[PATCH] powerpc/nvram: Add compression to fit more oops output into NVRAM
Jim Keniston
jkenisto at us.ibm.com
Tue Jul 26 03:54:50 EST 2011
Capture more than twice as much text from the printk buffer, and
compress it to fit it in the lnx,oops-log NVRAM partition. You
can view the compressed text using the new (as of July 20) --unzip
option of the nvram command in the powerpc-utils package.
Signed-off-by: Jim Keniston <jkenisto at us.ibm.com>
---
arch/powerpc/include/asm/rtas.h | 6 +
arch/powerpc/platforms/pseries/nvram.c | 171 +++++++++++++++++++++++++++++++-
2 files changed, 168 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 58625d1..41f69ae 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -249,10 +249,12 @@ extern void pSeries_log_error(char *buf, unsigned int err_type, int fatal);
#define ERR_FLAG_ALREADY_LOGGED 0x0
#define ERR_FLAG_BOOT 0x1 /* log was pulled from NVRAM on boot */
#define ERR_TYPE_RTAS_LOG 0x2 /* from rtas event-scan */
-#define ERR_TYPE_KERNEL_PANIC 0x4 /* from panic() */
+#define ERR_TYPE_KERNEL_PANIC 0x4 /* from die()/panic() */
+#define ERR_TYPE_KERNEL_PANIC_GZ 0x8 /* ditto, compressed */
/* All the types and not flags */
-#define ERR_TYPE_MASK (ERR_TYPE_RTAS_LOG | ERR_TYPE_KERNEL_PANIC)
+#define ERR_TYPE_MASK \
+ (ERR_TYPE_RTAS_LOG | ERR_TYPE_KERNEL_PANIC | ERR_TYPE_KERNEL_PANIC_GZ)
#define RTAS_DEBUG KERN_DEBUG "RTAS: "
diff --git a/arch/powerpc/platforms/pseries/nvram.c b/arch/powerpc/platforms/pseries/nvram.c
index 00cc3a0..a76b228 100644
--- a/arch/powerpc/platforms/pseries/nvram.c
+++ b/arch/powerpc/platforms/pseries/nvram.c
@@ -18,6 +18,8 @@
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/kmsg_dump.h>
+#include <linux/ctype.h>
+#include <linux/zlib.h>
#include <asm/uaccess.h>
#include <asm/nvram.h>
#include <asm/rtas.h>
@@ -78,8 +80,41 @@ static struct kmsg_dumper nvram_kmsg_dumper = {
#define NVRAM_RTAS_READ_TIMEOUT 5 /* seconds */
static unsigned long last_unread_rtas_event; /* timestamp */
-/* We preallocate oops_buf during init to avoid kmalloc during oops/panic. */
-static char *oops_buf;
+/*
+ * For capturing and compressing an oops or panic report...
+
+ * big_oops_buf[] holds the uncompressed text we're capturing.
+ *
+ * oops_buf[] holds the compressed text, preceded by a prefix.
+ * The prefix is just a u16 holding the length of the compressed* text.
+ * (*Or uncompressed, if compression fails.) oops_buf[] gets written
+ * to NVRAM.
+ *
+ * oops_len points to the prefix. oops_data points to the compressed text.
+ *
+ * +- oops_buf
+ * | +- oops_data
+ * v v
+ * +------------+-----------------------------------------------+
+ * | length | text |
+ * | (2 bytes) | (oops_data_sz bytes) |
+ * +------------+-----------------------------------------------+
+ * ^
+ * +- oops_len
+ *
+ * We preallocate these buffers during init to avoid kmalloc during oops/panic.
+ */
+static size_t big_oops_buf_sz;
+static char *big_oops_buf, *oops_buf;
+static u16 *oops_len;
+static char *oops_data;
+static size_t oops_data_sz;
+
+/* Compression parameters */
+#define COMPR_LEVEL 6
+#define WINDOW_BITS 12
+#define MEM_LEVEL 4
+static struct z_stream_s stream;
static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
{
@@ -387,11 +422,44 @@ static void __init nvram_init_oops_partition(int rtas_partition_exists)
sizeof(rtas_log_partition));
}
oops_buf = kmalloc(oops_log_partition.size, GFP_KERNEL);
+ if (!oops_buf) {
+ pr_err("nvram: No memory for %s partition\n",
+ oops_log_partition.name);
+ return;
+ }
+ oops_len = (u16*) oops_buf;
+ oops_data = oops_buf + sizeof(u16);
+ oops_data_sz = oops_log_partition.size - sizeof(u16);
+
+ /*
+ * Figure compression (preceded by elimination of each line's <n>
+ * severity prefix) will reduce the oops/panic report to at most
+ * 45% of its original size.
+ */
+ big_oops_buf_sz = (oops_data_sz * 100) / 45;
+ big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
+ if (big_oops_buf) {
+ stream.workspace = kmalloc(zlib_deflate_workspacesize(
+ WINDOW_BITS, MEM_LEVEL), GFP_KERNEL);
+ if (!stream.workspace) {
+ pr_err("nvram: No memory for compression workspace; "
+ "skipping compression of %s partition data\n",
+ oops_log_partition.name);
+ kfree(big_oops_buf);
+ big_oops_buf = NULL;
+ }
+ } else {
+ pr_err("No memory for uncompressed %s data; "
+ "skipping compression\n", oops_log_partition.name);
+ stream.workspace = NULL;
+ }
+
rc = kmsg_dump_register(&nvram_kmsg_dumper);
if (rc != 0) {
pr_err("nvram: kmsg_dump_register() failed; returned %d\n", rc);
kfree(oops_buf);
- return;
+ kfree(big_oops_buf);
+ kfree(stream.workspace);
}
}
@@ -473,7 +541,83 @@ static int clobbering_unread_rtas_event(void)
NVRAM_RTAS_READ_TIMEOUT);
}
-/* our kmsg_dump callback */
+/* Squeeze out each line's <n> severity prefix. */
+static size_t elide_severities(char *buf, size_t len)
+{
+ char *in, *out, *buf_end = buf + len;
+ /* Assume a <n> at the very beginning marks the start of a line. */
+ int newline = 1;
+
+ in = out = buf;
+ while (in < buf_end) {
+ if (newline && in+3 <= buf_end &&
+ *in == '<' && isdigit(in[1]) && in[2] == '>') {
+ in += 3;
+ newline = 0;
+ } else {
+ newline = (*in == '\n');
+ *out++ = *in++;
+ }
+ }
+ return out - buf;
+}
+
+/* Derived from logfs_compress() */
+static int nvram_compress(const void *in, void *out, size_t inlen,
+ size_t outlen)
+{
+ int err, ret;
+
+ ret = -EIO;
+ err = zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
+ MEM_LEVEL, Z_DEFAULT_STRATEGY);
+ if (err != Z_OK)
+ goto error;
+
+ stream.next_in = in;
+ stream.avail_in = inlen;
+ stream.total_in = 0;
+ stream.next_out = out;
+ stream.avail_out = outlen;
+ stream.total_out = 0;
+
+ err = zlib_deflate(&stream, Z_FINISH);
+ if (err != Z_STREAM_END)
+ goto error;
+
+ err = zlib_deflateEnd(&stream);
+ if (err != Z_OK)
+ goto error;
+
+ if (stream.total_out >= stream.total_in)
+ goto error;
+
+ ret = stream.total_out;
+error:
+ return ret;
+}
+
+/* Compress the text from big_oops_buf into oops_buf. */
+static int zip_oops(size_t text_len)
+{
+ int zipped_len = nvram_compress(big_oops_buf, oops_data, text_len,
+ oops_data_sz);
+ if (zipped_len < 0) {
+ pr_err("nvram: compression failed; returned %d\n", zipped_len);
+ pr_err("nvram: logging uncompressed oops/panic report\n");
+ return -1;
+ }
+ *oops_len = (u16) zipped_len;
+ return 0;
+}
+
+/*
+ * This is our kmsg_dump callback, called after an oops or panic report
+ * has been written to the printk buffer. We want to capture as much
+ * of the printk buffer as possible. First, capture as much as we can
+ * that we think will compress sufficiently to fit in the lnx,oops-log
+ * partition. If that's too much, go back and capture uncompressed text.
+ */
static void oops_to_nvram(struct kmsg_dumper *dumper,
enum kmsg_dump_reason reason,
const char *old_msgs, unsigned long old_len,
@@ -482,6 +626,8 @@ static void oops_to_nvram(struct kmsg_dumper *dumper,
static unsigned int oops_count = 0;
static bool panicking = false;
size_t text_len;
+ unsigned int err_type = ERR_TYPE_KERNEL_PANIC_GZ;
+ int rc = -1;
switch (reason) {
case KMSG_DUMP_RESTART:
@@ -509,8 +655,19 @@ static void oops_to_nvram(struct kmsg_dumper *dumper,
if (clobbering_unread_rtas_event())
return;
- text_len = capture_last_msgs(old_msgs, old_len, new_msgs, new_len,
- oops_buf, oops_log_partition.size);
+ if (big_oops_buf) {
+ text_len = capture_last_msgs(old_msgs, old_len,
+ new_msgs, new_len, big_oops_buf, big_oops_buf_sz);
+ text_len = elide_severities(big_oops_buf, text_len);
+ rc = zip_oops(text_len);
+ }
+ if (rc != 0) {
+ text_len = capture_last_msgs(old_msgs, old_len,
+ new_msgs, new_len, oops_data, oops_data_sz);
+ err_type = ERR_TYPE_KERNEL_PANIC;
+ *oops_len = (u16) text_len;
+ }
+
(void) nvram_write_os_partition(&oops_log_partition, oops_buf,
- (int) text_len, ERR_TYPE_KERNEL_PANIC, ++oops_count);
+ (int) (sizeof(*oops_len) + *oops_len), err_type, ++oops_count);
}
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