linux-kernel - [PATCH v1 2/2] perf arm64: Add argument support for SDT

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Date:   Wed, 23 Dec 2020 14:39:05 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Will Deacon <will@...nel.org>,
        John Garry <john.garry@...wei.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Alexandre Truong <alexandre.truong@....com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        He Zhe <zhe.he@...driver.com>,
        Thomas Richter <tmricht@...ux.ibm.com>,
        Sumanth Korikkar <sumanthk@...ux.ibm.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Leo Yan <leo.yan@...aro.org>
Subject: [PATCH v1 2/2] perf arm64: Add argument support for SDT

Now the two OP formats are used for SDT marker argument in Arm64 ELF,
one format is genreal register xNUM (e.g. x1, x2, etc), another is for
using stack pointer to access local variables (e.g. [sp], [sp, 8]).

This patch adds support SDT marker argument for Arm64, it parses OP and
converts to uprobe compatible format.

Signed-off-by: Leo Yan <leo.yan@...aro.org>
---
 tools/perf/arch/arm64/util/perf_regs.c | 94 ++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)

diff --git a/tools/perf/arch/arm64/util/perf_regs.c b/tools/perf/arch/arm64/util/perf_regs.c
index 54efa12fdbea..6b4b18283041 100644
--- a/tools/perf/arch/arm64/util/perf_regs.c
+++ b/tools/perf/arch/arm64/util/perf_regs.c
@@ -1,4 +1,12 @@
 // SPDX-License-Identifier: GPL-2.0
+#include <errno.h>
+#include <regex.h>
+#include <string.h>
+#include <linux/kernel.h>
+#include <linux/zalloc.h>
+
+#include "../../../util/debug.h"
+#include "../../../util/event.h"
 #include "../../../util/perf_regs.h"
 
 const struct sample_reg sample_reg_masks[] = {
@@ -37,3 +45,89 @@ const struct sample_reg sample_reg_masks[] = {
 	SMPL_REG(pc, PERF_REG_ARM64_PC),
 	SMPL_REG_END
 };
+
+/* %xNUM */
+#define SDT_OP_REGEX1  "^(x[1-2]?[0-9]|3[0-1])$"
+
+/* [sp], [sp, NUM] or [sp,NUM] */
+#define SDT_OP_REGEX2  "^\\[sp(, *)?([0-9]+)?\\]$"
+
+static regex_t sdt_op_regex1, sdt_op_regex2;
+
+static int sdt_init_op_regex(void)
+{
+	static int initialized;
+	int ret = 0;
+
+	if (initialized)
+		return 0;
+
+	ret = regcomp(&sdt_op_regex1, SDT_OP_REGEX1, REG_EXTENDED);
+	if (ret)
+		goto error;
+
+	ret = regcomp(&sdt_op_regex2, SDT_OP_REGEX2, REG_EXTENDED);
+	if (ret)
+		goto free_regex1;
+
+	initialized = 1;
+	return 0;
+
+free_regex1:
+	regfree(&sdt_op_regex1);
+error:
+	pr_debug4("Regex compilation error.\n");
+	return ret;
+}
+
+/*
+ * SDT marker arguments on Arm64 uses %xREG or [sp, NUM], currently
+ * support these two formats.
+ */
+int arch_sdt_arg_parse_op(char *old_op, char **new_op)
+{
+	int ret, new_len;
+	regmatch_t rm[5];
+
+	ret = sdt_init_op_regex();
+	if (ret < 0)
+		return ret;
+
+	if (!regexec(&sdt_op_regex1, old_op, 3, rm, 0)) {
+		/* Extract xNUM */
+		new_len = 2;	/* % NULL */
+		new_len += (int)(rm[1].rm_eo - rm[1].rm_so);
+
+		*new_op = zalloc(new_len);
+		if (!*new_op)
+			return -ENOMEM;
+
+		scnprintf(*new_op, new_len, "%%%.*s",
+			(int)(rm[1].rm_eo - rm[1].rm_so), old_op + rm[1].rm_so);
+	} else if (!regexec(&sdt_op_regex2, old_op, 5, rm, 0)) {
+		/* [sp], [sp, NUM] or [sp,NUM] */
+		new_len = 7;	/* + ( % s p ) NULL */
+
+		/* If the arugment is [sp], need to fill offset '0' */
+		if (rm[2].rm_so == -1)
+			new_len += 1;
+		else
+			new_len += (int)(rm[2].rm_eo - rm[2].rm_so);
+
+		*new_op = zalloc(new_len);
+		if (!*new_op)
+			return -ENOMEM;
+
+		if (rm[2].rm_so == -1)
+			scnprintf(*new_op, new_len, "+0(%%sp)");
+		else
+			scnprintf(*new_op, new_len, "+%.*s(%%sp)",
+				  (int)(rm[2].rm_eo - rm[2].rm_so),
+				  old_op + rm[2].rm_so);
+	} else {
+		pr_debug4("Skipping unsupported SDT argument: %s\n", old_op);
+		return SDT_ARG_SKIP;
+	}
+
+	return SDT_ARG_VALID;
+}
-- 
2.17.1