For CONFIG_STRICT_KERNEL_RWX align __init_begin to 16M. We use 16M
since its the larger of 2M on radix and 16M on hash for our linear
mapping. The plan is to have .text, .rodata and everything upto
__init_begin marked as RX. Note we still have executable read only
data. We could further align rodata to another 16M boundary. I've used
keeping text plus rodata as read-only-executable as a trade-off to
doing read-only-executable for text and read-only for rodata.

We don't use multi PT_LOAD in PHDRS because we are not sure if all
bootloaders support them. This patch keeps PHDRS in vmlinux.lds.S as
the same they are with just one PT_LOAD for all of the kernel marked
as RWX (7).

mpe: What this means is the added alignment bloats the resulting
binary on disk, a powernv kernel goes from 17M to 22M.

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Add --orphan-handling=warn to final link flags. This ensures we can
handle all sections explicitly. This would have caught subtle breakage
such as 7de3b27bac47da9de08409df1d69664acbb72197 at build-time.

Also bring existing orphan sections into the fold:
- .text.hot and .text.unlikely are compiler generated sections.
- .sdata2, .dynsbss, .plt are used by PPC32
- We previously did not specify DWARF_DEBUG or STABS_DEBUG
- DWARF_DEBUG did not include all DWARF sections that can be emitted
- A number of sections are unused and can be discarded.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Use a tool to check that the location of "fixed sections" are where
we expected them to be, which catches cases the linker script can't
(stubs being added to start of .text section), and which ends up
being neater.

Sample output:

  ERROR: start_text address is c000000000008100, should be c000000000008000
  ERROR: see comments in arch/powerpc/tools/head_check.sh

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fold in fix from Nick for 4.6 era toolchains]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Very large kernels may require linker stubs for branches from HEAD
text code. The linker may place these stubs before the HEAD text
sections, which breaks the assumption that HEAD text is located at 0
(or the .text section being located at 0x7000/0x8000 on Book3S
kernels).

Provide an option to create a small section just before the .text
section with an empty 256 - 4 bytes, and adjust the start of the .text
section to match. The linker will tend to put stubs in that section
and not break our relative-to-absolute offset assumptions.

This causes a small waste of space on common kernels, but allows large
kernels to build and boot. For now, it is an EXPERT config option,
defaulting to =n, but a reference is provided for it in the build-time
check for such breakage. This is good enough for allyesconfig and
custom users / hackers.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Pull powerpc updates from Michael Ellerman:
 "Highlights include:

   - Larger virtual address space on 64-bit server CPUs. By default we
     use a 128TB virtual address space, but a process can request access
     to the full 512TB by passing a hint to mmap().

   - Support for the new Power9 "XIVE" interrupt controller.

   - TLB flushing optimisations for the radix MMU on Power9.

   - Support for CAPI cards on Power9, using the "Coherent Accelerator
     Interface Architecture 2.0".

   - The ability to configure the mmap randomisation limits at build and
     runtime.

   - Several small fixes and cleanups to the kprobes code, as well as
     support for KPROBES_ON_FTRACE.

   - Major improvements to handling of system reset interrupts,
     correctly treating them as NMIs, giving them a dedicated stack and
     using a new hypervisor call to trigger them, all of which should
     aid debugging and robustness.

   - Many fixes and other minor enhancements.

  Thanks to: Alastair D'Silva, Alexey Kardashevskiy, Alistair Popple,
  Andrew Donnellan, Aneesh Kumar K.V, Anshuman Khandual, Anton
  Blanchard, Balbir Singh, Ben Hutchings, Benjamin Herrenschmidt,
  Bhupesh Sharma, Chris Packham, Christian Zigotzky, Christophe Leroy,
  Christophe Lombard, Daniel Axtens, David Gibson, Gautham R. Shenoy,
  Gavin Shan, Geert Uytterhoeven, Guilherme G. Piccoli, Hamish Martin,
  Hari Bathini, Kees Cook, Laurent Dufour, Madhavan Srinivasan, Mahesh J
  Salgaonkar, Mahesh Salgaonkar, Masami Hiramatsu, Matt Brown, Matthew
  R. Ochs, Michael Neuling, Naveen N. Rao, Nicholas Piggin, Oliver
  O'Halloran, Pan Xinhui, Paul Mackerras, Rashmica Gupta, Russell
  Currey, Sukadev Bhattiprolu, Thadeu Lima de Souza Cascardo, Tobin C.
  Harding, Tyrel Datwyler, Uma Krishnan, Vaibhav Jain, Vipin K Parashar,
  Yang Shi"

* tag 'powerpc-4.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (214 commits)
  powerpc/64s: Power9 has no LPCR[VRMASD] field so don't set it
  powerpc/powernv: Fix TCE kill on NVLink2
  powerpc/mm/radix: Drop support for CPUs without lockless tlbie
  powerpc/book3s/mce: Move add_taint() later in virtual mode
  powerpc/sysfs: Move #ifdef CONFIG_HOTPLUG_CPU out of the function body
  powerpc/smp: Document irq enable/disable after migrating IRQs
  powerpc/mpc52xx: Don't select user-visible RTAS_PROC
  powerpc/powernv: Document cxl dependency on special case in pnv_eeh_reset()
  powerpc/eeh: Clean up and document event handling functions
  powerpc/eeh: Avoid use after free in eeh_handle_special_event()
  cxl: Mask slice error interrupts after first occurrence
  cxl: Route eeh events to all drivers in cxl_pci_error_detected()
  cxl: Force context lock during EEH flow
  powerpc/64: Allow CONFIG_RELOCATABLE if COMPILE_TEST
  powerpc/xmon: Teach xmon oops about radix vectors
  powerpc/mm/hash: Fix off-by-one in comment about kernel contexts ids
  powerpc/pseries: Enable VFIO
  powerpc/powernv: Fix iommu table size calculation hook for small tables
  powerpc/powernv: Check kzalloc() return value in pnv_pci_table_alloc
  powerpc: Add arch/powerpc/tools directory
  ...

Introduce __head_end to mark end of the early fixed sections and use it to
blacklist all exception handlers from kprobes.

mpe: We do not need to do anything special for relocatable kernels, where the
exception vectors are split from the main kernel, as the split vectors are
already excluded by the check for kernel_text_address().

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
[mpe: Move __head_end outside #ifdef 64-bit to unbreak the 32-bit build]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The kbuild test robot reported this build failure on a number
of architectures:

 >         make.cross ARCH=arm
 >    lib/lib.a(bug.o): In function `find_bug':
 > >> lib/bug.c:135: undefined reference to `__start___bug_table'
 > >> lib/bug.c:135: undefined reference to `__stop___bug_table'

Caused by:

  19d436268dde ("debug: Add _ONCE() logic to report_bug()")

Which moved the BUG_TABLE from RO_DATA_SECTION() to RW_DATA_SECTION(),
but a number of architectures don't use RW_DATA_SECTION(), so they
ended up with no __bug_table[] ...

Ideally all those would use RW_DATA_SECTION() in their linker scripts,
but that's for another day.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kbuild test robot <fengguang.wu@intel.com>
Cc: kbuild-all@01.org
Cc: tipbuild@zytor.com
Link: http://lkml.kernel.org/r/20170330154927.o6qmgfp4bdhrajbm@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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 <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Merge updates from Andrew Morton:

 - fsnotify updates

 - ocfs2 updates

 - all of MM

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (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/<tid>/timerslack_ns
  proc: relax /proc/<tid>/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
  ...