[RESEND RFC PATCH 4/5] msghash: Add userland msghash tool
From: Hidehiro Kawai
Date: Thu Jul 25 2013 - 05:10:25 EST
This patch adds scripts/msghash/msghash. msghash scans a kmsg_meta
table between __start___kmsg_meta to __stop___kmsg_meta in the
target object file (vmlinux), computes a hash value for each
message format string, then replaces the format string with the
hash value. Valid flags are also set to entries in the kmsg_meta
table. When computing the hash value, prefixed loglevel characters
are ignored.
Even if configured with CONFIG_KMSG_HASH=y, without running msghash,
no hash values are output via /dev/kmsg. So msghash is executed
during the build process, just after generating vmlinux.
msghash also generate a Hash-and-message catalog named
"<objfile>.msglist". Each line in the .msglist file is output
in the form of:
<hash in hex>@<file>:<lineno>,<message format>
.msglist file is useful to match /dev/kmsg messages with messages
you concern.
Here is the example of .msglist:
...
b6be0058@init/main.c:180,"Parameter %s is obsolete, ignored"
72dfe336@init/main.c:403,"Malformed early option '%s'"
85788d36@init/do_mounts.c:573,"Waiting for root device %s..."
...
Currently, only vmlinux is supported. msghash can't update
the kmsg_meta tables of kernel modules.
Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@xxxxxxxxxxx>
---
.gitignore | 1
Makefile | 7 +
lib/Kconfig.debug | 5 +
scripts/Makefile | 1
scripts/link-vmlinux.sh | 5 +
scripts/msghash/.gitignore | 1
scripts/msghash/Makefile | 7 +
scripts/msghash/msghash.c | 241 ++++++++++++++++++++++++++++++++++++++++++++
scripts/msghash/msghash.sh | 45 ++++++++
9 files changed, 312 insertions(+), 1 deletions(-)
create mode 100644 scripts/msghash/.gitignore
create mode 100644 scripts/msghash/Makefile
create mode 100644 scripts/msghash/msghash.c
create mode 100755 scripts/msghash/msghash.sh
diff --git a/.gitignore b/.gitignore
index 3b8b9b3..3bb5735 100644
--- a/.gitignore
+++ b/.gitignore
@@ -32,6 +32,7 @@ modules.builtin
*.lzo
*.patch
*.gcno
+*.msglist
#
# Top-level generic files
diff --git a/Makefile b/Makefile
index a35f72a..6d11a09 100644
--- a/Makefile
+++ b/Makefile
@@ -766,6 +766,10 @@ vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN)
cmd_link-vmlinux = $(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux)
quiet_cmd_link-vmlinux = LINK $@
+# Remove old .msglist
+ cmd_rm-msglist = echo rm -f $@.msglist
+quiet_cmd_rm-msglist = CLEAN $@.msglist
+
# Include targets which we want to
# execute if the rest of the kernel build went well.
vmlinux: scripts/link-vmlinux.sh $(vmlinux-deps) FORCE
@@ -1274,7 +1278,8 @@ clean: $(clean-dirs)
-o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
-o -name '*.symtypes' -o -name 'modules.order' \
-o -name modules.builtin -o -name '.tmp_*.o.*' \
- -o -name '*.gcno' \) -type f -print | xargs rm -f
+ -o -name '*.gcno' -o -name '*.msglist' \) -type f -print |\
+ xargs rm -f
# Generate tags for editors
# ---------------------------------------------------------------------------
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 907f8cf..78d60f0 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -12,6 +12,11 @@ config PRINTK_TIME
to /dev/kmsg. This flag just specifies if the timestamp should
be included, not that the timestamp is recorded.
+ Hash values are calculated during the build process and
+ put into a table in object files. Hash-and-message catalogs
+ named <objfile>.msglist are also generated for convenience
+ in message handling in userland.
+
The behavior is also controlled by the kernel command line
parameter printk.time=1. See Documentation/kernel-parameters.txt
diff --git a/scripts/Makefile b/scripts/Makefile
index 01e7adb..7568e35 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -37,6 +37,7 @@ subdir-$(CONFIG_MODVERSIONS) += genksyms
subdir-y += mod
subdir-$(CONFIG_SECURITY_SELINUX) += selinux
subdir-$(CONFIG_DTC) += dtc
+subdir-$(CONFIG_KMSG_HASH) += msghash
# Let clean descend into subdirs
subdir- += basic kconfig package selinux
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 0149949..575c2bb 100644
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -228,5 +228,10 @@ if [ -n "${CONFIG_KALLSYMS}" ]; then
fi
fi
+if [ -n "${CONFIG_KMSG_HASH}" ]; then
+ rm -f vmlinux.msglist
+ ${srctree}/scripts/msghash/msghash.sh vmlinux || exit 1
+fi
+
# We made a new kernel - delete old version file
rm -f .old_version
diff --git a/scripts/msghash/.gitignore b/scripts/msghash/.gitignore
new file mode 100644
index 0000000..8bcfa1d
--- /dev/null
+++ b/scripts/msghash/.gitignore
@@ -0,0 +1 @@
+msghash
diff --git a/scripts/msghash/Makefile b/scripts/msghash/Makefile
new file mode 100644
index 0000000..add1e14
--- /dev/null
+++ b/scripts/msghash/Makefile
@@ -0,0 +1,7 @@
+hostprogs-y := msghash
+
+HOST_EXTRACFLAGS += -I$(srctree)/tools/include -I$(srctree)/include
+
+always := $(hostprogs-y)
+clean-files := $(hostprogs-y)
+
diff --git a/scripts/msghash/msghash.c b/scripts/msghash/msghash.c
new file mode 100644
index 0000000..832fdb9
--- /dev/null
+++ b/scripts/msghash/msghash.c
@@ -0,0 +1,241 @@
+/*
+ * msghash.c: calculate hash values of printk messages and update the
+ * kmsg_meta table in the target object file.
+ *
+ * Copyright 2013 Hidehiro Kawai <hidehiro.kawai.ez@xxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+typedef u_int8_t u8;
+typedef u_int16_t u16;
+typedef u_int32_t u32;
+typedef u_int64_t u64;
+
+#include <linux/kmsghash.h>
+#include <tools/jhash.h>
+
+#define KERN_SOH_ASCII '\001'
+static inline char *printk_skip_level(char *buffer)
+{
+ if (buffer[0] == KERN_SOH_ASCII && buffer[1]) {
+ switch (buffer[1]) {
+ case '0' ... '7':
+ case 'd': /* KERN_DEFAULT */
+ return buffer + 2;
+ }
+ }
+ return buffer;
+}
+
+static unsigned long rodata_addr;
+static unsigned long rodata_off;
+static FILE *outfp;
+struct msghash_stat {
+ int updated; /* number of entries updated successfully */
+ int skipped; /* skipped entries because of having a valid hash */
+ int invalid; /* entries whoes format string is not constant */
+} st;
+
+static inline unsigned long addr_to_offset(unsigned long addr)
+{
+ return addr - rodata_addr + rodata_off;
+}
+
+static void usage(void)
+{
+ fprintf(stderr,
+ "Usage: msghash [-o <outfile>] <objfile> <start_meta> <stop_meta>\n"
+ " <rodata_addr> <rodata_offset>\n");
+}
+
+/*
+ * Update the hash value of a given kmsg_meta object and write out
+ * a Hash-and-message line to the specified file.
+ */
+static void update_and_print_hash(char *buf, struct kmsg_meta *meta)
+{
+ static char fmtbuf[4096];
+ u_int32_t hash;
+ char *str;
+ int len;
+ int i, j, c;
+
+ if (meta->flags & KMSG_FLAGS_HASH_VALID) {
+ st.skipped++;
+ return;
+ }
+
+ /* Non-constant format case, skip it. */
+ if (!meta->u.format) {
+ st.invalid++;
+ return;
+ }
+
+ str = buf + addr_to_offset((unsigned long)meta->u.format);
+ str = printk_skip_level(str);
+ len = strlen(str);
+ hash = jhash(str, len, 0);
+ meta->u.format = 0;
+ meta->u.hash = hash;
+ meta->flags |= KMSG_FLAGS_HASH_VALID;
+
+ /*
+ * We output the kmsg metadata info only if the hash value
+ * has just been updated because a pointer to the format string
+ * is overwritten with a hash value.
+ */
+ if (outfp) {
+ /* Don't printout a newline at the tail. */
+ if (str[len - 1] == '\n')
+ len--;
+
+ /* Escape special codes same as reading /dev/kmsg */
+ for (i = 0, j = 0; i < len; i++) {
+ c = str[i];
+
+ if (c < ' ' || c >= 127 || c == '\\')
+ j += sprintf(fmtbuf + j, "\\x%02x", c);
+ else
+ fmtbuf[j++] = c;
+ }
+ fmtbuf[j] = 0;
+ fprintf(outfp, "%08x@%s:%d,\"%s\"\n", meta->u.hash,
+ buf + addr_to_offset((unsigned long)meta->filename),
+ meta->lineno, fmtbuf);
+ }
+
+ st.updated++;
+}
+
+/*
+ * Calculate hash values of printk message formats and replace it with
+ * the hash values. This means we modify kmsg_meta table in .rodata
+ * section of the target file (vmlinux).
+ */
+static void walk_kmsg_meta(char *buf, unsigned long start, unsigned long end)
+{
+ char *p;
+
+ for (p = buf + start; p < buf + end; p += sizeof(struct kmsg_meta))
+ update_and_print_hash(buf, (struct kmsg_meta *)p);
+}
+
+static char *do_mmap_objfile(const char *filename, size_t *len)
+{
+ int fd;
+ struct stat sb;
+ char *buf;
+
+ fd = open(filename, O_RDWR | O_APPEND);
+ if (fd < 0) {
+ perror("msghash: open");
+ return NULL;
+ }
+
+ if (fstat(fd, &sb) < 0) {
+ perror("msghash: fstat");
+ return NULL;
+ }
+
+ buf = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+ if (buf == MAP_FAILED) {
+ perror("msghash: mmap");
+ return NULL;
+ }
+ *len = sb.st_size;
+
+ return buf;
+}
+
+int main(int argc, char *argv[])
+{
+ unsigned long start_meta, stop_meta, start, end;
+ char *outfile = NULL;
+ char *buf;
+ size_t len;
+ int total;
+ int c;
+ int ret;
+
+ while ((c = getopt(argc, argv, "o:")) >= 0) {
+ switch (c) {
+ case 'o':
+ outfile = optarg;
+ break;
+ default:
+ usage();
+ return 1;
+ }
+ }
+
+ if (argc - optind < 5) {
+ usage();
+ return 1;
+ }
+
+ start_meta = strtoul(argv[optind + 1], NULL, 0);
+ stop_meta = strtoul(argv[optind + 2], NULL, 0);
+ rodata_addr = strtoul(argv[optind + 3], NULL, 0);
+ rodata_off = strtoul(argv[optind + 4], NULL, 0);
+
+ /* Do some sanity checks. */
+ if (!start_meta || !stop_meta || start_meta > stop_meta) {
+ fprintf(stderr, "msghash: Invalid arguments\n");
+ fprintf(stderr, " start_meta: 0x%08lx\n", start_meta);
+ fprintf(stderr, " stop_meta: 0x%08lx\n", stop_meta);
+ fprintf(stderr, " rodata_addr: 0x%08lx\n", rodata_addr);
+ fprintf(stderr, " rodata_off: 0x%08lx\n", rodata_off);
+ return 1;
+ }
+
+ if (start_meta == stop_meta) {
+ /* There is nothing to do. */
+ return 0;
+ }
+
+ buf = do_mmap_objfile(argv[optind], &len);
+ if (!buf)
+ return 1;
+ outfp = fopen(outfile, "w");
+ if (outfp < 0) {
+ perror("msghash: fopen output file");
+ return 1;
+ }
+
+ start = addr_to_offset(start_meta);
+ end = addr_to_offset(stop_meta);
+
+ walk_kmsg_meta(buf, start, end);
+ ret = msync(buf, len, MS_SYNC);
+ if (ret < 0) {
+ perror("msghash: msync");
+ return 1;
+ }
+
+ total = st.updated + st.skipped + st.invalid;
+ printf("msghash: %d/%d entries updated, %d skipped, %d invalid\n",
+ st.updated, total, st.skipped, st.invalid);
+
+ return 0;
+}
diff --git a/scripts/msghash/msghash.sh b/scripts/msghash/msghash.sh
new file mode 100755
index 0000000..a0b749f7
--- /dev/null
+++ b/scripts/msghash/msghash.sh
@@ -0,0 +1,45 @@
+#!/bin/sh
+#
+# msghash.sh -- calculate hash values of printk messages and update
+# the kmsg_meta table in a given object file.
+# A Message-and-hash catalog named <object file>.msglist
+# is also created.
+#
+# Usage: msghash.sh <object file>
+#
+# Copyright 2013 Hidehiro Kawai <hidehiro.kawai.ez@xxxxxxxxxxx>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+
+MSGHASH=${srctree}/scripts/msghash/msghash
+target="$1"
+outfile="${target}.msglist"
+
+start_meta=`nm "$target" | grep ' __start___kmsg_meta' | awk '{print "0x"$1}'`
+stop_meta=`nm "$target" | grep ' __stop___kmsg_meta' | awk '{print "0x"$1}'`
+tmp=`objdump -h "$target" | grep ' .rodata '`
+eval `echo "$tmp" | awk '{print "rodata_addr=0x"$4"; rodata_offset=0x"$6}'`
+
+if [ -z "$start_meta" -o -z "$stop_meta" ]; then
+ echo "msghash: Couldn't find the kmsg_meta table."
+ exit 1
+fi
+if [ -z "$rodata_addr" -o -z "$rodata_offset" ]; then
+ echo "msghash: Failed to get .rodata section info."
+ exit 1
+fi
+
+$MSGHASH -o $outfile "$target" $start_meta $stop_meta $rodata_addr $rodata_offset
+
+exit $?
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