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Re: [Xen-devel] [PATCH 10/13] xen/arm: vreg: Introduce vreg_emulate_cp{32, 64}



On Wed, 7 Dec 2016, Julien Grall wrote:
> Factorize the code to emulate 32-bit and 64-bit access to a co-processor
> in specific helpers.
> 
> The new helpers will be used in different components to simplify the
> emulation.
> 
> Finally, the prototypes for the callbacks to emulate 32-bit and 64-bit
> co-processor access are the same as the sysreg one. Rather than
> introducing new ones, repurpose the existent prototypes.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>  xen/arch/arm/vtimer.c      | 37 +++------------------------
>  xen/include/asm-arm/vreg.h | 64 
> ++++++++++++++++++++++++++++++++++++++++++----
>  2 files changed, 62 insertions(+), 39 deletions(-)
> 
> diff --git a/xen/arch/arm/vtimer.c b/xen/arch/arm/vtimer.c
> index 091b5e7..4ec3b95 100644
> --- a/xen/arch/arm/vtimer.c
> +++ b/xen/arch/arm/vtimer.c
> @@ -252,49 +252,28 @@ static bool vtimer_cntp_cval(struct cpu_user_regs 
> *regs, uint64_t *r,
>  static bool vtimer_emulate_cp32(struct cpu_user_regs *regs, union hsr hsr)
>  {
>      struct hsr_cp32 cp32 = hsr.cp32;
> -    /*
> -     * Initialize to zero to avoid leaking data if there is an
> -     * implementation error in the emulation (such as not correctly
> -     * setting r).
> -     */
> -    uint32_t r = 0;
> -    bool res;
> -
>  
>      if ( cp32.read )
>          perfc_incr(vtimer_cp32_reads);
>      else
>          perfc_incr(vtimer_cp32_writes);
>  
> -    if ( !cp32.read )
> -        r = get_user_reg(regs, cp32.reg);
> -
>      switch ( hsr.bits & HSR_CP32_REGS_MASK )
>      {
>      case HSR_CPREG32(CNTP_CTL):
> -        res = vtimer_cntp_ctl(regs, &r, cp32.read);
> -        break;
> +        return vreg_emulate_cp32(regs, hsr, vtimer_cntp_ctl);
>  
>      case HSR_CPREG32(CNTP_TVAL):
> -        res = vtimer_cntp_tval(regs, &r, cp32.read);
> -        break;
> +        return vreg_emulate_cp32(regs, hsr, vtimer_cntp_tval);
>  
>      default:
>          return false;
>      }
> -
> -    if ( res && cp32.read )
> -        set_user_reg(regs, cp32.reg, r);
> -
> -    return res;
>  }
>  
>  static bool vtimer_emulate_cp64(struct cpu_user_regs *regs, union hsr hsr)
>  {
>      struct hsr_cp64 cp64 = hsr.cp64;
> -    uint32_t r1 = get_user_reg(regs, cp64.reg1);
> -    uint32_t r2 = get_user_reg(regs, cp64.reg2);
> -    uint64_t x = (uint64_t)r1 | ((uint64_t)r2 << 32);
>  
>      if ( cp64.read )
>          perfc_incr(vtimer_cp64_reads);
> @@ -304,21 +283,11 @@ static bool vtimer_emulate_cp64(struct cpu_user_regs 
> *regs, union hsr hsr)
>      switch ( hsr.bits & HSR_CP64_REGS_MASK )
>      {
>      case HSR_CPREG64(CNTP_CVAL):
> -        if ( !vtimer_cntp_cval(regs, &x, cp64.read) )
> -            return false;
> -        break;
> +        return vreg_emulate_cp64(regs, hsr, vtimer_cntp_cval);
>  
>      default:
>          return false;
>      }
> -
> -    if ( cp64.read )
> -    {
> -        set_user_reg(regs, cp64.reg1, x & 0xffffffff);
> -        set_user_reg(regs, cp64.reg2, x >> 32);
> -    }
> -
> -    return true;
>  }
>  
>  #ifdef CONFIG_ARM_64
> diff --git a/xen/include/asm-arm/vreg.h b/xen/include/asm-arm/vreg.h
> index 2671f6e..ed2bd6f 100644
> --- a/xen/include/asm-arm/vreg.h
> +++ b/xen/include/asm-arm/vreg.h
> @@ -4,14 +4,68 @@
>  #ifndef __ASM_ARM_VREG__
>  #define __ASM_ARM_VREG__
>  
> -#ifdef CONFIG_ARM_64
> -typedef bool (*vreg_sysreg32_fn_t)(struct cpu_user_regs *regs, uint32_t *r,
> +typedef bool (*vreg_reg32_fn_t)(struct cpu_user_regs *regs, uint32_t *r,
>                                     bool read);
> -typedef bool (*vreg_sysreg64_fn_t)(struct cpu_user_regs *regs, uint64_t *r,
> +typedef bool (*vreg_reg64_fn_t)(struct cpu_user_regs *regs, uint64_t *r,
>                                     bool read);
>  
> +static inline bool vreg_emulate_cp32(struct cpu_user_regs *regs, union hsr 
> hsr,
> +                                     vreg_reg32_fn_t fn)
> +{
> +    struct hsr_cp32 cp32 = hsr.cp32;
> +    /*
> +     * Initialize to zero to avoid leaking data if there is an
> +     * implementation error in the emulation (such as not correctly
> +     * setting r).
> +     */
> +    uint32_t r = 0;
> +    bool ret;
> +
> +    if ( !cp32.read )
> +        r = get_user_reg(regs, cp32.reg);
> +
> +    ret = fn(regs, &r, cp32.read);
> +
> +    if ( ret && cp32.read )
> +        set_user_reg(regs, cp32.reg, r);
> +
> +    return ret;
> +}
> +
> +static inline bool vreg_emulate_cp64(struct cpu_user_regs *regs, union hsr 
> hsr,
> +                                     vreg_reg64_fn_t fn)
> +{
> +    struct hsr_cp64 cp64 = hsr.cp64;
> +    /*
> +     * Initialize to zero to avoid leaking data if there is an
> +     * implementation error in the emulation (such as not correctly
> +     * setting x).
> +     */
> +    uint64_t x = 0;
> +    bool ret;
> +
> +    if ( !cp64.read )
> +    {
> +        uint32_t r1 = get_user_reg(regs, cp64.reg1);
> +        uint32_t r2 = get_user_reg(regs, cp64.reg2);
> +
> +        x = (uint64_t)r1 | ((uint64_t)r2 << 32);
> +    }
> +
> +    ret = fn(regs, &x, cp64.read);
> +
> +    if ( ret && cp64.read )
> +    {
> +        set_user_reg(regs, cp64.reg1, x & 0xffffffff);
> +        set_user_reg(regs, cp64.reg2, x >> 32);
> +    }
> +
> +    return ret;
> +}
> +
> +#ifdef CONFIG_ARM_64
>  static inline bool vreg_emulate_sysreg32(struct cpu_user_regs *regs, union 
> hsr hsr,
> -                                         vreg_sysreg32_fn_t fn)
> +                                         vreg_reg32_fn_t fn)
>  {
>      struct hsr_sysreg sysreg = hsr.sysreg;
>      uint32_t r = 0;
> @@ -29,7 +83,7 @@ static inline bool vreg_emulate_sysreg32(struct 
> cpu_user_regs *regs, union hsr h
>  }
>  
>  static inline bool vreg_emulate_sysreg64(struct cpu_user_regs *regs, union 
> hsr hsr,
> -                                         vreg_sysreg64_fn_t fn)
> +                                         vreg_reg64_fn_t fn)
>  {
>      struct hsr_sysreg sysreg = hsr.sysreg;
>      /*
> -- 
> 1.9.1
> 

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