Parse error when we set arm64's cpus to one cluster for DynamIQ arch

ecause DynamIQ allows for more diverse core configurations within the same cluster, and even enables the mixing of cores with different performance levels. In fact, they belong to the same physical cluster. Currently, our SoC is configured with 6 A55 cores (0-5) and 2 A78 cores (6-7). and the CPU can be configured as follows in the device tree:

             cpu-map {
                      cluster0 {
                              core0 {
                                      cpu = <&CPU0>;
                              };

                              core1 {
                                      cpu = <&CPU1>;
                              };

                              core2 {
                                      cpu = <&CPU2>;
                              };

                              core3 {
                                      cpu = <&CPU3>;
                            };

                              core4 {
                                      cpu = <&CPU4>;
                              };

                              core5 {
                                      cpu = <&CPU5>;
                              };

                              core6 {
                                      cpu = <&CPU6>;
                              };

                              core7 {
                                      cpu = <&CPU7>;
                              };
                      };
              };

As a result:
the cpuinfo will parse the cpu as follow：

SoC name: Unknown
Microarchitectures:
8x Cortex-A55
Cores:
0: 1 processor (0), ARM Cortex-A55
1: 1 processor (1), ARM Cortex-A55
2: 1 processor (2), ARM Cortex-A55
3: 1 processor (3), ARM Cortex-A55
4: 1 processor (4), ARM Cortex-A55
5: 1 processor (5), ARM Cortex-A55
6: 1 processor (6), ARM Cortex-A55
7: 1 processor (7), ARM Cortex-A55
Clusters:
0: 8 processors (0-7), 0: 8 cores (0-7), ARM Cortex-A55
Logical processors (System ID):
0 (0)
1 (1)
2 (2)
3 (3)
4 (4)
5 (5)
6 (6)
7 (7)

This is because the cluster_cpus is all ff:
cat /sys/devices/system/cpu/cpu*/topology/cluster_cpus
ff
ff
ff
ff
ff
ff
ff
ff

As a result, we must set the devices tree as following:

              cpu-map {
                      cluster0 {
                              core0 {
                                      cpu = <&CPU0>;
                              };

                              core1 {
                                      cpu = <&CPU1>;
                              };

                              core2 {
                                      cpu = <&CPU2>;
                              };

                              core3 {
                                      cpu = <&CPU3>;
                             };

                              core4 {
                                      cpu = <&CPU4>;
                              };

                              core5 {
                                      cpu = <&CPU5>;
                              };
                      };
                      cluster1 {
                              core0 {
                                      cpu = <&CPU6>;
                              };

                              core1 {
                                      cpu = <&CPU7>;
                              };
                      };
              };

When set this, the cpuinfo's result is true:

Microarchitectures:
2x Cortex-A78
6x Cortex-A55
Cores:
0: 1 processor (0), ARM Cortex-A78
1: 1 processor (1), ARM Cortex-A78
2: 1 processor (2), ARM Cortex-A55
3: 1 processor (3), ARM Cortex-A55
4: 1 processor (4), ARM Cortex-A55
5: 1 processor (5), ARM Cortex-A55
6: 1 processor (6), ARM Cortex-A55
7: 1 processor (7), ARM Cortex-A55
Clusters:
0: 2 processors (0-1), 0: 2 core (0-1), ARM Cortex-A78
1: 6 processors (2-7), 1: 6 cores (2-7), ARM Cortex-A55
Logical processors (System ID):
0 (6)
1 (7)
2 (0)
3 (1)
4 (2)
5 (3)
6 (4)
7 (5)

This is because the following code:

for (uint32_t i = 0; i < arm_linux_processors_count; i++) {
if (bitmask_all(arm_linux_processors[i].flags, CPUINFO_LINUX_FLAG_VALID)) {
const uint32_t cluster_leader = arm_linux_processors[i].package_leader_id;
if (cluster_leader == i) {
/ Cluster leader: decode core vendor and uarch
/
cpuinfo_arm_decode_vendor_uarch(
arm_linux_processors[cluster_leader].midr,
#if CPUINFO_ARCH_ARM
!!(arm_linux_processors[cluster_leader].features &
CPUINFO_ARM_LINUX_FEATURE_VFPV4),
#endif
&arm_linux_processors[cluster_leader].vendor,
&arm_linux_processors[cluster_leader].uarch);
} else {
/ Cluster non-leader: copy vendor, uarch, MIDR,
* and frequency from cluster leader /
arm_linux_processors[i].flags |= arm_linux_processors[cluster_leader].flags &
(CPUINFO_ARM_LINUX_VALID_MIDR | CPUINFO_LINUX_FLAG_MAX_FREQUENCY);
arm_linux_processors[i].midr = arm_linux_processors[cluster_leader].midr;
arm_linux_processors[i].vendor = arm_linux_processors[cluster_leader].vendor;
arm_linux_processors[i].uarch = arm_linux_processors[cluster_leader].uarch;
arm_linux_processors[i].max_frequency =
arm_linux_processors[cluster_leader].max_frequency;
}
}
}

Because the clusters's cpus is 0-7, so it set cpu0 as the leader,and all other cpus copy the cpu0's feature, indeed, this is not true.

Thanks!

Start with the shown ARM Linux processor loop and the handling of cluster_cpus, then reproduce the issue using the single-cluster DynamIQ device-tree configuration described here. The fix is done when mixed Cortex-A55 and Cortex-A78 cores in one physical cluster are reported with their correct microarchitectures rather than inheriting CPU0's information.