Commit 3e86e4d74c04 ("kbuild: keep .modinfo section in
vmlinux.unstripped") added .modinfo to ELF_DETAILS while removing it
from COMMON_DISCARDS, as it was needed in vmlinux.unstripped and
ELF_DETAILS was present in all architecture specific vmlinux linker
scripts. While this shuffle is fine for vmlinux, ELF_DETAILS and
COMMON_DISCARDS may be used by other linker scripts, such as the s390
and x86 compressed boot images, which may not expect to have a .modinfo
section. In certain circumstances, this could result in a bootloader
failing to load the compressed kernel [1].

Commit ddc6cbef3ef1 ("s390/boot/vmlinux.lds.S: Ensure bzImage ends with
SecureBoot trailer") recently addressed this for the s390 bzImage but
the same bug remains for arm, parisc, and x86. The presence of .modinfo
in the x86 bzImage was the root cause of the issue worked around with
commit d50f21091358 ("kbuild: align modinfo section for Secureboot
Authenticode EDK2 compat"). misc.c in arch/x86/boot/compressed includes
lib/decompress_unzstd.c, which in turn includes lib/xxhash.c and its
MODULE_LICENSE / MODULE_DESCRIPTION macros due to the STATIC definition.

Split .modinfo out from ELF_DETAILS into its own macro and handle it in
all vmlinux linker scripts. Discard .modinfo in the places where it was
previously being discarded from being in COMMON_DISCARDS, as it has
never been necessary in those uses.

Cc: stable@vger.kernel.org
Fixes: 3e86e4d74c04 ("kbuild: keep .modinfo section in vmlinux.unstripped")
Reported-by: Ed W <lists@wildgooses.com>
Closes: https://lore.kernel.org/587f25e0-a80e-46a5-9f01-87cb40cfa377@wildgooses.com/ [1]
Tested-by: Ed W <lists@wildgooses.com> # x86_64
Link: https://patch.msgid.link/20260225-separate-modinfo-from-elf-details-v1-1-387ced6baf4b@kernel.org
Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Commit da30705c4621 ("arch/powerpc: Remove .interp section in vmlinux")
intended to drop the .interp section from vmlinux but even with this
change, relocatable kernels linked with ld.lld contain an empty .interp
section, which ends up causing crashes in GDB [1].

  $ make -skj"$(nproc)" ARCH=powerpc LLVM=1 clean pseries_le_defconfig vmlinux

  $ llvm-readelf -S vmlinux | grep interp
    [44] .interp           PROGBITS        c0000000021ddb34 21edb34 000000 00   A  0   0  1

There appears to be a subtle difference between GNU ld and ld.lld when
it comes to discarding sections that specify load addresses [2].

Since '--no-dynamic-linker' prevents emission of the .interp section,
there is no need to describe it in the output sections of the vmlinux
linker script. Drop the .interp section description from vmlinux.lds.S
to avoid this issue altogether.

Link: https://sourceware.org/bugzilla/show_bug.cgi?id=33481 [1]
Link: https://github.com/ClangBuiltLinux/linux/issues/2137 [2]
Reported-by: Vishal Chourasia <vishalc@linux.ibm.com>
Closes: https://lore.kernel.org/20251013040148.560439-1-vishalc@linux.ibm.com/
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Vishal Chourasia <vishalc@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20251018-ppc-fix-lld-interp-v1-1-a083de6dccc9@kernel.org

etext is not used anymore since commit 843a1ffaf6f2 ("powerpc/mm: use
core_kernel_text() helper")

edata and end have not been used since the merge of arch/ppc/ and
arch/ppc64/

Remove the three and remove macro PROVIDE32.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/d1686d36cdd6b9d681e7ee4dd677c386d43babb1.1736332415.git.christophe.leroy@csgroup.eu

Move the ftrace stub used to cover inittext before _einittext so that it
is within kernel text, as seen through core_kernel_text(). This is
required for a subsequent change to ftrace.

Signed-off-by: Naveen N Rao <naveen@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/20241030070850.1361304-9-hbathini@linux.ibm.com

This reverts commit eb8f689046b8 ("Use separate sections for __dev/
_cpu/__mem code/data").

Check section mismatch to __meminit* only when CONFIG_MEMORY_HOTPLUG=n.

With this change, the linker script and modpost become simpler, and we
can get rid of the __ref annotations from the memory hotplug code.

[sfr@canb.auug.org.au: remove MEM_KEEP from arch/powerpc/kernel/vmlinux.lds.S]
  Link: https://lkml.kernel.org/r/20240710093213.2aefb25f@canb.auug.org.au
Link: https://lkml.kernel.org/r/20240706160511.2331061-2-masahiroy@kernel.org
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Michael reported that we are seeing an ftrace bug on bootup when KASAN
is enabled and we are using -fpatchable-function-entry:

  ftrace: allocating 47780 entries in 18 pages
  ftrace-powerpc: 0xc0000000020b3d5c: No module provided for non-kernel address
  ------------[ ftrace bug ]------------
  ftrace faulted on modifying
  [<c0000000020b3d5c>] 0xc0000000020b3d5c
  Initializing ftrace call sites
  ftrace record flags: 0
   (0)
   expected tramp: c00000000008cef4
  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 0 at kernel/trace/ftrace.c:2180 ftrace_bug+0x3c0/0x424
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper Not tainted 6.5.0-rc3-00120-g0f71dcfb4aef #860
  Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1202 0xf000005 of:SLOF,HEAD hv:linux,kvm pSeries
  NIP:  c0000000003aa81c LR: c0000000003aa818 CTR: 0000000000000000
  REGS: c0000000033cfab0 TRAP: 0700   Not tainted  (6.5.0-rc3-00120-g0f71dcfb4aef)
  MSR:  8000000002021033 <SF,VEC,ME,IR,DR,RI,LE>  CR: 28028240  XER: 00000000
  CFAR: c0000000002781a8 IRQMASK: 3
  ...
  NIP [c0000000003aa81c] ftrace_bug+0x3c0/0x424
  LR [c0000000003aa818] ftrace_bug+0x3bc/0x424
  Call Trace:
   ftrace_bug+0x3bc/0x424 (unreliable)
   ftrace_process_locs+0x5f4/0x8a0
   ftrace_init+0xc0/0x1d0
   start_kernel+0x1d8/0x484

With CONFIG_FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY=y and
CONFIG_KASAN=y, compiler emits nops in functions that it generates for
registering and unregistering global variables (unlike with -pg and
-mprofile-kernel where calls to _mcount() are not generated in those
functions). Those functions then end up in INIT_TEXT and EXIT_TEXT
respectively. We don't expect to see any profiled functions in
EXIT_TEXT, so ftrace_init_nop() assumes that all addresses that aren't
in the core kernel text belongs to a module. Since these functions do
not match that criteria, we see the above bug.

Address this by having ftrace ignore all locations in the text exit
sections of vmlinux.

Fixes: 0f71dcfb4aef ("powerpc/ftrace: Add support for -fpatchable-function-entry")
Cc: stable@vger.kernel.org # v6.6+
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Naveen N Rao <naveen@kernel.org>
Reviewed-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240213175410.1091313-1-naveen@kernel.org

Commit 67361cf8071286 ("powerpc/ftrace: Handle large kernel configs")
added ftrace support for ppc64 kernel images with a text section larger
than 32MB. The approach itself isn't specific to ppc64, so extend the
same to also work on ppc32.

While at it, reduce the space reserved for the stub from 64 bytes to 32
bytes since the different stub variants are all less than 8
instructions.

To reduce use of #ifdef, a stub implementation is provided for
kernel_toc_address() and -SZ_2G is cast to 'long long' to prevent
errors on ppc32.

Signed-off-by: Naveen N Rao <naveen@kernel.org>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/9fa3258cbb9105cf8a0a8135214d44ffbc75fe84.1687166935.git.naveen@kernel.org

PC-Relative or PCREL addressing is an extension to the ELF ABI which
uses Power ISA v3.1 PC-relative instructions to calculate addresses,
rather than the traditional TOC scheme.

Add an option to build vmlinux using pcrel addressing. Modules continue
to use TOC addressing.

- TOC address helpers and r2 are poisoned with -1 when running vmlinux.
  r2 could be used for something useful once things are ironed out.

- Assembly must call C functions with @notoc annotation, or the linker
  complains aobut a missing nop after the call. This is done with the
  CFUNC macro introduced earlier.

- Boot: with the exception of prom_init, the execution branches to the
  kernel virtual address early in boot, before any addresses are
  generated, which ensures 34-bit pcrel addressing does not miss the
  high PAGE_OFFSET bits. TOC relative addressing has a similar
  requirement. prom_init does not go to the virtual address and its
  addresses should not carry over to the post-prom kernel.

- Ftrace trampolines are converted from TOC addressing to pcrel
  addressing, including module ftrace trampolines that currently use the
  kernel TOC to find ftrace target functions.

- BPF function prologue and function calling generation are converted
  from TOC to pcrel.

- copypage_64.S has an interesting problem, prefixed instructions have
  alignment restrictions so the linker can add padding, which makes the
  assembler treat the difference between two local labels as
  non-constant even if alignment is arranged so padding is not required.
  This may need toolchain help to solve nicely, for now move the prefix
  instruction out of the alternate patch section to work around it.

This reduces kernel text size by about 6%.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230408021752.862660-6-npiggin@gmail.com

When KASAN/KCSAN are enabled clang generates .text.asan/tsan sections.
Because they are not mentioned in the linker script warnings are
generated, and when orphan handling is set to error that becomes a build
error, eg:

  ld.lld: error: vmlinux.a(init/main.o):(.text.tsan.module_ctor) is
  being placed in '.text.tsan.module_ctor' ld.lld: error:
  vmlinux.a(init/version.o):(.text.tsan.module_ctor) is being placed in
  '.text.tsan.module_ctor'

Fix it by adding the sections to our linker script, similar to the
generic change made in 848378812e40 ("vmlinux.lds.h: Handle clang's
module.{c,d}tor sections").

Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230222060037.2897169-1-mpe@ellerman.id.au

Pick up fixes before merging another batch of cpuidle updates.

Signed-off-by: Ingo Molnar <mingo@kernel.org>