powerpc/nvram: Add compression to fit more oops output into NVRAM

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.

[BenH: Added select of ZLIB_DEFLATE]

Signed-off-by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Jim Keniston 2011-07-25 07:54:50 +00:00 committed by Benjamin Herrenschmidt
parent 7392769365
commit 6c493685f1
3 changed files with 169 additions and 9 deletions

View File

@ -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: "

View File

@ -15,6 +15,7 @@ config PPC_PSERIES
select PPC_UDBG_16550
select PPC_NATIVE
select PPC_PCI_CHOICE if EXPERT
select ZLIB_DEFLATE
default y
config PPC_SPLPAR

View File

@ -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);
}