[PATCH 04/17] x86, mpx: trace entry to bounds exception paths

[Dave Hansen]

From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>

There are two basic things that can happen as the result of
a bounds exception (#BR):

	1. We allocate a new bounds table
	2. We pass up a bounds exception to userspace.

This patch adds a trace point for the case where we are
passing the exception up to userspace with a signal.

We are also explicit that we're printing out the inverse of
the 'upper' that we encounter.  If you want to filter, for
instance, you need to ~ the value first.

Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
---

 b/arch/x86/include/asm/trace/mpx.h |   25 +++++++++++++++++++++++++
 b/arch/x86/mm/mpx.c                |    2 ++
 2 files changed, 27 insertions(+)

diff -puN arch/x86/include/asm/trace/mpx.h~x86-mpx-trace-1 arch/x86/include/asm/trace/mpx.h
--- a/arch/x86/include/asm/trace/mpx.h~x86-mpx-trace-1	2015-04-22 11:16:19.051857884 -0700
+++ b/arch/x86/include/asm/trace/mpx.h	2015-04-22 11:16:19.056858109 -0700
@@ -8,6 +8,31 @@
 
 #ifdef CONFIG_X86_INTEL_MPX
 
+TRACE_EVENT(mpx_bounds_register_exception,
+
+	TP_PROTO(void *addr_referenced,
+		 struct bndreg *bndreg),
+	TP_ARGS(addr_referenced, bndreg),
+
+	TP_STRUCT__entry(
+		__field(void *, addr_referenced)
+		__field(u64, lower_bound)
+		__field(u64, upper_bound)
+	),
+
+	TP_fast_assign(
+		__entry->addr_referenced = addr_referenced;
+		__entry->lower_bound = bndreg->lower_bound;
+		__entry->upper_bound = bndreg->upper_bound;
+	),
+
+	TP_printk("address referenced: 0x%p bounds: lower: 0x%llx ~upper: 0x%llx",
+		__entry->addr_referenced,
+		__entry->lower_bound,
+		~__entry->upper_bound
+	)
+);
+
 TRACE_EVENT(bounds_exception_mpx,
 
 	TP_PROTO(struct bndcsr *bndcsr),
diff -puN arch/x86/mm/mpx.c~x86-mpx-trace-1 arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~x86-mpx-trace-1	2015-04-22 11:16:19.053857974 -0700
+++ b/arch/x86/mm/mpx.c	2015-04-22 11:16:19.057858154 -0700
@@ -16,6 +16,7 @@
 #include <asm/mmu_context.h>
 #include <asm/mpx.h>
 #include <asm/processor.h>
+#include <asm/trace/mpx.h>
 #include <asm/fpu-internal.h>
 
 #define CREATE_TRACE_POINTS
@@ -337,6 +338,7 @@ siginfo_t *mpx_generate_siginfo(struct p
 		err = -EINVAL;
 		goto err_out;
 	}
+	trace_mpx_bounds_register_exception(info->si_addr, bndreg);
 	return info;
 err_out:
 	/* info might be NULL, but kfree() handles that */
_
--
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