linux.git/arch/x86/kernel/dumpstack.c, branch v4.17

x86/dumpstack: Unify show_regs()

2018-03-08T11:04:59+00:00

The 32-bit version uses KERN_EMERG and commit

  b0f4c4b32c8e ("bugs, x86: Fix printk levels for panic, softlockups and stack dumps")

changed the 64-bit version to KERN_DEFAULT. The same justification in
that commit that those messages do not belong in the terminal, holds
true for 32-bit also, so make it so.

Make code_bytes static, while at it.

Signed-off-by: Borislav Petkov 
Signed-off-by: Thomas Gleixner 
Cc: Peter Zijlstra 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Andy Lutomirski 
Link: https://lkml.kernel.org/r/20180306094920.16917-4-bp@alien8.de

x86/dumpstack: Avoid uninitlized variable

2018-02-02T22:33:50+00:00

In some configurations, 'partial' does not get initialized, as shown by
this gcc-8 warning:

arch/x86/kernel/dumpstack.c: In function 'show_trace_log_lvl':
arch/x86/kernel/dumpstack.c:156:4: error: 'partial' may be used uninitialized in this function [-Werror=maybe-uninitialized]
    show_regs_if_on_stack(&stack_info, regs, partial);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This initializes it to false, to get the previous behavior in this case.

Fixes: a9cdbe72c4e8 ("x86/dumpstack: Fix partial register dumps")
Signed-off-by: Arnd Bergmann 
Signed-off-by: Thomas Gleixner 
Cc: Andi Kleen 
Cc: Nicolas Pitre 
Cc: Peter Zijlstra 
Cc: Dave Hansen 
Cc: Andy Lutomirski 
Cc: Josh Poimboeuf 
Cc: Borislav Petkov 
Cc: Vlastimil Babka 
Link: https://lkml.kernel.org/r/20180202145634.200291-1-arnd@arndb.de

x86/dumpstack: Print registers for first stack frame

2018-01-03T15:14:46+00:00

In the stack dump code, if the frame after the starting pt_regs is also
a regs frame, the registers don't get printed.  Fix that.

Reported-by: Andy Lutomirski 
Tested-by: Alexander Tsoy 
Signed-off-by: Josh Poimboeuf 
Cc: Andy Lutomirski 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Toralf Förster 
Cc: stable@vger.kernel.org
Fixes: 3b3fa11bc700 ("x86/dumpstack: Print any pt_regs found on the stack")
Link: http://lkml.kernel.org/r/396f84491d2f0ef64eda4217a2165f5712f6a115.1514736742.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

x86/dumpstack: Fix partial register dumps

2018-01-03T15:14:46+00:00

The show_regs_safe() logic is wrong.  When there's an iret stack frame,
it prints the entire pt_regs -- most of which is random stack data --
instead of just the five registers at the end.

show_regs_safe() is also poorly named: the on_stack() checks aren't for
safety.  Rename the function to show_regs_if_on_stack() and add a
comment to explain why the checks are needed.

These issues were introduced with the "partial register dump" feature of
the following commit:

  b02fcf9ba121 ("x86/unwinder: Handle stack overflows more gracefully")

That patch had gone through a few iterations of development, and the
above issues were artifacts from a previous iteration of the patch where
'regs' pointed directly to the iret frame rather than to the (partially
empty) pt_regs.

Tested-by: Alexander Tsoy 
Signed-off-by: Josh Poimboeuf 
Cc: Andy Lutomirski 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Toralf Förster 
Cc: stable@vger.kernel.org
Fixes: b02fcf9ba121 ("x86/unwinder: Handle stack overflows more gracefully")
Link: http://lkml.kernel.org/r/5b05b8b344f59db2d3d50dbdeba92d60f2304c54.1514736742.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

x86/dumpstack: Indicate in Oops whether PTI is configured and enabled

2017-12-23T20:13:01+00:00

CONFIG_PAGE_TABLE_ISOLATION is relatively new and intrusive feature that may
still have some corner cases which could take some time to manifest and be
fixed. It would be useful to have Oops messages indicate whether it was
enabled for building the kernel, and whether it was disabled during boot.

Example of fully enabled:

	Oops: 0001 [#1] SMP PTI

Example of enabled during build, but disabled during boot:

	Oops: 0001 [#1] SMP NOPTI

We can decide to remove this after the feature has been tested in the field
long enough.

[ tglx: Made it use boot_cpu_has() as requested by Borislav ]

Signed-off-by: Vlastimil Babka 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Eduardo Valentin 
Acked-by: Dave Hansen 
Cc: Andy Lutomirski 
Cc: Andy Lutomirsky 
Cc: Boris Ostrovsky 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Dave Hansen 
Cc: David Laight 
Cc: Denys Vlasenko 
Cc: Greg KH 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Juergen Gross 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Will Deacon 
Cc: aliguori@amazon.com
Cc: bpetkov@suse.de
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: jkosina@suse.cz
Cc: keescook@google.com
Signed-off-by: Ingo Molnar

x86/cpu_entry_area: Move it out of the fixmap

2017-12-22T19:13:05+00:00

Put the cpu_entry_area into a separate P4D entry. The fixmap gets too big
and 0-day already hit a case where the fixmap PTEs were cleared by
cleanup_highmap().

Aside of that the fixmap API is a pain as it's all backwards.

Signed-off-by: Thomas Gleixner 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Dave Hansen 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Juergen Gross 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

x86/entry: Rename SYSENTER_stack to CPU_ENTRY_AREA_entry_stack

2017-12-22T19:13:02+00:00

If the kernel oopses while on the trampoline stack, it will print
"" even if SYSENTER is not involved.  That is rather confusing.

The "SYSENTER" stack is used for a lot more than SYSENTER now.  Give it a
better string to display in stack dumps, and rename the kernel code to
match.

Also move the 32-bit code over to the new naming even though it still uses
the entry stack only for SYSENTER.

Signed-off-by: Dave Hansen 
Signed-off-by: Thomas Gleixner 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Juergen Gross 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Signed-off-by: Ingo Molnar

x86/entry: Clean up the SYSENTER_stack code

2017-12-17T13:27:51+00:00

The existing code was a mess, mainly because C arrays are nasty.  Turn
SYSENTER_stack into a struct, add a helper to find it, and do all the
obvious cleanups this enables.

Signed-off-by: Andy Lutomirski 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Thomas Gleixner 
Reviewed-by: Borislav Petkov 
Cc: Boris Ostrovsky 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Dave Hansen 
Cc: Dave Hansen 
Cc: David Laight 
Cc: Denys Vlasenko 
Cc: Eduardo Valentin 
Cc: Greg KH 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Juergen Gross 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Rik van Riel 
Cc: Will Deacon 
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150606.653244723@linutronix.de
Signed-off-by: Ingo Molnar

x86/entry/64: Remove the SYSENTER stack canary

2017-12-17T13:27:51+00:00

Now that the SYSENTER stack has a guard page, there's no need for a canary
to detect overflow after the fact.

Signed-off-by: Andy Lutomirski 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Thomas Gleixner 
Reviewed-by: Borislav Petkov 
Cc: Boris Ostrovsky 
Cc: Borislav Petkov 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Dave Hansen 
Cc: Dave Hansen 
Cc: David Laight 
Cc: Denys Vlasenko 
Cc: Eduardo Valentin 
Cc: Greg KH 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Juergen Gross 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Rik van Riel 
Cc: Will Deacon 
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150606.572577316@linutronix.de
Signed-off-by: Ingo Molnar

x86/entry: Remap the TSS into the CPU entry area

2017-12-17T12:59:56+00:00

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: Andy Lutomirski 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Thomas Gleixner 
Reviewed-by: Borislav Petkov 
Cc: Boris Ostrovsky 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Dave Hansen 
Cc: Dave Hansen 
Cc: David Laight 
Cc: Denys Vlasenko 
Cc: Eduardo Valentin 
Cc: Greg KH 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Juergen Gross 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Rik van Riel 
Cc: Will Deacon 
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.de
Signed-off-by: Ingo Molnar