perf sdt powerpc: Add argument support

SDT marker argument is in N@OP format. Here OP is arch dependent
component. Add powerpc logic to parse OP and convert it to uprobe
compatible format.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexis Berlemont <alexis.berlemont@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170328094754.3156-4-ravi.bangoria@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/powerpc/util/perf_regs.c

@@ -1,5 +1,10 @@
+#include <string.h>
+#include <regex.h>
+
 #include "../../perf.h"
+#include "../../util/util.h"
 #include "../../util/perf_regs.h"
+#include "../../util/debug.h"
 
 const struct sample_reg sample_reg_masks[] = {
 	SMPL_REG(r0, PERF_REG_POWERPC_R0),
@@ -47,3 +52,109 @@ const struct sample_reg sample_reg_masks[] = {
 	SMPL_REG(dsisr, PERF_REG_POWERPC_DSISR),
 	SMPL_REG_END
 };
+
+/* REG or %rREG */
+#define SDT_OP_REGEX1  "^(%r)?([1-2]?[0-9]|3[0-1])$"
+
+/* -NUM(REG) or NUM(REG) or -NUM(%rREG) or NUM(%rREG) */
+#define SDT_OP_REGEX2  "^(\\-)?([0-9]+)\\((%r)?([1-2]?[0-9]|3[0-1])\\)$"
+
+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;
+}
+
+/*
+ * Parse OP and convert it into uprobe format, which is, +/-NUM(%gprREG).
+ * Possible variants of OP are:
+ *	Format		Example
+ *	-------------------------
+ *	NUM(REG)	48(18)
+ *	-NUM(REG)	-48(18)
+ *	NUM(%rREG)	48(%r18)
+ *	-NUM(%rREG)	-48(%r18)
+ *	REG		18
+ *	%rREG		%r18
+ *	iNUM		i0
+ *	i-NUM		i-1
+ *
+ * SDT marker arguments on Powerpc uses %rREG form with -mregnames flag
+ * and REG form with -mno-regnames. Here REG is general purpose register,
+ * which is in 0 to 31 range.
+ */
+int arch_sdt_arg_parse_op(char *old_op, char **new_op)
+{
+	int ret, new_len;
+	regmatch_t rm[5];
+	char prefix;
+
+	/* Constant argument. Uprobe does not support it */
+	if (old_op[0] == 'i') {
+		pr_debug4("Skipping unsupported SDT argument: %s\n", old_op);
+		return SDT_ARG_SKIP;
+	}
+
+	ret = sdt_init_op_regex();
+	if (ret < 0)
+		return ret;
+
+	if (!regexec(&sdt_op_regex1, old_op, 3, rm, 0)) {
+		/* REG or %rREG --> %gprREG */
+
+		new_len = 5;	/* % g p r NULL */
+		new_len += (int)(rm[2].rm_eo - rm[2].rm_so);
+
+		*new_op = zalloc(new_len);
+		if (!*new_op)
+			return -ENOMEM;
+
+		scnprintf(*new_op, new_len, "%%gpr%.*s",
+			(int)(rm[2].rm_eo - rm[2].rm_so), old_op + rm[2].rm_so);
+	} else if (!regexec(&sdt_op_regex2, old_op, 5, rm, 0)) {
+		/*
+		 * -NUM(REG) or NUM(REG) or -NUM(%rREG) or NUM(%rREG) -->
+		 *	+/-NUM(%gprREG)
+		 */
+		prefix = (rm[1].rm_so == -1) ? '+' : '-';
+
+		new_len = 8;	/* +/- ( % g p r ) NULL */
+		new_len += (int)(rm[2].rm_eo - rm[2].rm_so);
+		new_len += (int)(rm[4].rm_eo - rm[4].rm_so);
+
+		*new_op = zalloc(new_len);
+		if (!*new_op)
+			return -ENOMEM;
+
+		scnprintf(*new_op, new_len, "%c%.*s(%%gpr%.*s)", prefix,
+			(int)(rm[2].rm_eo - rm[2].rm_so), old_op + rm[2].rm_so,
+			(int)(rm[4].rm_eo - rm[4].rm_so), old_op + rm[4].rm_so);
+	} else {
+		pr_debug4("Skipping unsupported SDT argument: %s\n", old_op);
+		return SDT_ARG_SKIP;
+	}
+
+	return SDT_ARG_VALID;
+}