CC: llvm(a)lists.linux.dev CC: kbuild-all(a)lists.01.org CC: linux-kernel(a)vger.kernel.org TO: Jiri Olsa tree: https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git ftrace/direct head: 95a037919f1906d8bf164fb0c0066c9f298df139 commit: b45bdf4de5473d5c15090eceeb72a2d5082cde2d [5/8] ftrace: Add ftrace_add_rec_direct function :::::: branch date: 32 hours ago :::::: commit date: 32 hours ago config: i386-randconfig-c001-20210831 (attached as .config) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 4b1fde8a2b681dad2ce0c082a5d6422caa06b0bc) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git/commit/?id=b45bdf4de5473d5c15090eceeb72a2d5082cde2d git remote add jolsa-perf https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git git fetch --no-tags jolsa-perf ftrace/direct git checkout b45bdf4de5473d5c15090eceeb72a2d5082cde2d # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=i386 clang-analyzer If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot clang-analyzer warnings: (new ones prefixed by >>) ^ include/linux/irqflags.h:223:3: note: expanded from macro 'local_irq_restore' raw_local_irq_restore(flags); \ ^ include/linux/irqflags.h:174:2: note: expanded from macro 'raw_local_irq_restore' do { \ ^ kernel/trace/ftrace.c:6870:2: note: Loop condition is false. Exiting loop local_irq_restore(flags); ^ include/linux/irqflags.h:220:2: note: expanded from macro 'local_irq_restore' do { \ ^ kernel/trace/ftrace.c:6871:6: note: Assuming 'ret' is 0 if (ret) ^~~ kernel/trace/ftrace.c:6871:2: note: Taking false branch if (ret) ^ kernel/trace/ftrace.c:6875:6: note: Assuming 'count' is not equal to 0 if (!count) { ^~~~~~ kernel/trace/ftrace.c:6875:2: note: Taking false branch if (!count) { ^ kernel/trace/ftrace.c:6892:2: note: Calling 'set_ftrace_early_filters' set_ftrace_early_filters(); ^~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:5616:6: note: Assuming the condition is true if (ftrace_filter_buf[0]) ^~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:5616:2: note: Taking true branch if (ftrace_filter_buf[0]) ^ kernel/trace/ftrace.c:5617:3: note: Calling 'ftrace_set_early_filter' ftrace_set_early_filter(&global_ops, ftrace_filter_buf, 1); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:5608:2: note: Loop condition is true. Entering loop body while (buf) { ^ kernel/trace/ftrace.c:5610:3: note: Calling 'ftrace_set_regex' ftrace_set_regex(ops, func, strlen(func), 0, enable); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:5451:9: note: Calling 'ftrace_set_hash' return ftrace_set_hash(ops, buf, len, 0, 0, reset, enable); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:4991:6: note: Assuming 'ftrace_disabled' is 0 if (unlikely(ftrace_disabled)) ^ include/linux/compiler.h:48:24: note: expanded from macro 'unlikely' # define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x))) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/compiler.h:33:32: note: expanded from macro '__branch_check__' ______r = __builtin_expect(!!(x), expect); \ ^~~~ kernel/trace/ftrace.c:4991:2: note: Taking false branch if (unlikely(ftrace_disabled)) ^ kernel/trace/ftrace.c:4996:6: note: 'enable' is 1 if (enable) ^~~~~~ kernel/trace/ftrace.c:4996:2: note: Taking true branch if (enable) ^ kernel/trace/ftrace.c:5001:6: note: 'reset' is 0 if (reset) ^~~~~ kernel/trace/ftrace.c:5001:2: note: Taking false branch if (reset) ^ kernel/trace/ftrace.c:5004:63: note: Passing value via 2nd parameter 'hash' hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash); ^~~~~~~~~~ kernel/trace/ftrace.c:5004:10: note: Calling 'alloc_and_copy_ftrace_hash' hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:1324:6: note: Assuming 'new_hash' is non-null if (!new_hash) ^~~~~~~~~ kernel/trace/ftrace.c:1324:2: note: Taking false branch if (!new_hash) ^ kernel/trace/ftrace.c:1327:6: note: Assuming 'hash' is null if (hash) ^~~~ kernel/trace/ftrace.c:1327:6: note: Assuming pointer value is null if (hash) ^~~~ kernel/trace/ftrace.c:1327:2: note: Taking false branch if (hash) ^ kernel/trace/ftrace.c:1331:6: note: Assuming the condition is false if (ftrace_hash_empty(hash)) ^~~~~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:1331:2: note: Taking false branch if (ftrace_hash_empty(hash)) ^ kernel/trace/ftrace.c:1334:14: note: Access to field 'size_bits' results in a dereference of a null pointer (loaded from variable 'hash') size = 1 << hash->size_bits; ^~~~ >> kernel/trace/ftrace.c:5150:4: warning: 1st function call argument is an uninitialized value [clang-analyzer-core.CallAndMessage] kfree(entry); ^ ~~~~~ kernel/trace/ftrace.c:5114:2: note: 'entry' declared without an initial value struct ftrace_func_entry *entry; ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:5122:6: note: Calling 'ftrace_find_rec_direct' if (ftrace_find_rec_direct(ip)) ^~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:2391:6: note: Assuming 'entry' is null, which participates in a condition later if (!entry) ^~~~~~ kernel/trace/ftrace.c:2391:2: note: Taking true branch if (!entry) ^ kernel/trace/ftrace.c:2392:3: note: Returning zero, which participates in a condition later return 0; ^~~~~~~~ kernel/trace/ftrace.c:5122:6: note: Returning from 'ftrace_find_rec_direct' if (ftrace_find_rec_direct(ip)) ^~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:5122:2: note: Taking false branch if (ftrace_find_rec_direct(ip)) ^ kernel/trace/ftrace.c:5127:6: note: Assuming 'rec' is non-null if (!rec) ^~~~ kernel/trace/ftrace.c:5127:2: note: Taking false branch if (!rec) ^ kernel/trace/ftrace.c:5134:6: note: Assuming the condition is true if (WARN_ON(rec->flags & FTRACE_FL_DIRECT)) ^ include/asm-generic/bug.h:121:23: note: expanded from macro 'WARN_ON' int __ret_warn_on = !!(condition); \ ^~~~~~~~~~~~ kernel/trace/ftrace.c:5134:6: note: Taking false branch if (WARN_ON(rec->flags & FTRACE_FL_DIRECT)) ^ include/asm-generic/bug.h:122:2: note: expanded from macro 'WARN_ON' if (unlikely(__ret_warn_on)) \ ^ kernel/trace/ftrace.c:5134:2: note: Taking false branch if (WARN_ON(rec->flags & FTRACE_FL_DIRECT)) ^ kernel/trace/ftrace.c:5138:6: note: Assuming 'ip' is equal to field 'ip' if (ip != rec->ip) { ^~~~~~~~~~~~~ kernel/trace/ftrace.c:5138:2: note: Taking false branch if (ip != rec->ip) { ^ kernel/trace/ftrace.c:5147:6: note: Assuming 'direct' is null if (!direct) { ^~~~~~~ kernel/trace/ftrace.c:5147:2: note: Taking true branch if (!direct) { ^ kernel/trace/ftrace.c:5148:12: note: Calling 'ftrace_alloc_direct_func' direct = ftrace_alloc_direct_func(addr); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:5084:11: note: Calling 'kmalloc' direct = kmalloc(sizeof(*direct), GFP_KERNEL); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/slab.h:579:2: note: Taking false branch if (__builtin_constant_p(size)) { ^ include/linux/slab.h:596:2: note: Returning pointer, which participates in a condition later return __kmalloc(size, flags); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:5084:11: note: Returning from 'kmalloc' direct = kmalloc(sizeof(*direct), GFP_KERNEL); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:5085:6: note: Assuming 'direct' is null, which participates in a condition later if (!direct) ^~~~~~~ kernel/trace/ftrace.c:5085:2: note: Taking true branch if (!direct) ^ kernel/trace/ftrace.c:5086:3: note: Returning null pointer, which participates in a condition later return NULL; ^~~~~~~~~~~ kernel/trace/ftrace.c:5148:12: note: Returning from 'ftrace_alloc_direct_func' direct = ftrace_alloc_direct_func(addr); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:5149:8: note: 'direct' is null if (!direct) { ^~~~~~ kernel/trace/ftrace.c:5149:3: note: Taking true branch if (!direct) { ^ kernel/trace/ftrace.c:5150:4: note: 1st function call argument is an uninitialized value kfree(entry); ^ ~~~~~ kernel/trace/ftrace.c:6885:2: warning: Value stored to 'ret' is never read [clang-analyzer-deadcode.DeadStores] ret = ftrace_process_locs(NULL, ^ ~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/trace/ftrace.c:6885:2: note: Value stored to 'ret' is never read ret = ftrace_process_locs(NULL, ^ ~~~~~~~~~~~~~~~~~~~~~~~~~ Suppressed 10 warnings (7 in non-user code, 3 with check filters). Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well. vim +5150 kernel/trace/ftrace.c 8a141dd7f7060d1 Alexei Starovoitov 2021-03-16 5093 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5094) /** 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5095) * register_ftrace_direct - Call a custom trampoline directly 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5096) * @ip: The address of the nop at the beginning of a function 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5097) * @addr: The address of the trampoline to call at @ip 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5098) * 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5099) * This is used to connect a direct call from the nop location (@ip) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5100) * at the start of ftrace traced functions. The location that it calls 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5101) * (@addr) must be able to handle a direct call, and save the parameters 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5102) * of the function being traced, and restore them (or inject new ones 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5103) * if needed), before returning. 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5104) * 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5105) * Returns: 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5106) * 0 on success 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5107) * -EBUSY - Another direct function is already attached (there can be only one) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5108) * -ENODEV - @ip does not point to a ftrace nop location (or not supported) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5109) * -ENOMEM - There was an allocation failure. 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5110) */ 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5111) int register_ftrace_direct(unsigned long ip, unsigned long addr) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5112) { 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5113) struct ftrace_direct_func *direct; 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5114) struct ftrace_func_entry *entry; 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5115) struct ftrace_hash *free_hash = NULL; 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5116) struct dyn_ftrace *rec; 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5117) int ret = -EBUSY; 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5118) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5119) mutex_lock(&direct_mutex); 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5120) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5121) /* See if there's a direct function at @ip already */ ff205766dbbee02 Alexei Starovoitov 2019-12-08 5122 if (ftrace_find_rec_direct(ip)) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5123) goto out_unlock; 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5124) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5125) ret = -ENODEV; 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5126) rec = lookup_rec(ip, ip); 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5127) if (!rec) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5128) goto out_unlock; 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5129) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5130) /* 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5131) * Check if the rec says it has a direct call but we didn't 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5132) * find one earlier? 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5133) */ 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5134) if (WARN_ON(rec->flags & FTRACE_FL_DIRECT)) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5135) goto out_unlock; 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5136) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5137) /* Make sure the ip points to the exact record */ 406acdd32d3e7d5 Steven Rostedt (VMware 2019-11-15 5138) if (ip != rec->ip) { 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5139) ip = rec->ip; 406acdd32d3e7d5 Steven Rostedt (VMware 2019-11-15 5140) /* Need to check this ip for a direct. */ ff205766dbbee02 Alexei Starovoitov 2019-12-08 5141 if (ftrace_find_rec_direct(ip)) 406acdd32d3e7d5 Steven Rostedt (VMware 2019-11-15 5142) goto out_unlock; 406acdd32d3e7d5 Steven Rostedt (VMware 2019-11-15 5143) } 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5144) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5145) ret = -ENOMEM; 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5146) direct = ftrace_find_direct_func(addr); 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5147) if (!direct) { 8a141dd7f7060d1 Alexei Starovoitov 2021-03-16 5148 direct = ftrace_alloc_direct_func(addr); 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5149) if (!direct) { 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 @5150) kfree(entry); 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5151) goto out_unlock; 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5152) } 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5153) } 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5154) b45bdf4de5473d5 Jiri Olsa 2021-05-18 5155 entry = ftrace_add_rec_direct(ip, addr, &free_hash); b45bdf4de5473d5 Jiri Olsa 2021-05-18 5156 if (!entry) b45bdf4de5473d5 Jiri Olsa 2021-05-18 5157 goto out_unlock; 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5158) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5159) ret = ftrace_set_filter_ip(&direct_ops, ip, 0, 0); 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5160) if (ret) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5161) remove_hash_entry(direct_functions, entry); 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5162) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5163) if (!ret && !(direct_ops.flags & FTRACE_OPS_FL_ENABLED)) { 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5164) ret = register_ftrace_function(&direct_ops); 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5165) if (ret) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5166) ftrace_set_filter_ip(&direct_ops, ip, 1, 0); 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5167) } 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5168) 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5169) if (ret) { 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5170) kfree(entry); 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5171) if (!direct->count) { 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5172) list_del_rcu(&direct->next); 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5173) synchronize_rcu_tasks(); 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5174) kfree(direct); 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5175) if (free_hash) 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5176) free_ftrace_hash(free_hash); 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5177) free_hash = NULL; a3ad1a7e3968900 Steven Rostedt (VMware 2019-11-08 5178) ftrace_direct_func_count--; 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5179) } 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5180) } else { 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5181) direct->count++; 013bf0da0474816 Steven Rostedt (VMware 2019-11-08 5182) } 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5183) out_unlock: 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5184) mutex_unlock(&direct_mutex); 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5185) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5186) if (free_hash) { 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5187) synchronize_rcu_tasks(); 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5188) free_ftrace_hash(free_hash); 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5189) } 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5190) 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5191) return ret; 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5192) } 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5193) EXPORT_SYMBOL_GPL(register_ftrace_direct); 763e34e74bb7d5c Steven Rostedt (VMware 2019-11-08 5194) :::::: The code at line 5150 was first introduced by commit :::::: 013bf0da0474816f57739daa006c8564ad7396a3 ftrace: Add ftrace_find_direct_func() :::::: TO: Steven Rostedt (VMware) :::::: CC: Steven Rostedt (VMware) --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org