linux-kernel - [PATCH v1] perf callchain: fix kernel symbol resolution by remembering the cpumode

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Message-Id: <1427468906-41544-1-git-send-email-dahi@linux.vnet.ibm.com>
Date:	Fri, 27 Mar 2015 16:08:26 +0100
From:	David Hildenbrand <dahi@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	dahi@...ux.vnet.ibm.com, a.p.zijlstra@...llo.nl, paulus@...ba.org,
	mingo@...hat.com, acme@...nel.org, acme@...hat.com,
	jolsa@...nel.org, kan.liang@...el.com, namhyung@...nel.org,
	adrian.hunter@...el.com, ak@...ux.intel.com,
	brueckner@...ux.vnet.ibm.com, schwidefsky@...ibm.com
Subject: [PATCH v1] perf callchain: fix kernel symbol resolution by remembering the cpumode

Commit 2e77784bb7d8 ("perf callchain: Move cpumode resolve code to
add_callchain_ip") promised "No change in behavior.".

As this commit breaks callchains on s390x (symbols not getting resolved,
observed when profiling the kernel), this statement is wrong. The cpumode
must be kept when iterating over all ips, otherwise the default
(PERF_RECORD_MISC_USER) will be used by error.

Signed-off-by: David Hildenbrand <dahi@...ux.vnet.ibm.com>
---
 tools/perf/util/machine.c | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index e335330..c843652 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1408,29 +1408,27 @@ struct mem_info *sample__resolve_mem(struct perf_sample *sample,
 static int add_callchain_ip(struct thread *thread,
 			    struct symbol **parent,
 			    struct addr_location *root_al,
-			    bool branch_history,
+			    u8 *cpumode,
 			    u64 ip)
 {
 	struct addr_location al;
 
 	al.filtered = 0;
 	al.sym = NULL;
-	if (branch_history)
+	if (!cpumode) {
 		thread__find_cpumode_addr_location(thread, MAP__FUNCTION,
 						   ip, &al);
-	else {
-		u8 cpumode = PERF_RECORD_MISC_USER;
-
+	} else {
 		if (ip >= PERF_CONTEXT_MAX) {
 			switch (ip) {
 			case PERF_CONTEXT_HV:
-				cpumode = PERF_RECORD_MISC_HYPERVISOR;
+				*cpumode = PERF_RECORD_MISC_HYPERVISOR;
 				break;
 			case PERF_CONTEXT_KERNEL:
-				cpumode = PERF_RECORD_MISC_KERNEL;
+				*cpumode = PERF_RECORD_MISC_KERNEL;
 				break;
 			case PERF_CONTEXT_USER:
-				cpumode = PERF_RECORD_MISC_USER;
+				*cpumode = PERF_RECORD_MISC_USER;
 				break;
 			default:
 				pr_debug("invalid callchain context: "
@@ -1444,8 +1442,8 @@ static int add_callchain_ip(struct thread *thread,
 			}
 			return 0;
 		}
-		thread__find_addr_location(thread, cpumode, MAP__FUNCTION,
-				   ip, &al);
+		thread__find_addr_location(thread, *cpumode, MAP__FUNCTION,
+					   ip, &al);
 	}
 
 	if (al.sym != NULL) {
@@ -1604,6 +1602,7 @@ static int thread__resolve_callchain_sample(struct thread *thread,
 	struct branch_stack *branch = sample->branch_stack;
 	struct ip_callchain *chain = sample->callchain;
 	int chain_nr = min(max_stack, (int)chain->nr);
+	u8 cpumode = PERF_RECORD_MISC_USER;
 	int i, j, err;
 	int skip_idx = -1;
 	int first_call = 0;
@@ -1669,10 +1668,10 @@ static int thread__resolve_callchain_sample(struct thread *thread,
 
 		for (i = 0; i < nr; i++) {
 			err = add_callchain_ip(thread, parent, root_al,
-					       true, be[i].to);
+					       NULL, be[i].to);
 			if (!err)
 				err = add_callchain_ip(thread, parent, root_al,
-						       true, be[i].from);
+						       NULL, be[i].from);
 			if (err == -EINVAL)
 				break;
 			if (err)
@@ -1701,7 +1700,7 @@ check_calls:
 #endif
 		ip = chain->ips[j];
 
-		err = add_callchain_ip(thread, parent, root_al, false, ip);
+		err = add_callchain_ip(thread, parent, root_al, &cpumode, ip);
 
 		if (err)
 			return (err < 0) ? err : 0;
-- 
2.1.4

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