From: Rui Qi Date: Mon, 6 Jul 2026 13:04:14 +0000 (+0800) Subject: riscv: Gate FUNCTION_ALIGNMENT_4B on DYNAMIC_FTRACE X-Git-Tag: v7.2-rc4~1^2~4 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3a2694bf6ac8e47b3814293e80343f58fc72937f;p=thirdparty%2Flinux.git riscv: Gate FUNCTION_ALIGNMENT_4B on DYNAMIC_FTRACE The FUNCTION_ALIGNMENT_4B select forces the whole kernel to be built with -fmin-function-alignment=4. This alignment is only needed so the patchable-function-entry NOPs, which arch/riscv/Makefile emits under CONFIG_DYNAMIC_FTRACE, can be patched reliably on RISCV_ISA_C=y builds where compressed instructions otherwise allow 2-byte function alignment. The select is currently gated on HAVE_DYNAMIC_FTRACE, a capability bit that is selected whenever the toolchain supports dynamic ftrace, rather than on whether tracing is actually enabled. As a result every RISCV_ISA_C=y build gets 4-byte function alignment across the entire kernel even when function tracing is disabled, needlessly growing the kernel image and wasting instruction cache for a feature that is not in use. Gate the select on DYNAMIC_FTRACE instead, matching the condition under which arch/riscv/Makefile emits -fpatchable-function-entry, so the alignment is only applied when it is actually needed. Fixes: c41bf4326c7b ("riscv: ftrace: align patchable functions to 4 Byte boundary") Signed-off-by: Rui Qi Link: https://patch.msgid.link/20260706130415.463682-1-qirui.001@bytedance.com Signed-off-by: Paul Walmsley --- diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index c0a6992933e4..f7028caaeae0 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -157,7 +157,7 @@ config RISCV select HAVE_DEBUG_KMEMLEAK select HAVE_DMA_CONTIGUOUS if MMU select HAVE_DYNAMIC_FTRACE if MMU && (CLANG_SUPPORTS_DYNAMIC_FTRACE || GCC_SUPPORTS_DYNAMIC_FTRACE) - select FUNCTION_ALIGNMENT_4B if HAVE_DYNAMIC_FTRACE && RISCV_ISA_C + select FUNCTION_ALIGNMENT_4B if DYNAMIC_FTRACE && RISCV_ISA_C select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS if HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS select HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS if (DYNAMIC_FTRACE_WITH_ARGS && !CFI) select HAVE_DYNAMIC_FTRACE_WITH_ARGS if HAVE_DYNAMIC_FTRACE