Re: [PATCH] linux-user/elfload: Add missing arm64 hwcap values

[Marielle Novastrider]

> On 31 Oct 2023, at 00:56, Marielle Novastrider  
> wrote:
> 
>> On 30 Oct 2023, at 09:52, Peter Maydell  wrote:
>> 
>> ...but we don't implement FEAT_MTE3 yet. We would add this feature test
>> function, and the GET_FEATURE_ID() line, when we do, but we don't
>> need it until then.
> 
> Understood.
> 
> I made this patch as I noticed the discrepancy between cpuid and hwcap output.
> 
> The following code produces the value of 3 on current master, which would be 
> erroneous if FEAT_MT3 is unimplemented:
> 
> #include 
> #include 
> 
> int main() {
>uint64_t aa64pfr1;
>__asm__("mrs %0, s3_0_c0_c4_1" : "=r"(aa64pfr1));
>std::printf("%lu\n", (aa64pfr1 >> 8) & 0xf);
>return 0;
> }
> 
> I can submit another patch to correct this.
> 
> - Marielle
> 

I note that commit 86f0d4c7290eb2b21ec3eb44956ec245441275db suggests that 
FEAT_MTE3 is already implemented.

Re: [PATCH] linux-user/elfload: Add missing arm64 hwcap values

[Marielle Novastrider]

> On 30 Oct 2023, at 09:52, Peter Maydell  wrote:
> 
> ...but we don't implement FEAT_MTE3 yet. We would add this feature test
> function, and the GET_FEATURE_ID() line, when we do, but we don't
> need it until then.

Understood.

I made this patch as I noticed the discrepancy between cpuid and hwcap output.

The following code produces the value of 3 on current master, which would be 
erroneous if FEAT_MT3 is unimplemented:

#include 
#include 

int main() {
uint64_t aa64pfr1;
__asm__("mrs %0, s3_0_c0_c4_1" : "=r"(aa64pfr1));
std::printf("%lu\n", (aa64pfr1 >> 8) & 0xf);
return 0;
}

I can submit another patch to correct this.

- Marielle

[PATCH] linux-user/elfload: Add missing arm64 hwcap values

[Marielle Novastrider]

Specifically DIT, LSE2, and MTE3.

We already expose detection of these via the CPUID interface, but
missed these from ELF hwcaps.

Signed-off-by: Marielle Novastrider 
---
 linux-user/elfload.c | 3 +++
 target/arm/cpu.h | 5 +
 2 files changed, 8 insertions(+)

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 2e3809f03c..d9683809a1 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -768,12 +768,14 @@ uint32_t get_elf_hwcap(void)
 GET_FEATURE_ID(aa64_sm4, ARM_HWCAP_A64_SM4);
 GET_FEATURE_ID(aa64_fp16, ARM_HWCAP_A64_FPHP | ARM_HWCAP_A64_ASIMDHP);
 GET_FEATURE_ID(aa64_atomics, ARM_HWCAP_A64_ATOMICS);
+GET_FEATURE_ID(aa64_lse2, ARM_HWCAP_A64_USCAT);
 GET_FEATURE_ID(aa64_rdm, ARM_HWCAP_A64_ASIMDRDM);
 GET_FEATURE_ID(aa64_dp, ARM_HWCAP_A64_ASIMDDP);
 GET_FEATURE_ID(aa64_fcma, ARM_HWCAP_A64_FCMA);
 GET_FEATURE_ID(aa64_sve, ARM_HWCAP_A64_SVE);
 GET_FEATURE_ID(aa64_pauth, ARM_HWCAP_A64_PACA | ARM_HWCAP_A64_PACG);
 GET_FEATURE_ID(aa64_fhm, ARM_HWCAP_A64_ASIMDFHM);
+GET_FEATURE_ID(aa64_dit, ARM_HWCAP_A64_DIT);
 GET_FEATURE_ID(aa64_jscvt, ARM_HWCAP_A64_JSCVT);
 GET_FEATURE_ID(aa64_sb, ARM_HWCAP_A64_SB);
 GET_FEATURE_ID(aa64_condm_4, ARM_HWCAP_A64_FLAGM);
@@ -807,6 +809,7 @@ uint32_t get_elf_hwcap2(void)
 GET_FEATURE_ID(aa64_rndr, ARM_HWCAP2_A64_RNG);
 GET_FEATURE_ID(aa64_bti, ARM_HWCAP2_A64_BTI);
 GET_FEATURE_ID(aa64_mte, ARM_HWCAP2_A64_MTE);
+GET_FEATURE_ID(aa64_mte3, ARM_HWCAP2_A64_MTE3);
 GET_FEATURE_ID(aa64_sme, (ARM_HWCAP2_A64_SME |
   ARM_HWCAP2_A64_SME_F32F32 |
   ARM_HWCAP2_A64_SME_B16F32 |
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 76d4cef9e3..7605d6ee3a 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -4073,6 +4073,11 @@ static inline bool isar_feature_aa64_mte(const 
ARMISARegisters *id)
 return FIELD_EX64(id->id_aa64pfr1, ID_AA64PFR1, MTE) >= 2;
 }
 
+static inline bool isar_feature_aa64_mte3(const ARMISARegisters *id)
+{
+return FIELD_EX64(id->id_aa64pfr1, ID_AA64PFR1, MTE) >= 3;
+}
+
 static inline bool isar_feature_aa64_sme(const ARMISARegisters *id)
 {
 return FIELD_EX64(id->id_aa64pfr1, ID_AA64PFR1, SME) != 0;
-- 
2.39.3 (Apple Git-145)