pstore: Select compression at runtime

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>

4 files changed, 151 insertions, 84 deletions

diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index 898abafea7a5..e4e22026c7a1 100644
--- a/fs/pstore/Kconfig
+++ b/fs/pstore/Kconfig
@@ -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
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index d814723fb27d..5fcb845b9fec 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -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)
diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
index c029314478fa..fb767e28aeb2 100644
--- a/fs/pstore/internal.h
+++ b/fs/pstore/internal.h
@@ -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
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index df54dd87598a..06e3b280c3a5 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -77,6 +77,12 @@ 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
@@ -84,7 +90,11 @@ static char *backend;
 #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
 
@@ -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
@@ -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)
@@ -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
@@ -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
@@ -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)
@@ -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");
@@ -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");