Patch "perf annotate: Fix parsing aarch64 branch instructions after objdump update" has been added to the 4.18-stable tree

This is a note to let you know that I've just added the patch titled

perf annotate: Fix parsing aarch64 branch instructions after objdump update

to the 4.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
perf-annotate-fix-parsing-aarch64-branch-instructions-after-objdump-update.patch
and it can be found in the queue-4.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Kim Phillips <[email protected]>
Date: Mon, 27 Aug 2018 12:53:40 -0500
Subject: perf annotate: Fix parsing aarch64 branch instructions after objdump update

From: Kim Phillips <[email protected]>

[ Upstream commit 4e67b2a5df5d3f341776d12ee575e00ca3ef92de ]

Starting with binutils 2.28, aarch64 objdump adds comments to the disassembly output to show the alternative names of a condition code [1].

It is assumed that commas in objdump comments could occur in other arches now or in the future, so this fix is arch-independent.

The fix could have been done with arm64 specific jump__parse and jump__scnprintf functions, but the jump__scnprintf instruction would have to have its comment character be a literal, since the scnprintf functions cannot receive a struct arch easily.

This inconvenience also applies to the generic jump__scnprintf, which is why we add a raw_comment pointer to struct ins_operands, so the __parse function assigns it to be re-used by its corresponding __scnprintf function.

Example differences in 'perf annotate --stdio2' output on an aarch64 perf.data file:

BEFORE: ? b.cs ffff200008133d1c <unwind_frame+0x18c> // b.hs, dffff7ecc47b
AFTER : ? b.cs 18c

BEFORE: ? b.cc ffff200008d8d9cc <get_alloc_profile+0x31c> // b.lo, b.ul, dffff727295b
AFTER : ? b.cc 31c

The branch target labels 18c and 31c also now appear in the output:

BEFORE: add x26, x29, #0x80
AFTER : 18c: add x26, x29, #0x80

BEFORE: add x21, x21, #0x8
AFTER : 31c: add x21, x21, #0x8

The Fixes: tag below is added so stable branches will get the update; it doesn't necessarily mean that commit was broken at the time, rather it didn't withstand the aarch64 objdump update.

Tested no difference in output for sample x86_64, power arch perf.data files.

[1] https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=bb7eff5206e4795ac79c177a80fe9f4630aaf730

---
 tools/perf/util/annotate.c |   22 +++++++++++++++++++++-
 tools/perf/util/annotate.h |    1 +
 2 files changed, 22 insertions(+), 1 deletion(-)

@@ -281,7 +281,19 @@ bool ins__is_call(const struct ins *ins)
 	return ins->ops == &call_ops || ins->ops == &s390_call_ops;
 }
 
-static int jump__parse(struct arch *arch __maybe_unused, struct ins_operands *ops, struct map_symbol *ms)
+/*
+ * Prevents from matching commas in the comment section, e.g.:
+ * ffff200008446e70:       b.cs    ffff2000084470f4 <generic_exec_single+0x314>  // b.hs, b.nlast
+ */
+static inline const char *validate_comma(const char *c, struct ins_operands *ops)
+{
+	if (ops->raw_comment && c > ops->raw_comment)
+		return NULL;
+
+	return c;
+}
+
+static int jump__parse(struct arch *arch, struct ins_operands *ops, struct map_symbol *ms)
 {
 	struct map *map = ms->map;
 	struct symbol *sym = ms->sym;

@@ -290,6 +302,10 @@ static int jump__parse(struct arch *arch
 	};
 	const char *c = strchr(ops->raw, ',');
 	u64 start, end;
+
+	ops->raw_comment = strchr(ops->raw, arch->objdump.comment_char);
+	c = validate_comma(c, ops);
+
 	/*
 	 * Examples of lines to parse for the _cpp_lex_token@@Base
 	 * function:

@@ -309,6 +325,7 @@ static int jump__parse(struct arch *arch
 		ops->target.addr = strtoull(c, NULL, 16);
 		if (!ops->target.addr) {
 			c = strchr(c, ',');
+			c = validate_comma(c, ops);
 			if (c++ != NULL)
 				ops->target.addr = strtoull(c, NULL, 16);
 		}

@@ -366,9 +383,12 @@ static int jump__scnprintf(struct ins *i
 		return scnprintf(bf, size, "%-6s %s", ins->name, ops->target.sym->name);
 
 	c = strchr(ops->raw, ',');
+	c = validate_comma(c, ops);
+
 	if (c != NULL) {
 		const char *c2 = strchr(c + 1, ',');
 
+		c2 = validate_comma(c2, ops);
 		/* check for 3-op insn */
 		if (c2 != NULL)
 			c = c2;

@@ -21,6 +21,7 @@ struct ins {
 
 struct ins_operands {
 	char	*raw;
+	char	*raw_comment;
 	struct {
 		char	*raw;
 		char	*name;

Patches currently in stable-queue which might be from kim.phillips at arm.com are

queue-4.18/perf-annotate-properly-interpret-indirect-call.patch queue-4.18/perf-annotate-fix-parsing-aarch64-branch-instructions-after-objdump-update.patch