sorttable hardcodes before_func to 8 bytes on arm64 (two prefix NOPs). Make it configurable from CONFIG_ARM64_FUNCTION_PREFIX_NOPS instead. kCFI kernels with CALL_OPS need three NOPs. The symbol does not exist yet, so no functional change. Reviewed-by: Ben Cressey Reviewed-by: Florent Revest (Anthropic) Acked-by: Alexei Starovoitov Assisted-by: LLM Signed-off-by: Jose Fernandez (Anthropic) --- scripts/Makefile | 4 ++++ scripts/sorttable.c | 7 ++++++- 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/scripts/Makefile b/scripts/Makefile index d7fbb7ca098b..7ef1c84cf79d 100644 --- a/scripts/Makefile +++ b/scripts/Makefile @@ -54,6 +54,10 @@ endif ifdef CONFIG_BUILDTIME_MCOUNT_SORT HOSTCFLAGS_sorttable.o += -DMCOUNT_SORT_ENABLED +# 0 or unset (no prefix NOPs) leaves sorttable's built-in default in place. +ifneq ($(filter-out 0,$(CONFIG_ARM64_FUNCTION_PREFIX_NOPS)),) +HOSTCFLAGS_sorttable.o += -DFUNCTION_PREFIX_BYTES=$(shell expr 4 \* $(CONFIG_ARM64_FUNCTION_PREFIX_NOPS)) +endif endif hostprogs += gen_init_cpio diff --git a/scripts/sorttable.c b/scripts/sorttable.c index 88e49a5c4251..2e951f2f60e8 100644 --- a/scripts/sorttable.c +++ b/scripts/sorttable.c @@ -281,6 +281,11 @@ static int add_field(uint64_t addr, uint64_t size) /* Used for when mcount/fentry is before the function entry */ static int before_func; +/* How far before the function entry a patchable entry may be recorded */ +#ifndef FUNCTION_PREFIX_BYTES +#define FUNCTION_PREFIX_BYTES 8 +#endif + /* Only return match if the address lies inside the function size */ static int cmp_func_addr(const void *K, const void *A) { @@ -912,7 +917,7 @@ static int do_file(char const *const fname, void *addr) /* fallthrough */ case EM_RISCV: /* arm64 and RISC-V place patchable entries before the function. */ - before_func = 8; + before_func = FUNCTION_PREFIX_BYTES; #else case EM_AARCH64: case EM_RISCV: -- 2.54.0