From: Winston Wen <wen...@uniontech.com> Add a new kernel hacking option CONFIG_NO_AUTO_INLINE that prevents the compiler from auto-inlining functions not explicitly marked with the 'inline' keyword.
This enhancement improves function tracer capabilities as it can only trace functions that haven't been inlined by the compiler. Previous discussions: Link: https://lore.kernel.org/all/20181028130945.23581-3-changbin...@gmail.com/ This patch is modified from commit 917fad29febd ("kernel hacking: add a config option to disable compiler auto-inlining") which can be founded in linux-next-history: Link: https://web.git.kernel.org/pub/scm/linux/kernel/git/next/linux-next-history.git/commit/?id=917fad29febd Unlike the original implementation, this patch: 1. Make it depends on CC_IS_GCC, as Clang 18.1.3 break test_bitmap_const_eval() in lib/test_bitmap.c 2. Make it depends on X86 and LOONGARCH, as I haven't test other architectures 3. Removes unnecessary cc-option checks per commit 7d73c3e9c514 ("Makefile: remove stale cc-option checks"). 4. Update help information. Cc: Changbin Du <changbin...@gmail.com> Co-developed-by: Chen Linxuan <chenlinx...@uniontech.com> Signed-off-by: Chen Linxuan <chenlinx...@uniontech.com> Signed-off-by: Winston Wen <wen...@uniontech.com> --- Makefile | 6 ++++++ lib/Kconfig.debug | 15 +++++++++++++++ 2 files changed, 21 insertions(+) diff --git a/Makefile b/Makefile index c91afd55099ea6bc7ed89bc3ef9cf58a498596d4..52da2c27f94167d2d2892a67c065e5df15efbde0 100644 --- a/Makefile +++ b/Makefile @@ -1071,6 +1071,12 @@ endif # Ensure compilers do not transform certain loops into calls to wcslen() KBUILD_CFLAGS += -fno-builtin-wcslen +ifdef CONFIG_NO_AUTO_INLINE +KBUILD_CFLAGS += -fno-inline-functions \ + -fno-inline-small-functions \ + -fno-inline-functions-called-once +endif + # change __FILE__ to the relative path to the source directory ifdef building_out_of_srctree KBUILD_CPPFLAGS += $(call cc-option,-ffile-prefix-map=$(srcroot)/=) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 9fe4d8dfe5782981cc0b2b6614106aac570bd229..2ebb4802886ab4a48841dbdd8973b7d9883548b9 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -436,8 +436,23 @@ config GDB_SCRIPTS instance. See Documentation/process/debugging/gdb-kernel-debugging.rst for further details. + endif # DEBUG_INFO +config NO_AUTO_INLINE + bool "Disable compiler auto-inline optimizations (EXPERIMENTAL)" + default n + depends on CC_IS_GCC && (X86 || LOONGARCH) + help + This will prevent the compiler from optimizing the kernel by + auto-inlining functions not marked with the inline keyword. + With this option, only functions explicitly marked with + "inline" will be inlined. This will allow the function tracer + to trace more functions because it only traces functions that + the compiler has not inlined. + + If unsure, select N. + config FRAME_WARN int "Warn for stack frames larger than" range 0 8192 -- 2.48.1
