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kconfig: Remove the architecture specific config for Propeller

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The CONFIG_PROPELLER_CLANG option currently depends on
ARCH_SUPPORTS_PROPELLER_CLANG, but this dependency seems unnecessary.

Remove ARCH_SUPPORTS_PROPELLER_CLANG and allow users to control
Propeller builds solely through CONFIG_PROPELLER_CLANG. This simplifies
the kconfig and avoids potential confusion.

Move the .llvm_bb_addr_map sections grouping to
include/asm-generic/vmlinux.lds.h.

The Propeller documentation has been updated to reflect the most
recent tool location and now includes instructions for arm64.

Contributor Acknowledgments:
  * SPE instructions: Daniel Hoekwater <hoekwater@google.com>

Signed-off-by: Rong Xu <xur@google.com>
Suggested-by: Will Deacon <will@kernel.org>
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Yabin Cui <yabinc@google.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Link: https://patch.msgid.link/20260604195612.3757860-3-xur@google.com
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
This commit is contained in:
Rong Xu 2026-06-04 12:56:08 -07:00 committed by Nathan Chancellor
parent e88b2fe8b9
commit 2566fa7b2f
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GPG Key ID: 1D6B269171C01A96
6 changed files with 46 additions and 21 deletions
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49
Documentation/dev-tools/propeller.rst
View File

@ -28,8 +28,10 @@ A few important notes about adopting Propeller optimization:
and the linker(ld.lld).
#. In addition to LLVM toolchain, Propeller requires a profiling
conversion tool: https://github.com/google/autofdo with a release
after v0.30.1: https://github.com/google/autofdo/releases/tag/v0.30.1.
conversion tool: https://github.com/google/llvm-propeller.
Current supported architectures include x86/X86_64 (via LBR),
and arm64 (via SPE).
The Propeller optimization process involves the following steps:
@ -124,17 +126,30 @@ Here is an example workflow for building an AutoFDO+Propeller kernel:
$ perf record --pfm-event RETIRED_TAKEN_BRANCH_INSTRUCTIONS:k -a -N -b -c <count> -o <perf_file> -- <loadtest>
Note you can repeat the above steps to collect multiple <perf_file>s.
- For arm64 with SPE::
There are a few kernel features that must be enabled to collect SPE profiles on Arm.
Below is a list of the required features:
- CONFIG_ARM_SPE_PMU=y
- CONFIG_PID_IN_CONTEXTIDR=y
- kpti=off
Use the following command to generate SPE perf data file::
$ perf record -e 'arm_spe_0/branch_filter=1,load_filter=0,store_filter=0/' -a -N -c <count> --no-switch-events -o <perf_file> -- <loadtest>
Note you can repeat the above steps to collect multiple <perf_file>s.
4) (Optional) Download the raw perf file(s) to the host machine.
5) Use the create_llvm_prof tool (https://github.com/google/autofdo) to
5) Use the generate_propeller_profiles tool (https://github.com/google/llvm-propeller) to
generate Propeller profile. ::
$ create_llvm_prof --binary=<vmlinux> --profile=<perf_file>
--format=propeller --propeller_output_module_name
--out=<propeller_profile_prefix>_cc_profile.txt
--propeller_symorder=<propeller_profile_prefix>_ld_profile.txt
$ generate_propeller_profiles \
--binary=<vmlinux> --profile=<perf_file> \
--format=propeller --propeller_output_module_name \
--out=<propeller_profile_prefix>_cc_profile.txt \
--propeller_symorder=<propeller_profile_prefix>_ld_profile.txt
"<propeller_profile_prefix>" can be something like "/home/user/dir/any_string".
@ -146,10 +161,20 @@ Here is an example workflow for building an AutoFDO+Propeller kernel:
you can create a temp list file "<perf_file_list>" with each line
containing one perf file name and run::
$ create_llvm_prof --binary=<vmlinux> --profile=@<perf_file_list>
--format=propeller --propeller_output_module_name
--out=<propeller_profile_prefix>_cc_profile.txt
--propeller_symorder=<propeller_profile_prefix>_ld_profile.txt
$ generate_propeller_profiles \
--binary=<vmlinux> --profile=@<perf_file_list> \
--format=propeller --propeller_output_module_name \
--out=<propeller_profile_prefix>_cc_profile.txt \
--propeller_symorder=<propeller_profile_prefix>_ld_profile.txt
For arm64 SPE, add the option '--profiler=perf_spe', like::
$ generate_propeller_profiles \
--binary=<vmlinux> --profile=<perf_file> \
--profiler=perf_spe \
--format=propeller --propeller_output_module_name \
--out=<propeller_profile_prefix>_cc_profile.txt \
--propeller_symorder=<propeller_profile_prefix>_ld_profile.txt
6) Rebuild the kernel using the AutoFDO and Propeller
profiles. ::

5
arch/Kconfig
View File

@ -895,13 +895,10 @@ config AUTOFDO_CLANG
If unsure, say N.
config ARCH_SUPPORTS_PROPELLER_CLANG
bool
config PROPELLER_CLANG
bool "Enable Clang's Propeller build"
depends on ARCH_SUPPORTS_PROPELLER_CLANG
depends on CC_IS_CLANG && CLANG_VERSION >= 190000
depends on $(cc-option,-fbasic-block-sections=list=/dev/null)
help
This option enables Clang’s Propeller build. When the Propeller
profiles is specified in variable CLANG_PROPELLER_PROFILE_PREFIX

1
arch/arm64/kernel/vmlinux.lds.S
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@ -368,6 +368,7 @@ SECTIONS
STABS_DEBUG
DWARF_DEBUG
PROPELLER_DATA
MODINFO
ELF_DETAILS

1
arch/x86/Kconfig
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@ -130,7 +130,6 @@ config X86
select ARCH_SUPPORTS_LTO_CLANG
select ARCH_SUPPORTS_LTO_CLANG_THIN
select ARCH_SUPPORTS_RT
select ARCH_SUPPORTS_PROPELLER_CLANG if X86_64
select ARCH_USE_BUILTIN_BSWAP
select ARCH_USE_CMPXCHG_LOCKREF if X86_CX8
select ARCH_USE_MEMTEST

5
arch/x86/kernel/vmlinux.lds.S
View File

@ -423,10 +423,7 @@ SECTIONS
STABS_DEBUG
DWARF_DEBUG
#ifdef CONFIG_PROPELLER_CLANG
.llvm_bb_addr_map : { *(.llvm_bb_addr_map) }
#endif
PROPELLER_DATA
MODINFO
ELF_DETAILS

6
include/asm-generic/vmlinux.lds.h
View File

@ -1011,6 +1011,12 @@
#define PERCPU_DECRYPTED_SECTION
#endif
#ifdef CONFIG_PROPELLER_CLANG
#define PROPELLER_DATA \
.llvm_bb_addr_map : { *(.llvm_bb_addr_map) }
#else
#define PROPELLER_DATA
#endif
/*
* Default discarded sections.