From: Naveen N Rao Date: Wed, 13 Sep 2023 13:41:29 +0000 (+0530) Subject: powerpc: Fix build issue with LD_DEAD_CODE_DATA_ELIMINATION and FTRACE_MCOUNT_USE_PAT... X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=60d77ed24bb3068c0837fe45b8921b0a6598829d;p=linux.git powerpc: Fix build issue with LD_DEAD_CODE_DATA_ELIMINATION and FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY We recently added support for -fpatchable-function-entry and it is enabled by default on ppc32 (ppc64 needs gcc v13.1.0). When building the kernel for ppc32 and also enabling CONFIG_LD_DEAD_CODE_DATA_ELIMINATION, we see the below build error with older gcc versions: powerpc-linux-gnu-ld: init/main.o(__patchable_function_entries): error: need linked-to section for --gc-sections This error is thrown since __patchable_function_entries section would be garbage collected with --gc-sections since it does not reference any other kept sections. This has subsequently been fixed with: https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=b7d072167715829eed0622616f6ae0182900de3e Disable LD_DEAD_CODE_DATA_ELIMINATION for gcc versions before v11.1.0 if using -fpatchable-function-entry to avoid this bug. Fixes: 0f71dcfb4aef ("powerpc/ftrace: Add support for -fpatchable-function-entry") Reported-by: Michael Ellerman Signed-off-by: Naveen N Rao Signed-off-by: Michael Ellerman Link: https://msgid.link/20230913134129.2782088-1-naveen@kernel.org --- diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 54b9387c36916..3aaadfd2c8eb2 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -255,7 +255,7 @@ config PPC select HAVE_KPROBES select HAVE_KPROBES_ON_FTRACE select HAVE_KRETPROBES - select HAVE_LD_DEAD_CODE_DATA_ELIMINATION if HAVE_OBJTOOL_MCOUNT + select HAVE_LD_DEAD_CODE_DATA_ELIMINATION if HAVE_OBJTOOL_MCOUNT && (!ARCH_USING_PATCHABLE_FUNCTION_ENTRY || (!CC_IS_GCC || GCC_VERSION >= 110100)) select HAVE_LIVEPATCH if HAVE_DYNAMIC_FTRACE_WITH_REGS select HAVE_MOD_ARCH_SPECIFIC select HAVE_NMI if PERF_EVENTS || (PPC64 && PPC_BOOK3S)