linux-toradex.git/arch/powerpc/kernel/vmlinux.lds.S, branch v4.9.100

powerpc/64s: Add support for RFI flush of L1-D cache

2018-02-13T11:35:54+00:00

commit aa8a5e0062ac940f7659394f4817c948dc8c0667 upstream.

On some CPUs we can prevent the Meltdown vulnerability by flushing the
L1-D cache on exit from kernel to user mode, and from hypervisor to
guest.

This is known to be the case on at least Power7, Power8 and Power9. At
this time we do not know the status of the vulnerability on other CPUs
such as the 970 (Apple G5), pasemi CPUs (AmigaOne X1000) or Freescale
CPUs. As more information comes to light we can enable this, or other
mechanisms on those CPUs.

The vulnerability occurs when the load of an architecturally
inaccessible memory region (eg. userspace load of kernel memory) is
speculatively executed to the point where its result can influence the
address of a subsequent speculatively executed load.

In order for that to happen, the first load must hit in the L1,
because before the load is sent to the L2 the permission check is
performed. Therefore if no kernel addresses hit in the L1 the
vulnerability can not occur. We can ensure that is the case by
flushing the L1 whenever we return to userspace. Similarly for
hypervisor vs guest.

In order to flush the L1-D cache on exit, we add a section of nops at
each (h)rfi location that returns to a lower privileged context, and
patch that with some sequence. Newer firmwares are able to advertise
to us that there is a special nop instruction that flushes the L1-D.
If we do not see that advertised, we fall back to doing a displacement
flush in software.

For guest kernels we support migration between some CPU versions, and
different CPUs may use different flush instructions. So that we are
prepared to migrate to a machine with a different flush instruction
activated, we may have to patch more than one flush instruction at
boot if the hypervisor tells us to.

In the end this patch is mostly the work of Nicholas Piggin and
Michael Ellerman. However a cast of thousands contributed to analysis
of the issue, earlier versions of the patch, back ports testing etc.
Many thanks to all of them.

Tested-by: Jon Masters 
Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
[Balbir - back ported to stable with changes]
Signed-off-by: Balbir Singh 
Signed-off-by: Greg Kroah-Hartman

powerpc/64: Fix placement of .text to be immediately following .head.text

2016-12-01T11:26:31+00:00

Do not introduce any additional alignment. Placement of text section
will be set by fixed section macros. Without this, output section
alignment defaults to 4096, which makes BookE text section start at
0x1000 when it is expected to start at 0x100.

This was introduced by commit 57f266497d81 ("powerpc: Use gas sections
for arranging exception vectors") and was caught with the scripted head
section checker (not yet merged).

Fixes: 57f266497d81 ("powerpc: Use gas sections for arranging exception vectors")
Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman

Merge branch 'akpm' (patches from Andrew)

2016-10-08T04:38:00+00:00

Merge updates from Andrew Morton:

 - fsnotify updates

 - ocfs2 updates

 - all of MM

* emailed patches from Andrew Morton : (127 commits)
  console: don't prefer first registered if DT specifies stdout-path
  cred: simpler, 1D supplementary groups
  CREDITS: update Pavel's information, add GPG key, remove snail mail address
  mailmap: add Johan Hovold
  .gitattributes: set git diff driver for C source code files
  uprobes: remove function declarations from arch/{mips,s390}
  spelling.txt: "modeled" is spelt correctly
  nmi_backtrace: generate one-line reports for idle cpus
  arch/tile: adopt the new nmi_backtrace framework
  nmi_backtrace: do a local dump_stack() instead of a self-NMI
  nmi_backtrace: add more trigger_*_cpu_backtrace() methods
  min/max: remove sparse warnings when they're nested
  Documentation/filesystems/proc.txt: add more description for maps/smaps
  mm, proc: fix region lost in /proc/self/smaps
  proc: fix timerslack_ns CAP_SYS_NICE check when adjusting self
  proc: add LSM hook checks to /proc//timerslack_ns
  proc: relax /proc//timerslack_ns capability requirements
  meminfo: break apart a very long seq_printf with #ifdefs
  seq/proc: modify seq_put_decimal_[u]ll to take a const char *, not char
  proc: faster /proc/*/status
  ...

nmi_backtrace: generate one-line reports for idle cpus

2016-10-08T01:46:30+00:00

When doing an nmi backtrace of many cores, most of which are idle, the
output is a little overwhelming and very uninformative.  Suppress
messages for cpus that are idling when they are interrupted and just
emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN".

We do this by grouping all the cpuidle code together into a new
.cpuidle.text section, and then checking the address of the interrupted
PC to see if it lies within that section.

This commit suitably tags x86 and tile idle routines, and only adds in
the minimal framework for other architectures.

Link: http://lkml.kernel.org/r/1472487169-14923-5-git-send-email-cmetcalf@mellanox.com
Signed-off-by: Chris Metcalf 
Acked-by: Peter Zijlstra (Intel) 
Tested-by: Peter Zijlstra (Intel) 
Tested-by: Daniel Thompson  [arm]
Tested-by: Petr Mladek 
Cc: Aaron Tomlin 
Cc: Peter Zijlstra (Intel) 
Cc: "Rafael J. Wysocki" 
Cc: Russell King 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

powerpc: Use gas sections for arranging exception vectors

2016-10-04T02:06:56+00:00

Use assembler sections of fixed size and location to arrange the 64-bit
Book3S exception vector code (64-bit Book3E also uses it in head_64.S
for 0x0..0x100).

This allows better flexibility in arranging exception code and hiding
unimportant details behind macros.

Gas sections can be a bit painful to use this way, mainly because the
assembler does not know where they will be finally linked. Taking
absolute addresses requires a bit of trickery for example, but it can
be hidden behind macros for the most part.

Generated code is mostly the same except locations, offsets, alignments.

The "+ 0x2" is only required for the trap number / kvm exit number,
which gets loaded as a constant into a register.

Previously, code also used + 0x2 for label names, but we changed to
using "H" to distinguish HV case for that. Remove the last vestiges
of that.

__after_prom_start is taking absolute address of a label in another
fixed section. Newer toolchains seemed to compile this okay, but older
ones do not. FIXED_SYMBOL_ABS_ADDR is more foolproof, it just takes an
additional line to define.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman

powerpc: Ensure .mem(init|exit).text are within _stext/_etext

2016-09-19T00:53:56+00:00

In our linker script we open code the list of text sections, because we
need to include the __ftr_alt sections, which are arch-specific.

This means we can't use TEXT_TEXT as defined in vmlinux.lds.h, and so we
don't have the MEM_KEEP() logic for memory hotplug sections.

If we build the kernel with the gold linker, and with CONFIG_MEMORY_HOTPLUG=y,
we see that functions marked __meminit can end up outside of the
_stext/_etext range, and also outside of _sinittext/_einittext, eg:

    c000000000000000 T _stext
    c0000000009e0000 A _etext
    c0000000009e3f18 T hash__vmemmap_create_mapping
    c000000000ca0000 T _sinittext
    c000000000d00844 T _einittext

This causes them to not be recognised as text by is_kernel_text(), and
prevents them being patched by jump_label (and presumably ftrace/kprobes
etc.).

Fix it by adding MEM_KEEP() directives, mirroring what TEXT_TEXT does.

This isn't a problem when CONFIG_MEMORY_HOTPLUG=n, because we use the
standard INIT_TEXT_SECTION() and EXIT_TEXT macros from vmlinux.lds.h.

Signed-off-by: Michael Ellerman 
Tested-by: Anton Blanchard 
Signed-off-by: Michael Ellerman

powerpc/32: Remove RELOCATABLE_PPC32

2016-07-19T10:17:07+00:00

It is seldom used in the kernel code and can be easily replaced by
either RELOCATABLE or PPC32. So there is no reason to keep a separate
kernel option for this.

Signed-off-by: Kevin Hao 
Signed-off-by: Michael Ellerman

arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections

2016-03-25T23:37:42+00:00

KASAN needs to know whether the allocation happens in an IRQ handler.
This lets us strip everything below the IRQ entry point to reduce the
number of unique stack traces needed to be stored.

Move the definition of __irq_entry to  so that the
users don't need to pull in .  Also introduce the
__softirq_entry macro which is similar to __irq_entry, but puts the
corresponding functions to the .softirqentry.text section.

Signed-off-by: Alexander Potapenko 
Acked-by: Steven Rostedt 
Cc: Christoph Lameter 
Cc: Pekka Enberg 
Cc: David Rientjes 
Cc: Joonsoo Kim 
Cc: Andrey Konovalov 
Cc: Dmitry Vyukov 
Cc: Andrey Ryabinin 
Cc: Konstantin Serebryany 
Cc: Dmitry Chernenkov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

powerpc: discard .exit.data at runtime

2015-10-15T09:31:59+00:00

.exit.text is discarded at run time and there are some references from
that to .exit.data, so we need to discard .exit.data at run time as well.

Fixes these errors:

`.exit.data' referenced in section `.exit.text' of drivers/built-in.o: defined in discarded section `.exit.data' of drivers/built-in.o
`.exit.data' referenced in section `.exit.text' of drivers/built-in.o: defined in discarded section `.exit.data' of drivers/built-in.o

Signed-off-by: Stephen Rothwell 
Signed-off-by: Michael Ellerman

powerpc: Align TOC to 256 bytes

2015-05-14T06:59:21+00:00

Recent toolchains force the TOC to be 256 byte aligned. We need
to enforce this alignment in our linker script, otherwise pointers
to our TOC variables (__toc_start, __prom_init_toc_start) could
be incorrect.

If they are bad, we die a few hundred instructions into boot.

Cc: stable@vger.kernel.org
Signed-off-by: Anton Blanchard 
Signed-off-by: Michael Ellerman