Introduce an lvalue macro to wrap target_tlb_bit0.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/cpu.h           | 13 +++++++++++++
 target/arm/helper.c        |  2 +-
 target/arm/translate-a64.c |  2 +-
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index a5d3b6c9ee..3121836bdc 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -3393,6 +3393,19 @@ static inline uint64_t *aa64_vfp_qreg(CPUARMState *env, unsigned regno)
 /* Shared between translate-sve.c and sve_helper.c.  */
 extern const uint64_t pred_esz_masks[4];
 
+/* Helper for the macros below, validating the argument type. */
+static inline MemTxAttrs *typecheck_memtxattrs(MemTxAttrs *x)
+{
+    return x;
+}
+
+/*
+ * Lvalue macros for ARM TLB bits that we must cache in the TCG TLB.
+ * Using these should be a bit more self-documenting than using the
+ * generic target bits directly.
+ */
+#define arm_tlb_bti_gp(x) (typecheck_memtxattrs(x)->target_tlb_bit0)
+
 /*
  * Naming convention for isar_feature functions:
  * Functions which test 32-bit ID registers should have _aa32_ in
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 33f902387b..44a3f9fb48 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -11079,7 +11079,7 @@ static bool get_phys_addr_lpae(CPUARMState *env, target_ulong address,
     }
     /* When in aarch64 mode, and BTI is enabled, remember GP in the IOTLB.  */
     if (aarch64 && guarded && cpu_isar_feature(aa64_bti, cpu)) {
-        txattrs->target_tlb_bit0 = true;
+        arm_tlb_bti_gp(txattrs) = true;
     }
 
     if (cacheattrs != NULL) {
diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index 7e8263e86f..ec2295393d 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -14446,7 +14446,7 @@ static bool is_guarded_page(CPUARMState *env, DisasContext *s)
      * table entry even for that case.
      */
     return (tlb_hit(entry->addr_code, addr) &&
-            env_tlb(env)->d[mmu_idx].iotlb[index].attrs.target_tlb_bit0);
+            arm_tlb_bti_gp(&env_tlb(env)->d[mmu_idx].iotlb[index].attrs));
 #endif
 }
 
-- 
2.25.1

On Tue, 23 Jun 2020 at 20:37, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Introduce an lvalue macro to wrap target_tlb_bit0.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> +/* Helper for the macros below, validating the argument type. */
> +static inline MemTxAttrs *typecheck_memtxattrs(MemTxAttrs *x)
> +{
> +    return x;
> +}
> +
> +/*
> + * Lvalue macros for ARM TLB bits that we must cache in the TCG TLB.
> + * Using these should be a bit more self-documenting than using the
> + * generic target bits directly.
> + */
> +#define arm_tlb_bti_gp(x) (typecheck_memtxattrs(x)->target_tlb_bit0)

It seems unlikely that we wouldn't get a compile failure if
we passed something other than a MemTxAttrs* to this macro,
given the specificity of the field name, but I guess it
gives us a less confusing compiler error ?

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM

On 6/25/20 5:29 AM, Peter Maydell wrote:
> On Tue, 23 Jun 2020 at 20:37, Richard Henderson
> <richard.henderson@linaro.org> wrote:
>>
>> Introduce an lvalue macro to wrap target_tlb_bit0.
>>
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> +/* Helper for the macros below, validating the argument type. */
>> +static inline MemTxAttrs *typecheck_memtxattrs(MemTxAttrs *x)
>> +{
>> +    return x;
>> +}
>> +
>> +/*
>> + * Lvalue macros for ARM TLB bits that we must cache in the TCG TLB.
>> + * Using these should be a bit more self-documenting than using the
>> + * generic target bits directly.
>> + */
>> +#define arm_tlb_bti_gp(x) (typecheck_memtxattrs(x)->target_tlb_bit0)
> 
> It seems unlikely that we wouldn't get a compile failure if
> we passed something other than a MemTxAttrs* to this macro,
> given the specificity of the field name, but I guess it
> gives us a less confusing compiler error ?

Yes, it's a quite clear error with the function.  But you're right, we could
probably get away without it.


r~

> 
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> 
> thanks
> -- PMM
>