From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932585AbbFGSjX (ORCPT ); Sun, 7 Jun 2015 14:39:23 -0400 Received: from mga14.intel.com ([192.55.52.115]:19256 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751038AbbFGSgy (ORCPT ); Sun, 7 Jun 2015 14:36:54 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,569,1427785200"; d="scan'208";a="504417214" Subject: [PATCH 10/19] x86, mpx: Trace the attempts to find bounds tables To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, tglx@linutronix.de, Dave Hansen , dave.hansen@linux.intel.com From: Dave Hansen Date: Sun, 07 Jun 2015 11:37:03 -0700 References: <20150607183700.7E78D631@viggo.jf.intel.com> In-Reply-To: <20150607183700.7E78D631@viggo.jf.intel.com> Message-Id: <20150607183703.B9D2468B@viggo.jf.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dave Hansen 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 Reviewed-by: Thomas Gleixner --- b/arch/x86/include/asm/trace/mpx.h | 32 ++++++++++++++++++++++++++++++++ b/arch/x86/mm/mpx.c | 2 ++ 2 files changed, 34 insertions(+) diff -puN arch/x86/include/asm/trace/mpx.h~mpx-trace_unmap_zap arch/x86/include/asm/trace/mpx.h --- a/arch/x86/include/asm/trace/mpx.h~mpx-trace_unmap_zap 2015-06-01 10:24:06.928852740 -0700 +++ b/arch/x86/include/asm/trace/mpx.h 2015-06-01 10:24:06.934853011 -0700 @@ -63,6 +63,38 @@ TRACE_EVENT(bounds_exception_mpx, __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 /* diff -puN arch/x86/mm/mpx.c~mpx-trace_unmap_zap arch/x86/mm/mpx.c --- a/arch/x86/mm/mpx.c~mpx-trace_unmap_zap 2015-06-01 10:24:06.930852830 -0700 +++ b/arch/x86/mm/mpx.c 2015-06-01 10:24:06.934853011 -0700 @@ -668,6 +668,7 @@ static int zap_bt_entries(struct mm_stru len = min(vma->vm_end, end) - addr; zap_page_range(vma, addr, len, NULL); + trace_mpx_unmap_zap(addr, addr+len); vma = vma->vm_next; addr = vma->vm_start; @@ -840,6 +841,7 @@ 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 _