Reserved one of the spare fields in struct gmon to record the history

counter type, as threatened in rev.1.8 (the density doesn't need to
be recorded since it can be derived from other fields).  This doesn't
affect binary compatibility, but new utilities won't be able to depend
on the contents of this field because libc/gmon/gmon.c was broken --
it wrote garbage to the spare fields.

Added a history counter type field to struct gmonparam.  This breaks
binary compatibility a little, since kgmon wanted to read the whole
struct.  Fixed kgmon to only depend on reading the critical earlier
parts of the struct.  This should also fix 6+ year old breakage of
binary compatibility when the profrate field was added.

Only initialize the new field in struct gmon for now, so that the
compatibility code for this (in kgmon) gets tested.  The compatibility
code has to guesstimate the value.  The new field in struct gmonparam
is for the kernel to initialize so that kgmon doesn't have to guess.

1 files changed, 3 insertions, 2 deletions

diff --git a/sys/sys/gmon.h b/sys/sys/gmon.h
index 79434a4..90e4e22 100644
--- a/sys/sys/gmon.h
+++ b/sys/sys/gmon.h
@@ -48,8 +48,8 @@ struct gmonhdr {
 	int	ncnt;		/* size of sample buffer (plus this header) */
 	int	version;	/* version number */
 	int	profrate;	/* profiling clock rate */
-	int	spare[3];	/* reserved */
-	/* XXX should record counter size and density */
+	int	histcounter_type; /* size (in bits) and sign of HISTCOUNTER */
+	int	spare[2];	/* reserved */
 };
 #define GMONVERSION	0x00051879
 
@@ -180,6 +180,7 @@ struct gmonparam {
 	int		mexitcount_overhead;
 	int		mexitcount_post_overhead;
 	int		mexitcount_pre_overhead;
+	int		histcounter_type;
 };
 extern struct gmonparam _gmonparam;