1 // SPDX-License-Identifier: GPL-2.0-or-later
28  * The current module debugging statistics supported help keep track of module
29  * loading failures to enable improvements either for kernel module auto-loading
33  * to a type of module loading failure which is known to incur a certain amount
34  * of memory allocation loss. In the worst case loading a module will fail after
35  * a 3 step memory allocation process:
37  *   a) memory allocated with kernel_read_file_from_fd()
40  *      the decompressed module to a new local buffer which represents
41  *      a copy of the decompressed module passed from userspace. The buffer
44  *      place where we would keep the module if it were to be processed
47  * If a failure occurs after these three different allocations only one
50  * step b) a separate counter is used and incremented for the bytes freed and
64  * DOC: dup_failed_modules - tracks duplicate failed modules
77  * In practice on a typical boot today most finit_module() calls fail due to
83  * failed to load due to the fact that a module was already loaded or being
88  *   a) FAIL_DUP_MOD_BECOMING: at the end of early_mod_check() before
90  *	- with module decompression: 2 virtual memory allocation calls
91  *	- without module decompression: 1 virtual memory allocation calls
93  *   	- with module decompression 3 virtual memory allocation calls
94  *   	- without module decompression 2 virtual memory allocation calls
97  * is not empty it is a reflection of possible work or optimizations possible
98  * either in-kernel or in userspace.
131  *     failures can happen if we had a check in between a successful kernel_read_file_from_fd()
134  *     reason for this failure is when userspace is racing to load a module
136  *     add_unformed_module() will add a module to our &modules list and
141  *     duplicate failed modules are non-fatal, however they typically are
142  *     indicative of userspace not seeing a module in userspace loaded yet and
143  *     unnecessarily trying to load a module before the kernel even has a chance
145  *     non-fatal, we should try to reduce vmalloc() pressure proactively, so
153  *    * module_sig_check() - module signature checks
154  *    * elf_validity_cache_copy() - some ELF validation issue
160  *      * live patch requirements didn't check out
166  *     is unique.  A module can still fail to load if we detect the module is
168  *     this check right before processing the module as live and run its
169  *     initialization routines. Note that you have a failure of this type it
191  *    but it is perhaps not easy to fix them. A recent example are the modules
192  *    requests incurred for frequency modules, a separate module request was
193  *    being issued for each CPU on a system.
210 	if (test_bit(FAIL_DUP_MOD_BECOMING, &mod_fail->dup_fail_mask) &&  in mod_fail_to_str()
211 	    test_bit(FAIL_DUP_MOD_LOAD, &mod_fail->dup_fail_mask))  in mod_fail_to_str()
213 	if (test_bit(FAIL_DUP_MOD_BECOMING, &mod_fail->dup_fail_mask))  in mod_fail_to_str()
215 	if (test_bit(FAIL_DUP_MOD_LOAD, &mod_fail->dup_fail_mask))  in mod_fail_to_str()
217 	return "Bug-on-stats";  in mod_fail_to_str()
222 	atomic_long_add(info->len * 2, &invalid_mod_bytes);  in mod_stat_bump_invalid()
226 		atomic_long_add(info->compressed_len, &invalid_mod_bytes);  in mod_stat_bump_invalid()
233 	atomic_long_add(info->len, &invalid_becoming_bytes);  in mod_stat_bump_becoming()
236 		atomic_long_add(info->compressed_len, &invalid_becoming_bytes);  in mod_stat_bump_becoming()
246 		if (!strcmp(mod_fail->name, name)) {  in try_add_failed_module()
247 			atomic_long_inc(&mod_fail->count);  in try_add_failed_module()
248 			__set_bit(reason, &mod_fail->dup_fail_mask);  in try_add_failed_module()
255 		return -ENOMEM;  in try_add_failed_module()
256 	memcpy(mod_fail->name, name, strlen(name));  in try_add_failed_module()
257 	__set_bit(reason, &mod_fail->dup_fail_mask);  in try_add_failed_module()
258 	atomic_long_inc(&mod_fail->count);  in try_add_failed_module()
259 	list_add_rcu(&mod_fail->list, &dup_failed_modules);  in try_add_failed_module()
265  * At 64 bytes per module and assuming a 1024 bytes preamble we can fit the
303 		return -ENOMEM;  in read_file_mod_stats()
308 	len += scnprintf(buf + len, size - len, "%25s\t%u\n", "Mods failed on kread", fkreads);  in read_file_mod_stats()
310 	len += scnprintf(buf + len, size - len, "%25s\t%u\n", "Mods failed on decompress",  in read_file_mod_stats()
312 	len += scnprintf(buf + len, size - len, "%25s\t%u\n", "Mods failed on becoming", fbecoming);  in read_file_mod_stats()
314 	len += scnprintf(buf + len, size - len, "%25s\t%u\n", "Mods failed on load", floads);  in read_file_mod_stats()
316 	len += scnprintf(buf + len, size - len, "%25s\t%lu\n", "Total module size", total_size);  in read_file_mod_stats()
317 	len += scnprintf(buf + len, size - len, "%25s\t%lu\n", "Total mod text size", text_size);  in read_file_mod_stats()
319 	len += scnprintf(buf + len, size - len, "%25s\t%lu\n", "Failed kread bytes", ikread_bytes);  in read_file_mod_stats()
321 	len += scnprintf(buf + len, size - len, "%25s\t%lu\n", "Failed decompress bytes",  in read_file_mod_stats()
324 	len += scnprintf(buf + len, size - len, "%25s\t%lu\n", "Failed becoming bytes", ibecoming_bytes);  in read_file_mod_stats()
326 	len += scnprintf(buf + len, size - len, "%25s\t%lu\n", "Failed kmod bytes", imod_bytes);  in read_file_mod_stats()
328 …len += scnprintf(buf + len, size - len, "%25s\t%lu\n", "Virtual mem wasted bytes", total_virtual_l…  in read_file_mod_stats()
331 		len += scnprintf(buf + len, size - len, "%25s\t%lu\n", "Average mod size",  in read_file_mod_stats()
336 		len += scnprintf(buf + len, size - len, "%25s\t%lu\n", "Average mod text size",  in read_file_mod_stats()
342 	 * for keeping tabs on a type of failure with one type of byte counter.  in read_file_mod_stats()
349 		len += scnprintf(buf + len, size - len, "%25s\t%lu\n", "Avg fail kread bytes",  in read_file_mod_stats()
355 		len += scnprintf(buf + len, size - len, "%25s\t%lu\n", "Avg fail becoming bytes",  in read_file_mod_stats()
361 		len += scnprintf(buf + len, size - len, "%25s\t%lu\n", "Avg fail decomp bytes",  in read_file_mod_stats()
367 		len += scnprintf(buf + len, size - len, "%25s\t%lu\n", "Average fail load bytes",  in read_file_mod_stats()
379 	len += scnprintf(buf + len, size - len, "Duplicate failed modules:\n");  in read_file_mod_stats()
380 	len += scnprintf(buf + len, size - len, "%25s\t%15s\t%25s\n",  in read_file_mod_stats()
381 			 "Module-name", "How-many-times", "Reason");  in read_file_mod_stats()
388 		len += scnprintf(buf + len, size - len, "%25s\t%15lu\t%25s\n", mod_fail->name,  in read_file_mod_stats()
389 				 atomic_long_read(&mod_fail->count), mod_fail_to_str(mod_fail));  in read_file_mod_stats()