linux-stable.git/lib/Kconfig.debug, branch v5.15.208

lockdep: Fix upper limit for LOCKDEP_*_BITS configs

2025-03-13T11:50:17+00:00

[ Upstream commit e638072e61726cae363d48812815197a2a0e097f ]

Lockdep has a set of configs used to determine the size of the static
arrays that it uses. However, the upper limit that was initially setup
for these configs is too high (30 bit shift). This equates to several
GiB of static memory for individual symbols. Using such high values
leads to linker errors:

  $ make defconfig
  $ ./scripts/config -e PROVE_LOCKING --set-val LOCKDEP_BITS 30
  $ make olddefconfig all
  [...]
  ld: kernel image bigger than KERNEL_IMAGE_SIZE
  ld: section .bss VMA wraps around address space

Adjust the upper limits to the maximum values that avoid these issues.
The need for anything more, likely points to a problem elsewhere. Note
that LOCKDEP_CHAINS_BITS was intentionally left out as its upper limit
had a different symptom and has already been fixed [1].

Reported-by: J. R. Okajima 
Closes: https://lore.kernel.org/all/30795.1620913191@jrobl/ [1]
Cc: Peter Zijlstra 
Cc: Boqun Feng 
Cc: Ingo Molnar 
Cc: Waiman Long 
Cc: Will Deacon 
Acked-by: Waiman Long 
Signed-off-by: Carlos Llamas 
Signed-off-by: Boqun Feng 
Link: https://lore.kernel.org/r/20241024183631.643450-2-cmllamas@google.com
Signed-off-by: Sasha Levin

bpf, kconfig: Fix DEBUG_INFO_BTF_MODULES Kconfig definition

2024-05-17T09:50:46+00:00

[ Upstream commit 229087f6f1dc2d0c38feba805770f28529980ec0 ]

Turns out that due to CONFIG_DEBUG_INFO_BTF_MODULES not having an
explicitly specified "menu item name" in Kconfig, it's basically
impossible to turn it off (see [0]).

This patch fixes the issue by defining menu name for
CONFIG_DEBUG_INFO_BTF_MODULES, which makes it actually adjustable
and independent of CONFIG_DEBUG_INFO_BTF, in the sense that one can
have DEBUG_INFO_BTF=y and DEBUG_INFO_BTF_MODULES=n.

We still keep it as defaulting to Y, of course.

Fixes: 5f9ae91f7c0d ("kbuild: Build kernel module BTFs if BTF is enabled and pahole supports it")
Reported-by: Vincent Li 
Signed-off-by: Andrii Nakryiko 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/CAK3+h2xiFfzQ9UXf56nrRRP=p1+iUxGoEP5B+aq9MDT5jLXDSg@mail.gmail.com [0]
Link: https://lore.kernel.org/bpf/20240404220344.3879270-1-andrii@kernel.org
Signed-off-by: Sasha Levin

arch: Introduce CONFIG_FUNCTION_ALIGNMENT

2024-04-10T14:18:49+00:00

commit d49a0626216b95cd4bf696f6acf55f39a16ab0bb upstream.

Generic function-alignment infrastructure.

Architectures can select FUNCTION_ALIGNMENT_xxB symbols; the
FUNCTION_ALIGNMENT symbol is then set to the largest such selected
size, 0 otherwise.

>From this the -falign-functions compiler argument and __ALIGN macro
are set.

This incorporates the DEBUG_FORCE_FUNCTION_ALIGN_64B knob and future
alignment requirements for x86_64 (later in this series) into a single
place.

NOTE: also removes the 0x90 filler byte from the generic __ALIGN
      primitive, that value makes no sense outside of x86.

NOTE: .balign 0 reverts to a no-op.

Requested-by: Linus Torvalds 
Change-Id: I053b3c408d56988381feb8c8bdb5e27ea221755f
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/r/20220915111143.719248727@infradead.org
[cascardo: adjust context at arch/x86/Kconfig]
Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Greg Kroah-Hartman

lib/Kconfig.debug: do not enable DEBUG_PREEMPT by default

2023-10-25T09:58:54+00:00

commit cc6003916ed46d7a67d91ee32de0f9138047d55f upstream.

In workloads where this_cpu operations are frequently performed,
enabling DEBUG_PREEMPT may result in significant increase in
runtime overhead due to frequent invocation of
__this_cpu_preempt_check() function.

This can be demonstrated through benchmarks such as hackbench where this
configuration results in a 10% reduction in performance, primarily due to
the added overhead within memcg charging path.

Therefore, do not to enable DEBUG_PREEMPT by default and make users aware
of its potential impact on performance in some workloads.

hackbench-process-sockets
		      debug_preempt	 no_debug_preempt
Amean     1       0.4743 (   0.00%)      0.4295 *   9.45%*
Amean     4       1.4191 (   0.00%)      1.2650 *  10.86%*
Amean     7       2.2677 (   0.00%)      2.0094 *  11.39%*
Amean     12      3.6821 (   0.00%)      3.2115 *  12.78%*
Amean     21      6.6752 (   0.00%)      5.7956 *  13.18%*
Amean     30      9.6646 (   0.00%)      8.5197 *  11.85%*
Amean     48     15.3363 (   0.00%)     13.5559 *  11.61%*
Amean     79     24.8603 (   0.00%)     22.0597 *  11.27%*
Amean     96     30.1240 (   0.00%)     26.8073 *  11.01%*

Link: https://lkml.kernel.org/r/20230121033942.350387-1-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: Roman Gushchin 
Acked-by: Mel Gorman 
Acked-by: Davidlohr Bueso 
Cc: Ben Segall 
Cc: Christoph Lameter 
Cc: Daniel Bristot de Oliveira 
Cc: David Rientjes 
Cc: Dennis Zhou 
Cc: Dietmar Eggemann 
Cc: Ingo Molnar 
Cc: Johannes Weiner 
Cc: Joonsoo Kim 
Cc: Juri Lelli 
Cc: Matthew Wilcox 
Cc: Muchun Song 
Cc: Pekka Enberg 
Cc: Peter Zijlstra 
Cc: Shakeel Butt 
Cc: Steven Rostedt (Google) 
Cc: Tejun Heo 
Cc: Valentin Schneider 
Cc: Vincent Guittot 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Cc: Luiz Capitulino 
Signed-off-by: Greg Kroah-Hartman

lib/Kconfig.debug: Allow BTF + DWARF5 with pahole 1.21+

2023-02-25T11:06:46+00:00

commit 42d9b379e3e1790eafb87c799c9edfd0b37a37c7 upstream.

Commit 98cd6f521f10 ("Kconfig: allow explicit opt in to DWARF v5")
prevented CONFIG_DEBUG_INFO_DWARF5 from being selected when
CONFIG_DEBUG_INFO_BTF is enabled because pahole had issues with clang's
DWARF5 info. This was resolved by [1], which is in pahole v1.21.

Allow DEBUG_INFO_DWARF5 to be selected with DEBUG_INFO_BTF when using
pahole v1.21 or newer.

[1]: https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?id=7d8e829f636f47aba2e1b6eda57e74d8e31f733c

Signed-off-by: Nathan Chancellor 
Signed-off-by: Daniel Borkmann 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20220201205624.652313-6-nathan@kernel.org
Signed-off-by: Matthias Maennich 
Signed-off-by: Greg Kroah-Hartman

lib/Kconfig.debug: Use CONFIG_PAHOLE_VERSION

2023-02-25T11:06:46+00:00

commit 6323c81350b73a4569cf52df85f80273faa64071 upstream.

Now that CONFIG_PAHOLE_VERSION exists, use it in the definition of
CONFIG_PAHOLE_HAS_SPLIT_BTF and CONFIG_PAHOLE_HAS_BTF_TAG to reduce the
amount of duplication across the tree.

Signed-off-by: Nathan Chancellor 
Signed-off-by: Daniel Borkmann 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20220201205624.652313-5-nathan@kernel.org
[maennich: omitted patching non-existing config PAHOLE_HAS_BTF_TAG]
Signed-off-by: Matthias Maennich 
Signed-off-by: Greg Kroah-Hartman

Kconfig.debug: provide a little extra FRAME_WARN leeway when KASAN is enabled

2022-12-08T10:28:44+00:00

[ Upstream commit 152fe65f300e1819d59b80477d3e0999b4d5d7d2 ]

When enabled, KASAN enlarges function's stack-frames.  Pushing quite a few
over the current threshold.  This can mainly be seen on 32-bit
architectures where the present limit (when !GCC) is a lowly 1024-Bytes.

Link: https://lkml.kernel.org/r/20221125120750.3537134-3-lee@kernel.org
Signed-off-by: Lee Jones 
Acked-by: Arnd Bergmann 
Cc: Alex Deucher 
Cc: "Christian König" 
Cc: Daniel Vetter 
Cc: David Airlie 
Cc: Harry Wentland 
Cc: Leo Li 
Cc: Maarten Lankhorst 
Cc: Maxime Ripard 
Cc: Nathan Chancellor 
Cc: Nick Desaulniers 
Cc: "Pan, Xinhui" 
Cc: Rodrigo Siqueira 
Cc: Thomas Zimmermann 
Cc: Tom Rix 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Sasha Levin

parisc: Increase FRAME_WARN to 2048 bytes on parisc

2022-12-08T10:28:44+00:00

[ Upstream commit 8d192bec534bd5b778135769a12e5f04580771f7 ]

PA-RISC uses a much bigger frame size for functions than other
architectures. So increase it to 2048 for 32- and 64-bit kernels.
This fixes e.g. a warning in lib/xxhash.c.

Reported-by: kernel test robot 
Signed-off-by: Helge Deller 
Stable-dep-of: 152fe65f300e ("Kconfig.debug: provide a little extra FRAME_WARN leeway when KASAN is enabled")
Signed-off-by: Sasha Levin

error-injection: Add prompt for function error injection

2022-12-08T10:28:42+00:00

commit a4412fdd49dc011bcc2c0d81ac4cab7457092650 upstream.

The config to be able to inject error codes into any function annotated
with ALLOW_ERROR_INJECTION() is enabled when FUNCTION_ERROR_INJECTION is
enabled.  But unfortunately, this is always enabled on x86 when KPROBES
is enabled, and there's no way to turn it off.

As kprobes is useful for observability of the kernel, it is useful to
have it enabled in production environments.  But error injection should
be avoided.  Add a prompt to the config to allow it to be disabled even
when kprobes is enabled, and get rid of the "def_bool y".

This is a kernel debug feature (it's in Kconfig.debug), and should have
never been something enabled by default.

Cc: stable@vger.kernel.org
Fixes: 540adea3809f6 ("error-injection: Separate error-injection from kprobe")
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

lib/Kconfig.debug: Add check for non-constant .{s,u}leb128 support to DWARF5

2022-10-26T10:35:55+00:00

commit 0a6de78cff600cb991f2a1b7ed376935871796a0 upstream.

When building with a RISC-V kernel with DWARF5 debug info using clang
and the GNU assembler, several instances of the following error appear:

  /tmp/vgettimeofday-48aa35.s:2963: Error: non-constant .uleb128 is not supported

Dumping the .s file reveals these .uleb128 directives come from
.debug_loc and .debug_ranges:

  .Ldebug_loc0:
          .byte   4                               # DW_LLE_offset_pair
          .uleb128 .Lfunc_begin0-.Lfunc_begin0    #   starting offset
          .uleb128 .Ltmp1-.Lfunc_begin0           #   ending offset
          .byte   1                               # Loc expr size
          .byte   90                              # DW_OP_reg10
          .byte   0                               # DW_LLE_end_of_list

  .Ldebug_ranges0:
          .byte   4                               # DW_RLE_offset_pair
          .uleb128 .Ltmp6-.Lfunc_begin0           #   starting offset
          .uleb128 .Ltmp27-.Lfunc_begin0          #   ending offset
          .byte   4                               # DW_RLE_offset_pair
          .uleb128 .Ltmp28-.Lfunc_begin0          #   starting offset
          .uleb128 .Ltmp30-.Lfunc_begin0          #   ending offset
          .byte   0                               # DW_RLE_end_of_list

There is an outstanding binutils issue to support a non-constant operand
to .sleb128 and .uleb128 in GAS for RISC-V but there does not appear to
be any movement on it, due to concerns over how it would work with
linker relaxation.

To avoid these build errors, prevent DWARF5 from being selected when
using clang and an assembler that does not have support for these symbol
deltas, which can be easily checked in Kconfig with as-instr plus the
small test program from the dwz test suite from the binutils issue.

Link: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
Link: https://github.com/ClangBuiltLinux/linux/issues/1719
Signed-off-by: Nathan Chancellor 
Reviewed-by: Nick Desaulniers 
Signed-off-by: Masahiro Yamada 
[nathan: Fix conflicts due to lack of f9b3cd24578401e]
Signed-off-by: Nathan Chancellor 
Signed-off-by: Greg Kroah-Hartman