Commit e7126cf5 authored by Dave Hansen's avatar Dave Hansen Committed by Ingo Molnar
Browse files

x86/mpx: Trace #BR exceptions 



This is the first in a series of MPX tracing patches.
I've found these extremely useful in the process of
debugging applications and the kernel code itself.

This exception hooks in to the bounds (#BR) exception
very early and allows capturing the key registers which
would influence how the exception is handled.

Note that bndcfgu/bndstatus are technically still
64-bit registers even in 32-bit mode.

Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: default avatarThomas 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/20150607183703.5FE2619A@viggo.jf.intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 8c3641e9

arch/x86/include/asm/trace/mpx.h

0 → 100644
+50 −0
Original line number Diff line number Diff line 
#undef TRACE_SYSTEM

#define TRACE_SYSTEM mpx



#if !defined(_TRACE_MPX_H) || defined(TRACE_HEADER_MULTI_READ)

#define _TRACE_MPX_H



#include <linux/tracepoint.h>



#ifdef CONFIG_X86_INTEL_MPX



TRACE_EVENT(bounds_exception_mpx,



	TP_PROTO(const struct bndcsr *bndcsr),

	TP_ARGS(bndcsr),



	TP_STRUCT__entry(

		__field(u64, bndcfgu)

		__field(u64, bndstatus)

	),



	TP_fast_assign(

		/* need to get rid of the 'const' on bndcsr */

		__entry->bndcfgu   = (u64)bndcsr->bndcfgu;

		__entry->bndstatus = (u64)bndcsr->bndstatus;

	),



	TP_printk("bndcfgu:0x%llx bndstatus:0x%llx",

		__entry->bndcfgu,

		__entry->bndstatus)

);



#else



/*

 * This gets used outside of MPX-specific code, so we need a stub.

 */

static inline void trace_bounds_exception_mpx(const struct bndcsr *bndcsr)

{

}



#endif /* CONFIG_X86_INTEL_MPX */



#undef TRACE_INCLUDE_PATH

#define TRACE_INCLUDE_PATH asm/trace/

#undef TRACE_INCLUDE_FILE

#define TRACE_INCLUDE_FILE mpx

#endif /* _TRACE_MPX_H */



/* This part must be outside protection */

#include <trace/define_trace.h>

arch/x86/kernel/traps.c

+2 −0
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ 
#include <asm/mach_traps.h>

#include <asm/alternative.h>

#include <asm/fpu/xstate.h>

#include <asm/trace/mpx.h>

#include <asm/mpx.h>



#ifdef CONFIG_X86_64
@@ -399,6 +400,7 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code) 
	if (!bndcsr)

		goto exit_trap;



	trace_bounds_exception_mpx(bndcsr);

	/*

	 * The error code field of the BNDSTATUS register communicates status

	 * information of a bound range exception #BR or operation involving

arch/x86/mm/mpx.c

+3 −0
Original line number Diff line number Diff line
@@ -17,6 +17,9 @@ 
#include <asm/processor.h>

#include <asm/fpu/internal.h>



#define CREATE_TRACE_POINTS

#include <asm/trace/mpx.h>



static const char *mpx_mapping_name(struct vm_area_struct *vma)

{

	return "[mpx]";

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