On 9 August 2018 at 05:21, Richard Henderson <richard.hender...@linaro.org> wrote: > Unlike aa32, endianness cannot be adjusted by userland in aa64. > > Signed-off-by: Richard Henderson <richard.hender...@linaro.org> > --- > target/arm/cpu.h | 27 +++++++++++++++++---------- > 1 file changed, 17 insertions(+), 10 deletions(-) > > diff --git a/target/arm/cpu.h b/target/arm/cpu.h > index 9526ed27cb..2d6d7d03aa 100644 > --- a/target/arm/cpu.h > +++ b/target/arm/cpu.h > @@ -2709,8 +2709,6 @@ static inline bool arm_sctlr_b(CPUARMState *env) > /* Return true if the processor is in big-endian mode. */ > static inline bool arm_cpu_data_is_big_endian(CPUARMState *env) > { > - int cur_el; > - > /* In 32bit endianness is determined by looking at CPSR's E bit */ > if (!is_a64(env)) { > return > @@ -2729,15 +2727,24 @@ static inline bool > arm_cpu_data_is_big_endian(CPUARMState *env) > arm_sctlr_b(env) || > #endif > ((env->uncached_cpsr & CPSR_E) ? 1 : 0); > + } else { > +#ifdef CONFIG_USER_ONLY > + /* AArch64 does not have a SETEND instruction; endianness > + * for usermode is fixed at compile-time. > + */ > +# ifdef TARGET_WORDS_BIGENDIAN > + return true; > +# else > + return false; > +# endif > +#else > + int cur_el = arm_current_el(env); > + if (cur_el == 0) { > + return (env->cp15.sctlr_el[1] & SCTLR_E0E) != 0; > + } > + return (env->cp15.sctlr_el[cur_el] & SCTLR_EE) != 0; > +#endif > } > - > - cur_el = arm_current_el(env); > - > - if (cur_el == 0) { > - return (env->cp15.sctlr_el[1] & SCTLR_E0E) != 0; > - } > - > - return (env->cp15.sctlr_el[cur_el] & SCTLR_EE) != 0; > } >
When does this make a difference? For user-mode, we've already dealt with the "aa32" case, so the code here is aa64-only. In linux-user/aarch64/cpu_loop.c we set sctlr_el[1]'s E0E bit if TARGET_WORDS_BIGENDIAN is defined, and cur_el is definitely zero, so we should already be returning true from this function if TARGET_WORDS_BIGENDIAN and false otherwise. thanks -- PMM