Add convenience APIs pmc_width() and pmc_capabilities() to -lpmc.

Have pmcstat(8) and pmccontrol(8) use these APIs.

Return PMC class-related constants (PMC widths and capabilities)
with the OP GETCPUINFO call leaving OP PMCINFO to return only the
dynamic information associated with a PMC (i.e., whether enabled,
owner pid, reload count etc.).

Allow pmc_read() (i.e., OPS PMCRW) on active self-attached PMCs to
get upto-date values from hardware since we can guarantee that the
hardware is running the correct PMC at the time of the call.

Bug fixes:
 - (x86 class processors) Fix a bug that prevented an RDPMC
   instruction from being recognized as permitted till after the
   attached process had context switched out and back in again after
   a pmc_start() call.

   Tighten the rules for using RDPMC class instructions: a GETMSR
   OP is now allowed only after an OP ATTACH has been done by the
   PMC's owner to itself.  OP GETMSR is not allowed for PMCs that
   track descendants, for PMCs attached to processes other than
   their owner processes.

 - (P4/HTT processors only) Fix a bug that caused the MI and MD
   layers to get out of sync.  Add a new MD operation 'get_config()'
   as part of this fix.

 - Allow multiple system-mode PMCs at the same row-index but on
   different CPUs to be allocated.

 - Reject allocation of an administratively disabled PMC.

Misc. code cleanups and refactoring.  Improve a few comments.

1 files changed, 23 insertions, 1 deletions

diff --git a/lib/libpmc/pmc.3 b/lib/libpmc/pmc.3
index aed6735..0612ce7 100644
--- a/lib/libpmc/pmc.3
+++ b/lib/libpmc/pmc.3
@@ -29,6 +29,7 @@
 .Sh NAME
 .Nm pmc_allocate ,
 .Nm pmc_attach ,
+.Nm pmc_capabilities ,
 .Nm pmc_configure_logfile ,
 .Nm pmc_cpuinfo ,
 .Nm pmc_detach ,
@@ -53,6 +54,7 @@
 .Nm pmc_start ,
 .Nm pmc_stop ,
 .Nm pmc_write ,
+.Nm pmc_width ,
 .Nm pmc_x86_get_msr
 .Nd programming API for using hardware performance monitoring counters
 .Sh LIBRARY
@@ -73,6 +75,8 @@
 .Fa "pid_t pid"
 .Fc
 .Ft int
+.Fn pmc_capabilities "pmc_id_t pmc" "uint32_t *caps"
+.Ft int
 .Fn pmc_configure_logfile "int fd"
 .Ft int
 .Fn pmc_cpuinfo "const struct pmc_op_getcpuinfo **cpu_info"
@@ -130,6 +134,8 @@
 .Ft int
 .Fn pmc_write "pmc_id_t pmc" "pmc_value_t value"
 .Ft int
+.Fn pmc_width "pmc_id_t pmc" "uint32_t *width"
+.Ft int
 .Fn pmc_x86_get_msr "int pmc" "uint32_t *msr"
 .Sh DESCRIPTION
 These functions implement a high-level library for using the
@@ -252,6 +258,20 @@ the allocated PMC.
 The read and write operation may be combined using
 .Fn pmc_rw .
 .Pp
+The function
+.Fn pmc_capabilities
+sets argument
+.Fa caps
+to a bitmask of capabilities supported by the PMC denoted by
+argument
+.Fa pmc .
+The function
+.Fn pmc_width
+sets argument
+.Fa width
+to the width of the PMC denoted by argument
+.Fa pmc .
+.Pp
 The
 .Fn pmc_configure_logfile
 function causes the
@@ -3011,13 +3031,15 @@ library.
 .El
 .Pp
 A call to
+.Fn pmc_capabilities ,
 .Fn pmc_name_of_capability ,
 .Fn pmc_name_of_disposition ,
 .Fn pmc_name_of_state ,
 .Fn pmc_name_of_event ,
 .Fn pmc_name_of_mode
-and
 .Fn pmc_name_of_class
+and
+.Fn pmc_width
 may fail with the following error:
 .Bl -tag -width Er
 .It Bq Er EINVAL