Re: [PATCH] pstore: add lzo/lz4 compression support

From: Kees Cook
Date: Wed Feb 17 2016 - 18:12:02 EST

Next message: Paul E. McKenney: "Re: rcu_preempt self-detected stall on CPU from 4.5-rc3, since 3.17"
Previous message: Nicolas Pitre: "Re: [PATCH] ARM: move __kuser_cmpxchg{32,64} into .kprobes.text"
In reply to: Geliang Tang: "[PATCH] pstore: add lzo/lz4 compression support"
Next in thread: Geliang Tang: "[PATCH v2] pstore: add lzo/lz4 compression support"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

On Tue, Feb 16, 2016 at 5:52 AM, Geliang Tang <geliangtang@xxxxxxx> wrote:
> Like zlib compression in pstore, this patch added lzo and lz4
> compression support so that users can have more options and better
> compression ratio.

Cool! This looks really good. Some comments below...

>
> The original code treats the compressed data together with the
> uncompressed ECC correction notice by using zlib decompress. The
> ECC correction notice is missing in the decompression process. The
> treatment also makes lzo and lz4 not working. So I treat them
> separately by using pstore_decompress() to treat the compressed
> data, and memcpy() to treat the uncompressed ECC correction notice.
>
> Signed-off-by: Geliang Tang <geliangtang@xxxxxxx>
> ---
> drivers/firmware/efi/efi-pstore.c | 1 +
> fs/pstore/Kconfig | 34 +++++-
> fs/pstore/platform.c | 217 ++++++++++++++++++++++++++++++++++++--
> fs/pstore/ram.c | 10 +-
> include/linux/pstore.h | 3 +-
> 5 files changed, 250 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
> index eac76a7..cd8c35f 100644
> --- a/drivers/firmware/efi/efi-pstore.c
> +++ b/drivers/firmware/efi/efi-pstore.c
> @@ -210,6 +210,7 @@ static int efi_pstore_sysfs_entry_iter(void *data, struct efivar_entry **pos)
> static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
> int *count, struct timespec *timespec,
> char **buf, bool *compressed,
> + ssize_t *ecc_notice_size,
> struct pstore_info *psi)
> {
> struct pstore_read_data data;
> diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
> index 360ae43..8777616 100644
> --- a/fs/pstore/Kconfig
> +++ b/fs/pstore/Kconfig
> @@ -1,8 +1,6 @@
> config PSTORE
> tristate "Persistent store support"
> default n
> - select ZLIB_DEFLATE
> - select ZLIB_INFLATE
> help
> This option enables generic access to platform level
> persistent storage via "pstore" filesystem that can
> @@ -14,6 +12,38 @@ config PSTORE
> If you don't have a platform persistent store driver,
> say N.
>
> +choice
> + prompt "Choose compression algorithm"
> + depends on PSTORE
> + default PSTORE_ZLIB_COMPRESS
> + help
> + This option chooses compression algorithm.
> +
> +config PSTORE_ZLIB_COMPRESS
> + bool "ZLIB"
> + depends on PSTORE

I don't think each config choice here needs to have the PSTORE depends
repeated, as it's already listed under the choice prompt.

> + select ZLIB_DEFLATE
> + select ZLIB_INFLATE
> + help
> + This option enables ZLIB compression algorithm support.
> +
> +config PSTORE_LZO_COMPRESS
> + bool "LZO"
> + depends on PSTORE
> + select LZO_COMPRESS
> + select LZO_DECOMPRESS
> + help
> + This option enables LZO compression algorithm support.
> +
> +config PSTORE_LZ4_COMPRESS
> + bool "LZ4"
> + depends on PSTORE
> + select LZ4_COMPRESS
> + select LZ4_DECOMPRESS
> + help
> + This option enables LZ4 compression algorithm support.
> +endchoice
> +
> config PSTORE_CONSOLE
> bool "Log kernel console messages"
> depends on PSTORE
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index 588461b..ce09f5b 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -28,7 +28,15 @@
> #include <linux/console.h>
> #include <linux/module.h>
> #include <linux/pstore.h>
> +#ifdef CONFIG_PSTORE_ZLIB_COMPRESS
> #include <linux/zlib.h>
> +#endif
> +#ifdef CONFIG_PSTORE_LZO_COMPRESS
> +#include <linux/lzo.h>
> +#endif
> +#ifdef CONFIG_PSTORE_LZ4_COMPRESS
> +#include <linux/lz4.h>
> +#endif
> #include <linux/string.h>
> #include <linux/timer.h>
> #include <linux/slab.h>
> @@ -69,10 +77,23 @@ struct pstore_info *psinfo;
> static char *backend;
>
> /* Compression parameters */
> +#ifdef CONFIG_PSTORE_ZLIB_COMPRESS
> #define COMPR_LEVEL 6
> #define WINDOW_BITS 12
> #define MEM_LEVEL 4
> static struct z_stream_s stream;
> +#else
> +static unsigned char *workspace;
> +#endif
> +
> +struct pstore_zbackend {
> + int (*compress)(const void *in, void *out, size_t inlen, size_t outlen);
> + int (*decompress)(void *in, void *out, size_t inlen, size_t outlen);
> + void (*allocate)(void);
> + void (*free)(void);
> +
> + const char *name;
> +};
>
> static char *big_oops_buf;
> static size_t big_oops_buf_sz;
> @@ -129,9 +150,9 @@ bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
> }
> EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
>
> +#ifdef CONFIG_PSTORE_ZLIB_COMPRESS
> /* Derived from logfs_compress() */
> -static int pstore_compress(const void *in, void *out, size_t inlen,
> - size_t outlen)
> +static int compress_zlib(const void *in, void *out, size_t inlen, size_t outlen)
> {
> int err, ret;
>
> @@ -165,7 +186,7 @@ error:
> }
>
> /* Derived from logfs_uncompress */
> -static int pstore_decompress(void *in, void *out, size_t inlen, size_t outlen)
> +static int decompress_zlib(void *in, void *out, size_t inlen, size_t outlen)
> {
> int err, ret;
>
> @@ -194,7 +215,7 @@ error:
> return ret;
> }
>
> -static void allocate_buf_for_compression(void)
> +static void allocate_zlib(void)
> {
> size_t size;
> size_t cmpr;
> @@ -237,7 +258,7 @@ static void allocate_buf_for_compression(void)
>
> }
>
> -static void free_buf_for_compression(void)
> +static void free_zlib(void)
> {
> kfree(stream.workspace);
> stream.workspace = NULL;
> @@ -245,6 +266,183 @@ static void free_buf_for_compression(void)
> big_oops_buf = NULL;
> }
>
> +static struct pstore_zbackend backend_zlib = {
> + .compress = compress_zlib,
> + .decompress = decompress_zlib,
> + .allocate = allocate_zlib,
> + .free = free_zlib,
> + .name = "zlib",
> +};
> +#endif
> +
> +#ifdef CONFIG_PSTORE_LZO_COMPRESS
> +static int compress_lzo(const void *in, void *out, size_t inlen, size_t outlen)
> +{
> + int ret;
> +
> + ret = lzo1x_1_compress(in, inlen, out, &outlen, workspace);
> + if (ret != LZO_E_OK) {
> + pr_err("lzo_compress error, ret = %d!\n", ret);
> + return -EIO;
> + }
> +
> + return outlen;
> +}
> +
> +static int decompress_lzo(void *in, void *out, size_t inlen, size_t outlen)
> +{
> + int ret;
> +
> + ret = lzo1x_decompress_safe(in, inlen, out, &outlen);
> + if (ret != LZO_E_OK) {
> + pr_err("lzo_decompress error, ret = %d!\n", ret);
> + return -EIO;
> + }
> +
> + return outlen;
> +}
> +
> +static void allocate_lzo(void)
> +{
> + big_oops_buf_sz = lzo1x_worst_compress(psinfo->bufsize);
> + big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
> + if (big_oops_buf) {
> + workspace = kmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
> + if (!workspace) {
> + pr_err("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");
> + workspace = NULL;
> + }
> +}
> +
> +static void free_lzo(void)
> +{
> + kfree(workspace);
> + kfree(big_oops_buf);
> + big_oops_buf = NULL;

Please set big_oops_buf_sz to 0 here too, just to be sure.

> +}
> +
> +static struct pstore_zbackend backend_lzo = {
> + .compress = compress_lzo,
> + .decompress = decompress_lzo,
> + .allocate = allocate_lzo,
> + .free = free_lzo,
> + .name = "lzo",
> +};
> +#endif
> +
> +#ifdef CONFIG_PSTORE_LZ4_COMPRESS
> +static int compress_lz4(const void *in, void *out, size_t inlen, size_t outlen)
> +{
> + int ret;
> +
> + ret = lz4_compress(in, inlen, out, &outlen, workspace);
> + if (ret) {
> + pr_err("lz4_compress error, ret = %d!\n", ret);
> + return -EIO;
> + }
> +
> + return outlen;
> +}
> +
> +static int decompress_lz4(void *in, void *out, size_t inlen, size_t outlen)
> +{
> + int ret;
> +
> + ret = lz4_decompress_unknownoutputsize(in, inlen, out, &outlen);
> + if (ret) {
> + pr_err("lz4_decompress error, ret = %d!\n", ret);
> + return -EIO;
> + }
> +
> + return outlen;
> +}
> +
> +static void allocate_lz4(void)
> +{
> + big_oops_buf_sz = lz4_compressbound(psinfo->bufsize);
> + big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
> + if (big_oops_buf) {
> + workspace = kmalloc(LZ4_MEM_COMPRESS, GFP_KERNEL);
> + if (!workspace) {
> + pr_err("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");
> + workspace = NULL;
> + }
> +}
> +
> +static void free_lz4(void)
> +{
> + kfree(workspace);
> + kfree(big_oops_buf);
> + big_oops_buf = NULL;

Same thing here.

> +}
> +
> +static struct pstore_zbackend backend_lz4 = {
> + .compress = compress_lz4,
> + .decompress = decompress_lz4,
> + .allocate = allocate_lz4,
> + .free = free_lz4,
> + .name = "lz4",
> +};
> +#endif
> +
> +static struct pstore_zbackend *zbackend[] = {
> +#ifdef CONFIG_PSTORE_ZLIB_COMPRESS
> + &backend_zlib,
> +#endif
> +#ifdef CONFIG_PSTORE_LZO_COMPRESS
> + &backend_lzo,
> +#endif
> +#ifdef CONFIG_PSTORE_LZ4_COMPRESS
> + &backend_lz4,
> +#endif
> + NULL
> +};

I'm confused about the use of an array here (and the [0] and [1] tests
below). Since they're mutually exclusive, and one must be defined.
(Should it be possible to select no compression?)

static struct pstore_zbackend *zbackend =
#ifdef CONFIG_PSTORE_ZLIB_COMPRESS
&backend_zlib;
#elif ....
...
#else
NULL;
#endif

And make the tests below just "if (zbackend)" etc?

> +
> +static int pstore_compress(const void *in, void *out,
> + size_t inlen, size_t outlen)
> +{
> + if (zbackend[0] && !zbackend[1])
> + return zbackend[0]->compress(in, out, inlen, outlen);
> + else
> + return -EIO;
> +}
> +
> +static int pstore_decompress(void *in, void *out, size_t inlen, size_t outlen)
> +{
> + if (zbackend[0] && !zbackend[1])
> + return zbackend[0]->decompress(in, out, inlen, outlen);
> + else
> + return -EIO;
> +}
> +
> +static void allocate_buf_for_compression(void)
> +{
> + if (zbackend[0] && !zbackend[1]) {
> + pr_info("using %s compression\n", zbackend[0]->name);
> + zbackend[0]->allocate();
> + } else {
> + pr_err("allocate compression buffer error!\n");
> + }
> +}
> +
> +static void free_buf_for_compression(void)
> +{
> + if (zbackend[0] && !zbackend[1])
> + zbackend[0]->free();
> + else
> + pr_err("free compression buffer error!\n");
> +}
> +
> /*
> * Called when compression fails, since the printk buffer
> * would be fetched for compression calling it again when
> @@ -527,6 +725,7 @@ void pstore_get_records(int quiet)
> int failed = 0, rc;
> bool compressed;
> int unzipped_len = -1;
> + ssize_t ecc_notice_size = 0;
>
> if (!psi)
> return;
> @@ -536,7 +735,7 @@ void pstore_get_records(int quiet)
> goto out;
>
> while ((size = psi->read(&id, &type, &count, &time, &buf, &compressed,
> - psi)) > 0) {
> + &ecc_notice_size, psi)) > 0) {
> if (compressed && (type == PSTORE_TYPE_DMESG)) {
> if (big_oops_buf)
> unzipped_len = pstore_decompress(buf,
> @@ -544,6 +743,9 @@ void pstore_get_records(int quiet)
> big_oops_buf_sz);
>
> if (unzipped_len > 0) {
> + if (ecc_notice_size)
> + memcpy(big_oops_buf + unzipped_len,
> + buf + size, ecc_notice_size);
> kfree(buf);
> buf = big_oops_buf;
> size = unzipped_len;
> @@ -555,7 +757,8 @@ void pstore_get_records(int quiet)
> }
> }
> rc = pstore_mkfile(type, psi->name, id, count, buf,
> - compressed, (size_t)size, time, psi);
> + compressed, size + ecc_notice_size,
> + time, psi);
> if (unzipped_len < 0) {
> /* Free buffer other than big oops */
> kfree(buf);
> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> index 319c3a6..11ec024 100644
> --- a/fs/pstore/ram.c
> +++ b/fs/pstore/ram.c
> @@ -181,10 +181,10 @@ static bool prz_ok(struct persistent_ram_zone *prz)
> static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
> int *count, struct timespec *time,
> char **buf, bool *compressed,
> + ssize_t *ecc_notice_size,
> struct pstore_info *psi)
> {
> ssize_t size;
> - ssize_t ecc_notice_size;
> struct ramoops_context *cxt = psi->data;
> struct persistent_ram_zone *prz = NULL;
> int header_length = 0;
> @@ -229,16 +229,16 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
> size = persistent_ram_old_size(prz) - header_length;
>
> /* ECC correction notice */
> - ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0);
> + *ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0);
>
> - *buf = kmalloc(size + ecc_notice_size + 1, GFP_KERNEL);
> + *buf = kmalloc(size + *ecc_notice_size + 1, GFP_KERNEL);
> if (*buf == NULL)
> return -ENOMEM;
>
> memcpy(*buf, (char *)persistent_ram_old(prz) + header_length, size);
> - persistent_ram_ecc_string(prz, *buf + size, ecc_notice_size + 1);
> + persistent_ram_ecc_string(prz, *buf + size, *ecc_notice_size + 1);
>
> - return size + ecc_notice_size;
> + return size;
> }
>
> static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz,
> diff --git a/include/linux/pstore.h b/include/linux/pstore.h
> index 831479f..899e95e 100644
> --- a/include/linux/pstore.h
> +++ b/include/linux/pstore.h
> @@ -58,7 +58,8 @@ struct pstore_info {
> int (*close)(struct pstore_info *psi);
> ssize_t (*read)(u64 *id, enum pstore_type_id *type,
> int *count, struct timespec *time, char **buf,
> - bool *compressed, struct pstore_info *psi);
> + bool *compressed, ssize_t *ecc_notice_size,
> + struct pstore_info *psi);
> int (*write)(enum pstore_type_id type,
> enum kmsg_dump_reason reason, u64 *id,
> unsigned int part, int count, bool compressed,
> --
> 2.5.0
>
>

-Kees

--
Kees Cook
Chrome OS & Brillo Security

Next message: Paul E. McKenney: "Re: rcu_preempt self-detected stall on CPU from 4.5-rc3, since 3.17"
Previous message: Nicolas Pitre: "Re: [PATCH] ARM: move __kuser_cmpxchg{32,64} into .kprobes.text"
In reply to: Geliang Tang: "[PATCH] pstore: add lzo/lz4 compression support"
Next in thread: Geliang Tang: "[PATCH v2] pstore: add lzo/lz4 compression support"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]