Test whether gcc supports -fpatchable-function-entry and use it to promote DYNAMIC_FTRACE to DYNAMIC_FTRACE_WITH_REGS. Amend support for the new object section that holds the locations (__patchable_function_entries) and define a proper "notrace" attribute to switch it off.
Signed-off-by: Torsten Duwe <[email protected]> --- arch/arm64/Kconfig | 2 ++ arch/arm64/Makefile | 5 +++++ include/asm-generic/vmlinux.lds.h | 1 + include/linux/compiler_types.h | 2 ++ kernel/module.c | 7 ++++++- 5 files changed, 16 insertions(+), 1 deletion(-) --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -132,6 +132,8 @@ config ARM64 select HAVE_DEBUG_KMEMLEAK select HAVE_DMA_CONTIGUOUS select HAVE_DYNAMIC_FTRACE + select HAVE_DYNAMIC_FTRACE_WITH_REGS \ + if $(cc-option,-fpatchable-function-entry=2) select HAVE_EFFICIENT_UNALIGNED_ACCESS select HAVE_FTRACE_MCOUNT_RECORD select HAVE_FUNCTION_TRACER --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -89,6 +89,11 @@ ifeq ($(CONFIG_ARM64_MODULE_PLTS),y) KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/arm64/kernel/module.lds endif +ifeq ($(CONFIG_DYNAMIC_FTRACE_WITH_REGS),y) + KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FENTRY + CC_FLAGS_FTRACE := -fpatchable-function-entry=2 +endif + # Default value head-y := arch/arm64/kernel/head.o --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -113,6 +113,7 @@ #define MCOUNT_REC() . = ALIGN(8); \ __start_mcount_loc = .; \ KEEP(*(__mcount_loc)) \ + KEEP(*(__patchable_function_entries)) \ __stop_mcount_loc = .; #else #define MCOUNT_REC() --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -112,6 +112,8 @@ struct ftrace_likely_data { #if defined(CC_USING_HOTPATCH) #define notrace __attribute__((hotpatch(0, 0))) +#elif defined(CC_USING_PATCHABLE_FENTRY) +#define notrace __attribute__((patchable_function_entry(0))) #else #define notrace __attribute__((__no_instrument_function__)) #endif --- a/kernel/module.c +++ b/kernel/module.c @@ -3122,7 +3122,12 @@ static int find_module_sections(struct m #endif #ifdef CONFIG_FTRACE_MCOUNT_RECORD /* sechdrs[0].sh_size is always zero */ - mod->ftrace_callsites = section_objs(info, "__mcount_loc", + mod->ftrace_callsites = section_objs(info, +#ifdef CC_USING_PATCHABLE_FENTRY + "__patchable_function_entries", +#else + "__mcount_loc", +#endif sizeof(*mod->ftrace_callsites), &mod->num_ftrace_callsites); #endif
