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From: kan.liang@linux.intel.com
To: peterz@infradead.org, acme@kernel.org, mingo@kernel.org,
	linux-kernel@vger.kernel.org
Cc: jolsa@kernel.org, namhyung@kernel.org,
	vitaly.slobodskoy@intel.com, pavel.gerasimov@intel.com,
	ak@linux.intel.com, eranian@google.com,
	Kan Liang <kan.liang@linux.intel.com>
Subject: [PATCH V2 07/13] perf machine: Refine the function for LBR call stack reconstruction
Date: Mon, 21 Oct 2019 13:03:08 -0700	[thread overview]
Message-ID: <20191021200314.1613-8-kan.liang@linux.intel.com> (raw)
In-Reply-To: <20191021200314.1613-1-kan.liang@linux.intel.com>

From: Kan Liang <kan.liang@linux.intel.com>

LBR only collect the user call stack. To reconstruct a call stack, both
kernel call stack and user call stack are required. The function
resolve_lbr_callchain_sample() mix the kernel call stack and user
call stack. Now, with the help of TOS, perf tool can reconstruct a more
complete call stack by adding some user call stack from previous sample.
However, current implementation is hard to be extended to support it.

Abstract two new functions to resolve user call stack and kernel
call stack respectively.

No functional changes.

Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
---
 tools/perf/util/machine.c | 186 ++++++++++++++++++++++++--------------
 1 file changed, 119 insertions(+), 67 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 70a9f8716a4b..e3e516e30093 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -2183,6 +2183,96 @@ static int remove_loops(struct branch_entry *l, int nr,
 	return nr;
 }
 
+
+static int lbr_callchain_add_kernel_ip(struct thread *thread,
+				       struct callchain_cursor *cursor,
+				       struct perf_sample *sample,
+				       struct symbol **parent,
+				       struct addr_location *root_al,
+				       bool callee, int end)
+{
+	struct ip_callchain *chain = sample->callchain;
+	u8 cpumode = PERF_RECORD_MISC_USER;
+	int err, i;
+
+	if (callee) {
+		for (i = 0; i < end + 1; i++) {
+			err = add_callchain_ip(thread, cursor, parent,
+					       root_al, &cpumode, chain->ips[i],
+					       false, NULL, NULL, 0);
+			if (err)
+				return err;
+		}
+	} else {
+		for (i = end; i >= 0; i--) {
+			err = add_callchain_ip(thread, cursor, parent,
+					       root_al, &cpumode, chain->ips[i],
+					       false, NULL, NULL, 0);
+			if (err)
+				return err;
+		}
+	}
+
+	return 0;
+}
+
+static int lbr_callchain_add_lbr_ip(struct thread *thread,
+				    struct callchain_cursor *cursor,
+				    struct perf_sample *sample,
+				    struct symbol **parent,
+				    struct addr_location *root_al,
+				    bool callee)
+{
+	struct branch_stack *lbr_stack = sample->branch_stack;
+	u8 cpumode = PERF_RECORD_MISC_USER;
+	int lbr_nr = lbr_stack->nr;
+	struct branch_flags *flags;
+	u64 ip, branch_from = 0;
+	int err, i;
+
+	if (callee) {
+		ip = lbr_stack->entries[0].to;
+		flags = &lbr_stack->entries[0].flags;
+		branch_from = lbr_stack->entries[0].from;
+		err = add_callchain_ip(thread, cursor, parent,
+				       root_al, &cpumode, ip,
+				       true, flags, NULL, branch_from);
+		if (err)
+			return err;
+
+		for (i = 0; i < lbr_nr; i++) {
+			ip = lbr_stack->entries[i].from;
+			flags = &lbr_stack->entries[i].flags;
+			err = add_callchain_ip(thread, cursor, parent,
+					       root_al, &cpumode, ip,
+					       true, flags, NULL, branch_from);
+			if (err)
+				return err;
+		}
+	} else {
+		for (i = lbr_nr - 1; i >= 0; i--) {
+			ip = lbr_stack->entries[i].from;
+			flags = &lbr_stack->entries[i].flags;
+			err = add_callchain_ip(thread, cursor, parent,
+					       root_al, &cpumode, ip,
+					       true, flags, NULL, branch_from);
+			if (err)
+				return err;
+		}
+
+		ip = lbr_stack->entries[0].to;
+		flags = &lbr_stack->entries[0].flags;
+		branch_from = lbr_stack->entries[0].from;
+		err = add_callchain_ip(thread, cursor, parent,
+				       root_al, &cpumode, ip,
+				       true, flags, NULL, branch_from);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
 /*
  * Recolve LBR callstack chain sample
  * Return:
@@ -2198,82 +2288,44 @@ static int resolve_lbr_callchain_sample(struct thread *thread,
 					int max_stack)
 {
 	struct ip_callchain *chain = sample->callchain;
-	int chain_nr = min(max_stack, (int)chain->nr), i;
-	u8 cpumode = PERF_RECORD_MISC_USER;
-	u64 ip, branch_from = 0;
+	int chain_nr = min(max_stack, (int)chain->nr);
+	int i, err;
 
 	for (i = 0; i < chain_nr; i++) {
 		if (chain->ips[i] == PERF_CONTEXT_USER)
 			break;
 	}
 
-	/* LBR only affects the user callchain */
-	if (i != chain_nr) {
-		struct branch_stack *lbr_stack = sample->branch_stack;
-		int lbr_nr = lbr_stack->nr, j, k;
-		bool branch;
-		struct branch_flags *flags;
-		/*
-		 * LBR callstack can only get user call chain.
-		 * The mix_chain_nr is kernel call chain
-		 * number plus LBR user call chain number.
-		 * i is kernel call chain number,
-		 * 1 is PERF_CONTEXT_USER,
-		 * lbr_nr + 1 is the user call chain number.
-		 * For details, please refer to the comments
-		 * in callchain__printf
-		 */
-		int mix_chain_nr = i + 1 + lbr_nr + 1;
-
-		for (j = 0; j < mix_chain_nr; j++) {
-			int err;
-			branch = false;
-			flags = NULL;
-
-			if (callchain_param.order == ORDER_CALLEE) {
-				if (j < i + 1)
-					ip = chain->ips[j];
-				else if (j > i + 1) {
-					k = j - i - 2;
-					ip = lbr_stack->entries[k].from;
-					branch = true;
-					flags = &lbr_stack->entries[k].flags;
-				} else {
-					ip = lbr_stack->entries[0].to;
-					branch = true;
-					flags = &lbr_stack->entries[0].flags;
-					branch_from =
-						lbr_stack->entries[0].from;
-				}
-			} else {
-				if (j < lbr_nr) {
-					k = lbr_nr - j - 1;
-					ip = lbr_stack->entries[k].from;
-					branch = true;
-					flags = &lbr_stack->entries[k].flags;
-				}
-				else if (j > lbr_nr)
-					ip = chain->ips[i + 1 - (j - lbr_nr)];
-				else {
-					ip = lbr_stack->entries[0].to;
-					branch = true;
-					flags = &lbr_stack->entries[0].flags;
-					branch_from =
-						lbr_stack->entries[0].from;
-				}
-			}
+	/*
+	 * LBR only affects the user callchain.
+	 * Fall back if there is no user callchain.
+	 */
+	if (i == chain_nr)
+		return 0;
 
-			err = add_callchain_ip(thread, cursor, parent,
-					       root_al, &cpumode, ip,
-					       branch, flags, NULL,
-					       branch_from);
-			if (err)
-				return (err < 0) ? err : 0;
-		}
-		return 1;
+	if (callchain_param.order == ORDER_CALLEE) {
+		err = lbr_callchain_add_kernel_ip(thread, cursor, sample,
+						  parent, root_al, true, i);
+		if (err)
+			goto error;
+		err = lbr_callchain_add_lbr_ip(thread, cursor, sample,
+					       parent, root_al, true);
+		if (err)
+			goto error;
+	} else {
+		err = lbr_callchain_add_lbr_ip(thread, cursor, sample,
+					       parent, root_al, false);
+		if (err)
+			goto error;
+		err = lbr_callchain_add_kernel_ip(thread, cursor, sample,
+						  parent, root_al, false, i);
+		if (err)
+			goto error;
 	}
 
-	return 0;
+	return 1;
+error:
+	return (err < 0) ? err : 0;
 }
 
 static int find_prev_cpumode(struct ip_callchain *chain, struct thread *thread,
-- 
2.17.1


  parent reply	other threads:[~2019-10-21 20:04 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-21 20:03 [PATCH V2 00/13] Stitch LBR call stack kan.liang
2019-10-21 20:03 ` [PATCH V2 01/13] perf/core: Add new branch sample type for LBR TOS kan.liang
2019-10-22  9:39   ` Peter Zijlstra
2019-10-22 15:39     ` Liang, Kan
2019-10-21 20:03 ` [PATCH V2 02/13] perf/x86/intel: Output LBR TOS information kan.liang
2019-10-21 20:03 ` [PATCH V2 03/13] perf tools: Support new branch sample type for LBR TOS kan.liang
2019-10-21 20:03 ` [PATCH V2 04/13] perf header: Add check for event attr kan.liang
2019-10-21 20:03 ` [PATCH V2 05/13] perf pmu: Add support for PMU capabilities kan.liang
2019-10-21 20:03 ` [PATCH V2 06/13] perf header: Support CPU " kan.liang
2019-10-21 20:03 ` kan.liang [this message]
2019-10-21 20:03 ` [PATCH V2 08/13] perf tools: Stitch LBR call stack kan.liang
2019-10-21 20:03 ` [PATCH V2 09/13] perf report: Add option to enable the LBR stitching approach kan.liang
2019-10-21 20:03 ` [PATCH V2 10/13] perf script: " kan.liang
2019-10-21 20:03 ` [PATCH V2 11/13] perf top: " kan.liang
2019-10-21 20:03 ` [PATCH V2 12/13] perf c2c: " kan.liang
2019-10-21 20:03 ` [RFC PATCH V2 13/13] perf hist: Add fast path for duplicate entries check kan.liang

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