[peterz-queue:x86/core 2/6] arch/x86/kernel/kprobes/core.c:326:7: error: call to undeclared function 'is_cfi_trap'; ISO C99 and later do not support implicit function declarations

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

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git x86/core
head:   1e68adb59894117251d942316d32514d45bd23ef
commit: 9289e7bef6851d3b50619eab6b28d4d9ff69a12a [2/6] x86/kprobes: Prohibit probing on compiler generated CFI checking code
config: x86_64-randconfig-x002-20230726 (https://download.01.org/0day-ci/archive/20230726/202307262307.LETETZsF-lkp@intel.com/config)
compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07)
reproduce: (https://download.01.org/0day-ci/archive/20230726/202307262307.LETETZsF-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202307262307.LETETZsF-lkp@intel.com/

All errors (new ones prefixed by >>):

>> arch/x86/kernel/kprobes/core.c:326:7: error: call to undeclared function 'is_cfi_trap'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
                   if (is_cfi_trap(addr + offset))
                       ^
   1 error generated.


vim +/is_cfi_trap +326 arch/x86/kernel/kprobes/core.c

   254	
   255	/* Check if paddr is at an instruction boundary */
   256	static int can_probe(unsigned long paddr)
   257	{
   258		unsigned long addr, __addr, offset = 0;
   259		struct insn insn;
   260		kprobe_opcode_t buf[MAX_INSN_SIZE];
   261	
   262		if (!kallsyms_lookup_size_offset(paddr, NULL, &offset))
   263			return 0;
   264	
   265		/* Decode instructions */
   266		addr = paddr - offset;
   267		while (addr < paddr) {
   268			int ret;
   269	
   270			/*
   271			 * Check if the instruction has been modified by another
   272			 * kprobe, in which case we replace the breakpoint by the
   273			 * original instruction in our buffer.
   274			 * Also, jump optimization will change the breakpoint to
   275			 * relative-jump. Since the relative-jump itself is
   276			 * normally used, we just go through if there is no kprobe.
   277			 */
   278			__addr = recover_probed_instruction(buf, addr);
   279			if (!__addr)
   280				return 0;
   281	
   282			ret = insn_decode_kernel(&insn, (void *)__addr);
   283			if (ret < 0)
   284				return 0;
   285	
   286	#ifdef CONFIG_KGDB
   287			/*
   288			 * If there is a dynamically installed kgdb sw breakpoint,
   289			 * this function should not be probed.
   290			 */
   291			if (insn.opcode.bytes[0] == INT3_INSN_OPCODE &&
   292			    kgdb_has_hit_break(addr))
   293				return 0;
   294	#endif
   295			addr += insn.length;
   296		}
   297		if (IS_ENABLED(CONFIG_CFI_CLANG)) {
   298			/*
   299			 * The compiler generates the following instruction sequence
   300			 * for indirect call checks and cfi.c decodes this;
   301			 *
   302			 *   movl    -<id>, %r10d       ; 6 bytes
   303			 *   addl    -4(%reg), %r10d    ; 4 bytes
   304			 *   je      .Ltmp1             ; 2 bytes
   305			 *   ud2                        ; <- regs->ip
   306			 *   .Ltmp1:
   307			 *
   308			 * Also, these movl and addl are used for showing expected
   309			 * type. So those must not be touched.
   310			 */
   311			__addr = recover_probed_instruction(buf, addr);
   312			if (!__addr)
   313				return 0;
   314	
   315			if (insn_decode_kernel(&insn, (void *)__addr) < 0)
   316				return 0;
   317	
   318			if (insn.opcode.value == 0xBA)
   319				offset = 12;
   320			else if (insn.opcode.value == 0x3)
   321				offset = 6;
   322			else
   323				goto out;
   324	
   325			/* This movl/addl is used for decoding CFI. */
 > 326			if (is_cfi_trap(addr + offset))
   327				return 0;
   328		}
   329	
   330	out:
   331		return (addr == paddr);
   332	}
   333	

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