Error building from develop branch, cpuid problems

[Vascom]

I try build commit c7874f8
And it failed with this errors:

/builddir/build/BUILD/stlink-org-stlink-c7874f8/tests/usb.c: In function 'main':
/builddir/build/BUILD/stlink-org-stlink-c7874f8/tests/usb.c:34:9: error: 'cpuid.revision' may be used uninitialized in this func
tion [-Werror=maybe-uninitialized]
   34 |         printf("cpuid:part = %#x, rev = %#x\n", cpuid.part, cpuid.revision);
      |         ^
/builddir/build/BUILD/stlink-org-stlink-c7874f8/tests/usb.c:31:27: note: 'cpuid.revision' was declared here
   31 |         cortex_m3_cpuid_t cpuid;
      |                           ^
/builddir/build/BUILD/stlink-org-stlink-c7874f8/tests/usb.c:34:9: error: 'cpuid.part' may be used uninitialized in this function [-Werror=maybe-uninitialized]
   34 |         printf("cpuid:part = %#x, rev = %#x\n", cpuid.part, cpuid.revision);
      |         ^
/builddir/build/BUILD/stlink-org-stlink-c7874f8/tests/usb.c:31:27: note: 'cpuid.part' was declared here
   31 |         cortex_m3_cpuid_t cpuid;
      |                           ^
/builddir/build/BUILD/stlink-org-stlink-c7874f8/tests/usb.c:33:9: error: 'cpuid.variant' may be used uninitialized in this function [-Werror=maybe-uninitialized]
   33 |         printf("cpuid:impl_id = %0#x, variant = %#x\n", cpuid.implementer_id, cpuid.variant);
      |         ^
/builddir/build/BUILD/stlink-org-stlink-c7874f8/tests/usb.c:31:27: note: 'cpuid.variant' was declared here
   31 |         cortex_m3_cpuid_t cpuid;
      |                           ^
/builddir/build/BUILD/stlink-org-stlink-c7874f8/tests/usb.c:33:9: error: 'cpuid.implementer_id' may be used uninitialized in this function [-Werror=maybe-uninitialized]
   33 |         printf("cpuid:impl_id = %0#x, variant = %#x\n", cpuid.implementer_id, cpuid.variant);
      |         ^
/builddir/build/BUILD/stlink-org-stlink-c7874f8/tests/usb.c:31:27: note: 'cpuid.implementer_id' was declared here
   31 |         cortex_m3_cpuid_t cpuid;
      |                           ^
lto1: all warnings being treated as errors

How it can be fixed?

[chenguokai]

On macOS, the code builds well.

In src/common.c

int stlink_cpu_id(stlink_t *sl, cortex_m3_cpuid_t *cpuid) {
    uint32_t raw;

    if (stlink_read_debug32(sl, STLINK_REG_CM3_CPUID, &raw))
        return -1;

    cpuid->implementer_id = (raw >> 24) & 0x7f;
    cpuid->variant = (raw >> 20) & 0xf;
    cpuid->part = (raw >> 4) & 0xfff;
    cpuid->revision = raw & 0xf;
    return 0;
}

It seems that cpuid.part and cpuid.revision is indeed initialized here. Maybe a compiler misbehave?

[Vascom]

    if (stlink_read_debug32(sl, STLINK_REG_CM3_CPUID, &raw))
        return -1;

In this case cpuid.* stay uninitialized.

[Ant-ON]

On Ubuntu successful compiled too. Variable cpuid may use uninited in the case of error read register.

--- a/tests/usb.c
+++ b/tests/usb.c
@@ -29,7 +29,11 @@ int main(int ac, char** av) {
printf("-- core_id: %#x\n", sl->core_id);

     cortex_m3_cpuid_t cpuid;

•    stlink_cpu_id(sl, &cpuid);
  

•    if (stlink_cpu_id(sl, &cpuid))
  

•    {
  

•        printf("unknown chip\n");
  

•        memset(&cpuid, 0, sizeof(cortex_m3_cpuid_t))
  

•    }
     printf("cpuid:impl_id = %0#x, variant = %#x\n", cpuid.implementer_id, cpuid.variant);
     printf("cpuid:part = %#x, rev = %#x\n", cpuid.part, cpuid.revision);
  

[chenguokai]

I think it can be fixed by adding a return value check on stlink_cpu_id and initialize those values to zero. I will give it a try.

[Vascom]

I have -Werror=maybe-uninitialized because during configure:

-- Performing Test C_SUPPORTS_WMAYBE_UNINITIALIZED
-- Performing Test C_SUPPORTS_WMAYBE_UNINITIALIZED - Success

[chenguokai]

@Vascom May you test my branch https://github.com/chenguokai/stlink/tree/issue937 ?
If it works, I will raise a PR.

[Vascom]

@Vascom May you test my branch https://github.com/chenguokai/stlink/tree/issue937 ?
If it works, I will raise a PR.

Yes, it works.