[PATCH 06/17] x86, mpx: trace attempts to find bounds tables

Dave Hansen
2015-03-26T18:37:50Z

From: Dave Hansen <dave.hansen@linux.intel.com>

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.

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>
---

b/arch/x86/include/asm/trace/mpx.h | 22 ++++++++++++++++++++++
b/arch/x86/mm/mpx.c | 1 +
2 files changed, 23 insertions(+)

diff -puN arch/x86/include/asm/trace/mpx.h~mpx-trace_unmap_search arch/x86/include/asm/trace/mpx.h
--- a/arch/x86/include/asm/trace/mpx.h~mpx-trace_unmap_search 2015-03-26 11:27:06.684292099 -0700
+++ b/arch/x86/include/asm/trace/mpx.h 2015-03-26 11:27:06.689292324 -0700
@@ -75,6 +75,28 @@ TRACE_EVENT(mpx_unmap_zap,
)
);

+TRACE_EVENT(mpx_unmap_search,
+
+ 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
+ )
+);
+
#else

/*
diff -puN arch/x86/mm/mpx.c~mpx-trace_unmap_search arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~mpx-trace_unmap_search 2015-03-26 11:27:06.686292189 -0700
+++ b/arch/x86/mm/mpx.c 2015-03-26 11:27:06.689292324 -0700
@@ -843,6 +843,7 @@ static int mpx_unmap_tables(struct mm_st
long __user *bd_entry, *bde_start, *bde_end;
unsigned long bt_addr;

+ trace_mpx_unmap_search(start, end);
/*
* "Edge" bounds tables are those which are being used by the region
* (start -> end), but that may be shared with adjacent areas. If they
_