Author: gnn
Date: Tue Jul 13 19:37:45 2010
New Revision: 210012
URL: http://svn.freebsd.org/changeset/base/210012

Log:
  Fix a panic brought about by writing an MSR without a proper mask.
  All of the necessary wrmsr calls are now preceded by a rdmsr
  and we leave the reserved bits alone.
  Document the bits in the relevant registers for future reference.
  
  Tested by:    mdf
  MFC after:    1 week

Modified:
  head/sys/dev/hwpmc/hwpmc_core.c
  head/sys/dev/hwpmc/hwpmc_core.h

Modified: head/sys/dev/hwpmc/hwpmc_core.c
==============================================================================
--- head/sys/dev/hwpmc/hwpmc_core.c     Tue Jul 13 19:33:46 2010        
(r210011)
+++ head/sys/dev/hwpmc/hwpmc_core.c     Tue Jul 13 19:37:45 2010        
(r210012)
@@ -147,6 +147,7 @@ core_pcpu_fini(struct pmc_mdep *md, int 
        int core_ri, n, npmc;
        struct pmc_cpu *pc;
        struct core_cpu *cc;
+       uint64_t msr = 0;
 
        KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
            ("[core,%d] insane cpu number (%d)", __LINE__, cpu));
@@ -166,11 +167,14 @@ core_pcpu_fini(struct pmc_mdep *md, int 
        npmc = md->pmd_classdep[PMC_MDEP_CLASS_INDEX_IAP].pcd_num;
        core_ri = md->pmd_classdep[PMC_MDEP_CLASS_INDEX_IAP].pcd_ri;
 
-       for (n = 0; n < npmc; n++)
-               wrmsr(IAP_EVSEL0 + n, 0);
+       for (n = 0; n < npmc; n++) {
+               msr = rdmsr(IAP_EVSEL0 + n);
+               wrmsr(IAP_EVSEL0 + n, msr & ~IAP_EVSEL_MASK);
+       }
 
        if (core_cputype != PMC_CPU_INTEL_CORE) {
-               wrmsr(IAF_CTRL, 0);
+               msr = rdmsr(IAF_CTRL);
+               wrmsr(IAF_CTRL, msr & ~IAF_CTRL_MASK);
                npmc += md->pmd_classdep[PMC_MDEP_CLASS_INDEX_IAF].pcd_num;
        }
 
@@ -374,6 +378,7 @@ iaf_start_pmc(int cpu, int ri)
 {
        struct pmc *pm;
        struct core_cpu *iafc;
+       uint64_t msr = 0;
 
        KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
            ("[core,%d] illegal CPU value %d", __LINE__, cpu));
@@ -387,12 +392,15 @@ iaf_start_pmc(int cpu, int ri)
 
        iafc->pc_iafctrl |= pm->pm_md.pm_iaf.pm_iaf_ctrl;
 
-       wrmsr(IAF_CTRL, iafc->pc_iafctrl);
+       msr = rdmsr(IAF_CTRL);
+       wrmsr(IAF_CTRL, msr | (iafc->pc_iafctrl & IAF_CTRL_MASK));
 
        do {
                iafc->pc_resync = 0;
                iafc->pc_globalctrl |= (1ULL << (ri + IAF_OFFSET));
-               wrmsr(IA_GLOBAL_CTRL, iafc->pc_globalctrl);
+               msr = rdmsr(IA_GLOBAL_CTRL);
+               wrmsr(IA_GLOBAL_CTRL, msr | (iafc->pc_globalctrl & 
+                                            IAF_GLOBAL_CTRL_MASK));
        } while (iafc->pc_resync != 0);
 
        PMCDBG(MDP,STA,1,"iafctrl=%x(%x) globalctrl=%jx(%jx)",
@@ -407,6 +415,7 @@ iaf_stop_pmc(int cpu, int ri)
 {
        uint32_t fc;
        struct core_cpu *iafc;
+       uint64_t msr = 0;
 
        PMCDBG(MDP,STO,1,"iaf-stop cpu=%d ri=%d", cpu, ri);
 
@@ -425,12 +434,15 @@ iaf_stop_pmc(int cpu, int ri)
        iafc->pc_iafctrl &= ~fc;
 
        PMCDBG(MDP,STO,1,"iaf-stop iafctrl=%x", iafc->pc_iafctrl);
-       wrmsr(IAF_CTRL, iafc->pc_iafctrl);
+       msr = rdmsr(IAF_CTRL);
+       wrmsr(IAF_CTRL, msr | (iafc->pc_iafctrl & IAF_CTRL_MASK));
 
        do {
                iafc->pc_resync = 0;
                iafc->pc_globalctrl &= ~(1ULL << (ri + IAF_OFFSET));
-               wrmsr(IA_GLOBAL_CTRL, iafc->pc_globalctrl);
+               msr = rdmsr(IA_GLOBAL_CTRL);
+               wrmsr(IA_GLOBAL_CTRL, msr | (iafc->pc_globalctrl &
+                                            IAF_GLOBAL_CTRL_MASK));
        } while (iafc->pc_resync != 0);
 
        PMCDBG(MDP,STO,1,"iafctrl=%x(%x) globalctrl=%jx(%jx)",
@@ -445,6 +457,7 @@ iaf_write_pmc(int cpu, int ri, pmc_value
 {
        struct core_cpu *cc;
        struct pmc *pm;
+       uint64_t msr;
 
        KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
            ("[core,%d] illegal cpu value %d", __LINE__, cpu));
@@ -460,9 +473,11 @@ iaf_write_pmc(int cpu, int ri, pmc_value
        if (PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm)))
                v = iaf_reload_count_to_perfctr_value(v);
 
-       wrmsr(IAF_CTRL, 0);     /* Turn off fixed counters */
-       wrmsr(IAF_CTR0 + ri, v);
-       wrmsr(IAF_CTRL, cc->pc_iafctrl);
+       msr = rdmsr(IAF_CTRL);
+       wrmsr(IAF_CTRL, msr & ~IAF_CTRL_MASK);
+       wrmsr(IAF_CTR0 + ri, v & ((1ULL << core_iaf_width) - 1));
+       msr = rdmsr(IAF_CTRL);
+       wrmsr(IAF_CTRL, msr | (cc->pc_iafctrl & IAF_CTRL_MASK));
 
        PMCDBG(MDP,WRI,1, "iaf-write cpu=%d ri=%d msr=0x%x v=%jx iafctrl=%jx "
            "pmc=%jx", cpu, ri, IAF_RI_TO_MSR(ri), v,
@@ -1879,6 +1894,7 @@ iap_stop_pmc(int cpu, int ri)
 {
        struct pmc *pm;
        struct core_cpu *cc;
+       uint64_t msr;
 
        KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
            ("[core,%d] illegal cpu value %d", __LINE__, cpu));
@@ -1894,7 +1910,8 @@ iap_stop_pmc(int cpu, int ri)
 
        PMCDBG(MDP,STO,1, "iap-stop cpu=%d ri=%d", cpu, ri);
 
-       wrmsr(IAP_EVSEL0 + ri, 0);      /* stop hw */
+       msr = rdmsr(IAP_EVSEL0 + ri);
+       wrmsr(IAP_EVSEL0 + ri, msr & IAP_EVSEL_MASK);   /* stop hw */
 
        if (core_cputype == PMC_CPU_INTEL_CORE)
                return (0);
@@ -1937,7 +1954,7 @@ iap_write_pmc(int cpu, int ri, pmc_value
         * a stopped state when the pcd_write() entry point is called.
         */
 
-       wrmsr(IAP_PMC0 + ri, v);
+       wrmsr(IAP_PMC0 + ri, v & ((1ULL << core_iap_width) - 1));
 
        return (0);
 }
@@ -1987,6 +2004,7 @@ core_intr(int cpu, struct trapframe *tf)
        struct pmc *pm;
        struct core_cpu *cc;
        int error, found_interrupt, ri;
+       uint64_t msr = 0;
 
        PMCDBG(MDP,INT, 1, "cpu=%d tf=0x%p um=%d", cpu, (void *) tf,
            TRAPF_USERMODE(tf));
@@ -2018,7 +2036,8 @@ core_intr(int cpu, struct trapframe *tf)
                 * Stop the counter, reload it but only restart it if
                 * the PMC is not stalled.
                 */
-               wrmsr(IAP_EVSEL0 + ri, 0);
+               msr = rdmsr(IAP_EVSEL0 + ri);
+               wrmsr(IAP_EVSEL0 + ri, msr & ~IAP_EVSEL_MASK);
                wrmsr(IAP_PMC0 + ri, v);
 
                if (error)

Modified: head/sys/dev/hwpmc/hwpmc_core.h
==============================================================================
--- head/sys/dev/hwpmc/hwpmc_core.h     Tue Jul 13 19:33:46 2010        
(r210011)
+++ head/sys/dev/hwpmc/hwpmc_core.h     Tue Jul 13 19:37:45 2010        
(r210012)
@@ -67,20 +67,59 @@ struct pmc_md_iap_op_pmcallocate {
 /*
  * Fixed-function counters.
  */
+
 #define        IAF_MASK                                0xF
 
+#define        IAF_COUNTER_MASK                        0x0000ffffffffffff
 #define        IAF_CTR0                                0x309
 #define        IAF_CTR1                                0x30A
 #define        IAF_CTR2                                0x30B
 
+/*
+ * The IAF_CTRL MSR is laid out in the following way.
+ *
+ * Bit Position    Use
+ * 63 - 12         Reserved (do not touch)
+ * 11              Ctr 2 PMI
+ * 10              Reserved (do not touch)
+ * 9-8             Ctr 2 Enable
+ * 7               Ctr 1 PMI
+ * 6               Reserved (do not touch)
+ * 5-4             Ctr 1 Enable
+ * 3               Ctr 0 PMI
+ * 2               Reserved (do not touch)
+ * 1-0             Ctr 0 Enable (3: All Levels, 2: User, 1: OS, 0: Disable)
+ */
+
 #define        IAF_OFFSET                              32
 #define        IAF_CTRL                                0x38D
+#define        IAF_CTRL_MASK                           0x0000000000000bbb
 
 /*
  * Programmable counters.
  */
 
 #define        IAP_PMC0                                0x0C1
+
+/*
+ * IAP_EVSEL(n) is laid out in the following way.
+ *
+ * Bit Position    Use
+ * 63-31           Reserved (do not touch)
+ * 31-24           Counter Mask
+ * 23              Invert
+ * 22              Enable
+ * 21              Reserved (do not touch)
+ * 20              APIC Interrupt Enable
+ * 19              Pin Control
+ * 18              Edge Detect
+ * 17              OS
+ * 16              User
+ * 15-8            Unit Mask
+ * 7-0             Event Select
+ */
+
+#define        IAP_EVSEL_MASK                          0x00000000ffdfffff
 #define        IAP_EVSEL0                              0x186
 
 /*
@@ -90,6 +129,21 @@ struct pmc_md_iap_op_pmcallocate {
 
 #define        IA_GLOBAL_STATUS                        0x38E
 #define        IA_GLOBAL_CTRL                          0x38F
+
+/*
+ * IA_GLOBAL_CTRL is layed out in the following way.
+ * 
+ * Bit Position    Use
+ * 63-35           Reserved (do not touch)
+ * 34              IAF Counter 2 Enable
+ * 33              IAF Counter 1 Enable
+ * 32              IAF Counter 0 Enable
+ * 31-0            Depends on programmable counters
+ */
+
+/* The mask is only for the fixed porttion of the register. */
+#define        IAF_GLOBAL_CTRL_MASK                    0x0000000700000000
+
 #define        IA_GLOBAL_OVF_CTRL                      0x390
 
 #define        IA_GLOBAL_STATUS_FLAG_CONDCHG           (1ULL << 63)
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