Subject: [PATCH v4 2/2] kconfig: Remove the architecture specific config for Propeller

From: [email-masked]
Date: Thu, 4 Jun 2026 12:56:08 -0700

From: Rong Xu <[email-masked]>

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 <[email-masked]>

Signed-off-by: Rong Xu <[email-masked]>
Suggested-by: Will Deacon <[email-masked]>
Suggested-by: Nathan Chancellor <[email-masked]>
Tested-by: Yabin Cui <[email-masked]>
Reviewed-by: Kees Cook <[email-masked]>
---
 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