From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754730AbbCBO0K (ORCPT ); Mon, 2 Mar 2015 09:26:10 -0500 Received: from szxga02-in.huawei.com ([119.145.14.65]:16306 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753143AbbCBO0G (ORCPT ); Mon, 2 Mar 2015 09:26:06 -0500 From: Wang Nan To: , , , , CC: , , , Subject: [RFC PATCH v4 22/34] ftrace: allow search ftrace addr before ftrace fully inited. Date: Mon, 2 Mar 2015 22:25:00 +0800 Message-ID: <1425306312-3437-23-git-send-email-wangnan0@huawei.com> X-Mailer: git-send-email 1.8.4 In-Reply-To: <1425306312-3437-1-git-send-email-wangnan0@huawei.com> References: <1425306312-3437-1-git-send-email-wangnan0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.197.247] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch enables ftrace_location() to be used before ftrace_init(). The first user should be early kprobes, which can insert kprobes to kernel code even before setup_arch() finishes. This patch gives it a chance to determine whether it is probing ftrace entries and allows it do some special treatment. ftrace_cmp_ips_insn() is introduced to make early ftrace_location() behavior consistent with normal ftrace_location(). With existing ftrace_cmp_ips(), searching an address in middle of an instruction will fail, which is inconsistent with ftrace_cmp_recs() used by normal ftrace_location(). With this and previous patch ftrace_location() now is able to be called in and after setup_arch(). Signed-off-by: Wang Nan --- kernel/trace/ftrace.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index fa3cdd3..7fa88d0 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1539,6 +1539,8 @@ static unsigned long ftrace_location_range(unsigned long start, unsigned long en return 0; } +static unsigned long ftrace_search_mcount_ip(unsigned long ip); + /** * ftrace_location - return true if the ip giving is a traced location * @ip: the instruction pointer to check @@ -1550,6 +1552,9 @@ static unsigned long ftrace_location_range(unsigned long start, unsigned long en */ unsigned long ftrace_location(unsigned long ip) { + if (unlikely(!ftrace_pages_start)) + return ftrace_search_mcount_ip(ip); + return ftrace_location_range(ip, ip); } @@ -4733,6 +4738,18 @@ static int ftrace_cmp_ips(const void *a, const void *b) return 0; } +static int ftrace_cmp_ips_insn(const void *a, const void *b) +{ + const unsigned long *ipa = a; + const unsigned long *ipb = b; + + if (*ipa >= *ipb + MCOUNT_INSN_SIZE) + return 1; + if (*ipa < *ipb) + return -1; + return 0; +} + static void ftrace_swap_ips(void *a, void *b, int size) { unsigned long *ipa = a; @@ -4770,6 +4787,27 @@ static void ftrace_sort_mcount_area(unsigned long *start, unsigned long *end) kernel_mcount_sorted = true; } +static unsigned long ftrace_search_mcount_ip(unsigned long ip) +{ + extern unsigned long __start_mcount_loc[]; + extern unsigned long __stop_mcount_loc[]; + + unsigned long *mcount_start = __start_mcount_loc; + unsigned long *mcount_end = __stop_mcount_loc; + unsigned long count = mcount_end - mcount_start; + unsigned long *retval; + + if (!kernel_mcount_sorted) + return 0; + + retval = bsearch(&ip, mcount_start, count, + sizeof(unsigned long), ftrace_cmp_ips_insn); + if (!retval) + return 0; + + return ftrace_call_adjust(ip); +} + static int ftrace_process_locs(struct module *mod, unsigned long *start, unsigned long *end) -- 1.8.4