From fd092be23982c160a3855f1e396b7311b5225bf9 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 26 Mar 2020 13:18:48 +0900 Subject: Add get_current_el_maybe_constant() There are some cases where we want to run EL-dependent code in the shared code. We could use #ifdef, but it leaves slight possibility where we do not know the exception level at the build-time (e.g. library code). The counter approach is to use get_current_el(), but it is run-time detection, so all EL code is linked, some of which might be unneeded. This commit adds get_current_el_maybe_constant(). This is a static inline function that returns a constant value if we know the exception level at build-time. This is mostly the case. if (get_current_el_maybe_constant() == 1) { /* do something for EL1 */ } else if (get_current_el_maybe_constant() == 3) { /* do something for EL3 */ } If get_current_el_maybe_constant() is build-time constant, the compiler will optimize out the unreachable code. If such code is included from the library code, it is not built-time constant. In this case, it falls back to get_current_el(), so it still works. Change-Id: Idb03c20342a5b5173fe2d6b40e1fac7998675ad3 Signed-off-by: Masahiro Yamada --- include/arch/aarch64/arch_helpers.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'include/arch') diff --git a/include/arch/aarch64/arch_helpers.h b/include/arch/aarch64/arch_helpers.h index 240c1fbda..7c30758d0 100644 --- a/include/arch/aarch64/arch_helpers.h +++ b/include/arch/aarch64/arch_helpers.h @@ -531,6 +531,23 @@ static inline unsigned int get_current_el(void) return GET_EL(read_CurrentEl()); } +static inline unsigned int get_current_el_maybe_constant(void) +{ +#if defined(IMAGE_AT_EL1) + return 1; +#elif defined(IMAGE_AT_EL2) + return 2; /* no use-case in TF-A */ +#elif defined(IMAGE_AT_EL3) + return 3; +#else + /* + * If we do not know which exception level this is being built for + * (e.g. built for library), fall back to run-time detection. + */ + return get_current_el(); +#endif +} + /* * Check if an EL is implemented from AA64PFR0 register fields. */ -- cgit v1.2.3