Link: http://lkml.kernel.org/r/20170615011203.144108-1-thgarnie@google.com
2017-07-08 14:05:32 +02:00
Dmitry Safonov 280e87e98c ARM: 8683/1: ARM32: Support mremap() for sigpage/vDSO
CRIU restores application mappings on the same place where they
were before Checkpoint. That means, that we need to move vDSO
and sigpage during restore on exactly the same place where
they were before C/R.

Make mremap() code update mm->context.{sigpage,vdso} pointers
during VMA move. Sigpage is used for landing after handling
a signal - if the pointer is not updated during moving, the
application might crash on any signal after mremap().

vDSO pointer on ARM32 is used only for setting auxv at this moment,
update it during mremap() in case of future usage.

Without those updates, current work of CRIU on ARM32 is not reliable.
Historically, we error Checkpointing if we find vDSO page on ARM32
and suggest user to disable CONFIG_VDSO.
But that's not correct - it goes from x86 where signal processing
is ended in vDSO blob. For arm32 it's sigpage, which is not disabled
with `CONFIG_VDSO=n'.

Looks like C/R was working by luck - because userspace on ARM32 at
this moment always sets SA_RESTORER.

Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Will Deacon <will.deacon@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Christopher Covington <cov@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2017-06-21 13:02:58 +01:00
Kirill A. Shutemov cbe0317bf1 x86/asm: Fix comment in return_from_SYSCALL_64()
On x86-64 __VIRTUAL_MASK_SHIFT depends on paging mode now.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170606113133.22974-3-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-13 08:56:51 +02:00
Josh Poimboeuf ebd574994c Revert "x86/entry: Fix the end of the stack for newly forked tasks"
Petr Mladek reported the following warning when loading the livepatch
sample module:

  WARNING: CPU: 1 PID: 3699 at arch/x86/kernel/stacktrace.c:132 save_stack_trace_tsk_reliable+0x133/0x1a0
  ...
  Call Trace:
   __schedule+0x273/0x820
   schedule+0x36/0x80
   kthreadd+0x305/0x310
   ? kthread_create_on_cpu+0x80/0x80
   ? icmp_echo.part.32+0x50/0x50
   ret_from_fork+0x2c/0x40

That warning means the end of the stack is no longer recognized as such
for newly forked tasks.  The problem was introduced with the following
commit:

  ff3f7e2475 ("x86/entry: Fix the end of the stack for newly forked tasks")

... which was completely misguided.  It only partially fixed the
reported issue, and it introduced another bug in the process.  None of
the other entry code saves the frame pointer before calling into C code,
so it doesn't make sense for ret_from_fork to do so either.

Contrary to what I originally thought, the original issue wasn't related
to newly forked tasks.  It was actually related to ftrace.  When entry
code calls into a function which then calls into an ftrace handler, the
stack frame looks different than normal.

The original issue will be fixed in the unwinder, in a subsequent patch.

Reported-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: live-patching@vger.kernel.org
Fixes: ff3f7e2475 ("x86/entry: Fix the end of the stack for newly forked tasks")
Link: http://lkml.kernel.org/r/f350760f7e82f0750c8d1dd093456eb212751caa.1495553739.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-24 09:05:16 +02:00
Linus Torvalds 76f1948a79 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching
Pull livepatch updates from Jiri Kosina:

 - a per-task consistency model is being added for architectures that
   support reliable stack dumping (extending this, currently rather
   trivial set, is currently in the works).

   This extends the nature of the types of patches that can be applied
   by live patching infrastructure. The code stems from the design
   proposal made [1] back in November 2014. It's a hybrid of SUSE's
   kGraft and RH's kpatch, combining advantages of both: it uses
   kGraft's per-task consistency and syscall barrier switching combined
   with kpatch's stack trace switching. There are also a number of
   fallback options which make it quite flexible.

   Most of the heavy lifting done by Josh Poimboeuf with help from
   Miroslav Benes and Petr Mladek

   [1] https://lkml.kernel.org/r/20141107140458.GA21774@suse.cz

 - module load time patch optimization from Zhou Chengming

 - a few assorted small fixes

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching:
  livepatch: add missing printk newlines
  livepatch: Cancel transition a safe way for immediate patches
  livepatch: Reduce the time of finding module symbols
  livepatch: make klp_mutex proper part of API
  livepatch: allow removal of a disabled patch
  livepatch: add /proc/<pid>/patch_state
  livepatch: change to a per-task consistency model
  livepatch: store function sizes
  livepatch: use kstrtobool() in enabled_store()
  livepatch: move patching functions into patch.c
  livepatch: remove unnecessary object loaded check
  livepatch: separate enabled and patched states
  livepatch/s390: add TIF_PATCH_PENDING thread flag
  livepatch/s390: reorganize TIF thread flag bits
  livepatch/powerpc: add TIF_PATCH_PENDING thread flag
  livepatch/x86: add TIF_PATCH_PENDING thread flag
  livepatch: create temporary klp_update_patch_state() stub
  x86/entry: define _TIF_ALLWORK_MASK flags explicitly
  stacktrace/x86: add function for detecting reliable stack traces
2017-05-02 18:24:16 -07:00
Linus Torvalds 204f144c9f Merge branch 'work.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull fs/compat.c cleanups from Al Viro:
 "More moving of compat syscalls from fs/compat.c to fs/*.c where the
  native counterparts live.

  And death to compat_sys_getdents64() - the only architecture that used
  to need it was ia64, and _that_ has lost biarch support quite a few
  years ago"

* 'work.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fs/compat.c: trim unused includes
  move compat_rw_copy_check_uvector() over to fs/read_write.c
  fhandle: move compat syscalls from compat.c
  open: move compat syscalls from compat.c
  stat: move compat syscalls from compat.c
  fcntl: move compat syscalls from compat.c
  readdir: move compat syscalls from compat.c
  statfs: move compat syscalls from compat.c
  utimes: move compat syscalls from compat.c
  move compat select-related syscalls to fs/select.c
  Remove compat_sys_getdents64()
2017-05-02 11:54:26 -07:00
Linus Torvalds d3b5d35290 Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 mm updates from Ingo Molnar:
 "The main x86 MM changes in this cycle were:

   - continued native kernel PCID support preparation patches to the TLB
     flushing code (Andy Lutomirski)

   - various fixes related to 32-bit compat syscall returning address
     over 4Gb in applications, launched from 64-bit binaries - motivated
     by C/R frameworks such as Virtuozzo. (Dmitry Safonov)

   - continued Intel 5-level paging enablement: in particular the
     conversion of x86 GUP to the generic GUP code. (Kirill A. Shutemov)

   - x86/mpx ABI corner case fixes/enhancements (Joerg Roedel)

   - ... plus misc updates, fixes and cleanups"

* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (62 commits)
  mm, zone_device: Replace {get, put}_zone_device_page() with a single reference to fix pmem crash
  x86/mm: Fix flush_tlb_page() on Xen
  x86/mm: Make flush_tlb_mm_range() more predictable
  x86/mm: Remove flush_tlb() and flush_tlb_current_task()
  x86/vm86/32: Switch to flush_tlb_mm_range() in mark_screen_rdonly()
  x86/mm/64: Fix crash in remove_pagetable()
  Revert "x86/mm/gup: Switch GUP to the generic get_user_page_fast() implementation"
  x86/boot/e820: Remove a redundant self assignment
  x86/mm: Fix dump pagetables for 4 levels of page tables
  x86/mpx, selftests: Only check bounds-vs-shadow when we keep shadow
  x86/mpx: Correctly report do_mpx_bt_fault() failures to user-space
  Revert "x86/mm/numa: Remove numa_nodemask_from_meminfo()"
  x86/espfix: Add support for 5-level paging
  x86/kasan: Extend KASAN to support 5-level paging
  x86/mm: Add basic defines/helpers for CONFIG_X86_5LEVEL=y
  x86/paravirt: Add 5-level support to the paravirt code
  x86/mm: Define virtual memory map for 5-level paging
  x86/asm: Remove __VIRTUAL_MASK_SHIFT==47 assert
  x86/boot: Detect 5-level paging support
  x86/mm/numa: Remove numa_nodemask_from_meminfo()
  ...
2017-05-01 23:54:56 -07:00
Linus Torvalds aa2a4b6569 Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 vdso updates from Ingo Molnar:
 "Add support for vDSO acceleration of the "Hyper-V TSC page", to speed
  up clock reading on Hyper-V guests"

* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/vdso: Add VCLOCK_HVCLOCK vDSO clock read method
  x86/hyperv: Move TSC reading method to asm/mshyperv.h
  x86/hyperv: Implement hv_get_tsc_page()
2017-05-01 23:08:46 -07:00
Linus Torvalds 3fb9268e43 Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm updates from Ingo Molnar:
 "The main changes in this cycle were:

   - unwinder fixes and enhancements

   - improve ftrace interaction with the unwinder

   - optimize the code footprint of WARN() and related debugging
     constructs

   - ... plus misc updates, cleanups and fixes"

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  x86/unwind: Dump all stacks in unwind_dump()
  x86/unwind: Silence more entry-code related warnings
  x86/ftrace: Fix ebp in ftrace_regs_caller that screws up unwinder
  x86/unwind: Remove unused 'sp' parameter in unwind_dump()
  x86/unwind: Prepend hex mask value with '0x' in unwind_dump()
  x86/unwind: Properly zero-pad 32-bit values in unwind_dump()
  x86/unwind: Ensure stack pointer is aligned
  debug: Avoid setting BUGFLAG_WARNING twice
  x86/unwind: Silence entry-related warnings
  x86/unwind: Read stack return address in update_stack_state()
  x86/unwind: Move common code into update_stack_state()
  debug: Fix __bug_table[] in arch linker scripts
  debug: Add _ONCE() logic to report_bug()
  x86/debug: Define BUG() again for !CONFIG_BUG
  x86/debug: Implement __WARN() using UD0
  x86/ftrace: Use Makefile logic instead of #ifdef for compiling ftrace_*.o
  x86/ftrace: Add -mfentry support to x86_32 with DYNAMIC_FTRACE set
  x86/ftrace: Clean up ftrace_regs_caller
  x86/ftrace: Add stack frame pointer to ftrace_caller
  x86/ftrace: Move the ftrace specific code out of entry_32.S
  ...
2017-05-01 22:07:51 -07:00
Linus Torvalds 6dc2cce932 Merge branch 'x86-process-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pul x86/process updates from Ingo Molnar:
 "The main change in this cycle was to add the ARCH_[GET|SET]_CPUID
  prctl() ABI extension to control the availability of the CPUID
  instruction, analogously to the existing PR_GET|SET_TSC ABI that
  controls RDTSC.

  Motivation: the 'rr' user-space record-and-replay execution debugger
  would like to trap and emulate the CPUID instruction - which
  instruction is normally unprivileged.

  Trapping CPUID is possible on IvyBridge and later Intel CPUs - expose
  this hardware capability"

* 'x86-process-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/syscalls/32: Ignore arch_prctl for other architectures
  um/arch_prctl: Fix fallout from x86 arch_prctl() rework
  x86/arch_prctl: Add ARCH_[GET|SET]_CPUID
  x86/cpufeature: Detect CPUID faulting support
  x86/syscalls/32: Wire up arch_prctl on x86-32
  x86/arch_prctl: Add do_arch_prctl_common()
  x86/arch_prctl/64: Rename do_arch_prctl() to do_arch_prctl_64()
  x86/arch_prctl/64: Use SYSCALL_DEFINE2 to define sys_arch_prctl()
  x86/arch_prctl: Rename 'code' argument to 'option'
  x86/msr: Rename MISC_FEATURE_ENABLES to MISC_FEATURES_ENABLES
  x86/process: Optimize TIF_NOTSC switch
  x86/process: Correct and optimize TIF_BLOCKSTEP switch
  x86/process: Optimize TIF checks in __switch_to_xtra()
2017-05-01 19:57:58 -07:00
Al Viro 2611dc1939 Remove compat_sys_getdents64()
Unlike normal compat syscall variants, it is needed only for
biarch architectures that have different alignement requirements for
u64 in 32bit and 64bit ABI *and* have __put_user() that won't handle
a store of 64bit value at 32bit-aligned address.  We used to have one
such (ia64), but its biarch support has been gone since 2010 (after
being broken in 2008, which went unnoticed since nobody had been using
it).

It had escaped removal at the same time only because back in 2004
a patch that switched several syscalls on amd64 from private wrappers to
generic compat ones had switched to use of compat_sys_getdents64(), which
hadn't needed (or used) a compat wrapper on amd64.

Let's bury it - it's at least 7 years overdue.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-04-17 12:52:22 -04:00
Mathias Krause c06989da39 x86/vdso: Ensure vdso32_enabled gets set to valid values only
vdso_enabled can be set to arbitrary integer values via the kernel command
line 'vdso32=' parameter or via 'sysctl abi.vsyscall32'.

load_vdso32() only maps VDSO if vdso_enabled == 1, but ARCH_DLINFO_IA32
merily checks for vdso_enabled != 0. As a consequence the AT_SYSINFO_EHDR
auxiliary vector for the VDSO_ENTRY is emitted with a NULL pointer which
causes a segfault when the application tries to use the VDSO.

Restrict the valid arguments on the command line and the sysctl to 0 and 1.

Fixes: b0b49f2673 ("x86, vdso: Remove compat vdso support")
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Cc: Roland McGrath <roland@redhat.com>
Link: http://lkml.kernel.org/r/1491424561-7187-1-git-send-email-minipli@googlemail.com
Link: http://lkml.kernel.org/r/20170410151723.518412863@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-04-10 18:31:41 +02:00
Kirill A. Shutemov 361b4b58ec x86/asm: Remove __VIRTUAL_MASK_SHIFT==47 assert
We don't need the assert anymore, as:

  17be0aec74 ("x86/asm/entry/64: Implement better check for canonical addresses")

made canonical address checks generic wrt. address width.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170330080731.65421-3-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-04-04 08:22:33 +02:00
Steven Rostedt (VMware) 3d82c59c6e x86/ftrace: Move the ftrace specific code out of entry_32.S
The function tracing hook code for ftrace is not an entry point from
userspace and does not belong in the entry_*.S files. It has already been
moved out of entry_64.S.

Move it out of entry_32.S into its own ftrace_32.S file.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20170323143445.645218946@goodmis.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-03-24 10:14:07 +01:00
Ingo Molnar 1f9ca18404 Merge branch 'x86/process' into x86/mm, to create new base for further patches
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-23 08:28:19 +01:00
Ingo Molnar 4ccb6aea4b Merge branch 'linus' into x86/asm, to refresh the topic tree with fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-23 07:35:15 +01:00
Kyle Huey 79170fda31 x86/syscalls/32: Wire up arch_prctl on x86-32
Hook up arch_prctl to call do_arch_prctl() on x86-32, and in 32 bit compat
mode on x86-64. This allows to have arch_prctls that are not specific to 64
bits.

On UML, simply stub out this syscall.

Signed-off-by: Kyle Huey <khuey@kylehuey.com>
Cc: Grzegorz Andrejczuk <grzegorz.andrejczuk@intel.com>
Cc: kvm@vger.kernel.org
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: linux-kselftest@vger.kernel.org
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Robert O'Callahan <robert@ocallahan.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: user-mode-linux-user@lists.sourceforge.net
Cc: David Matlack <dmatlack@google.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: linux-fsdevel@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Link: http://lkml.kernel.org/r/20170320081628.18952-7-khuey@kylehuey.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-03-20 16:10:33 +01:00
Thomas Garnier 69218e4799 x86: Remap GDT tables in the fixmap section
Each processor holds a GDT in its per-cpu structure. The sgdt
instruction gives the base address of the current GDT. This address can
be used to bypass KASLR memory randomization. With another bug, an
attacker could target other per-cpu structures or deduce the base of
the main memory section (PAGE_OFFSET).

This patch relocates the GDT table for each processor inside the
fixmap section. The space is reserved based on number of supported
processors.

For consistency, the remapping is done by default on 32 and 64-bit.

Each processor switches to its remapped GDT at the end of
initialization. For hibernation, the main processor returns with the
original GDT and switches back to the remapping at completion.

This patch was tested on both architectures. Hibernation and KVM were
both tested specially for their usage of the GDT.

Thanks to Boris Ostrovsky <boris.ostrovsky@oracle.com> for testing and
recommending changes for Xen support.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Luis R . Rodriguez <mcgrof@kernel.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rafael J . Wysocki <rjw@rjwysocki.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: kasan-dev@googlegroups.com
Cc: kernel-hardening@lists.openwall.com
Cc: kvm@vger.kernel.org
Cc: lguest@lists.ozlabs.org
Cc: linux-doc@vger.kernel.org
Cc: linux-efi@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-pm@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Cc: zijun_hu <zijun_hu@htc.com>
Link: http://lkml.kernel.org/r/20170314170508.100882-2-thgarnie@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16 09:06:35 +01:00
Vitaly Kuznetsov 90b20432ae x86/vdso: Add VCLOCK_HVCLOCK vDSO clock read method
Hyper-V TSC page clocksource is suitable for vDSO, however, the protocol
defined by the hypervisor is different from VCLOCK_PVCLOCK. Implement the
required support by adding hvclock_page VVAR.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: devel@linuxdriverproject.org
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: virtualization@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/20170303132142.25595-4-vkuznets@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-03-11 14:47:28 +01:00
Josh Poimboeuf afb94c9e0b livepatch/x86: add TIF_PATCH_PENDING thread flag
Add the TIF_PATCH_PENDING thread flag to enable the new livepatch
per-task consistency model for x86_64.  The bit getting set indicates
the thread has a pending patch which needs to be applied when the thread
exits the kernel.

The bit is placed in the _TIF_ALLWORK_MASK macro, which results in
exit_to_usermode_loop() calling klp_update_patch_state() when it's set.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>        # for the x86 changes
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-03-08 09:19:41 +01:00
Linus Torvalds 590dce2d49 Merge branch 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs 'statx()' update from Al Viro.

This adds the new extended stat() interface that internally subsumes our
previous stat interfaces, and allows user mode to specify in more detail
what kind of information it wants.

It also allows for some explicit synchronization information to be
passed to the filesystem, which can be relevant for network filesystems:
is the cached value ok, or do you need open/close consistency, or what?

From David Howells.

Andreas Dilger points out that the first version of the extended statx
interface was posted June 29, 2010:

    https://www.spinics.net/lists/linux-fsdevel/msg33831.html

* 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  statx: Add a system call to make enhanced file info available
2017-03-03 11:38:56 -08:00
David Howells a528d35e8b statx: Add a system call to make enhanced file info available
Add a system call to make extended file information available, including
file creation and some attribute flags where available through the
underlying filesystem.

The getattr inode operation is altered to take two additional arguments: a
u32 request_mask and an unsigned int flags that indicate the
synchronisation mode.  This change is propagated to the vfs_getattr*()
function.

Functions like vfs_stat() are now inline wrappers around new functions
vfs_statx() and vfs_statx_fd() to reduce stack usage.

========
OVERVIEW
========

The idea was initially proposed as a set of xattrs that could be retrieved
with getxattr(), but the general preference proved to be for a new syscall
with an extended stat structure.

A number of requests were gathered for features to be included.  The
following have been included:

 (1) Make the fields a consistent size on all arches and make them large.

 (2) Spare space, request flags and information flags are provided for
     future expansion.

 (3) Better support for the y2038 problem [Arnd Bergmann] (tv_sec is an
     __s64).

 (4) Creation time: The SMB protocol carries the creation time, which could
     be exported by Samba, which will in turn help CIFS make use of
     FS-Cache as that can be used for coherency data (stx_btime).

     This is also specified in NFSv4 as a recommended attribute and could
     be exported by NFSD [Steve French].

 (5) Lightweight stat: Ask for just those details of interest, and allow a
     netfs (such as NFS) to approximate anything not of interest, possibly
     without going to the server [Trond Myklebust, Ulrich Drepper, Andreas
     Dilger] (AT_STATX_DONT_SYNC).

 (6) Heavyweight stat: Force a netfs to go to the server, even if it thinks
     its cached attributes are up to date [Trond Myklebust]
     (AT_STATX_FORCE_SYNC).

And the following have been left out for future extension:

 (7) Data version number: Could be used by userspace NFS servers [Aneesh
     Kumar].

     Can also be used to modify fill_post_wcc() in NFSD which retrieves
     i_version directly, but has just called vfs_getattr().  It could get
     it from the kstat struct if it used vfs_xgetattr() instead.

     (There's disagreement on the exact semantics of a single field, since
     not all filesystems do this the same way).

 (8) BSD stat compatibility: Including more fields from the BSD stat such
     as creation time (st_btime) and inode generation number (st_gen)
     [Jeremy Allison, Bernd Schubert].

 (9) Inode generation number: Useful for FUSE and userspace NFS servers
     [Bernd Schubert].

     (This was asked for but later deemed unnecessary with the
     open-by-handle capability available and caused disagreement as to
     whether it's a security hole or not).

(10) Extra coherency data may be useful in making backups [Andreas Dilger].

     (No particular data were offered, but things like last backup
     timestamp, the data version number and the DOS archive bit would come
     into this category).

(11) Allow the filesystem to indicate what it can/cannot provide: A
     filesystem can now say it doesn't support a standard stat feature if
     that isn't available, so if, for instance, inode numbers or UIDs don't
     exist or are fabricated locally...

     (This requires a separate system call - I have an fsinfo() call idea
     for this).

(12) Store a 16-byte volume ID in the superblock that can be returned in
     struct xstat [Steve French].

     (Deferred to fsinfo).

(13) Include granularity fields in the time data to indicate the
     granularity of each of the times (NFSv4 time_delta) [Steve French].

     (Deferred to fsinfo).

(14) FS_IOC_GETFLAGS value.  These could be translated to BSD's st_flags.
     Note that the Linux IOC flags are a mess and filesystems such as Ext4
     define flags that aren't in linux/fs.h, so translation in the kernel
     may be a necessity (or, possibly, we provide the filesystem type too).

     (Some attributes are made available in stx_attributes, but the general
     feeling was that the IOC flags were to ext[234]-specific and shouldn't
     be exposed through statx this way).

(15) Mask of features available on file (eg: ACLs, seclabel) [Brad Boyer,
     Michael Kerrisk].

     (Deferred, probably to fsinfo.  Finding out if there's an ACL or
     seclabal might require extra filesystem operations).

(16) Femtosecond-resolution timestamps [Dave Chinner].

     (A __reserved field has been left in the statx_timestamp struct for
     this - if there proves to be a need).

(17) A set multiple attributes syscall to go with this.

===============
NEW SYSTEM CALL
===============

The new system call is:

	int ret = statx(int dfd,
			const char *filename,
			unsigned int flags,
			unsigned int mask,
			struct statx *buffer);

The dfd, filename and flags parameters indicate the file to query, in a
similar way to fstatat().  There is no equivalent of lstat() as that can be
emulated with statx() by passing AT_SYMLINK_NOFOLLOW in flags.  There is
also no equivalent of fstat() as that can be emulated by passing a NULL
filename to statx() with the fd of interest in dfd.

Whether or not statx() synchronises the attributes with the backing store
can be controlled by OR'ing a value into the flags argument (this typically
only affects network filesystems):

 (1) AT_STATX_SYNC_AS_STAT tells statx() to behave as stat() does in this
     respect.

 (2) AT_STATX_FORCE_SYNC will require a network filesystem to synchronise
     its attributes with the server - which might require data writeback to
     occur to get the timestamps correct.

 (3) AT_STATX_DONT_SYNC will suppress synchronisation with the server in a
     network filesystem.  The resulting values should be considered
     approximate.

mask is a bitmask indicating the fields in struct statx that are of
interest to the caller.  The user should set this to STATX_BASIC_STATS to
get the basic set returned by stat().  It should be noted that asking for
more information may entail extra I/O operations.

buffer points to the destination for the data.  This must be 256 bytes in
size.

======================
MAIN ATTRIBUTES RECORD
======================

The following structures are defined in which to return the main attribute
set:

	struct statx_timestamp {
		__s64	tv_sec;
		__s32	tv_nsec;
		__s32	__reserved;
	};

	struct statx {
		__u32	stx_mask;
		__u32	stx_blksize;
		__u64	stx_attributes;
		__u32	stx_nlink;
		__u32	stx_uid;
		__u32	stx_gid;
		__u16	stx_mode;
		__u16	__spare0[1];
		__u64	stx_ino;
		__u64	stx_size;
		__u64	stx_blocks;
		__u64	__spare1[1];
		struct statx_timestamp	stx_atime;
		struct statx_timestamp	stx_btime;
		struct statx_timestamp	stx_ctime;
		struct statx_timestamp	stx_mtime;
		__u32	stx_rdev_major;
		__u32	stx_rdev_minor;
		__u32	stx_dev_major;
		__u32	stx_dev_minor;
		__u64	__spare2[14];
	};

The defined bits in request_mask and stx_mask are:

	STATX_TYPE		Want/got stx_mode & S_IFMT
	STATX_MODE		Want/got stx_mode & ~S_IFMT
	STATX_NLINK		Want/got stx_nlink
	STATX_UID		Want/got stx_uid
	STATX_GID		Want/got stx_gid
	STATX_ATIME		Want/got stx_atime{,_ns}
	STATX_MTIME		Want/got stx_mtime{,_ns}
	STATX_CTIME		Want/got stx_ctime{,_ns}
	STATX_INO		Want/got stx_ino
	STATX_SIZE		Want/got stx_size
	STATX_BLOCKS		Want/got stx_blocks
	STATX_BASIC_STATS	[The stuff in the normal stat struct]
	STATX_BTIME		Want/got stx_btime{,_ns}
	STATX_ALL		[All currently available stuff]

stx_btime is the file creation time, stx_mask is a bitmask indicating the
data provided and __spares*[] are where as-yet undefined fields can be
placed.

Time fields are structures with separate seconds and nanoseconds fields
plus a reserved field in case we want to add even finer resolution.  Note
that times will be negative if before 1970; in such a case, the nanosecond
fields will also be negative if not zero.

The bits defined in the stx_attributes field convey information about a
file, how it is accessed, where it is and what it does.  The following
attributes map to FS_*_FL flags and are the same numerical value:

	STATX_ATTR_COMPRESSED		File is compressed by the fs
	STATX_ATTR_IMMUTABLE		File is marked immutable
	STATX_ATTR_APPEND		File is append-only
	STATX_ATTR_NODUMP		File is not to be dumped
	STATX_ATTR_ENCRYPTED		File requires key to decrypt in fs

Within the kernel, the supported flags are listed by:

	KSTAT_ATTR_FS_IOC_FLAGS

[Are any other IOC flags of sufficient general interest to be exposed
through this interface?]

New flags include:

	STATX_ATTR_AUTOMOUNT		Object is an automount trigger

These are for the use of GUI tools that might want to mark files specially,
depending on what they are.

Fields in struct statx come in a number of classes:

 (0) stx_dev_*, stx_blksize.

     These are local system information and are always available.

 (1) stx_mode, stx_nlinks, stx_uid, stx_gid, stx_[amc]time, stx_ino,
     stx_size, stx_blocks.

     These will be returned whether the caller asks for them or not.  The
     corresponding bits in stx_mask will be set to indicate whether they
     actually have valid values.

     If the caller didn't ask for them, then they may be approximated.  For
     example, NFS won't waste any time updating them from the server,
     unless as a byproduct of updating something requested.

     If the values don't actually exist for the underlying object (such as
     UID or GID on a DOS file), then the bit won't be set in the stx_mask,
     even if the caller asked for the value.  In such a case, the returned
     value will be a fabrication.

     Note that there are instances where the type might not be valid, for
     instance Windows reparse points.

 (2) stx_rdev_*.

     This will be set only if stx_mode indicates we're looking at a
     blockdev or a chardev, otherwise will be 0.

 (3) stx_btime.

     Similar to (1), except this will be set to 0 if it doesn't exist.

=======
TESTING
=======

The following test program can be used to test the statx system call:

	samples/statx/test-statx.c

Just compile and run, passing it paths to the files you want to examine.
The file is built automatically if CONFIG_SAMPLES is enabled.

Here's some example output.  Firstly, an NFS directory that crosses to
another FSID.  Note that the AUTOMOUNT attribute is set because transiting
this directory will cause d_automount to be invoked by the VFS.

	[root@andromeda ~]# /tmp/test-statx -A /warthog/data
	statx(/warthog/data) = 0
	results=7ff
	  Size: 4096            Blocks: 8          IO Block: 1048576  directory
	Device: 00:26           Inode: 1703937     Links: 125
	Access: (3777/drwxrwxrwx)  Uid:     0   Gid:  4041
	Access: 2016-11-24 09:02:12.219699527+0000
	Modify: 2016-11-17 10:44:36.225653653+0000
	Change: 2016-11-17 10:44:36.225653653+0000
	Attributes: 0000000000001000 (-------- -------- -------- -------- -------- -------- ---m---- --------)

Secondly, the result of automounting on that directory.

	[root@andromeda ~]# /tmp/test-statx /warthog/data
	statx(/warthog/data) = 0
	results=7ff
	  Size: 4096            Blocks: 8          IO Block: 1048576  directory
	Device: 00:27           Inode: 2           Links: 125
	Access: (3777/drwxrwxrwx)  Uid:     0   Gid:  4041
	Access: 2016-11-24 09:02:12.219699527+0000
	Modify: 2016-11-17 10:44:36.225653653+0000
	Change: 2016-11-17 10:44:36.225653653+0000

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-03-02 20:51:15 -05:00
Ingo Molnar 589ee62844 sched/headers: Prepare to remove the <linux/mm_types.h> dependency from <linux/sched.h>
Update code that relied on sched.h including various MM types for them.

This will allow us to remove the <linux/mm_types.h> include from <linux/sched.h>.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:37 +01:00
Ingo Molnar 68db0cf106 sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h>
We are going to split <linux/sched/task_stack.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/task_stack.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:36 +01:00
Ingo Molnar 3f07c01441 sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h>
We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/signal.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:29 +01:00
Jan Beulich 2140a9942b x86/entry/64: Relax pvops stub clobber specifications
Except for the error_exit case, none of the code paths following the
{DIS,EN}ABLE_INTERRUPTS() invocations being modified here make any
assumptions on register values, so all registers can be clobbered
there. In the error_exit case a minor adjustment to register usage
(at once eliminating an instruction) also allows for this to be true.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Andy Lutomirski <luto@kernel.org>
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: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/5894556D02000078001366D3@prv-mh.provo.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-01 10:16:35 +01:00
Jan Beulich fdbd518adf x86/entry/32: Relax a pvops stub clobber specification
The code at .Lrestore_nocheck does not make any assumptions on register
values, so all registers can be clobbered on code paths leading there.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Andy Lutomirski <luto@kernel.org>
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: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/5894542B02000078001366C5@prv-mh.provo.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-01 10:16:30 +01:00
Mike Rapoport 897ab3e0c4 userfaultfd: non-cooperative: add event for memory unmaps
When a non-cooperative userfaultfd monitor copies pages in the
background, it may encounter regions that were already unmapped.
Addition of UFFD_EVENT_UNMAP allows the uffd monitor to track precisely
changes in the virtual memory layout.

Since there might be different uffd contexts for the affected VMAs, we
first should create a temporary representation for the unmap event for
each uffd context and then notify them one by one to the appropriate
userfault file descriptors.

The event notification occurs after the mmap_sem has been released.

[arnd@arndb.de: fix nommu build]
  Link: http://lkml.kernel.org/r/20170203165141.3665284-1-arnd@arndb.de
[mhocko@suse.com: fix nommu build]
  Link: http://lkml.kernel.org/r/20170202091503.GA22823@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/1485542673-24387-3-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24 17:46:55 -08:00
Josh Poimboeuf ff3f7e2475 x86/entry: Fix the end of the stack for newly forked tasks
When unwinding a task, the end of the stack is always at the same offset
right below the saved pt_regs, regardless of which syscall was used to
enter the kernel.  That convention allows the unwinder to verify that a
stack is sane.

However, newly forked tasks don't always follow that convention, as
reported by the following unwinder warning seen by Dave Jones:

  WARNING: kernel stack frame pointer at ffffc90001443f30 in kworker/u8:8:30468 has bad value           (null)

The warning was due to the following call chain:

  (ftrace handler)
  call_usermodehelper_exec_async+0x5/0x140
  ret_from_fork+0x22/0x30

The problem is that ret_from_fork() doesn't create a stack frame before
calling other functions.  Fix that by carefully using the frame pointer
macros.

In addition to conforming to the end of stack convention, this also
makes related stack traces more sensible by making it clear to the user
that ret_from_fork() was involved.

Reported-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/8854cdaab980e9700a81e9ebf0d4238e4bbb68ef.1483978430.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-12 09:28:29 +01:00
Linus Torvalds 3ddc76dfc7 Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer type cleanups from Thomas Gleixner:
 "This series does a tree wide cleanup of types related to
  timers/timekeeping.

   - Get rid of cycles_t and use a plain u64. The type is not really
     helpful and caused more confusion than clarity

   - Get rid of the ktime union. The union has become useless as we use
     the scalar nanoseconds storage unconditionally now. The 32bit
     timespec alike storage got removed due to the Y2038 limitations
     some time ago.

     That leaves the odd union access around for no reason. Clean it up.

  Both changes have been done with coccinelle and a small amount of
  manual mopping up"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  ktime: Get rid of ktime_equal()
  ktime: Cleanup ktime_set() usage
  ktime: Get rid of the union
  clocksource: Use a plain u64 instead of cycle_t
2016-12-25 14:30:04 -08:00