From: jbaron@redhat.com <jbaron@redhat.com>
Date: Fri, 22 Aug 2008 14:04:52 -0400
Subject: [misc] markers and tracepoints: create Module.markers
Message-id: 1219428298-7519-9-git-send-email-jbaron@redhat.com
O-Subject: [rhel5.3 patch 08/14] markers and tracepoints - create Module.markers file
Bugzilla: 329821

bz# 329821

diff --git a/include/linux/marker.h b/include/linux/marker.h
index ea04250..c2e3d97 100644
--- a/include/linux/marker.h
+++ b/include/linux/marker.h
@@ -61,15 +61,12 @@ struct marker {
  */
 #define __trace_mark(name, call_private, format, args...)		\
 	do {								\
-		static const char __mstrtab_name_##name[]		\
+		static const char __mstrtab_##name[]			\
 		__attribute__((section("__markers_strings")))		\
-		= #name;						\
-		static const char __mstrtab_format_##name[]		\
-		__attribute__((section("__markers_strings")))		\
-		= format;						\
+		= #name "\0" format;					\
 		static struct marker __mark_##name			\
 		__attribute__((section("__markers"), aligned(8))) =	\
-		{ __mstrtab_name_##name, __mstrtab_format_##name,	\
+		{ __mstrtab_##name, &__mstrtab_##name[sizeof(#name)],   \
 		0, 0, marker_probe_cb,                                  \
 		{ __mark_empty_function, NULL}, NULL };                 \
 		__mark_check_format(format, ## args);			\
diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index 0a64688..1932573 100644
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -13,6 +13,7 @@
 # 2) modpost is then used to
 # 3)  create one <module>.mod.c file pr. module
 # 4)  create one Module.symvers file with CRC for all exported symbols
+# 4a) [CONFIG_MARKERS] create one Module.markers file listing defined markers
 # 5) compile all <module>.mod.c files
 # 6) final link of the module to a <module.ko> file
 
@@ -41,6 +42,10 @@ include scripts/Makefile.lib
 
 kernelsymfile := $(objtree)/Module.symvers
 modulesymfile := $(KBUILD_EXTMOD)/Module.symvers
+kernelmarkersfile := $(objtree)/Module.markers
+modulemarkersfile := $(KBUILD_EXTMOD)/Module.markers
+
+markersfile = $(if $(KBUILD_EXTMOD),$(modulemarkersfile),$(kernelmarkersfile))
 
 # Step 1), find all modules listed in $(MODVERDIR)/
 __modules := $(sort $(shell grep -h '\.ko' /dev/null $(wildcard $(MODVERDIR)/*.mod)))
@@ -58,6 +63,8 @@ quiet_cmd_modpost = MODPOST
 	$(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile) \
 	$(if $(KBUILD_EXTMOD),-I $(modulesymfile)) \
 	$(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \
+	$(if $(CONFIG_MARKERS),-K $(kernelmarkersfile)) \
+	$(if $(CONFIG_MARKERS),-M $(markersfile)) \
 	$(filter-out FORCE,$^)
 
 PHONY += __modpost
@@ -68,6 +75,10 @@ __modpost: $(wildcard vmlinux) $(modules:.ko=.o) FORCE
 $(symverfile):         __modpost ;
 $(modules:.ko=.mod.c): __modpost ;
 
+ifdef CONFIG_MARKERS
+$(markersfile):	       __modpost ;
+endif
+
 
 # Step 5), compile all *.mod.c files
 
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 0ec3321..e6c3e55 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -11,6 +11,8 @@
  * Usage: modpost vmlinux module1.o module2.o ...
  */
 
+#define _GNU_SOURCE
+#include <stdio.h>
 #include <ctype.h>
 #include "modpost.h"
 #include "../../include/linux/license.h"
@@ -385,6 +387,8 @@ static void parse_elf(struct elf_info *info, const char *filename)
 			info->export_unused_gpl_sec = i;
 		else if (strcmp(secname, "__ksymtab_gpl_future") == 0)
 			info->export_gpl_future_sec = i;
+		else if (strcmp(secname, "__markers_strings") == 0)
+			info->markers_strings_sec = i;
 
 		if (sechdrs[i].sh_type != SHT_SYMTAB)
 			continue;
@@ -1054,6 +1058,62 @@ static int exit_section_ref_ok(const char *name)
 	return 0;
 }
 
+static void get_markers(struct elf_info *info, struct module *mod)
+{
+	const Elf_Shdr *sh = &info->sechdrs[info->markers_strings_sec];
+	const char *strings = (const char *) info->hdr + sh->sh_offset;
+	const Elf_Sym *sym, *first_sym, *last_sym;
+	size_t n;
+
+	if (!info->markers_strings_sec)
+		return;
+
+	/*
+	 * First count the strings.  We look for all the symbols defined
+	 * in the __markers_strings section named __mstrtab_*.  For
+	 * these local names, the compiler puts a random .NNN suffix on,
+	 * so the names don't correspond exactly.
+	 */
+	first_sym = last_sym = NULL;
+	n = 0;
+	for (sym = info->symtab_start; sym < info->symtab_stop; sym++)
+		if (ELF_ST_TYPE(sym->st_info) == STT_OBJECT &&
+		    sym->st_shndx == info->markers_strings_sec &&
+		    !strncmp(info->strtab + sym->st_name,
+			     "__mstrtab_", sizeof "__mstrtab_" - 1)) {
+			if (first_sym == NULL)
+				first_sym = sym;
+			last_sym = sym;
+			++n;
+		}
+
+	if (n == 0)
+		return;
+
+	/*
+	 * Now collect each name and format into a line for the output.
+	 * Lines look like:
+	 *	marker_name	vmlinux	marker %s format %d
+	 * The format string after the second \t can use whitespace.
+	 */
+	mod->markers = NOFAIL(malloc(sizeof mod->markers[0] * n));
+	mod->nmarkers = n;
+
+	n = 0;
+	for (sym = first_sym; sym <= last_sym; sym++)
+		if (ELF_ST_TYPE(sym->st_info) == STT_OBJECT &&
+		    sym->st_shndx == info->markers_strings_sec &&
+		    !strncmp(info->strtab + sym->st_name,
+			     "__mstrtab_", sizeof "__mstrtab_" - 1)) {
+			const char *name = strings + sym->st_value;
+			const char *fmt = strchr(name, '\0') + 1;
+			char *line = NULL;
+			asprintf(&line, "%s\t%s\t%s\n", name, mod->name, fmt);
+			NOFAIL(line);
+			mod->markers[n++] = line;
+		}
+}
+
 static void read_symbols(char *modname)
 {
 	const char *symname;
@@ -1103,6 +1163,8 @@ static void read_symbols(char *modname)
 		get_src_version(modname, mod->srcversion,
 				sizeof(mod->srcversion)-1);
 
+	get_markers(&info, mod);
+
 	parse_elf_finish(&info);
 
 	/* Our trick to get versioning for struct_module - it's
@@ -1436,6 +1498,92 @@ static void write_dump(const char *fname)
 	write_if_changed(&buf, fname);
 }
 
+static void add_marker(struct module *mod, const char *name, const char *fmt)
+{
+	char *line = NULL;
+	asprintf(&line, "%s\t%s\t%s\n", name, mod->name, fmt);
+	NOFAIL(line);
+
+	mod->markers = NOFAIL(realloc(mod->markers, ((mod->nmarkers + 1) *
+						     sizeof mod->markers[0])));
+	mod->markers[mod->nmarkers++] = line;
+}
+
+static void read_markers(const char *fname)
+{
+	unsigned long size, pos = 0;
+	void *file = grab_file(fname, &size);
+	char *line;
+
+	if (!file)		/* No old markers, silently ignore */
+		return;
+
+	while ((line = get_next_line(&pos, file, size))) {
+		char *marker, *modname, *fmt;
+		struct module *mod;
+
+		marker = line;
+		modname = strchr(marker, '\t');
+		if (!modname)
+			goto fail;
+		*modname++ = '\0';
+		fmt = strchr(modname, '\t');
+		if (!fmt)
+			goto fail;
+		*fmt++ = '\0';
+		if (*marker == '\0' || *modname == '\0')
+			goto fail;
+
+		mod = find_module(modname);
+		if (!mod) {
+			if (is_vmlinux(modname))
+				have_vmlinux = 1;
+			mod = new_module(NOFAIL(strdup(modname)));
+			mod->skip = 1;
+		}
+
+		add_marker(mod, marker, fmt);
+	}
+	return;
+fail:
+	fatal("parse error in markers list file\n");
+}
+
+static int compare_strings(const void *a, const void *b)
+{
+	return strcmp(*(const char **) a, *(const char **) b);
+}
+
+static void write_markers(const char *fname)
+{
+	struct buffer buf = { };
+	struct module *mod;
+	size_t i;
+
+	for (mod = modules; mod; mod = mod->next)
+		if ((!external_module || !mod->skip) && mod->markers != NULL) {
+			/*
+			 * Sort the strings so we can skip duplicates when
+			 * we write them out.
+			 */
+			qsort(mod->markers, mod->nmarkers,
+			      sizeof mod->markers[0], &compare_strings);
+			for (i = 0; i < mod->nmarkers; ++i) {
+				char *line = mod->markers[i];
+				buf_write(&buf, line, strlen(line));
+				while (i + 1 < mod->nmarkers &&
+				       !strcmp(mod->markers[i],
+					       mod->markers[i + 1]))
+					free(mod->markers[i++]);
+				free(mod->markers[i]);
+			}
+			free(mod->markers);
+			mod->markers = NULL;
+		}
+
+	write_if_changed(&buf, fname);
+}
+
 int main(int argc, char **argv)
 {
 	struct module *mod;
@@ -1443,9 +1591,11 @@ int main(int argc, char **argv)
 	char fname[SZ];
 	char *kernel_read = NULL, *module_read = NULL;
 	char *dump_write = NULL;
+	char *markers_read = NULL;
+	char *markers_write = NULL;
 	int opt;
 
-	while ((opt = getopt(argc, argv, "i:I:mo:a")) != -1) {
+	while ((opt = getopt(argc, argv, "i:I:mo:aM:K:")) != -1) {
 		switch(opt) {
 			case 'i':
 				kernel_read = optarg;
@@ -1463,6 +1613,12 @@ int main(int argc, char **argv)
 			case 'a':
 				all_versions = 1;
 				break;
+			case 'M':
+				markers_write = optarg;
+				break;
+			case 'K':
+				markers_read = optarg;
+				break;
 			default:
 				exit(1);
 		}
@@ -1502,5 +1658,11 @@ int main(int argc, char **argv)
 	if (dump_write)
 		write_dump(dump_write);
 
+	if (markers_read)
+		read_markers(markers_read);
+
+	if (markers_write)
+		write_markers(markers_write);
+
 	return 0;
 }
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index d398c61..b660f00 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -107,6 +107,8 @@ struct module {
 	int has_init;
 	int has_cleanup;
 	struct buffer dev_table_buf;
+	char **markers;
+	size_t nmarkers;
 	char	     srcversion[25];
 };
 
@@ -121,6 +123,7 @@ struct elf_info {
 	Elf_Section  export_gpl_sec;
 	Elf_Section  export_unused_gpl_sec;
 	Elf_Section  export_gpl_future_sec;
+	Elf_Section  markers_strings_sec;
 	const char   *strtab;
 	char	     *modinfo;
 	unsigned int modinfo_len;