cbmem: Add new command line flag to dump console for one boot only

Even though the persistent CBMEM console is obviously awesome, there may
be cases where we only want to look at console output from the last boot.
It's easy to tell where one boot ends and another begins from the banner
message that coreboot prints at the start of every stage, but in order
to make it easier to find that point (especially for external tools),
let's put that functionality straight into the cbmem utility with a new
command line flag. Use the POSIX/libc regular expression API to find the
banner string for maximum compatilibity, even though it's kinda icky.

Change-Id: Ic17383507a884d84de9a2a880380cb15b25708a1
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/19497
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Philippe Mathieu-Daudé <philippe.mathieu.daude@gmail.com>
Reviewed-by: Sumeet R Pawnikar <sumeet.r.pawnikar@intel.com>

1 files changed, 37 insertions, 4 deletions

diff --git a/util/cbmem/cbmem.c b/util/cbmem/cbmem.c
index 7b7f10d53f..c1b1caa572 100644
--- a/util/cbmem/cbmem.c
+++ b/util/cbmem/cbmem.c
@@ -31,6 +31,7 @@
 #include <sys/mman.h>
 #include <libgen.h>
 #include <assert.h>
+#include <regex.h>
 #include <commonlib/cbmem_id.h>
 #include <commonlib/timestamp_serialized.h>
 #include <commonlib/coreboot_tables.h>
@@ -611,7 +612,7 @@ struct cbmem_console {
 #define CBMC_OVERFLOW (1 << 31)
 
 /* dump the cbmem console */
-static void dump_console(void)
+static void dump_console(int one_boot_only)
 {
 	struct cbmem_console *console_p;
 	char *console_c;
@@ -659,8 +660,32 @@ static void dump_console(void)
 	for (cursor = 0; cursor < size; cursor++)
 		if (!isprint(console_c[cursor]) && !isspace(console_c[cursor]))
 			console_c[cursor] = '?';
-	printf("%s\n", console_c);
 
+	/* We detect the last boot by looking for a bootblock, romstage or
+	   ramstage banner, in that order (to account for platforms without
+	   CONFIG_BOOTBLOCK_CONSOLE and/or CONFIG_EARLY_CONSOLE). Once we find
+	   a banner, store the last match for that stage in cursor and stop. */
+	cursor = 0;
+	if (one_boot_only) {
+#define BANNER_REGEX(stage) "\n\ncoreboot-[^\n]* " stage " starting\\.\\.\\.\n"
+		const char *regex[] = { BANNER_REGEX("bootblock"),
+					BANNER_REGEX("romstage"),
+					BANNER_REGEX("ramstage")};
+		int i;
+
+		for (i = 0; !cursor && i < ARRAY_SIZE(regex); i++) {
+			regex_t re;
+			regmatch_t match;
+			assert(!regcomp(&re, regex[i], 0));
+
+			/* Keep looking for matches so we find the last one. */
+			while (!regexec(&re, console_c + cursor, 1, &match, 0))
+				cursor += match.rm_so + 1;
+			regfree(&re);
+		}
+	}
+
+	puts(console_c + cursor);
 	free(console_c);
 	unmap_memory();
 }
@@ -936,6 +961,7 @@ static void print_usage(const char *name, int exit_code)
 	printf("usage: %s [-cCltTxVvh?]\n", name);
 	printf("\n"
 	     "   -c | --console:                   print cbmem console\n"
+	     "   -1 | --oneboot:                   print cbmem console for last boot only\n"
 	     "   -C | --coverage:                  dump coverage information\n"
 	     "   -l | --list:                      print cbmem table of contents\n"
 	     "   -x | --hexdump:                   print hexdump of cbmem area\n"
@@ -1074,11 +1100,13 @@ int main(int argc, char** argv)
 	int print_rawdump = 0;
 	int print_timestamps = 0;
 	int machine_readable_timestamps = 0;
+	int one_boot_only = 0;
 	unsigned int rawdump_id = 0;
 
 	int opt, option_index = 0;
 	static struct option long_options[] = {
 		{"console", 0, 0, 'c'},
+		{"oneboot", 0, 0, '1'},
 		{"coverage", 0, 0, 'C'},
 		{"list", 0, 0, 'l'},
 		{"timestamps", 0, 0, 't'},
@@ -1090,13 +1118,18 @@ int main(int argc, char** argv)
 		{"help", 0, 0, 'h'},
 		{0, 0, 0, 0}
 	};
-	while ((opt = getopt_long(argc, argv, "cCltTxVvh?r:",
+	while ((opt = getopt_long(argc, argv, "c1CltTxVvh?r:",
 				  long_options, &option_index)) != EOF) {
 		switch (opt) {
 		case 'c':
 			print_console = 1;
 			print_defaults = 0;
 			break;
+		case '1':
+			print_console = 1;
+			one_boot_only = 1;
+			print_defaults = 0;
+			break;
 		case 'C':
 			print_coverage = 1;
 			print_defaults = 0;
@@ -1211,7 +1244,7 @@ int main(int argc, char** argv)
 #endif
 
 	if (print_console)
-		dump_console();
+		dump_console(one_boot_only);
 
 	if (print_coverage)
 		dump_coverage();