Parse /sys/firmware/memmap.

After the patch that provides /sys/firmware/memmap has been merged in the 'tip'
tree by Ingo Molnar, kexec should use that interface.

This patch implements architecture-independent parsing in a new file called
firmware_memmap.c. The x86 part is ported to use that memory map for
kexec. We don't use that memory map for building the ELF core headers,
that was the intention for that new interface.

Signed-off-by: Bernhard Walle <bwalle@suse.de>
Signed-off-by: Simon Horman <horms@verge.net.au>

1 files changed, 278 insertions, 0 deletions

diff --git a/kexec/firmware_memmap.c b/kexec/firmware_memmap.c
new file mode 100644
index 0000000..b0d4f62
--- /dev/null
+++ b/kexec/firmware_memmap.c
@@ -0,0 +1,278 @@
+/*
+ * firmware_memmap.c: Read /sys/firmware/memmap
+ *
+ * Created by: Bernhard Walle (bwalle@suse.de)
+ * Copyright (C) SUSE LINUX Products GmbH, 2008. All rights reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation (version 2 of the License).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#define _GNU_SOURCE /* for ULLONG_MAX without C99 */
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <limits.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include "firmware_memmap.h"
+#include "kexec.h"
+
+/*
+ * If the system is too old for ULLONG_MAX or LLONG_MAX, define it here.
+ */
+#ifndef ULLONG_MAX
+#    define ULLONG_MAX (~0ULL)
+#endif /* ULLONG_MAX */
+
+#ifndef LLONG_MAX
+#    define LLONG_MAX (~0ULL >> 1)
+#endif /* LLONG_MAX */
+
+
+/**
+ * The full path to the sysfs interface that provides the memory map.
+ */
+#define FIRMWARE_MEMMAP_DIR  "/sys/firmware/memmap"
+
+/**
+ * Parses a file that only contains one number. Typical for sysfs files.
+ *
+ * @param[in] filename the name of the file that should be parsed
+ * @return the value that has been read or ULLONG_MAX on error.
+ */
+static unsigned long long parse_numeric_sysfs(const char *filename)
+{
+	FILE *fp;
+	char linebuffer[BUFSIZ];
+	unsigned long long retval;
+
+	fp = fopen(filename, "r");
+	if (!fp) {
+		fprintf(stderr, "Opening \"%s\" failed: %s\n",
+			filename, strerror(errno));
+		return ULLONG_MAX;
+	}
+
+	fgets(linebuffer, BUFSIZ, fp);
+	linebuffer[BUFSIZ-1] = 0;
+
+	/* let strtoll() detect the base */
+	retval = strtoll(linebuffer, NULL, 0);
+
+	fclose(fp);
+
+	return retval;
+}
+
+/**
+ * Reads the contents of a one-line sysfs file to buffer. (This function is
+ * not threadsafe.)
+ *
+ * @param[in] filename the name of the file that should be read
+ *
+ * @return NULL on failure, a pointer to a static buffer (that should be copied
+ *         with strdup() if the caller plans to use it after next function call)
+ */
+static char *parse_string_sysfs(const char *filename)
+{
+	FILE *fp;
+	static char linebuffer[BUFSIZ];
+	char *end;
+
+	fp = fopen(filename, "r");
+	if (!fp) {
+		fprintf(stderr, "Opening \"%s\" failed: %s\n",
+			filename, strerror(errno));
+		return NULL;
+	}
+
+	fgets(linebuffer, BUFSIZ, fp);
+	linebuffer[BUFSIZ-1] = 0;
+
+	/* truncate trailing newline(s) */
+	end = linebuffer + strlen(linebuffer) - 1;
+	while (*end == '\n')
+		*end-- = 0;
+
+	fclose(fp);
+
+	return linebuffer;
+
+}
+
+static int parse_memmap_entry(const char *entry, struct memory_range *range)
+{
+	char filename[PATH_MAX];
+	char *type;
+
+	/*
+	 * entry/start
+	 */
+	snprintf(filename, PATH_MAX, "%s/%s", entry, "start");
+	filename[PATH_MAX-1] = 0;
+
+	range->start = parse_numeric_sysfs(filename);
+	if (range->start == ULLONG_MAX)
+		return -1;
+
+	/*
+	 * entry/end
+	 */
+	snprintf(filename, PATH_MAX, "%s/%s", entry, "end");
+	filename[PATH_MAX-1] = 0;
+
+	range->end = parse_numeric_sysfs(filename);
+	if (range->end == ULLONG_MAX)
+		return -1;
+	range->end++; /* inclusive vs. exclusive ranges */
+
+	/*
+	 * entry/type
+	 */
+	snprintf(filename, PATH_MAX, "%s/%s", entry, "type");
+	filename[PATH_MAX-1] = 0;
+
+	type = parse_string_sysfs(filename);
+	if (!type)
+		return -1;
+
+	if (strcmp(type, "System RAM") == 0)
+		range->type = RANGE_RAM;
+	else if (strcmp(type, "ACPI Tables") == 0)
+		range->type = RANGE_ACPI;
+	else if (strcmp(type, "reserved") == 0)
+		range->type = RANGE_RESERVED;
+	else if (strcmp(type, "ACPI Non-volatile Storage") == 0)
+		range->type = RANGE_ACPI_NVS;
+	else {
+		fprintf(stderr, "Unknown type (%s) while parsing %s. Please "
+			"report this as bug. Using RANGE_RESERVED now.\n",
+			type, filename);
+		range->type = RANGE_RESERVED;
+	}
+
+	return 0;
+}
+
+/**
+ * Compares two memory ranges according to their start address. This function
+ * can be used with qsort() as @c compar function.
+ *
+ * @param[in] first a pointer to the first memory range
+ * @param[in] second a pointer to the second memory range
+ * @return 0 if @p first and @p second have the same start address,
+ *         a value less then 0 if the start address of @p first is less than
+ *         the start address of @p second, and a value greater than 0 if
+ *         the opposite is in case.
+ */
+static int compare_ranges(const void *first, const void *second)
+{
+	const struct memory_range *first_range = first;
+	const struct memory_range *second_range = second;
+
+	/*
+	 * don't use the "first_range->start - second_range->start"
+	 * notation because unsigned long long might overflow
+	 */
+	if (first_range->start > second_range->start)
+		return 1;
+	else if (first_range->start < second_range->start)
+		return -1;
+	else /* first_range->start == second_range->start */
+		return 0;
+}
+
+/* documentation: firmware_memmap.h */
+int have_sys_firmware_memmap(void)
+{
+	int ret;
+	struct stat mystat;
+
+	ret = stat(FIRMWARE_MEMMAP_DIR, &mystat);
+	if (ret != 0)
+		return 0;
+
+	return S_ISDIR(mystat.st_mode);
+}
+
+/* documentation: firmware_memmap.h */
+int get_firmware_memmap_ranges(struct memory_range *range, size_t *ranges)
+{
+	DIR *firmware_memmap_dir = NULL;
+	struct dirent *dirent;
+	int i = 0;
+
+	/* argument checking */
+	if (!range || !ranges) {
+		fprintf(stderr, "%s: Invalid arguments.\n", __FUNCTION__);
+		return -1;
+	}
+
+	/* open the directory */
+	firmware_memmap_dir = opendir(FIRMWARE_MEMMAP_DIR);
+	if (!firmware_memmap_dir) {
+		perror("Could not open \"" FIRMWARE_MEMMAP_DIR "\"");
+		goto error;
+	}
+
+	/* parse the entries */
+	while ((dirent = readdir(firmware_memmap_dir)) != NULL) {
+		int ret;
+		char full_path[PATH_MAX];
+
+		/* array overflow check */
+		if ((size_t)i >= *ranges) {
+			fprintf(stderr, "The firmware provides more entries "
+				"allowed (%d). Please report that as bug.\n",
+				*ranges);
+			goto error;
+		}
+
+		/* exclude '.' and '..' */
+		if (dirent->d_name[0] && dirent->d_name[0] == '.') {
+			continue;
+		}
+
+		snprintf(full_path, PATH_MAX, "%s/%s", FIRMWARE_MEMMAP_DIR,
+			dirent->d_name);
+		full_path[PATH_MAX-1] = 0;
+		ret = parse_memmap_entry(full_path, &range[i]);
+		if (ret < 0) {
+			goto error;
+		}
+
+		i++;
+	}
+
+	/* close the dir as we don't need it any more */
+	closedir(firmware_memmap_dir);
+
+	/* update the number of ranges for the caller */
+	*ranges = i;
+
+	/* and finally sort the entries with qsort */
+	qsort(range, *ranges, sizeof(struct memory_range), compare_ranges);
+
+	return 0;
+
+error:
+	if (firmware_memmap_dir) {
+		closedir(firmware_memmap_dir);
+	}
+	return -1;
+}
+