Commit b0aad7a9 authored by Aruna Balakrishnaiah's avatar Aruna Balakrishnaiah Committed by Tony Luck

pstore: Add compression support to pstore

Add compression support to pstore which will help in capturing more data.
Initially, pstore will make a call to kmsg_dump with a bigger buffer
and will pass the size of bigger buffer to kmsg_dump and then compress
the data to registered buffer of registered size.

In case compression fails, pstore will capture the uncompressed
data by making a call again to kmsg_dump with registered_buffer
of registered size.

Pstore will indicate the data is compressed or not with a flag
in the write callback.
Signed-off-by: default avatarAruna Balakrishnaiah <aruna@linux.vnet.ibm.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 90ce4ca6
...@@ -26,6 +26,7 @@ ...@@ -26,6 +26,7 @@
#include <linux/console.h> #include <linux/console.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/pstore.h> #include <linux/pstore.h>
#include <linux/zlib.h>
#include <linux/string.h> #include <linux/string.h>
#include <linux/timer.h> #include <linux/timer.h>
#include <linux/slab.h> #include <linux/slab.h>
...@@ -65,6 +66,15 @@ struct pstore_info *psinfo; ...@@ -65,6 +66,15 @@ struct pstore_info *psinfo;
static char *backend; static char *backend;
/* Compression parameters */
#define COMPR_LEVEL 6
#define WINDOW_BITS 12
#define MEM_LEVEL 4
static struct z_stream_s stream;
static char *big_oops_buf;
static size_t big_oops_buf_sz;
/* How much of the console log to snapshot */ /* How much of the console log to snapshot */
static unsigned long kmsg_bytes = 10240; static unsigned long kmsg_bytes = 10240;
...@@ -117,6 +127,91 @@ bool pstore_cannot_block_path(enum kmsg_dump_reason reason) ...@@ -117,6 +127,91 @@ bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
} }
EXPORT_SYMBOL_GPL(pstore_cannot_block_path); EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
/* Derived from logfs_compress() */
static int pstore_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;
}
static void allocate_buf_for_compression(void)
{
size_t size;
big_oops_buf_sz = (psinfo->bufsize * 100) / 45;
big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
if (big_oops_buf) {
size = max(zlib_deflate_workspacesize(WINDOW_BITS, MEM_LEVEL),
zlib_inflate_workspacesize());
stream.workspace = kmalloc(size, GFP_KERNEL);
if (!stream.workspace) {
pr_err("pstore: No memory for compression workspace; "
"skipping compression\n");
kfree(big_oops_buf);
big_oops_buf = NULL;
}
} else {
pr_err("No memory for uncompressed data; "
"skipping compression\n");
stream.workspace = NULL;
}
}
/*
* Called when compression fails, since the printk buffer
* would be fetched for compression calling it again when
* compression fails would have moved the iterator of
* printk buffer which results in fetching old contents.
* Copy the recent messages from big_oops_buf to psinfo->buf
*/
static size_t copy_kmsg_to_buffer(int hsize, size_t len)
{
size_t total_len;
size_t diff;
total_len = hsize + len;
if (total_len > psinfo->bufsize) {
diff = total_len - psinfo->bufsize + hsize;
memcpy(psinfo->buf, big_oops_buf, hsize);
memcpy(psinfo->buf + hsize, big_oops_buf + diff,
psinfo->bufsize - hsize);
total_len = psinfo->bufsize;
} else
memcpy(psinfo->buf, big_oops_buf, total_len);
return total_len;
}
/* /*
* callback from kmsg_dump. (s2,l2) has the most recently * callback from kmsg_dump. (s2,l2) has the most recently
* written bytes, older bytes are in (s1,l1). Save as much * written bytes, older bytes are in (s1,l1). Save as much
...@@ -148,23 +243,56 @@ static void pstore_dump(struct kmsg_dumper *dumper, ...@@ -148,23 +243,56 @@ static void pstore_dump(struct kmsg_dumper *dumper,
char *dst; char *dst;
unsigned long size; unsigned long size;
int hsize; int hsize;
int zipped_len = -1;
size_t len; size_t len;
bool compressed = false; bool compressed;
size_t total_len;
dst = psinfo->buf; if (big_oops_buf) {
hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part); dst = big_oops_buf;
size = psinfo->bufsize - hsize; hsize = sprintf(dst, "%s#%d Part%d\n", why,
dst += hsize; oopscount, part);
size = big_oops_buf_sz - hsize;
if (!kmsg_dump_get_buffer(dumper, true, dst, size, &len)) if (!kmsg_dump_get_buffer(dumper, true, dst + hsize,
break; size, &len))
break;
zipped_len = pstore_compress(dst, psinfo->buf,
hsize + len, psinfo->bufsize);
if (zipped_len > 0) {
compressed = true;
total_len = zipped_len;
} else {
pr_err("pstore: compression failed for Part %d"
" returned %d\n", part, zipped_len);
pr_err("pstore: Capture uncompressed"
" oops/panic report of Part %d\n", part);
compressed = false;
total_len = copy_kmsg_to_buffer(hsize, len);
}
} else {
dst = psinfo->buf;
hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount,
part);
size = psinfo->bufsize - hsize;
dst += hsize;
if (!kmsg_dump_get_buffer(dumper, true, dst,
size, &len))
break;
compressed = false;
total_len = hsize + len;
}
ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part, ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
oopscount, compressed, hsize + len, psinfo); oopscount, compressed, total_len, psinfo);
if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted()) if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
pstore_new_entry = 1; pstore_new_entry = 1;
total += hsize + len; total += total_len;
part++; part++;
} }
if (pstore_cannot_block_path(reason)) { if (pstore_cannot_block_path(reason)) {
...@@ -262,6 +390,8 @@ int pstore_register(struct pstore_info *psi) ...@@ -262,6 +390,8 @@ int pstore_register(struct pstore_info *psi)
return -EINVAL; return -EINVAL;
} }
allocate_buf_for_compression();
if (pstore_is_mounted()) if (pstore_is_mounted())
pstore_get_records(0); pstore_get_records(0);
......
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