[PATCH] format_proc_cpuinfo: add microcode registry lookup values

[Lavrentiev, Anton (NIH/NLM/NCBI) [C]]

Hi,

This is shifting up, IMO:

+		  microcode <<= 32;		/* shift them down */

Thanks,
Anton

> -----Original Message-----
> From: Brian Inglis <Brian.Inglis@SystematicSW.ab.ca>
> Sent: Tuesday, July 07, 2020 1:34 PM
> To: cygwin-patches@cygwin.com
> Subject: [PATCH] format_proc_cpuinfo: add microcode registry lookup values
> 
> Re: CPU microcode reported wrong in /proc/cpuinfo
>     https://sourceware.org/pipermail/cygwin/2020-May/245063.html
> earlier Windows releases used different registry values to store microcode
> revisions depending on the MSR name being used to get microcode revisions:
> add these alternative registry values to the cpuinfo registry value lookup;
> iterate thru the registry data until a valid microcode revision is found;
> some revision values are in the high bits, so if the low bits are all clear,
> shift the revision value down into the low bits
> ---
>  winsup/cygwin/fhandler_proc.cc | 44 +++++++++++++++++++++++++++-------
>  1 file changed, 35 insertions(+), 9 deletions(-)
> 
> diff --git a/winsup/cygwin/fhandler_proc.cc b/winsup/cygwin/fhandler_proc.cc
> index f1bc1c7405..f637dfd8e4 100644
> --- a/winsup/cygwin/fhandler_proc.cc
> +++ b/winsup/cygwin/fhandler_proc.cc
> @@ -692,26 +692,52 @@ format_proc_cpuinfo (void *, char *&destbuf)
>        union
>          {
>  	  LONG uc_len;		/* -max size of buffer before call */
> -	  char uc_microcode[16];
> -        } uc;
> +	  char uc_microcode[16];	/* at least 8 bytes */
> +        } uc[4];		/* microcode values changed historically */
> 
> -      RTL_QUERY_REGISTRY_TABLE tab[3] =
> +      RTL_QUERY_REGISTRY_TABLE tab[6] =
>          {
>  	  { NULL, RTL_QUERY_REGISTRY_DIRECT | RTL_QUERY_REGISTRY_NOSTRING,
> -	    L"~Mhz", &cpu_mhz, REG_NONE, NULL, 0 },
> +	    L"~Mhz",		       &cpu_mhz, REG_NONE, NULL, 0 },
>  	  { NULL, RTL_QUERY_REGISTRY_DIRECT | RTL_QUERY_REGISTRY_NOSTRING,
> -	    L"Update Revision", &uc, REG_NONE, NULL, 0 },
> +	    L"Update Revision",		 &uc[0], REG_NONE, NULL, 0 },
> +							/* latest MSR */
> +	  { NULL, RTL_QUERY_REGISTRY_DIRECT | RTL_QUERY_REGISTRY_NOSTRING,
> +	    L"Update Signature",	 &uc[1], REG_NONE, NULL, 0 },
> +							/* previous MSR */
> +	  { NULL, RTL_QUERY_REGISTRY_DIRECT | RTL_QUERY_REGISTRY_NOSTRING,
> +	    L"CurrentPatchLevel",	 &uc[2], REG_NONE, NULL, 0 },
> +							/* earlier MSR */
> +	  { NULL, RTL_QUERY_REGISTRY_DIRECT | RTL_QUERY_REGISTRY_NOSTRING,
> +	    L"Platform Specific Field1", &uc[3], REG_NONE, NULL, 0 },
> +							/* alternative */
>  	  { NULL, 0, NULL, NULL, 0, NULL, 0 }
>          };
> 
> -      memset (&uc, 0, sizeof (uc.uc_microcode));
> -      uc.uc_len = -16;	/* -max size of microcode buffer */
> +      for (size_t uci = 0; uci < sizeof (uc)/sizeof (*uc); ++uci)
> +	{
> +	  memset (&uc[uci], 0, sizeof (uc[uci]));
> +	  uc[uci].uc_len = -(LONG)sizeof (uc[0].uc_microcode);
> +							/* neg buffer size */
> +	}
> +
>        RtlQueryRegistryValues (RTL_REGISTRY_ABSOLUTE, cpu_key, tab,
>  			      NULL, NULL);
>        cpu_mhz = ((cpu_mhz - 1) / 10 + 1) * 10;	/* round up to multiple of 10 */
>        DWORD bogomips = cpu_mhz * 2; /* bogomips is double cpu MHz since MMX */
> -      long long microcode = 0;	/* at least 8 bytes for AMD */
> -      memcpy (&microcode, &uc, sizeof (microcode));
> +
> +      unsigned long long microcode = 0;	/* needs 8 bytes */
> +      for (size_t uci = 0; uci < sizeof (uc)/sizeof (*uc) && !microcode; ++uci)
> +	{
> +	  /* still neg buffer size => no data */
> +	  if (-(LONG)sizeof (uc[uci].uc_microcode) != uc[uci].uc_len)
> +	    {
> +	      memcpy (&microcode, uc[uci].uc_microcode, sizeof (microcode));
> +
> +	      if (!(microcode & 0xFFFFFFFFLL))	/* some values in high bits */
> +		  microcode <<= 32;		/* shift them down */
> +	    }
> +	}
> 
>        bufptr += __small_sprintf (bufptr, "processor\t: %d\n", cpu_number);
>        uint32_t maxf, vendor_id[4], unused;
> --
> 2.27.0