arch/riscv/kernel/ftrace.c:15:5: sparse: sparse: context imbalance in 'ftrace_arch_code_modify_prepare' - wrong count at exit

[kernel test robot <lkp@intel.com>]

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   4bcf69e57063c9b1b15df1a293c969e80a1c97e6
commit: 0ff7c3b331276f584bde3ae9a16bacd8fa3d01e6 riscv: Use text_mutex instead of patch_lock
date:   3 months ago
config: riscv-randconfig-s032-20200810 (attached as .config)
compiler: riscv64-linux-gcc (GCC) 9.3.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # apt-get install sparse
        # sparse version: v0.6.2-141-g19506bc2-dirty
        git checkout 0ff7c3b331276f584bde3ae9a16bacd8fa3d01e6
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=riscv 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>


sparse warnings: (new ones prefixed by >>)

>> arch/riscv/kernel/ftrace.c:15:5: sparse: sparse: context imbalance in 'ftrace_arch_code_modify_prepare' - wrong count at exit
>> arch/riscv/kernel/ftrace.c:21:5: sparse: sparse: context imbalance in 'ftrace_arch_code_modify_post_process' - wrong count at exit

vim +/ftrace_arch_code_modify_prepare +15 arch/riscv/kernel/ftrace.c

    13	
    14	#ifdef CONFIG_DYNAMIC_FTRACE
  > 15	int ftrace_arch_code_modify_prepare(void) __acquires(&text_mutex)
    16	{
    17		mutex_lock(&text_mutex);
    18		return 0;
    19	}
    20	
  > 21	int ftrace_arch_code_modify_post_process(void) __releases(&text_mutex)
    22	{
    23		mutex_unlock(&text_mutex);
    24		return 0;
    25	}
    26	
    27	static int ftrace_check_current_call(unsigned long hook_pos,
    28					     unsigned int *expected)
    29	{
    30		unsigned int replaced[2];
    31		unsigned int nops[2] = {NOP4, NOP4};
    32	
    33		/* we expect nops at the hook position */
    34		if (!expected)
    35			expected = nops;
    36	
    37		/*
    38		 * Read the text we want to modify;
    39		 * return must be -EFAULT on read error
    40		 */
    41		if (probe_kernel_read(replaced, (void *)hook_pos, MCOUNT_INSN_SIZE))
    42			return -EFAULT;
    43	
    44		/*
    45		 * Make sure it is what we expect it to be;
    46		 * return must be -EINVAL on failed comparison
    47		 */
    48		if (memcmp(expected, replaced, sizeof(replaced))) {
    49			pr_err("%p: expected (%08x %08x) but got (%08x %08x)\n",
    50			       (void *)hook_pos, expected[0], expected[1], replaced[0],
    51			       replaced[1]);
    52			return -EINVAL;
    53		}
    54	
    55		return 0;
    56	}
    57	
    58	static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target,
    59					bool enable)
    60	{
    61		unsigned int call[2];
    62		unsigned int nops[2] = {NOP4, NOP4};
    63	
    64		make_call(hook_pos, target, call);
    65	
    66		/* Replace the auipc-jalr pair at once. Return -EPERM on write error. */
    67		if (patch_text_nosync
    68		    ((void *)hook_pos, enable ? call : nops, MCOUNT_INSN_SIZE))
    69			return -EPERM;
    70	
    71		return 0;
    72	}
    73	
    74	int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
    75	{
    76		int ret = ftrace_check_current_call(rec->ip, NULL);
    77	
    78		if (ret)
    79			return ret;
    80	
    81		return __ftrace_modify_call(rec->ip, addr, true);
    82	}
    83	
    84	int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
    85			    unsigned long addr)
    86	{
    87		unsigned int call[2];
    88		int ret;
    89	
    90		make_call(rec->ip, addr, call);
    91		ret = ftrace_check_current_call(rec->ip, call);
    92	
    93		if (ret)
    94			return ret;
    95	
    96		return __ftrace_modify_call(rec->ip, addr, false);
    97	}
    98	
    99	int ftrace_update_ftrace_func(ftrace_func_t func)
   100	{
   101		int ret = __ftrace_modify_call((unsigned long)&ftrace_call,
   102					       (unsigned long)func, true);
   103		if (!ret) {
   104			ret = __ftrace_modify_call((unsigned long)&ftrace_regs_call,
   105						   (unsigned long)func, true);
   106		}
   107	
   108		return ret;
   109	}
   110	
   111	int __init ftrace_dyn_arch_init(void)
   112	{
   113		return 0;
   114	}
   115	#endif
   116	
   117	#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
   118	int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
   119			       unsigned long addr)
   120	{
   121		unsigned int call[2];
   122		int ret;
   123	
   124		make_call(rec->ip, old_addr, call);
   125		ret = ftrace_check_current_call(rec->ip, call);
   126	
   127		if (ret)
   128			return ret;
   129	
   130		return __ftrace_modify_call(rec->ip, addr, true);
   131	}
   132	#endif
   133	
   134	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
   135	/*
   136	 * Most of this function is copied from arm64.
   137	 */
 > 138	void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
   139				   unsigned long frame_pointer)
   140	{
   141		unsigned long return_hooker = (unsigned long)&return_to_handler;
   142		unsigned long old;
   143	
   144		if (unlikely(atomic_read(&current->tracing_graph_pause)))
   145			return;
   146	
   147		/*
   148		 * We don't suffer access faults, so no extra fault-recovery assembly
   149		 * is needed here.
   150		 */
   151		old = *parent;
   152	
   153		if (!function_graph_enter(old, self_addr, frame_pointer, parent))
   154			*parent = return_hooker;
   155	}
   156	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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