Some functions defined in `arch/powerpc/kernel` (and one in `arch/powerpc/
kexec`) are deserving of an `__init` macro attribute. These functions are
only called by other initialization functions and therefore should inherit
the attribute.
Also, change function declarations in header files to include `__init`.

Signed-off-by: Nick Child <nick.child@ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211216220035.605465-2-nick.child@ibm.com

prom_getprop() can return PROM_ERROR. Binary operator can not identify
it.

Fixes: 94d2dde738a5 ("[POWERPC] Efika: prune fixups and make them more carefull")
Signed-off-by: Peiwei Hu <jlu.hpw@foxmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/tencent_BA28CC6897B7C95A92EB8C580B5D18589105@qq.com

Pull Kbuild updates from Masahiro Yamada:

 - Add -s option (strict mode) to merge_config.sh to make it fail when
   any symbol is redefined.

 - Show a warning if a different compiler is used for building external
   modules.

 - Infer --target from ARCH for CC=clang to let you cross-compile the
   kernel without CROSS_COMPILE.

 - Make the integrated assembler default (LLVM_IAS=1) for CC=clang.

 - Add <linux/stdarg.h> to the kernel source instead of borrowing
   <stdarg.h> from the compiler.

 - Add Nick Desaulniers as a Kbuild reviewer.

 - Drop stale cc-option tests.

 - Fix the combination of CONFIG_TRIM_UNUSED_KSYMS and CONFIG_LTO_CLANG
   to handle symbols in inline assembly.

 - Show a warning if 'FORCE' is missing for if_changed rules.

 - Various cleanups

* tag 'kbuild-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (39 commits)
  kbuild: redo fake deps at include/ksym/*.h
  kbuild: clean up objtool_args slightly
  modpost: get the *.mod file path more simply
  checkkconfigsymbols.py: Fix the '--ignore' option
  kbuild: merge vmlinux_link() between ARCH=um and other architectures
  kbuild: do not remove 'linux' link in scripts/link-vmlinux.sh
  kbuild: merge vmlinux_link() between the ordinary link and Clang LTO
  kbuild: remove stale *.symversions
  kbuild: remove unused quiet_cmd_update_lto_symversions
  gen_compile_commands: extract compiler command from a series of commands
  x86: remove cc-option-yn test for -mtune=
  arc: replace cc-option-yn uses with cc-option
  s390: replace cc-option-yn uses with cc-option
  ia64: move core-y in arch/ia64/Makefile to arch/ia64/Kbuild
  sparc: move the install rule to arch/sparc/Makefile
  security: remove unneeded subdir-$(CONFIG_...)
  kbuild: sh: remove unused install script
  kbuild: Fix 'no symbols' warning when CONFIG_TRIM_UNUSD_KSYMS=y
  kbuild: Switch to 'f' variants of integrated assembler flag
  kbuild: Shuffle blank line to improve comment meaning
  ...

Ship minimal stdarg.h (1 type, 4 macros) as <linux/stdarg.h>.
stdarg.h is the only userspace header commonly used in the kernel.

GPL 2 version of <stdarg.h> can be extracted from
http://archive.debian.org/debian/pool/main/g/gcc-4.2/gcc-4.2_4.2.4.orig.tar.gz

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

PAPR interface currently supports two different ways of communicating resource
grouping details to the OS. These are referred to as Form 0 and Form 1
associativity grouping. Form 0 is the older format and is now considered
deprecated. This patch adds another resource grouping named FORM2.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210812132223.225214-6-aneesh.kumar@linux.ibm.com

Also make related code cleanup that will allow adding FORM2_AFFINITY in
later patches. No functional change in this patch.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210812132223.225214-3-aneesh.kumar@linux.ibm.com

When we boot from open firmware (OF) using PPC_OF_BOOT_TRAMPOLINE, aka.
prom_init, we run parts of the kernel at an address other than the link
address. That happens because OF loads the kernel above zero (OF is at
zero) and we run prom_init before copying the kernel down to zero.

Currently that works even for non-relocatable kernels, because we do
various fixups to the prom_init code to make it run where it's loaded.

However those fixups are not sufficient if the kernel becomes large
enough. In that case prom_init()'s final call to __start() can end up
generating a plt branch:

bl      c000000002000018 <00000078.plt_branch.__start>

That results in the kernel jumping to the linked address of __start,
0xc000000000000000, when really it needs to jump to the
0xc000000000000000 + the runtime address because the kernel is still
running at the load address.

We could do further shenanigans to handle that, see Jordan's patch for
example:
  https://lore.kernel.org/linuxppc-dev/20210421021721.1539289-1-jniethe5@gmail.com

However it is much simpler to just require a kernel with prom_init() to
be built relocatable. The result works in all configurations without
further work, and requires less code.

This should have no effect on most people, as our defconfigs and
essentially all distro configs already have RELOCATABLE enabled.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210623130454.2542945-1-mpe@ellerman.id.au

When an interrupt is taken, the SRR registers are set to return to where
it left off. Unless they are modified in the meantime, or the return
address or MSR are modified, there is no need to reload these registers
when returning from interrupt.

Introduce per-CPU flags that track the validity of SRR and HSRR
registers. These are cleared when returning from interrupt, when
using the registers for something else (e.g., OPAL calls), when
adjusting the return address or MSR of a context, and when context
switching (which changes the return address and MSR).

This improves the performance of interrupt returns.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fold in fixup patch from Nick]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210617155116.2167984-5-npiggin@gmail.com

Pass the value of linux_banner to firmware via option vector 7.

Option vector 7 is described in "LoPAR" Linux on Power Architecture
Reference v2.9, in table B.7 on page 824:

  An ASCII character formatted null terminated string that describes
  the client operating system. The string shall be human readable and
  may be displayed on the console.

The string can be up to 256 bytes total, including the nul terminator.

linux_banner contains lots of information, and should make it possible
to identify the exact kernel version that is running:

  const char linux_banner[] =
  "Linux version " UTS_RELEASE " (" LINUX_COMPILE_BY "@"
  LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION "\n";

For example:
  Linux version 4.15.0-144-generic (buildd@bos02-ppc64el-018) (gcc
  version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)) #148-Ubuntu SMP Sat May 8
  02:32:13 UTC 2021 (Ubuntu 4.15.0-144.148-generic 4.15.18)

It's also printed at boot to the console/dmesg, which should make it
possible to correlate what firmware receives with the console/dmesg on
the machine.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210621064938.2021419-2-mpe@ellerman.id.au

In a subsequent patch we'd like to have something like a strscpy_pad()
implementation usable in prom_init.c.

Currently we have a strcpy() implementation with only one caller, so
convert it into strscpy_pad() and update the caller.

Reviewed-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210621064938.2021419-1-mpe@ellerman.id.au