x86/mpx: Trace the attempts to find bounds tables
There are two different events being traced here. They are
doing similar things so share a trace "EVENT_CLASS" and are
presented together.
1. Trace when MPX is zapping pages "mpx_unmap_zap":
When MPX can not free an entire bounds table, it will
instead try to zap unused parts of a bounds table to free
the backing memory. This decreases RSS (resident set
size) without decreasing the virtual space allocated
for bounds tables.
2. Trace attempts to find bounds tables "mpx_unmap_search":
This event traces any time we go looking to unmap a
bounds table for a given virtual address range. This is
useful to ensure that the kernel actually "tried" to free
a bounds table versus times it succeeded in finding one.
It might try and fail if it realized that a table was
shared with an adjacent VMA which is not being unmapped.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183703.B9D2468B@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/include/asm/trace/mpx.h b/arch/x86/include/asm/trace/mpx.h
index 5c3af06..c13c6fa 100644
--- a/arch/x86/include/asm/trace/mpx.h
+++ b/arch/x86/include/asm/trace/mpx.h
@@ -63,6 +63,38 @@
__entry->bndstatus)
);
+DECLARE_EVENT_CLASS(mpx_range_trace,
+
+ TP_PROTO(unsigned long start,
+ unsigned long end),
+ TP_ARGS(start, end),
+
+ TP_STRUCT__entry(
+ __field(unsigned long, start)
+ __field(unsigned long, end)
+ ),
+
+ TP_fast_assign(
+ __entry->start = start;
+ __entry->end = end;
+ ),
+
+ TP_printk("[0x%p:0x%p]",
+ (void *)__entry->start,
+ (void *)__entry->end
+ )
+);
+
+DEFINE_EVENT(mpx_range_trace, mpx_unmap_zap,
+ TP_PROTO(unsigned long start, unsigned long end),
+ TP_ARGS(start, end)
+);
+
+DEFINE_EVENT(mpx_range_trace, mpx_unmap_search,
+ TP_PROTO(unsigned long start, unsigned long end),
+ TP_ARGS(start, end)
+);
+
#else
/*