[v2,07/10] target-arm: remove last users of cpsr_write

And use the new machinery to to save and restore program state. The old
cpsr_write function did some special handling for mode switches which
has been moved into the helper function.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

---
v2:
  - rebase
  - add mask helper function
  - checkpatch fixes

On Thu, Jul 10, 2014 at 04:50:04PM +0100, Alex Bennée wrote:
> And use the new machinery to to save and restore program state. The old
> cpsr_write function did some special handling for mode switches which
> has been moved into the helper function.

Again for the linux-user part,

Acked-by: Riku Voipio <riku.voipio@linaro.org>

> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> 
> ---
> v2:
>   - rebase
>   - add mask helper function
>   - checkpatch fixes
> 
> diff --git a/linux-user/main.c b/linux-user/main.c
> index 9101541..5f7cc31 100644
> --- a/linux-user/main.c
> +++ b/linux-user/main.c
> @@ -4184,7 +4184,7 @@ int main(int argc, char **argv, char **envp)
>  #elif defined(TARGET_ARM)
>      {
>          int i;
> -        cpsr_write(env, regs->uregs[16], 0xffffffff);
> +        restore_state_from_spsr(env, regs->uregs[16]);
>          for(i = 0; i < 16; i++) {
>              env->regs[i] = regs->uregs[i];
>          }
> diff --git a/linux-user/signal.c b/linux-user/signal.c
> index 9c6727b..b6f9ef4 100644
> --- a/linux-user/signal.c
> +++ b/linux-user/signal.c
> @@ -1599,38 +1599,39 @@ get_sigframe(struct target_sigaction *ka, CPUARMState *regs, int framesize)
>  
>  static void
>  setup_return(CPUARMState *env, struct target_sigaction *ka,
> -	     abi_ulong *rc, abi_ulong frame_addr, int usig, abi_ulong rc_addr)
> +             abi_ulong *rc, abi_ulong frame_addr, int usig, abi_ulong rc_addr)
>  {
> -	abi_ulong handler = ka->_sa_handler;
> -	abi_ulong retcode;
> -	int thumb = handler & 1;
> -	uint32_t cpsr = save_state_to_spsr(env);
> +        abi_ulong handler = ka->_sa_handler;
> +        abi_ulong retcode;
> +        int thumb = handler & 1;
> +        uint32_t cpsr = save_state_to_spsr(env);
>  
> -	cpsr &= ~CPSR_IT;
> -	if (thumb) {
> -		cpsr |= CPSR_T;
> -	} else {
> -		cpsr &= ~CPSR_T;
> -	}
> +        cpsr &= ~CPSR_IT;
> +        if (thumb) {
> +                cpsr |= CPSR_T;
> +        } else {
> +                cpsr &= ~CPSR_T;
> +        }
>  
> -	if (ka->sa_flags & TARGET_SA_RESTORER) {
> -		retcode = ka->sa_restorer;
> -	} else {
> -		unsigned int idx = thumb;
> +        if (ka->sa_flags & TARGET_SA_RESTORER) {
> +                retcode = ka->sa_restorer;
> +        } else {
> +                unsigned int idx = thumb;
>  
> -		if (ka->sa_flags & TARGET_SA_SIGINFO)
> -			idx += 2;
> +                if (ka->sa_flags & TARGET_SA_SIGINFO) {
> +                        idx += 2;
> +                }
>  
> -        __put_user(retcodes[idx], rc);
> +                __put_user(retcodes[idx], rc);
>  
> -		retcode = rc_addr + thumb;
> -	}
> +                retcode = rc_addr + thumb;
> +        }
>  
> -	env->regs[0] = usig;
> -	env->regs[13] = frame_addr;
> -	env->regs[14] = retcode;
> -	env->regs[15] = handler & (thumb ? ~1 : ~3);
> -	cpsr_write(env, cpsr, 0xffffffff);
> +        env->regs[0] = usig;
> +        env->regs[13] = frame_addr;
> +        env->regs[14] = retcode;
> +        env->regs[15] = handler & (thumb ? ~1 : ~3);
> +        restore_state_from_spsr(env, cpsr);
>  }
>  
>  static abi_ulong *setup_sigframe_v2_vfp(abi_ulong *regspace, CPUARMState *env)
> @@ -1858,12 +1859,14 @@ restore_sigcontext(CPUARMState *env, struct target_sigcontext *sc)
>      __get_user(env->regs[15], &sc->arm_pc);
>  #ifdef TARGET_CONFIG_CPU_32
>      __get_user(cpsr, &sc->arm_cpsr);
> -        cpsr_write(env, cpsr, CPSR_USER | CPSR_EXEC);
> +    restore_state_from_masked_spsr(env,
> +                                   (CPSR_USER | CPSR_EXEC),
> +                                   cpsr);
>  #endif
>  
> -	err |= !valid_user_regs(env);
> +    err |= !valid_user_regs(env);
>  
> -	return err;
> +    return err;
>  }
>  
>  static long do_sigreturn_v1(CPUARMState *env)
> diff --git a/target-arm/cpu.h b/target-arm/cpu.h
> index 3f23167..b56f1a8 100644
> --- a/target-arm/cpu.h
> +++ b/target-arm/cpu.h
> @@ -795,6 +795,15 @@ static inline void restore_state_from_spsr(CPUARMState *env,
>      }
>  }
>  
> +/* Restore a few masked bits of the program state */
> +static inline void restore_state_from_masked_spsr(CPUARMState *env,
> +                                                  uint32_t mask,
> +                                                  uint32_t saved_state)
> +{
> +    uint32_t spsr = (save_state_to_spsr(env) & ~mask);
> +    spsr |= (saved_state & mask);
> +    return restore_state_from_spsr(env, spsr);
> +}
>  
>  void arm_cpu_list(FILE *f, fprintf_function cpu_fprintf);
>  
> diff --git a/target-arm/gdbstub.c b/target-arm/gdbstub.c
> index ec25f30..5e60589 100644
> --- a/target-arm/gdbstub.c
> +++ b/target-arm/gdbstub.c
> @@ -93,8 +93,12 @@ int arm_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
>          }
>          return 4;
>      case 25:
> -        /* CPSR */
> -        cpsr_write(env, tmp, 0xffffffff);
> +        /* CPSR
> +         * FIXME?: as restore_state_from_spsr() doesn't do aarch32
> +         * special mode fixups this may break. However GDB doesn't
> +         * seem to be able to handle tracing over a mode switch anyway
> +         */
> +        restore_state_from_spsr(env, tmp);
>          return 4;
>      }
>      /* Unknown register.  */
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index 030bcdd..6d755c0 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -2970,68 +2970,6 @@ void arm_cp_reset_ignore(CPUARMState *env, const ARMCPRegInfo *opaque)
>      /* Helper coprocessor reset function for do-nothing-on-reset registers */
>  }
>  
> -static int bad_mode_switch(CPUARMState *env, int mode)
> -{
> -    /* Return true if it is not valid for us to switch to
> -     * this CPU mode (ie all the UNPREDICTABLE cases in
> -     * the ARM ARM CPSRWriteByInstr pseudocode).
> -     */
> -    switch (mode) {
> -    case ARM_CPU_MODE_USR:
> -    case ARM_CPU_MODE_SYS:
> -    case ARM_CPU_MODE_SVC:
> -    case ARM_CPU_MODE_ABT:
> -    case ARM_CPU_MODE_UND:
> -    case ARM_CPU_MODE_IRQ:
> -    case ARM_CPU_MODE_FIQ:
> -        return 0;
> -    default:
> -        return 1;
> -    }
> -}
> -
> -void cpsr_write(CPUARMState *env, uint32_t val, uint32_t mask)
> -{
> -    if (mask & CPSR_NZCV) {
> -        env->ZF = (~val) & CPSR_Z;
> -        env->NF = val;
> -        env->CF = (val >> 29) & 1;
> -        env->VF = (val << 3) & 0x80000000;
> -    }
> -    if (mask & CPSR_Q)
> -        env->QF = ((val & CPSR_Q) != 0);
> -    if (mask & CPSR_T)
> -        env->thumb = ((val & CPSR_T) != 0);
> -    if (mask & CPSR_IT_0_1) {
> -        env->condexec_bits &= ~3;
> -        env->condexec_bits |= (val >> 25) & 3;
> -    }
> -    if (mask & CPSR_IT_2_7) {
> -        env->condexec_bits &= 3;
> -        env->condexec_bits |= (val >> 8) & 0xfc;
> -    }
> -    if (mask & CPSR_GE) {
> -        env->GE = (val >> 16) & 0xf;
> -    }
> -
> -    env->daif &= ~(CPSR_AIF & mask);
> -    env->daif |= val & CPSR_AIF & mask;
> -
> -    if ((env->uncached_cpsr ^ val) & mask & CPSR_M) {
> -        if (bad_mode_switch(env, val & CPSR_M)) {
> -            /* Attempt to switch to an invalid mode: this is UNPREDICTABLE.
> -             * We choose to ignore the attempt and leave the CPSR M field
> -             * untouched.
> -             */
> -            mask &= ~CPSR_M;
> -        } else {
> -            switch_mode(env, val & CPSR_M);
> -        }
> -    }
> -    mask &= ~CACHED_CPSR_BITS;
> -    env->uncached_cpsr = (env->uncached_cpsr & ~mask) | (val & mask);
> -}
> -
>  /* Sign/zero extend */
>  uint32_t HELPER(sxtb16)(uint32_t x)
>  {
> diff --git a/target-arm/kvm32.c b/target-arm/kvm32.c
> index 789f52f..39117c7 100644
> --- a/target-arm/kvm32.c
> +++ b/target-arm/kvm32.c
> @@ -464,7 +464,7 @@ int kvm_arch_get_registers(CPUState *cs)
>      if (ret) {
>          return ret;
>      }
> -    cpsr_write(env, cpsr, 0xffffffff);
> +    restore_state_from_spsr(env, cpsr);
>  
>      /* Make sure the current mode regs are properly set */
>      mode = env->uncached_cpsr & CPSR_M;
> diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
> index 052a4bd..c17bdba 100644
> --- a/target-arm/op_helper.c
> +++ b/target-arm/op_helper.c
> @@ -261,9 +261,47 @@ uint32_t HELPER(cpsr_read)(CPUARMState *env)
>      return save_state_to_spsr(env) & ~CPSR_EXEC;
>  }
>  
> +static int bad_mode_switch(CPUARMState *env, int mode)
> +{
> +    /* Return true if it is not valid for us to switch to
> +     * this CPU mode (ie all the UNPREDICTABLE cases in
> +     * the ARM ARM CPSRWriteByInstr pseudocode).
> +     */
> +    switch (mode) {
> +    case ARM_CPU_MODE_USR:
> +    case ARM_CPU_MODE_SYS:
> +    case ARM_CPU_MODE_SVC:
> +    case ARM_CPU_MODE_ABT:
> +    case ARM_CPU_MODE_UND:
> +    case ARM_CPU_MODE_IRQ:
> +    case ARM_CPU_MODE_FIQ:
> +        return 0;
> +    default:
> +        return 1;
> +    }
> +}
> +
>  void HELPER(cpsr_write)(CPUARMState *env, uint32_t val, uint32_t mask)
>  {
> -    cpsr_write(env, val, mask);
> +    uint32_t current_cpsr = save_state_to_spsr(env);
> +    uint32_t new_cpsr;
> +
> +    /* we may be triggering a mode change */
> +    if ((current_cpsr ^ val) & mask & CPSR_M) {
> +        if (bad_mode_switch(env, val & CPSR_M)) {
> +            /* Attempt to switch to an invalid mode: this is UNPREDICTABLE.
> +             * We choose to ignore the attempt and leave the CPSR M field
> +             * untouched.
> +             */
> +            mask &= ~CPSR_M;
> +        } else {
> +            switch_mode(env, val & CPSR_M);
> +        }
> +    }
> +
> +    new_cpsr = current_cpsr & ~mask;
> +    new_cpsr |= (val & mask);
> +    restore_state_from_spsr(env, new_cpsr);
>  }
>  
>  /* Access to user mode registers from privileged modes.  */
> -- 
> 2.0.1
>

On 10 July 2014 16:50, Alex Bennée <alex.bennee@linaro.org> wrote:
> And use the new machinery to to save and restore program state. The old
> cpsr_write function did some special handling for mode switches which
> has been moved into the helper function.

Are you really sure all the old places we did cpsr_write() don't
want the mode switch handling? That was kind of the whole
point of that function...

-- PMM