kprobes + nptl01 (test in ltp testsuite) problem

["manjunath k" <kmanjunat at gmail dot com>]

Hi,

 Ive been using the kprobes on X86 m/c and found the following problem with
the following kprobe and the testsuite.

1. A probe is placed for the sys_gettimeofday with the pre/post/fault handlers
  defined (k-test.c is attached).

2. The nptl01 test from the ltp testuite is executed and the system gets into an
infinite loop (nptl01.c is attached).

Ive attached the log file that contains the output that was seen when
the above test is performed (kprobe-nptl.log), the log file is
stripped for the purpose of attaching.

Please provide me some information regarding the above failure.


-Manjunath
{\rtf1\ansi\ansicpg1252\deff0\deflang1033{\fonttbl{\f0\fswiss\fcharset0 Arial;}}
\viewkind4\uc1\pard\f0\fs20 #include <linux/module.h>\par
#include <linux/init.h>\par
#include <linux/kprobes.h>\par
#include <linux/kallsyms.h>\par
#include <linux/utsname.h>\par
#include <asm/uaccess.h>\par
\par
static struct kprobe k_004_kpr;\par
\par
void k_004_CPY_FROM_USER(struct file *file, char *buf, int len)\par
\{\par
\par
        char x = 'a';\par
\par
        if (put_user(x, buf)) \{\par
                printk("put_user : -EFAULT\\n");\par
        \}\par
\par
        printk("CPY_FROM_USER\\n");\par
\}\par
\par
static void __exit k_004_exit_probe(void)\par
\{\par
        printk("\\nModule exiting from sys_gettimeofday \\n");\par
        unregister_kprobe(&k_004_kpr);\par
\}\par
\par
static int k_004_before_hook(struct kprobe *k_004_kpr, struct pt_regs *p)\par
\{\par
        int len = 500;\par
        struct file *file = NULL;\par
\par
        printk("\\nBefore hook in sys_gettimeofday");\par
        printk("\\nThis is the Kprobe pre \\n"\par
               "handler for instruction at" "%p\\n", k_004_kpr->addr);\par
        printk("Stack Dump:\\n");\par
        dump_stack();\par
        printk("The Registers are:\\n");\par
        k_004_CPY_FROM_USER(file, NULL, len);\par
        return 0;\par
\}\par
\par
static int k_004_after_hook(struct kprobe *k_004_kpr,\par
                            struct pt_regs *p, unsigned long flags)\par
\{\par
        printk("\\nAfter hook in sys_gettimeofday");\par
        printk("\\nThis is the Kprobe post \\n"\par
               "handler for instruction at" " %p\\n", k_004_kpr->addr);\par
        printk("Stack Dump:\\n");\par
        dump_stack();\par
        printk("The Registers are:\\n");\par
        return 0;\par
\}\par
\par
int k_004_fault_probe(struct kprobe *p, struct pt_regs *regs, int trapnr)\par
\{\par
        printk("\\nThis is the Kprobe fault \\n"\par
               "handler for sys_gettimeodday\\n");\par
        printk("fault_handler:p->addr=0x%p\\n", p->addr);\par
        printk("Stack Dump:\\n");\par
        dump_stack();\par
        printk("The Registers are:\\n");\par
        return 0;\par
\}\par
\par
static int __init k_004_init_probe(void)\par
\{\par
        printk("\\nInserting the kprobes  for sys_gettimeofday\\n");\par
\par
        /* Registering a kprobe */\par
        k_004_kpr.pre_handler = (kprobe_pre_handler_t) k_004_before_hook;\par
        k_004_kpr.post_handler = (kprobe_post_handler_t) k_004_after_hook;\par
        k_004_kpr.fault_handler = (kprobe_fault_handler_t) k_004_fault_probe;\par
#if 0\par
        k_004_kpr.addr =\par
            (kprobe_opcode_t *) kallsyms_lookup_name("sys_gettimeofday");\par
        if (k_004_kpr.addr == NULL) \{\par
                printk("kallsyms_lookup_name could not find address "\par
                       "for the specified symbol name\\n");\par
                return 1;\par
        \}\par
#endif\par
        k_004_kpr.symbol_name = "sys_gettimeofday";\par
        if( register_kprobe(&k_004_kpr) <0 ) \{\par
                printk("k-004.c: register_kprobe is failed\\n");\par
                return -1;\par
        \}\par
\par
        printk("register_kprobe is successful\\n");\par
        printk("\\nAddress where the kprobe is \\n"\par
               "going to be inserted - %p\\n", k_004_kpr.addr);\par
        register_kprobe(&k_004_kpr);\par
        return 0;\par
\}\par
\par
module_init(k_004_init_probe);\par
module_exit(k_004_exit_probe);\par
\par
MODULE_DESCRIPTION("Kprobes test module");\par
MODULE_LICENSE("GPL");\par
}

Attachment: nptl01.c
Description: Text document

Attachment: kprobes-nptl.log
Description: Binary data