| Message ID | 20180809042206.15726-6-richard.henderson@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | target/arm: sve system mode patches | expand |
On 9 August 2018 at 05:21, Richard Henderson <richard.henderson@linaro.org> wrote: > Unlike aa32, endianness cannot be adjusted by userland in aa64. > > Signed-off-by: Richard Henderson <richard.henderson@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
On 08/17/2018 09:02 AM, Peter Maydell wrote: > On 9 August 2018 at 05:21, Richard Henderson > <richard.henderson@linaro.org> wrote: >> Unlike aa32, endianness cannot be adjusted by userland in aa64. >> >> Signed-off-by: Richard Henderson <richard.henderson@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. I should have re-ordered this after the other following simplifications to see if it still matters. But I was after a code-size reduction. r~
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; } #include "exec/cpu-all.h"
Unlike aa32, endianness cannot be adjusted by userland in aa64. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- target/arm/cpu.h | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) -- 2.17.1