Author: jkim
Date: Mon Apr  2 18:17:51 2012
New Revision: 233798
URL: http://svn.freebsd.org/changeset/base/233798

Log:
  MFC:  r233702
  
  Work around Erratum 721 for AMD Family 10h and 12h processors.

Modified:
  stable/9/sys/amd64/amd64/initcpu.c
Directory Properties:
  stable/9/sys/   (props changed)

Modified: stable/9/sys/amd64/amd64/initcpu.c
==============================================================================
--- stable/9/sys/amd64/amd64/initcpu.c  Mon Apr  2 18:13:29 2012        
(r233797)
+++ stable/9/sys/amd64/amd64/initcpu.c  Mon Apr  2 18:17:51 2012        
(r233798)
@@ -79,6 +79,27 @@ SYSCTL_UINT(_hw, OID_AUTO, via_feature_r
 SYSCTL_UINT(_hw, OID_AUTO, via_feature_xcrypt, CTLFLAG_RD,
        &via_feature_xcrypt, 0, "VIA xcrypt feature available in CPU");
 
+static void
+init_amd(void)
+{
+
+       /*
+        * Work around Erratum 721 for Family 10h and 12h processors.
+        * These processors may incorrectly update the stack pointer
+        * after a long series of push and/or near-call instructions,
+        * or a long series of pop and/or near-return instructions.
+        *
+        * http://support.amd.com/us/Processor_TechDocs/41322_10h_Rev_Gd.pdf
+        * http://support.amd.com/us/Processor_TechDocs/44739_12h_Rev_Gd.pdf
+        */
+       switch (CPUID_TO_FAMILY(cpu_id)) {
+       case 0x10:
+       case 0x12:
+               wrmsr(0xc0011029, rdmsr(0xc0011029) | 1);
+               break;
+       }
+}
+
 /*
  * Initialize special VIA features
  */
@@ -135,8 +156,14 @@ initializecpu(void)
                wrmsr(MSR_EFER, msr);
                pg_nx = PG_NX;
        }
-       if (cpu_vendor_id == CPU_VENDOR_CENTAUR)
+       switch (cpu_vendor_id) {
+       case CPU_VENDOR_AMD:
+               init_amd();
+               break;
+       case CPU_VENDOR_CENTAUR:
                init_via();
+               break;
+       }
 }
 
 void
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