Handling SYSCALL is tricky: the SYSCALL handler is entered with every
single register (except FLAGS), including RSP, live.  It somehow needs
to set RSP to point to a valid stack, which means it needs to save the
user RSP somewhere and find its own stack pointer.  The canonical way
to do this is with SWAPGS, which lets us access percpu data using the
%gs prefix.

With PAGE_TABLE_ISOLATION-like pagetable switching, this is
problematic.  Without a scratch register, switching CR3 is impossible, so
%gs-based percpu memory would need to be mapped in the user pagetables.
Doing that without information leaks is difficult or impossible.

Instead, use a different sneaky trick.  Map a copy of the first part
of the SYSCALL asm at a different address for each CPU.  Now RIP
varies depending on the CPU, so we can use RIP-relative memory access
to access percpu memory.  By putting the relevant information (one
scratch slot and the stack address) at a constant offset relative to
RIP, we can make SYSCALL work without relying on %gs.

A nice thing about this approach is that we can easily switch it on
and off if we want pagetable switching to be configurable.

The compat variant of SYSCALL doesn't have this problem in the first
place -- there are plenty of scratch registers, since we don't care
about preserving r8-r15.  This patch therefore doesn't touch SYSCALL32
at all.

This patch actually seems to be a small speedup.  With this patch,
SYSCALL touches an extra cache line and an extra virtual page, but
the pipeline no longer stalls waiting for SWAPGS.  It seems that, at
least in a tight loop, the latter outweights the former.

Thanks to David Laight for an optimization tip.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bpetkov@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150606.403607157@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

By itself, this is useless.  It gives us the ability to run some final code
before exit that cannnot run on the kernel stack.  This could include a CR3
switch a la PAGE_TABLE_ISOLATION or some kernel stack erasing, for
example.  (Or even weird things like *changing* which kernel stack gets
used as an ASLR-strengthening mechanism.)

The SYSRET32 path is not covered yet.  It could be in the future or
we could just ignore it and force the slow path if needed.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150606.306546484@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

Historically, IDT entries from usermode have always gone directly
to the running task's kernel stack.  Rearrange it so that we enter on
a per-CPU trampoline stack and then manually switch to the task's stack.
This touches a couple of extra cachelines, but it gives us a chance
to run some code before we touch the kernel stack.

The asm isn't exactly beautiful, but I think that fully refactoring
it can wait.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150606.225330557@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

When we start using an entry trampoline, a #GP from userspace will
be delivered on the entry stack, not on the task stack.  Fix the
espfix64 #DF fixup to set up #GP according to TSS.SP0, rather than
assuming that pt_regs + 1 == SP0.  This won't change anything
without an entry stack, but it will make the code continue to work
when an entry stack is added.

While we're at it, improve the comments to explain what's actually
going on.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150606.130778051@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

On 64-bit kernels, we used to assume that TSS.sp0 was the current
top of stack.  With the addition of an entry trampoline, this will
no longer be the case.  Store the current top of stack in TSS.sp1,
which is otherwise unused but shares the same cacheline.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150606.050864668@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

This has a secondary purpose: it puts the entry stack into a region
with a well-controlled layout.  A subsequent patch will take
advantage of this to streamline the SYSCALL entry code to be able to
find it more easily.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bpetkov@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150605.962042855@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

SYSENTER_stack should have reliable overflow detection, which
means that it needs to be at the bottom of a page, not the top.
Move it to the beginning of struct tss_struct and page-align it.

Also add an assertion to make sure that the fixed hardware TSS
doesn't cross a page boundary.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150605.881827433@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

We currently special-case stack overflow on the task stack.  We're
going to start putting special stacks in the fixmap with a custom
layout, so they'll have guard pages, too.  Teach the unwinder to be
able to unwind an overflow of any of the stacks.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150605.802057305@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

A future patch will move SYSENTER_stack to the beginning of cpu_tss
to help detect overflow.  Before this can happen, fix several code
paths that hardcode assumptions about the old layout.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NDave Hansen <dave.hansen@intel.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150605.722425540@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

The cpu_entry_area will contain stacks.  Make sure that KASAN has
appropriate shadow mappings for them.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: kasan-dev@googlegroups.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150605.642806442@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

Currently, the GDT is an ad-hoc array of pages, one per CPU, in the
fixmap.  Generalize it to be an array of a new 'struct cpu_entry_area'
so that we can cleanly add new things to it.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150605.563271721@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

We currently have CPU 0's GDT at the top of the GDT range and
higher-numbered CPUs at lower addresses.  This happens because the
fixmap is upside down (index 0 is the top of the fixmap).

Flip it so that GDTs are in ascending order by virtual address.
This will simplify a future patch that will generalize the GDT
remap to contain multiple pages.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150605.471561421@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

get_stack_info() doesn't currently know about the SYSENTER stack, so
unwinding will fail if we entered the kernel on the SYSENTER stack
and haven't fully switched off.  Teach get_stack_info() about the
SYSENTER stack.

With future patches applied that run part of the entry code on the
SYSENTER stack and introduce an intentional BUG(), I would get:

  PANIC: double fault, error_code: 0x0
  ...
  RIP: 0010:do_error_trap+0x33/0x1c0
  ...
  Call Trace:
  Code: ...

With this patch, I get:

  PANIC: double fault, error_code: 0x0
  ...
  Call Trace:
   <SYSENTER>
   ? async_page_fault+0x36/0x60
   ? invalid_op+0x22/0x40
   ? async_page_fault+0x36/0x60
   ? sync_regs+0x3c/0x40
   ? sync_regs+0x2e/0x40
   ? error_entry+0x6c/0xd0
   ? async_page_fault+0x36/0x60
   </SYSENTER>
  Code: ...

which is a lot more informative.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150605.392711508@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

This will simplify future changes that want scratch variables early in
the SYSENTER handler -- they'll be able to spill registers to the
stack.  It also lets us get rid of a SWAPGS_UNSAFE_STACK user.

This does not depend on CONFIG_IA32_EMULATION=y because we'll want the
stack space even without IA32 emulation.

As far as I can tell, the reason that this wasn't done from day 1 is
that we use IST for #DB and #BP, which is IMO rather nasty and causes
a lot more problems than it solves.  But, since #DB uses IST, we don't
actually need a real stack for SYSENTER (because SYSENTER with TF set
will invoke #DB on the IST stack rather than the SYSENTER stack).

I want to remove IST usage from these vectors some day, and this patch
is a prerequisite for that as well.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150605.312726423@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

In case something goes wrong with unwind (not unlikely in case of
overflow), print the offending IP where we detected the overflow.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150605.231677119@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

That race has been fixed and code cleaned up for a while now.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150605.150551639@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

There are at least two unwinder bugs hindering the debugging of
stack-overflow crashes:

- It doesn't deal gracefully with the case where the stack overflows and
  the stack pointer itself isn't on a valid stack but the
  to-be-dereferenced data *is*.

- The ORC oops dump code doesn't know how to print partial pt_regs, for the
  case where if we get an interrupt/exception in *early* entry code
  before the full pt_regs have been saved.

Fix both issues.

http://lkml.kernel.org/r/20171126024031.uxi4numpbjm5rlbr@trebleSigned-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bpetkov@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150605.071425003@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

If the stack overflows into a guard page and the ORC unwinder should work
well: by construction, there can't be any meaningful data in the guard page
because no writes to the guard page will have succeeded.

But there is a bug that prevents unwinding from working correctly: if the
starting register state has RSP pointing into a stack guard page, the ORC
unwinder bails out immediately.

Instead of bailing out immediately check whether the next page up is a
valid check page and if so analyze that. As a result the ORC unwinder will
start the unwind.

Tested by intentionally overflowing the task stack.  The result is an
accurate call trace instead of a trace consisting purely of '?' entries.

There are a few other bugs that are triggered if the unwinder encounters a
stack overflow after the first step, but they are outside the scope of this
fix.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150604.991389777@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

Commit 1d3e53e8 ("x86/entry/64: Refactor IRQ stacks and make them
NMI-safe") added DEBUG_ENTRY_ASSERT_IRQS_OFF macro that acceses eflags
using 'pushfq' instruction when testing for IF bit. On PV Xen guests
looking at IF flag directly will always see it set, resulting in 'ud2'.

Introduce SAVE_FLAGS() macro that will use appropriate save_fl pv op when
running paravirt.
Signed-off-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NJuergen Gross <jgross@suse.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: xen-devel@lists.xenproject.org
Link: https://lkml.kernel.org/r/20171204150604.899457242@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

[ Note, this is a Git cherry-pick of the following commit:

    d17a1d97: ("x86/mm/kasan: don't use vmemmap_populate() to initialize shadow")

  ... for easier x86 PTI code testing and back-porting. ]

The KASAN shadow is currently mapped using vmemmap_populate() since that
provides a semi-convenient way to map pages into init_top_pgt.  However,
since that no longer zeroes the mapped pages, it is not suitable for
KASAN, which requires zeroed shadow memory.

Add kasan_populate_shadow() interface and use it instead of
vmemmap_populate().  Besides, this allows us to take advantage of
gigantic pages and use them to populate the shadow, which should save us
some memory wasted on page tables and reduce TLB pressure.

Link: http://lkml.kernel.org/r/20171103185147.2688-2-pasha.tatashin@oracle.comSigned-off-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: NPavel Tatashin <pasha.tatashin@oracle.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Bob Picco <bob.picco@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

[ Note, this is a Git cherry-pick of the following commit:

    506458ef ("locking/barriers: Convert users of lockless_dereference() to READ_ONCE()")

  ... for easier x86 PTI code testing and back-porting. ]

READ_ONCE() now has an implicit smp_read_barrier_depends() call, so it
can be used instead of lockless_dereference() without any change in
semantics.
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-4-git-send-email-will.deacon@arm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

[ Note, this is a Git cherry-pick of the following commit:

    a47ba4d7 ("perf/x86: Enable free running PEBS for REGS_USER/INTR")

  ... for easier x86 PTI code testing and back-porting. ]

Currently free running PEBS is disabled when user or interrupt
registers are requested. Most of the registers are actually
available in the PEBS record and can be supported.

So we just need to check for the supported registers and then
allow it: it is all except for the segment register.

For user registers this only works when the counter is limited
to ring 3 only, so this also needs to be checked.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.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/20170831214630.21892-1-andi@firstfloor.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

[ Note, this is a Git cherry-pick of the following commit:

    2b67799bdf25 ("x86: Make X86_BUG_FXSAVE_LEAK detectable in CPUID on AMD")

  ... for easier x86 PTI code testing and back-porting. ]

The latest AMD AMD64 Architecture Programmer's Manual
adds a CPUID feature XSaveErPtr (CPUID_Fn80000008_EBX[2]).

If this feature is set, the FXSAVE, XSAVE, FXSAVEOPT, XSAVEC, XSAVES
/ FXRSTOR, XRSTOR, XRSTORS always save/restore error pointers,
thus making the X86_BUG_FXSAVE_LEAK workaround obsolete on such CPUs.
Signed-Off-By: NRudolf Marek <r.marek@assembler.cz>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Tested-by: NBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: https://lkml.kernel.org/r/bdcebe90-62c5-1f05-083c-eba7f08b2540@assembler.czSigned-off-by: NIngo Molnar <mingo@kernel.org>

[ Note, this is a Git cherry-pick of the following commit: (limited to the cpufeatures.h file)

    3522c2a6 ("x86/cpufeature: Add User-Mode Instruction Prevention definitions")

  ... for easier x86 PTI code testing and back-porting. ]

User-Mode Instruction Prevention is a security feature present in new
Intel processors that, when set, prevents the execution of a subset of
instructions if such instructions are executed in user mode (CPL > 0).
Attempting to execute such instructions causes a general protection
exception.

The subset of instructions comprises:

 * SGDT - Store Global Descriptor Table
 * SIDT - Store Interrupt Descriptor Table
 * SLDT - Store Local Descriptor Table
 * SMSW - Store Machine Status Word
 * STR  - Store Task Register

This feature is also added to the list of disabled-features to allow
a cleaner handling of build-time configuration.
Signed-off-by: NRicardo Neri <ricardo.neri-calderon@linux.intel.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chen Yucong <slaoub@gmail.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi V. Shankar <ravi.v.shankar@intel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: ricardo.neri@intel.com
Link: http://lkml.kernel.org/r/1509935277-22138-7-git-send-email-ricardo.neri-calderon@linux.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

This reverts commit 941f5f0f.

Sadly, it turns out that we really can't just do the cross-CPU IPI to
all CPU's to get their proper frequencies, because it's much too
expensive on systems with lots of cores.

So we'll have to revert this for now, and revisit it using a smarter
model (probably doing one system-wide IPI at open time, and doing all
the frequency calculations in parallel).
Reported-by: NWANG Chao <chao.wang@ucloud.cn>
Reported-by: NIngo Molnar <mingo@kernel.org>
Cc: Rafael J Wysocki <rafael.j.wysocki@intel.com>
Cc: stable@kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The x86_hyper pointer is only used for checking whether a virtual
device is supporting the hypervisor the system is running on.

Use an enum for that purpose instead and drop the x86_hyper pointer.
Signed-off-by: NJuergen Gross <jgross@suse.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NXavier Deguillard <xdeguillard@vmware.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: akataria@vmware.com
Cc: arnd@arndb.de
Cc: boris.ostrovsky@oracle.com
Cc: devel@linuxdriverproject.org
Cc: dmitry.torokhov@gmail.com
Cc: gregkh@linuxfoundation.org
Cc: haiyangz@microsoft.com
Cc: kvm@vger.kernel.org
Cc: kys@microsoft.com
Cc: linux-graphics-maintainer@vmware.com
Cc: linux-input@vger.kernel.org
Cc: moltmann@vmware.com
Cc: pbonzini@redhat.com
Cc: pv-drivers@vmware.com
Cc: rkrcmar@redhat.com
Cc: sthemmin@microsoft.com
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/20171109132739.23465-3-jgross@suse.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Instead of x86_hyper being either NULL on bare metal or a pointer to a
struct hypervisor_x86 in case of the kernel running as a guest merge
the struct into x86_platform and x86_init.

This will remove the need for wrappers making it hard to find out what
is being called. With dummy functions added for all callbacks testing
for a NULL function pointer can be removed, too.
Suggested-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NJuergen Gross <jgross@suse.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: akataria@vmware.com
Cc: boris.ostrovsky@oracle.com
Cc: devel@linuxdriverproject.org
Cc: haiyangz@microsoft.com
Cc: kvm@vger.kernel.org
Cc: kys@microsoft.com
Cc: pbonzini@redhat.com
Cc: rkrcmar@redhat.com
Cc: rusty@rustcorp.com.au
Cc: sthemmin@microsoft.com
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/20171109132739.23465-2-jgross@suse.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Commit:

  9a93848f ("x86/debug: Implement __WARN() using UD0")

turned warnings into UD0, but the fixup code only runs after the
notify_die() chain. This is a problem, in particular, with kgdb,
which kicks in as if it was a BUG().

Fix this by running the fixup code before the notifier chain in
the invalid op handler path.
Signed-off-by: NAlexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: NIlya Dryomov <idryomov@gmail.com>
Acked-by: NDaniel Thompson <daniel.thompson@linaro.org>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Weinberger <richard.weinberger@gmail.com>
Cc: <stable@vger.kernel.org> # v4.12+
Link: http://lkml.kernel.org/r/20170724100428.19173-1-alexander.shishkin@linux.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

On machines with 5-level paging we don't want to allocate mapping above
47-bit unless user explicitly asked for it. See b569bab7 ("x86/mm:
Prepare to expose larger address space to userspace") for details.

c715b72c ("mm: revert x86_64 and arm64 ELF_ET_DYN_BASE base
changes") broke the behaviour. After the commit elf binary and heap got
mapped above 47-bits.

Use DEFAULT_MAP_WINDOW instead of TASK_SIZE to determine ELF_ET_DYN_BASE so
it's forced to be below 47-bits unconditionally.

Fixes: c715b72c ("mm: revert x86_64 and arm64 ELF_ET_DYN_BASE base changes")
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/20171107103804.47341-1-kirill.shutemov@linux.intel.com

Commit 7744ccdb ("x86/mm: Add Secure Memory Encryption (SME)
support") as a side-effect made PAGE_KERNEL all of a sudden unavailable
to modules which can't make use of EXPORT_SYMBOL_GPL() symbols.

This is because once SME is enabled, sme_me_mask (which is introduced as
EXPORT_SYMBOL_GPL) makes its way to PAGE_KERNEL through _PAGE_ENC,
causing imminent build failure for all the modules which make use of all
the EXPORT-SYMBOL()-exported API (such as vmap(), __vmalloc(),
remap_pfn_range(), ...).

Exporting (as EXPORT_SYMBOL()) interfaces (and having done so for ages)
that take pgprot_t argument, while making it impossible to -- all of a
sudden -- pass PAGE_KERNEL to it, feels rather incosistent.

Restore the original behavior and make it possible to pass PAGE_KERNEL
to all its EXPORT_SYMBOL() consumers.

[ This is all so not wonderful. We shouldn't need that "sme_me_mask"
  access at all in all those places that really don't care about that
  level of detail, and just want _PAGE_KERNEL or whatever.

  We have some similar issues with _PAGE_CACHE_WP and _PAGE_NOCACHE,
  both of which hide a "cachemode2protval()" call, and which also ends
  up using another EXPORT_SYMBOL(), but at least that only triggers for
  the much more rare cases.

  Maybe we could move these dynamic page table bits to be generated much
  deeper down in the VM layer, instead of hiding them in the macros that
  everybody uses.

  So this all would merit some cleanup. But not today.   - Linus ]

Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>
Despised-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit b70543a0("x86/idt: Move regular trap init to tables") moves
regular trap init for each trap vector into a table based
initialization. It introduced the initialization for vector X86_TRAP_BP
which was not in the code which it replaced. This breaks uprobe
functionality for x86_32; the probed program segfaults instead of handling
the probe proper.

The reason for this is that TRAP_BP is set up as system interrupt gate
(DPL3) in the early IDT and then replaced by a regular interrupt gate
(DPL0) in idt_setup_traps(). The DPL0 restriction causes the int3 trap
to fail with a #GP resulting in a SIGSEGV of the probed program.

On 64bit this does not cause a problem because the IDT entry is replaced
with a system interrupt gate (DPL3) with interrupt stack afterwards.

Remove X86_TRAP_BP from the def_idts table which is used in
idt_setup_traps(). Remove a redundant entry for X86_TRAP_NMI in def_idts
while at it. Tested on both x86_64 and x86_32.

[ tglx: Amended changelog with a description of the root cause ]

Fixes: b70543a0("x86/idt: Move regular trap init to tables")
Reported-and-tested-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: a.p.zijlstra@chello.nl
Cc: ast@fb.com
Cc: oleg@redhat.com
Cc: luto@kernel.org
Cc: kernel-team@fb.com
Link: https://lkml.kernel.org/r/20171108192845.552709-1-yhs@fb.com

The warning below says it all:

  BUG: using __this_cpu_read() in preemptible [00000000] code: swapper/0/1
  caller is __this_cpu_preempt_check
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.14.0-rc8 #4
  Call Trace:
   dump_stack
   check_preemption_disabled
   ? do_early_param
   __this_cpu_preempt_check
   arch_perfmon_init
   op_nmi_init
   ? alloc_pci_root_info
   oprofile_arch_init
   oprofile_init
   do_one_initcall
   ...

These accessors should not have been used in the first place: it is PPro so
no mixed silicon revisions and thus it can simply use boot_cpu_data.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Tested-by: NFengguang Wu <fengguang.wu@intel.com>
Fix-creation-mandated-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Robert Richter <rric@kernel.org>
Cc: x86@kernel.org
Cc: stable@vger.kernel.org

Fengguang reported a KASAN warning:

  Kprobe smoke test: started
  ==================================================================
  BUG: KASAN: stack-out-of-bounds in deref_stack_reg+0xb5/0x11a
  Read of size 8 at addr ffff8800001c7cd8 by task swapper/1

  CPU: 0 PID: 1 Comm: swapper Not tainted 4.14.0-rc8 #26
  Call Trace:
   <#DB>
   ...
   save_trace+0xd9/0x1d3
   mark_lock+0x5f7/0xdc3
   __lock_acquire+0x6b4/0x38ef
   lock_acquire+0x1a1/0x2aa
   _raw_spin_lock_irqsave+0x46/0x55
   kretprobe_table_lock+0x1a/0x42
   pre_handler_kretprobe+0x3f5/0x521
   kprobe_int3_handler+0x19c/0x25f
   do_int3+0x61/0x142
   int3+0x30/0x60
  [...]

The ORC unwinder got confused by some kprobes changes, which isn't
surprising since the runtime code no longer matches vmlinux and the
stack was modified for kretprobes.

Until we have a way for generated code to register changes with the
unwinder, these types of warnings are inevitable.  So just disable KASAN
checks for stack accesses in the ORC unwinder.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171108021934.zbl6unh5hpugybc5@trebleSigned-off-by: NIngo Molnar <mingo@kernel.org>

If the TSC has constant frequency then the delay calibration can be skipped
when it has been calibrated for a package already. This is checked in
calibrate_delay_is_known(), but that function is buggy in two aspects:

It returns 'false' if

  (!tsc_disabled && !cpu_has(&cpu_data(cpu), X86_FEATURE_CONSTANT_TSC)

which is obviously the reverse of the intended check and the check for the
sibling mask cannot work either because the topology links have not been
set up yet.

Correct the condition and move the call to set_cpu_sibling_map() before
invoking calibrate_delay() so the sibling check works correctly.

[ tglx: Rewrote changelong ]

Fixes: c25323c0 ("x86/tsc: Use topology functions")
Signed-off-by: NPavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: peterz@infradead.org
Cc: bob.picco@oracle.com
Cc: steven.sistare@oracle.com
Cc: daniel.m.jordan@oracle.com
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20171028001100.26603-1-pasha.tatashin@oracle.com

Replace ghes_io{re,un}map_pfn_{nmi,irq}()s use of ioremap_page_range()
with __set_fixmap() as ioremap_page_range() may sleep to allocate a new
level of page-table, even if its passed an existing final-address to
use in the mapping.

The GHES driver can only be enabled for architectures that select
HAVE_ACPI_APEI: Add fixmap entries to both x86 and arm64.

clear_fixmap() does the TLB invalidation in __set_fixmap() for arm64
and __set_pte_vaddr() for x86. In each case its the same as the
respective arch_apei_flush_tlb_one().
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Suggested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJames Morse <james.morse@arm.com>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Tested-by: NTyler Baicar <tbaicar@codeaurora.org>
Tested-by: NToshi Kani <toshi.kani@hpe.com>
[ For the arm64 bits: ]
Acked-by: NWill Deacon <will.deacon@arm.com>
[ For the x86 bits: ]
Acked-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: All applicable <stable@vger.kernel.org>

Kept this commit separate from the re-tabulation changes, to make
the changes easier to review:

 - add better explanation for entries with no explanation
 - fix/enhance the text of some of the entries
 - fix the vertical alignment of some of the feature number definitions
 - fix inconsistent capitalization
 - ... and lots of other small details

i.e. make it all more of a coherent unit, instead of a patchwork of years of additions.

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: Denys Vlasenko <dvlasenk@redhat.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/20171031121723.28524-4-mingo@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

Over the years asm/cpufeatures.h has become somewhat of a mess: the original
tabulation style was too narrow, while x86 feature names also kept growing
in length, creating frequent field width overflows.

Re-tabulate it to make it wider and easier to read/modify. Also harmonize
the tabulation of the other defines in this file to match it.

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: Denys Vlasenko <dvlasenk@redhat.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/20171031121723.28524-3-mingo@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

... so that the difference is obvious.

No functionality change.
Signed-off-by: NBorislav Petkov <bp@suse.de>
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/20171103102028.20284-1-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

There have been some cases where external tooling (e.g., kpatch-build)
creates a corrupt relocation which targets the wrong address.  This is a
silent failure which can corrupt memory in unexpected places.

On x86, the bytes of data being overwritten by relocations are always
initialized to zero beforehand.  Use that knowledge to add sanity checks
to detect such cases before they corrupt memory.
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jeyu@kernel.org
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/37450d6c6225e54db107fba447ce9e56e5f758e9.1509713553.git.jpoimboe@redhat.com
[ Restructured the messages, as it's unclear whether the relocation or the target is corrupted. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>

This reverts commit 43858b4f.

The reason I removed the leave_mm() calls in question is because the
heuristic wasn't needed after that patch.  With the original version
of my PCID series, we never flushed a "lazy cpu" (i.e. a CPU running
kernel thread) due a flush on the loaded mm.

Unfortunately, that caused architectural issues, so now I've
reinstated these flushes on non-PCID systems in:

    commit b956575b ("x86/mm: Flush more aggressively in lazy TLB mode").

That, in turn, gives us a power management and occasionally
performance regression as compared to old kernels: a process that
goes into a deep idle state on a given CPU and gets its mm flushed
due to activity on a different CPU will wake the idle CPU.

Reinstate the old ugly heuristic: if a CPU goes into ACPI C3 or an
intel_idle state that is likely to cause a TLB flush gets its mm
switched to init_mm before going idle.

FWIW, this heuristic is lousy.  Whether we should change CR3 before
idle isn't a good hint except insofar as the performance hit is a bit
lower if the TLB is getting flushed by the idle code anyway.  What we
really want to know is whether we anticipate being idle long enough
that the mm is likely to be flushed before we wake up.  This is more a
matter of the expected latency than the idle state that gets chosen.
This heuristic also completely fails on systems that don't know
whether the TLB will be flushed (e.g. AMD systems?).  OTOH it may be a
bit obsolete anyway -- PCID systems don't presently benefit from this
heuristic at all.

We also shouldn't do this callback from innermost bit of the idle code
due to the RCU nastiness it causes.  All the information need is
available before rcu_idle_enter() needs to happen.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.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>
Fixes: 43858b4f "x86/mm: Stop calling leave_mm() in idle code"
Link: http://lkml.kernel.org/r/c513bbd4e653747213e05bc7062de000bf0202a5.1509793738.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>