[PATCH v4 2/2] kconfig: Remove the architecture specific config for Propeller
xur at google.com
xur at google.com
Thu Jun 4 12:56:08 PDT 2026
From: Rong Xu <xur at google.com>
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 at google.com>
Signed-off-by: Rong Xu <xur at google.com>
Suggested-by: Will Deacon <will at kernel.org>
Suggested-by: Nathan Chancellor <nathan at kernel.org>
Tested-by: Yabin Cui <yabinc at google.com>
Reviewed-by: Kees Cook <kees at kernel.org>
---
Documentation/dev-tools/propeller.rst | 49 ++++++++++++++++++++-------
arch/Kconfig | 5 +--
arch/arm64/kernel/vmlinux.lds.S | 1 +
arch/x86/Kconfig | 1 -
arch/x86/kernel/vmlinux.lds.S | 5 +--
include/asm-generic/vmlinux.lds.h | 6 ++++
6 files changed, 46 insertions(+), 21 deletions(-)
diff --git a/Documentation/dev-tools/propeller.rst b/Documentation/dev-tools/propeller.rst
index 92195958e3db..e927319941c9 100644
--- a/Documentation/dev-tools/propeller.rst
+++ b/Documentation/dev-tools/propeller.rst
@@ -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. ::
diff --git a/arch/Kconfig b/arch/Kconfig
index 5e878924939a..99c2017eb515 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -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
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index e1ac876200a3..8aaf404980a7 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -368,6 +368,7 @@ SECTIONS
STABS_DEBUG
DWARF_DEBUG
+ PROPELLER_DATA
MODINFO
ELF_DETAILS
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 10bf3984102e..b875d2f27e48 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -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
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 4711a35e706c..74e336d7f9dd 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -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
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 60c8c22fd3e4..5659f4b5a125 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -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.
--
2.54.0.1032.g2f8565e1d1-goog
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