riscv: Select HAVE_DYNAMIC_FTRACE when -fpatchable-function-entry is …

…available

clang prior to 13.0.0 does not support -fpatchable-function-entry for
RISC-V.

clang: error: unsupported option '-fpatchable-function-entry=8' for target 'riscv64-unknown-linux-gnu'

To avoid this error, only select HAVE_DYNAMIC_FTRACE when this option is
not available.

Fixes: afc76b8 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT")
Link: ClangBuiltLinux#1268
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Fangrui Song <maskray@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/Kconfig

@@ -231,7 +231,7 @@ config ARCH_RV64I
  bool "RV64I"
  select 64BIT
  select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 && GCC_VERSION >= 50000
- select HAVE_DYNAMIC_FTRACE if MMU
+ select HAVE_DYNAMIC_FTRACE if MMU && $(cc-option,-fpatchable-function-entry=8)
  select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
  select HAVE_FTRACE_MCOUNT_RECORD
  select HAVE_FUNCTION_GRAPH_TRACER