[PATCH] format_proc_cpuinfo: add microcode registry lookup values
Brian Inglis
Brian.Inglis@SystematicSW.ab.ca
Tue Jul 7 17:33:41 GMT 2020
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 (µcode, &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 (µcode, 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
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