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pstore: Select compression at runtime
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To allow for easier build test coverage and run-time testing, this allows
multiple compression algorithms to be built into pstore. Still only one
is supported to operate at a time (which can be selected at build time
or at boot time, similar to how LSMs are selected).

Signed-off-by: Kees Cook <keescook@chromium.org>
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Kees Cook committed Mar 7, 2018
1 parent 5559740 commit fe1d475
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Showing 4 changed files with 151 additions and 84 deletions.
96 changes: 67 additions & 29 deletions fs/pstore/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -12,55 +12,93 @@ 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.

Currently, pstore has support for 5 compression algorithms:
zlib, lzo, lz4, lz4hc and 842.

The default compression algorithm is zlib.

config PSTORE_ZLIB_COMPRESS
bool "ZLIB"
select ZLIB_DEFLATE
select ZLIB_INFLATE
help
This option enables ZLIB compression algorithm support.
bool "ZLIB compression"
default y
depends on PSTORE
select ZLIB_DEFLATE
select ZLIB_INFLATE
help
This option enables ZLIB compression algorithm support.

config PSTORE_LZO_COMPRESS
bool "LZO"
select LZO_COMPRESS
select LZO_DECOMPRESS
help
This option enables LZO compression algorithm support.
bool "LZO compression"
depends on PSTORE
select LZO_COMPRESS
select LZO_DECOMPRESS
help
This option enables LZO compression algorithm support.

config PSTORE_LZ4_COMPRESS
bool "LZ4"
select LZ4_COMPRESS
select LZ4_DECOMPRESS
help
This option enables LZ4 compression algorithm support.
bool "LZ4 compression"
depends on PSTORE
select LZ4_COMPRESS
select LZ4_DECOMPRESS
help
This option enables LZ4 compression algorithm support.

config PSTORE_LZ4HC_COMPRESS
bool "LZ4HC"
bool "LZ4HC compression"
depends on PSTORE
select LZ4HC_COMPRESS
select LZ4_DECOMPRESS
help
This option enables LZ4HC (high compression) mode algorithm.

config PSTORE_842_COMPRESS
bool "842"
bool "842 compression"
depends on PSTORE
select 842_COMPRESS
select 842_DECOMPRESS
help
This option enables 842 compression algorithm support.

config PSTORE_COMPRESS
def_bool y
depends on PSTORE
depends on PSTORE_ZLIB_COMPRESS || PSTORE_LZO_COMPRESS || \
PSTORE_LZ4_COMPRESS || PSTORE_LZ4HC_COMPRESS || \
PSTORE_842_COMPRESS

choice
prompt "Default pstore compression algorithm"
depends on PSTORE_COMPRESS
help
This option chooses the default active compression algorithm.
This change be changed at boot with "pstore.compress=..." on
the kernel command line.

Currently, pstore has support for 5 compression algorithms:
zlib, lzo, lz4, lz4hc and 842.

The default compression algorithm is zlib.

config PSTORE_ZLIB_COMPRESS_DEFAULT
bool "zlib" if PSTORE_ZLIB_COMPRESS=y

config PSTORE_LZO_COMPRESS_DEFAULT
bool "lzo" if PSTORE_LZO_COMPRESS=y

config PSTORE_LZ4_COMPRESS_DEFAULT
bool "lz4" if PSTORE_LZ4_COMPRESS=y

config PSTORE_LZ4HC_COMPRESS_DEFAULT
bool "lz4hc" if PSTORE_LZ4HC_COMPRESS=y

config PSTORE_842_COMPRESS_DEFAULT
bool "842" if PSTORE_842_COMPRESS=y

endchoice

config PSTORE_COMPRESS_DEFAULT
string
depends on PSTORE_COMPRESS
default "zlib" if PSTORE_ZLIB_COMPRESS_DEFAULT
default "lzo" if PSTORE_LZO_COMPRESS_DEFAULT
default "lz4" if PSTORE_LZ4_COMPRESS_DEFAULT
default "lz4hc" if PSTORE_LZ4HC_COMPRESS_DEFAULT
default "842" if PSTORE_842_COMPRESS_DEFAULT

config PSTORE_CONSOLE
bool "Log kernel console messages"
depends on PSTORE
Expand Down
2 changes: 2 additions & 0 deletions fs/pstore/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -486,6 +486,8 @@ static int __init init_pstore_fs(void)
{
int err;

pstore_choose_compression();

/* Create a convenient mount point for people to access pstore */
err = sysfs_create_mount_point(fs_kobj, "pstore");
if (err)
Expand Down
3 changes: 3 additions & 0 deletions fs/pstore/internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -37,4 +37,7 @@ extern bool pstore_is_mounted(void);
extern void pstore_record_init(struct pstore_record *record,
struct pstore_info *psi);

/* Called during module_init() */
extern void __init pstore_choose_compression(void);

#endif
134 changes: 79 additions & 55 deletions fs/pstore/platform.c
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Original file line number Diff line number Diff line change
Expand Up @@ -77,14 +77,24 @@ static DEFINE_SPINLOCK(pstore_lock);
struct pstore_info *psinfo;

static char *backend;
static char *compress =
#ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
CONFIG_PSTORE_COMPRESS_DEFAULT;
#else
NULL;
#endif

/* 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
#endif
#if defined(CONFIG_PSTORE_LZO_COMPRESS) || \
defined(CONFIG_PSTORE_LZ4_COMPRESS) || \
defined(CONFIG_PSTORE_LZ4HC_COMPRESS) || \
defined(CONFIG_PSTORE_842_COMPRESS)
static unsigned char *workspace;
#endif

Expand Down Expand Up @@ -268,14 +278,6 @@ static void free_zlib(void)
big_oops_buf = NULL;
big_oops_buf_sz = 0;
}

static const 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
Expand Down Expand Up @@ -329,14 +331,6 @@ static void free_lzo(void)
big_oops_buf = NULL;
big_oops_buf_sz = 0;
}

static const struct pstore_zbackend backend_lzo = {
.compress = compress_lzo,
.decompress = decompress_lzo,
.allocate = allocate_lzo,
.free = free_lzo,
.name = "lzo",
};
#endif

#if defined(CONFIG_PSTORE_LZ4_COMPRESS) || defined(CONFIG_PSTORE_LZ4HC_COMPRESS)
Expand Down Expand Up @@ -396,14 +390,6 @@ static void allocate_lz4(void)
workspace = NULL;
}
}

static const struct pstore_zbackend backend_lz4 = {
.compress = compress_lz4,
.decompress = decompress_lz4,
.allocate = allocate_lz4,
.free = free_lz4,
.name = "lz4",
};
#endif

#ifdef CONFIG_PSTORE_LZ4HC_COMPRESS
Expand Down Expand Up @@ -438,14 +424,6 @@ static void allocate_lz4hc(void)
workspace = NULL;
}
}

static const struct pstore_zbackend backend_lz4hc = {
.compress = compress_lz4hc,
.decompress = decompress_lz4,
.allocate = allocate_lz4hc,
.free = free_lz4,
.name = "lz4hc",
};
#endif

#ifdef CONFIG_PSTORE_842_COMPRESS
Expand Down Expand Up @@ -508,30 +486,58 @@ static void free_842(void)
big_oops_buf = NULL;
big_oops_buf_sz = 0;
}

static const struct pstore_zbackend backend_842 = {
.compress = compress_842,
.decompress = decompress_842,
.allocate = allocate_842,
.free = free_842,
.name = "842",
};
#endif

static const struct pstore_zbackend *zbackend =
#if defined(CONFIG_PSTORE_ZLIB_COMPRESS)
&backend_zlib;
#elif defined(CONFIG_PSTORE_LZO_COMPRESS)
&backend_lzo;
#elif defined(CONFIG_PSTORE_LZ4_COMPRESS)
&backend_lz4;
#elif defined(CONFIG_PSTORE_LZ4HC_COMPRESS)
&backend_lz4hc;
#elif defined(CONFIG_PSTORE_842_COMPRESS)
&backend_842;
#else
NULL;
static const struct pstore_zbackend *zbackend __ro_after_init;

static const struct pstore_zbackend zbackends[] = {
#ifdef CONFIG_PSTORE_ZLIB_COMPRESS
{
.compress = compress_zlib,
.decompress = decompress_zlib,
.allocate = allocate_zlib,
.free = free_zlib,
.name = "zlib",
},
#endif
#ifdef CONFIG_PSTORE_LZO_COMPRESS
{
.compress = compress_lzo,
.decompress = decompress_lzo,
.allocate = allocate_lzo,
.free = free_lzo,
.name = "lzo",
},
#endif
#ifdef CONFIG_PSTORE_LZ4_COMPRESS
{
.compress = compress_lz4,
.decompress = decompress_lz4,
.allocate = allocate_lz4,
.free = free_lz4,
.name = "lz4",
},
#endif
#ifdef CONFIG_PSTORE_LZ4HC_COMPRESS
{
.compress = compress_lz4hc,
.decompress = decompress_lz4,
.allocate = allocate_lz4hc,
.free = free_lz4,
.name = "lz4hc",
},
#endif
#ifdef CONFIG_PSTORE_842_COMPRESS
{
.compress = compress_842,
.decompress = decompress_842,
.allocate = allocate_842,
.free = free_842,
.name = "842",
},
#endif
{ }
};

static int pstore_compress(const void *in, void *out,
size_t inlen, size_t outlen)
Expand All @@ -553,7 +559,6 @@ static int pstore_decompress(void *in, void *out, size_t inlen, size_t outlen)
static void allocate_buf_for_compression(void)
{
if (zbackend) {
pr_info("using %s compression\n", zbackend->name);
zbackend->allocate();
} else {
pr_err("allocate compression buffer error!\n");
Expand Down Expand Up @@ -1022,5 +1027,24 @@ static void pstore_timefunc(struct timer_list *unused)
jiffies + msecs_to_jiffies(pstore_update_ms));
}

void __init pstore_choose_compression(void)
{
const struct pstore_zbackend *step;

if (!compress)
return;

for (step = zbackends; step->name; step++) {
if (!strcmp(compress, step->name)) {
zbackend = step;
pr_info("using %s compression\n", zbackend->name);
return;
}
}
}

module_param(compress, charp, 0444);
MODULE_PARM_DESC(compress, "Pstore compression to use");

module_param(backend, charp, 0444);
MODULE_PARM_DESC(backend, "Pstore backend to use");

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