diff options
| -rw-r--r-- | modutils/Config.in | 16 | ||||
| -rw-r--r-- | modutils/modutils-24.c | 25 | ||||
| -rw-r--r-- | modutils/modutils.c | 63 | ||||
| -rw-r--r-- | modutils/modutils.h | 6 |
4 files changed, 93 insertions, 17 deletions
diff --git a/modutils/Config.in b/modutils/Config.in index d2a2e04d1..83c12b67f 100644 --- a/modutils/Config.in +++ b/modutils/Config.in @@ -121,6 +121,22 @@ config FEATURE_2_4_MODULES This increases size considerably. Say N unless you plan to run ancient kernels. +config FEATURE_INSMOD_TRY_MMAP + bool "Try to load module from a mmap'ed area" + default n + depends on INSMOD || MODPROBE_SMALL + help + This option causes module loading code to try to mmap + module first. If it does not work (for example, + it does not work for compressed modules), module will be read + (and unpacked if needed) into a memory block allocated by malloc. + + The only case when mmap works but malloc does not is when + you are trying to load a big module on a very memory-constrained + machine. Malloc will momentarily need 2x as much memory as mmap. + + Choosing N saves about 250 bytes of code (on 32-bit x86). + config FEATURE_INSMOD_VERSION_CHECKING bool "Enable module version checking" default n diff --git a/modutils/modutils-24.c b/modutils/modutils-24.c index e5ff54d29..a878e740c 100644 --- a/modutils/modutils-24.c +++ b/modutils/modutils-24.c @@ -3783,12 +3783,20 @@ int FAST_FUNC bb_init_module_24(const char *m_filename, const char *options) int m_has_modinfo; #endif char *image; - size_t image_size = 64 * 1024 * 1024; - - /* Load module into memory and unzip if compressed */ - image = xmalloc_open_zipped_read_close(m_filename, &image_size); - if (!image) - return EXIT_FAILURE; + size_t image_size; + bool mmaped; + + image_size = INT_MAX - 4095; + mmaped = 0; + image = try_to_mmap_module(m_filename, &image_size); + if (image) { + mmaped = 1; + } else { + /* Load module into memory and unzip if compressed */ + image = xmalloc_open_zipped_read_close(m_filename, &image_size); + if (!image) + return EXIT_FAILURE; + } m_name = xstrdup(bb_basename(m_filename)); /* "module.o[.gz]" -> "module" */ @@ -3901,7 +3909,10 @@ int FAST_FUNC bb_init_module_24(const char *m_filename, const char *options) exit_status = EXIT_SUCCESS; out: - free(image); + if (mmaped) + munmap(image, image_size); + else + free(image); free(m_name); return exit_status; diff --git a/modutils/modutils.c b/modutils/modutils.c index 969926db9..850a8683b 100644 --- a/modutils/modutils.c +++ b/modutils/modutils.c @@ -62,7 +62,7 @@ char* FAST_FUNC filename2modname(const char *filename, char *modname) return modname; } -char * FAST_FUNC parse_cmdline_module_options(char **argv) +char* FAST_FUNC parse_cmdline_module_options(char **argv) { char *options; int optlen; @@ -77,6 +77,40 @@ char * FAST_FUNC parse_cmdline_module_options(char **argv) return options; } +#if ENABLE_FEATURE_INSMOD_TRY_MMAP +void* FAST_FUNC try_to_mmap_module(const char *filename, size_t *image_size_p) +{ + /* We have user reports of failure to load 3MB module + * on a 16MB RAM machine. Apparently even a transient + * memory spike to 6MB during module load + * is too big for that system. */ + void *image; + struct stat st; + int fd; + + fd = xopen(filename, O_RDONLY); + fstat(fd, &st); + image = NULL; + /* st.st_size is off_t, we can't just pass it to mmap */ + if (st.st_size <= *image_size_p) { + size_t image_size = st.st_size; + image = mmap(NULL, image_size, PROT_READ, MAP_PRIVATE, fd, 0); + if (image == MAP_FAILED) { + image = NULL; + } else if (*(uint32_t*)image != SWAP_BE32(0x7f454C46)) { + /* No ELF signature. Compressed module? */ + munmap(image, image_size); + image = NULL; + } else { + /* Success. Report the size */ + *image_size_p = image_size; + } + } + close(fd); + return image; +} +#endif + /* Return: * 0 on success, * -errno on open/read error, @@ -84,9 +118,10 @@ char * FAST_FUNC parse_cmdline_module_options(char **argv) */ int FAST_FUNC bb_init_module(const char *filename, const char *options) { - size_t len; + size_t image_size; char *image; int rc; + bool mmaped; if (!options) options = ""; @@ -97,17 +132,25 @@ int FAST_FUNC bb_init_module(const char *filename, const char *options) return bb_init_module_24(filename, options); #endif - /* Use the 2.6 way */ - len = INT_MAX - 4095; - errno = ENOMEM; /* may be changed by e.g. open errors below */ - image = xmalloc_open_zipped_read_close(filename, &len); - if (!image) - return -errno; + image_size = INT_MAX - 4095; + mmaped = 0; + image = try_to_mmap_module(filename, &image_size); + if (image) { + mmaped = 1; + } else { + errno = ENOMEM; /* may be changed by e.g. open errors below */ + image = xmalloc_open_zipped_read_close(filename, &image_size); + if (!image) + return -errno; + } errno = 0; - init_module(image, len, options); + init_module(image, image_size, options); rc = errno; - free(image); + if (mmaped) + munmap(image, image_size); + else + free(image); return rc; } diff --git a/modutils/modutils.h b/modutils/modutils.h index 1cf4bba95..131a5087b 100644 --- a/modutils/modutils.h +++ b/modutils/modutils.h @@ -51,6 +51,12 @@ enum { #endif }; +#if ENABLE_FEATURE_INSMOD_TRY_MMAP +void* FAST_FUNC try_to_mmap_module(const char *filename, size_t *image_size_p); +#else +# define try_to_mmap_module(filename, image_size) NULL +#endif + /* Return: * 0 on success, * -errno on open/read error, |