diff mbox series

[bpf] scripts: Exclude Rust CUs with pahole

Message ID 20221220203901.1333304-1-yakoyoku@gmail.com
State New
Headers
Series [bpf] scripts: Exclude Rust CUs with pahole |

Commit Message

Martin Rodriguez Reboredo Dec. 20, 2022, 8:39 p.m. UTC 
  Version 1.24 of pahole has the capability to exclude compilation units
(CUs) of specific languages. Rust, as of writing, is not currently
supported by pahole and if it's used with a build that has BTF debugging
enabled it results in malformed kernel and module binaries (see
Rust-for-Linux/linux#735). So it's better for pahole to exclude Rust
CUs until support for it arrives.

Reviewed-by: Eric Curtin <ecurtin@redhat.com>
Tested-by: Eric Curtin <ecurtin@redhat.com>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Tested-by: Neal Gompa <neal@gompa.dev>
Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
---
 init/Kconfig            | 2 +-
 lib/Kconfig.debug       | 9 +++++++++
 scripts/pahole-flags.sh | 8 ++++++++
 3 files changed, 18 insertions(+), 1 deletion(-)

Comments

Miguel Ojeda Dec. 20, 2022, 8:56 p.m. UTC | #1 
On Tue, Dec 20, 2022 at 9:39 PM Martin Rodriguez Reboredo
<yakoyoku@gmail.com> wrote:
>
> Version 1.24 of pahole has the capability to exclude compilation units
> (CUs) of specific languages. Rust, as of writing, is not currently
> supported by pahole and if it's used with a build that has BTF debugging
> enabled it results in malformed kernel and module binaries (see
> Rust-for-Linux/linux#735). So it's better for pahole to exclude Rust
> CUs until support for it arrives.

Cc'ing Arnaldo explicitly since he added `--lang_exclude` support for
this (thanks again!).

Cheers,
Miguel
kernel test robot Jan. 1, 2023, 8:54 a.m. UTC | #2 
Hi Martin,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on bpf/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Martin-Rodriguez-Reboredo/scripts-Exclude-Rust-CUs-with-pahole/20221221-112806
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git master
patch link:    https://lore.kernel.org/r/20221220203901.1333304-1-yakoyoku%40gmail.com
patch subject: [PATCH bpf] scripts: Exclude Rust CUs with pahole
config: sh-se7724_defconfig
compiler: sh4-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/24aac5fd4ea59e02e9c203d3a59be6f13c5e702f
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Martin-Rodriguez-Reboredo/scripts-Exclude-Rust-CUs-with-pahole/20221221-112806
        git checkout 24aac5fd4ea59e02e9c203d3a59be6f13c5e702f
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=sh olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=sh distclean

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> grep: include/config/auto.conf: No such file or directory
--
>> grep: include/config/auto.conf: No such file or directory
>> grep: include/config/auto.conf: No such file or directory
>> grep: include/config/auto.conf: No such file or directory
diff mbox series

Patch

diff --git a/init/Kconfig b/init/Kconfig
index 694f7c160c9c..360aef8d7292 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1913,7 +1913,7 @@  config RUST
 	depends on !MODVERSIONS
 	depends on !GCC_PLUGINS
 	depends on !RANDSTRUCT
-	depends on !DEBUG_INFO_BTF
+	depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
 	select CONSTRUCTORS
 	help
 	  Enables Rust support in the kernel.
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ea4c903c9868..d473d491e709 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -364,6 +364,15 @@  config PAHOLE_HAS_BTF_TAG
 	  btf_decl_tag) or not. Currently only clang compiler implements
 	  these attributes, so make the config depend on CC_IS_CLANG.
 
+config PAHOLE_HAS_LANG_EXCLUDE
+	def_bool PAHOLE_VERSION >= 124
+	help
+	  Support for the --lang_exclude flag which makes pahole exclude
+	  compilation units from the supplied language. Used in Kbuild to
+	  omit Rust CUs which are not supported in version 1.24 of pahole,
+	  otherwise it would emit malformed kernel and module binaries when
+	  using DEBUG_INFO_BTF_MODULES.
+
 config DEBUG_INFO_BTF_MODULES
 	def_bool y
 	depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
diff --git a/scripts/pahole-flags.sh b/scripts/pahole-flags.sh
index 0d99ef17e4a5..1071d2cd9b28 100755
--- a/scripts/pahole-flags.sh
+++ b/scripts/pahole-flags.sh
@@ -9,6 +9,10 @@  fi
 
 pahole_ver=$($(dirname $0)/pahole-version.sh ${PAHOLE})
 
+is_enabled() {
+	grep -q "^$1=y" include/config/auto.conf
+}
+
 if [ "${pahole_ver}" -ge "118" ] && [ "${pahole_ver}" -le "121" ]; then
 	# pahole 1.18 through 1.21 can't handle zero-sized per-CPU vars
 	extra_paholeopt="${extra_paholeopt} --skip_encoding_btf_vars"
@@ -19,5 +23,9 @@  fi
 if [ "${pahole_ver}" -ge "122" ]; then
 	extra_paholeopt="${extra_paholeopt} -j"
 fi
+if is_enabled CONFIG_RUST; then
+	# see PAHOLE_HAS_LANG_EXCLUDE
+	extra_paholeopt="${extra_paholeopt} --lang_exclude=rust"
+fi
 
 echo ${extra_paholeopt}