Hi Aleksa, Thank you for the patch! Yet something to improve:
[auto build test ERROR on tip/perf/core] [also build test ERROR on v4.19 next-20181101] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Aleksa-Sarai/kretprobe-produce-sane-stack-traces/20181102-034111 config: i386-randconfig-h1-11021006 (attached as .config) compiler: gcc-4.9 (Debian 4.9.4-2) 4.9.4 reproduce: # save the attached .config to linux build tree make ARCH=i386 All errors (new ones prefixed by >>): kernel/kprobes.c: In function 'pre_handler_kretprobe': kernel/kprobes.c:1846:10: error: variable 'trace' has initializer but incomplete type struct stack_trace trace = {}; ^ kernel/kprobes.c:1846:22: error: storage size of 'trace' isn't known struct stack_trace trace = {}; ^ >> kernel/kprobes.c:1858:3: error: implicit declaration of function >> 'save_stack_trace_regs' [-Werror=implicit-function-declaration] save_stack_trace_regs(regs, &trace); ^ kernel/kprobes.c:1846:22: warning: unused variable 'trace' [-Wunused-variable] struct stack_trace trace = {}; ^ kernel/kprobes.c: In function 'kretprobe_save_stack_trace': >> kernel/kprobes.c:1922:16: error: dereferencing pointer to incomplete type for (i = trace->skip; i < krt->nr_entries; i++) { ^ kernel/kprobes.c:1923:12: error: dereferencing pointer to incomplete type if (trace->nr_entries >= trace->max_entries) ^ kernel/kprobes.c:1923:33: error: dereferencing pointer to incomplete type if (trace->nr_entries >= trace->max_entries) ^ kernel/kprobes.c:1925:8: error: dereferencing pointer to incomplete type trace->entries[trace->nr_entries++] = krt->entries[i]; ^ kernel/kprobes.c:1925:23: error: dereferencing pointer to incomplete type trace->entries[trace->nr_entries++] = krt->entries[i]; ^ cc1: some warnings being treated as errors vim +/save_stack_trace_regs +1858 kernel/kprobes.c 1819 1820 #ifdef CONFIG_KRETPROBES 1821 /* 1822 * This kprobe pre_handler is registered with every kretprobe. When probe 1823 * hits it will set up the return probe. 1824 */ 1825 static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) 1826 { 1827 struct kretprobe *rp = container_of(p, struct kretprobe, kp); 1828 unsigned long hash, flags = 0; 1829 struct kretprobe_instance *ri; 1830 1831 /* 1832 * To avoid deadlocks, prohibit return probing in NMI contexts, 1833 * just skip the probe and increase the (inexact) 'nmissed' 1834 * statistical counter, so that the user is informed that 1835 * something happened: 1836 */ 1837 if (unlikely(in_nmi())) { 1838 rp->nmissed++; 1839 return 0; 1840 } 1841 1842 /* TODO: consider to only swap the RA after the last pre_handler fired */ 1843 hash = hash_ptr(current, KPROBE_HASH_BITS); 1844 raw_spin_lock_irqsave(&rp->lock, flags); 1845 if (!hlist_empty(&rp->free_instances)) { > 1846 struct stack_trace trace = {}; 1847 1848 ri = hlist_entry(rp->free_instances.first, 1849 struct kretprobe_instance, hlist); 1850 hlist_del(&ri->hlist); 1851 raw_spin_unlock_irqrestore(&rp->lock, flags); 1852 1853 ri->rp = rp; 1854 ri->task = current; 1855 1856 trace.entries = &ri->entry.entries[0]; 1857 trace.max_entries = KRETPROBE_TRACE_SIZE; > 1858 save_stack_trace_regs(regs, &trace); 1859 ri->entry.nr_entries = trace.nr_entries; 1860 1861 if (rp->entry_handler && rp->entry_handler(ri, regs)) { 1862 raw_spin_lock_irqsave(&rp->lock, flags); 1863 hlist_add_head(&ri->hlist, &rp->free_instances); 1864 raw_spin_unlock_irqrestore(&rp->lock, flags); 1865 return 0; 1866 } 1867 1868 arch_prepare_kretprobe(ri, regs); 1869 1870 /* XXX(hch): why is there no hlist_move_head? */ 1871 INIT_HLIST_NODE(&ri->hlist); 1872 kretprobe_table_lock(hash, &flags); 1873 hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]); 1874 kretprobe_table_unlock(hash, &flags); 1875 } else { 1876 rp->nmissed++; 1877 raw_spin_unlock_irqrestore(&rp->lock, flags); 1878 } 1879 return 0; 1880 } 1881 NOKPROBE_SYMBOL(pre_handler_kretprobe); 1882 1883 /* 1884 * Return the kretprobe_instance associated with the current_kprobe. Calling 1885 * this is only reasonable from within a kretprobe handler context (otherwise 1886 * return NULL). 1887 * 1888 * Must be called within a kretprobe_hash_lock(current, ...) context. 1889 */ 1890 struct kretprobe_instance *current_kretprobe_instance(void) 1891 { 1892 struct kprobe *kp; 1893 struct kretprobe *rp; 1894 struct kretprobe_instance *ri; 1895 struct hlist_head *head; 1896 unsigned long hash = hash_ptr(current, KPROBE_HASH_BITS); 1897 1898 kp = kprobe_running(); 1899 if (!kp || !kprobe_is_retprobe(kp)) 1900 return NULL; 1901 if (WARN_ON(!kretprobe_hash_is_locked(current))) 1902 return NULL; 1903 1904 rp = container_of(kp, struct kretprobe, kp); 1905 head = &kretprobe_inst_table[hash]; 1906 1907 hlist_for_each_entry(ri, head, hlist) { 1908 if (ri->task == current && ri->rp == rp) 1909 return ri; 1910 } 1911 return NULL; 1912 } 1913 EXPORT_SYMBOL_GPL(current_kretprobe_instance); 1914 NOKPROBE_SYMBOL(current_kretprobe_instance); 1915 1916 void kretprobe_save_stack_trace(struct kretprobe_instance *ri, 1917 struct stack_trace *trace) 1918 { 1919 int i; 1920 struct kretprobe_trace *krt = &ri->entry; 1921 > 1922 for (i = trace->skip; i < krt->nr_entries; i++) { 1923 if (trace->nr_entries >= trace->max_entries) 1924 break; 1925 trace->entries[trace->nr_entries++] = krt->entries[i]; 1926 } 1927 } 1928 --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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