perf/sdt/x86: Move OP parser to tools/perf/arch/x86/

SDT marker argument is in N@OP format. N is the size of argument and OP
is the actual assembly operand. OP is arch dependent component and hence
it's parsing logic also should be placed under tools/perf/arch/.

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/20170328094754.3156-3-ravi.bangoria@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/x86/util/perf_regs.c

@@ -1,8 +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(AX, PERF_REG_X86_AX),
@@ -37,7 +39,7 @@ struct sdt_name_reg {
 #define SDT_NAME_REG(n, m) {.sdt_name = "%" #n, .uprobe_name = "%" #m}
 #define SDT_NAME_REG_END {.sdt_name = NULL, .uprobe_name = NULL}
 
-static const struct sdt_name_reg sdt_reg_renamings[] = {
+static const struct sdt_name_reg sdt_reg_tbl[] = {
 	SDT_NAME_REG(eax, ax),
 	SDT_NAME_REG(rax, ax),
 	SDT_NAME_REG(al,  ax),
@@ -95,45 +97,158 @@ static const struct sdt_name_reg sdt_reg_renamings[] = {
 	SDT_NAME_REG_END,
 };
 
-int sdt_rename_register(char **pdesc, char *old_name)
+/*
+ * Perf only supports OP which is in  +/-NUM(REG)  form.
+ * Here plus-minus sign, NUM and parenthesis are optional,
+ * only REG is mandatory.
+ *
+ * SDT events also supports indirect addressing mode with a
+ * symbol as offset, scaled mode and constants in OP. But
+ * perf does not support them yet. Below are few examples.
+ *
+ * OP with scaled mode:
+ *     (%rax,%rsi,8)
+ *     10(%ras,%rsi,8)
+ *
+ * OP with indirect addressing mode:
+ *     check_action(%rip)
+ *     mp_+52(%rip)
+ *     44+mp_(%rip)
+ *
+ * OP with constant values:
+ *     $0
+ *     $123
+ *     $-1
+ */
+#define SDT_OP_REGEX  "^([+\\-]?)([0-9]*)(\\(?)(%[a-z][a-z0-9]+)(\\)?)$"
+
+static regex_t sdt_op_regex;
+
+static int sdt_init_op_regex(void)
 {
-	const struct sdt_name_reg *rnames = sdt_reg_renamings;
-	char *new_desc, *old_desc = *pdesc;
-	size_t prefix_len, sdt_len, uprobe_len, old_desc_len, offset;
-	int ret = -1;
-
-	while (ret != 0 && rnames->sdt_name != NULL) {
-		sdt_len = strlen(rnames->sdt_name);
-		ret = strncmp(old_name, rnames->sdt_name, sdt_len);
-		rnames += !!ret;
-	}
+	static int initialized;
+	int ret = 0;
 
-	if (rnames->sdt_name == NULL)
+	if (initialized)
 		return 0;
 
-	sdt_len = strlen(rnames->sdt_name);
-	uprobe_len = strlen(rnames->uprobe_name);
-	old_desc_len = strlen(old_desc) + 1;
+	ret = regcomp(&sdt_op_regex, SDT_OP_REGEX, REG_EXTENDED);
+	if (ret < 0) {
+		pr_debug4("Regex compilation error.\n");
+		return ret;
+	}
 
-	new_desc = zalloc(old_desc_len + uprobe_len - sdt_len);
-	if (new_desc == NULL)
-		return -1;
+	initialized = 1;
+	return 0;
+}
 
-	/* Copy the chars before the register name (at least '%') */
-	prefix_len = old_name - old_desc;
-	memcpy(new_desc, old_desc, prefix_len);
+/*
+ * Max x86 register name length is 5(ex: %r15d). So, 6th char
+ * should always contain NULL. This helps to find register name
+ * length using strlen, insted of maintaing one more variable.
+ */
+#define SDT_REG_NAME_SIZE  6
 
-	/* Copy the new register name */
-	memcpy(new_desc + prefix_len, rnames->uprobe_name, uprobe_len);
+/*
+ * The uprobe parser does not support all gas register names;
+ * so, we have to replace them (ex. for x86_64: %rax -> %ax).
+ * Note: If register does not require renaming, just copy
+ * paste as it is, but don't leave it empty.
+ */
+static void sdt_rename_register(char *sdt_reg, int sdt_len, char *uprobe_reg)
+{
+	int i = 0;
 
-	/* Copy the chars after the register name (if need be) */
-	offset = prefix_len + sdt_len;
-	if (offset < old_desc_len)
-		memcpy(new_desc + prefix_len + uprobe_len,
-			old_desc + offset, old_desc_len - offset);
+	for (i = 0; sdt_reg_tbl[i].sdt_name != NULL; i++) {
+		if (!strncmp(sdt_reg_tbl[i].sdt_name, sdt_reg, sdt_len)) {
+			strcpy(uprobe_reg, sdt_reg_tbl[i].uprobe_name);
+			return;
+		}
+	}
 
-	free(old_desc);
-	*pdesc = new_desc;
+	strncpy(uprobe_reg, sdt_reg, sdt_len);
+}
 
-	return 0;
+int arch_sdt_arg_parse_op(char *old_op, char **new_op)
+{
+	char new_reg[SDT_REG_NAME_SIZE] = {0};
+	int new_len = 0, ret;
+	/*
+	 * rm[0]:  +/-NUM(REG)
+	 * rm[1]:  +/-
+	 * rm[2]:  NUM
+	 * rm[3]:  (
+	 * rm[4]:  REG
+	 * rm[5]:  )
+	 */
+	regmatch_t rm[6];
+	/*
+	 * Max prefix length is 2 as it may contains sign(+/-)
+	 * and displacement 0 (Both sign and displacement 0 are
+	 * optional so it may be empty). Use one more character
+	 * to hold last NULL so that strlen can be used to find
+	 * prefix length, instead of maintaing one more variable.
+	 */
+	char prefix[3] = {0};
+
+	ret = sdt_init_op_regex();
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * If unsupported OR does not match with regex OR
+	 * register name too long, skip it.
+	 */
+	if (strchr(old_op, ',') || strchr(old_op, '$') ||
+	    regexec(&sdt_op_regex, old_op, 6, rm, 0)   ||
+	    rm[4].rm_eo - rm[4].rm_so > SDT_REG_NAME_SIZE) {
+		pr_debug4("Skipping unsupported SDT argument: %s\n", old_op);
+		return SDT_ARG_SKIP;
+	}
+
+	/*
+	 * Prepare prefix.
+	 * If SDT OP has parenthesis but does not provide
+	 * displacement, add 0 for displacement.
+	 *     SDT         Uprobe     Prefix
+	 *     -----------------------------
+	 *     +24(%rdi)   +24(%di)   +
+	 *     24(%rdi)    +24(%di)   +
+	 *     %rdi        %di
+	 *     (%rdi)      +0(%di)    +0
+	 *     -80(%rbx)   -80(%bx)   -
+	 */
+	if (rm[3].rm_so != rm[3].rm_eo) {
+		if (rm[1].rm_so != rm[1].rm_eo)
+			prefix[0] = *(old_op + rm[1].rm_so);
+		else if (rm[2].rm_so != rm[2].rm_eo)
+			prefix[0] = '+';
+		else
+			strncpy(prefix, "+0", 2);
+	}
+
+	/* Rename register */
+	sdt_rename_register(old_op + rm[4].rm_so, rm[4].rm_eo - rm[4].rm_so,
+			    new_reg);
+
+	/* Prepare final OP which should be valid for uprobe_events */
+	new_len = strlen(prefix)              +
+		  (rm[2].rm_eo - rm[2].rm_so) +
+		  (rm[3].rm_eo - rm[3].rm_so) +
+		  strlen(new_reg)             +
+		  (rm[5].rm_eo - rm[5].rm_so) +
+		  1;					/* NULL */
+
+	*new_op = zalloc(new_len);
+	if (!*new_op)
+		return -ENOMEM;
+
+	scnprintf(*new_op, new_len, "%.*s%.*s%.*s%.*s%.*s",
+		  strlen(prefix), prefix,
+		  (int)(rm[2].rm_eo - rm[2].rm_so), old_op + rm[2].rm_so,
+		  (int)(rm[3].rm_eo - rm[3].rm_so), old_op + rm[3].rm_so,
+		  strlen(new_reg), new_reg,
+		  (int)(rm[5].rm_eo - rm[5].rm_so), old_op + rm[5].rm_so);
+
+	return SDT_ARG_VALID;
 }

tools/perf/util/perf_regs.c

@@ -6,10 +6,10 @@ const struct sample_reg __weak sample_reg_masks[] = {
 	SMPL_REG_END
 };
 
-int __weak sdt_rename_register(char **pdesc __maybe_unused,
-			char *old_name __maybe_unused)
+int __weak arch_sdt_arg_parse_op(char *old_op __maybe_unused,
+				 char **new_op __maybe_unused)
 {
-	return 0;
+	return SDT_ARG_SKIP;
 }
 
 #ifdef HAVE_PERF_REGS_SUPPORT

tools/perf/util/perf_regs.h

@@ -15,11 +15,12 @@ struct sample_reg {
 
 extern const struct sample_reg sample_reg_masks[];
 
-/*
- * The table sdt_reg_renamings is used for adjusting gcc/gas-generated
- * registers before filling the uprobe tracer interface.
- */
-int sdt_rename_register(char **pdesc, char *old_name);
+enum {
+	SDT_ARG_VALID = 0,
+	SDT_ARG_SKIP,
+};
+
+int arch_sdt_arg_parse_op(char *old_op, char **new_op);
 
 #ifdef HAVE_PERF_REGS_SUPPORT
 #include <perf_regs.h>

tools/perf/util/probe-file.c

@@ -694,10 +694,29 @@ static const char * const type_to_suffix[] = {
 	"", ":u8", ":u16", "", ":u32", "", "", "", ":u64"
 };
 
+/*
+ * Isolate the string number and convert it into a decimal value;
+ * this will be an index to get suffix of the uprobe name (defining
+ * the type)
+ */
+static int sdt_arg_parse_size(char *n_ptr, const char **suffix)
+{
+	long type_idx;
+
+	type_idx = strtol(n_ptr, NULL, 10);
+	if (type_idx < -8 || type_idx > 8) {
+		pr_debug4("Failed to get a valid sdt type\n");
+		return -1;
+	}
+
+	*suffix = type_to_suffix[type_idx + 8];
+	return 0;
+}
+
 static int synthesize_sdt_probe_arg(struct strbuf *buf, int i, const char *arg)
 {
-	char *tmp, *desc = strdup(arg);
-	const char *prefix = "", *suffix = "";
+	char *op, *desc = strdup(arg), *new_op = NULL;
+	const char *suffix = "";
 	int ret = -1;
 
 	if (desc == NULL) {
@@ -705,112 +724,37 @@ static int synthesize_sdt_probe_arg(struct strbuf *buf, int i, const char *arg)
 		return ret;
 	}
 
-	tmp = strchr(desc, '@');
-	if (tmp) {
-		long type_idx;
-		/*
-		 * Isolate the string number and convert it into a
-		 * binary value; this will be an index to get suffix
-		 * of the uprobe name (defining the type)
-		 */
-		tmp[0] = '\0';
-		type_idx = strtol(desc, NULL, 10);
-		/* Check that the conversion went OK */
-		if (type_idx == LONG_MIN || type_idx == LONG_MAX) {
-			pr_debug4("Failed to parse sdt type\n");
-			goto error;
-		}
-		/* Check that the converted value is OK */
-		if (type_idx < -8 || type_idx > 8) {
-			pr_debug4("Failed to get a valid sdt type\n");
-			goto error;
-		}
-		suffix = type_to_suffix[type_idx + 8];
-		/* Get rid of the sdt prefix which is now useless */
-		tmp++;
-		memmove(desc, tmp, strlen(tmp) + 1);
-	}
-
 	/*
-	 * The uprobe tracer format does not support all the
-	 * addressing modes (notably: in x86 the scaled mode); so, we
-	 * detect ',' characters, if there is just one, there is no
-	 * use converting the sdt arg into a uprobe one.
+	 * Argument is in N@OP format. N is size of the argument and OP is
+	 * the actual assembly operand. N can be omitted; in that case
+	 * argument is just OP(without @).
 	 */
-	if (strchr(desc, ',')) {
-		pr_debug4("Skipping unsupported SDT argument; %s\n", desc);
-		goto out;
-	}
+	op = strchr(desc, '@');
+	if (op) {
+		op[0] = '\0';
+		op++;
 
-	/*
-	 * If the argument addressing mode is indirect, we must check
-	 * a few things...
-	 */
-	tmp = strchr(desc, '(');
-	if (tmp) {
-		int j;
-
-		/*
-		 * ...if the addressing mode is indirect with a
-		 * positive offset (ex.: "1608(%ax)"), we need to add
-		 * a '+' prefix so as to be compliant with uprobe
-		 * format.
-		 */
-		if (desc[0] != '+' && desc[0] != '-')
-			prefix = "+";
-
-		/*
-		 * ...or if the addressing mode is indirect with a symbol
-		 * as offset, the argument will not be supported by
-		 * the uprobe tracer format; so, let's skip this one.
-		 */
-		for (j = 0; j < tmp - desc; j++) {
-			if (desc[j] != '+' && desc[j] != '-' &&
-				!isdigit(desc[j])) {
-				pr_debug4("Skipping unsupported SDT argument; "
-					"%s\n", desc);
-				goto out;
-			}
-		}
+		if (sdt_arg_parse_size(desc, &suffix))
+			goto error;
+	} else {
+		op = desc;
 	}
 
-	/*
-	 * The uprobe tracer format does not support constants; if we
-	 * find one in the current argument, let's skip the argument.
-	 */
-	if (strchr(desc, '$')) {
-		pr_debug4("Skipping unsupported SDT argument; %s\n", desc);
-		goto out;
-	}
+	ret = arch_sdt_arg_parse_op(op, &new_op);
 
-	/*
-	 * The uprobe parser does not support all gas register names;
-	 * so, we have to replace them (ex. for x86_64: %rax -> %ax);
-	 * the loop below looks for the register names (starting with
-	 * a '%' and tries to perform the needed renamings.
-	 */
-	tmp = strchr(desc, '%');
-	while (tmp) {
-		size_t offset = tmp - desc;
+	if (ret < 0)
+		goto error;
 
-		ret = sdt_rename_register(&desc, desc + offset);
+	if (ret == SDT_ARG_VALID) {
+		ret = strbuf_addf(buf, " arg%d=%s%s", i + 1, new_op, suffix);
 		if (ret < 0)
 			goto error;
-
-		/*
-		 * The desc pointer might have changed; so, let's not
-		 * try to reuse tmp for next lookup
-		 */
-		tmp = strchr(desc + offset + 1, '%');
 	}
 
-	if (strbuf_addf(buf, " arg%d=%s%s%s", i + 1, prefix, desc, suffix) < 0)
-		goto error;
-
-out:
 	ret = 0;
 error:
 	free(desc);
+	free(new_op);
 	return ret;
 }