Re: [PATCH] MIPS: Add basic support for ptrace single step

[kernel test robot <lkp@xxxxxxxxx>]

Hi Tiezhu,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v5.11-rc6 next-20210125]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Tiezhu-Yang/MIPS-Add-basic-support-for-ptrace-single-step/20210209-083755
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 61556703b610a104de324e4f061dc6cf7b218b46
config: mips-randconfig-r036-20210209 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project c9439ca36342fb6013187d0a69aef92736951476)
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
        # install mips cross compiling tool for clang build
        # apt-get install binutils-mips-linux-gnu
        # https://github.com/0day-ci/linux/commit/67449dfde58fecf3a9e68bec9de5211788fbe22a
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Tiezhu-Yang/MIPS-Add-basic-support-for-ptrace-single-step/20210209-083755
        git checkout 67449dfde58fecf3a9e68bec9de5211788fbe22a
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips 

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

All warnings (new ones prefixed by >>):

>> arch/mips/kernel/ptrace.c:1127:25: warning: variable 'mips_insn' is uninitialized when used here [-Wuninitialized]
           if (insn_has_delayslot(mips_insn)) {
                                  ^~~~~~~~~
   arch/mips/kernel/ptrace.c:1114:2: note: variable 'mips_insn' is declared here
           union mips_instruction mips_insn;
           ^
   1 warning generated.

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for SSB_EMBEDDED
   Depends on SSB && SSB_DRIVER_MIPS && SSB_PCICORE_HOSTMODE
   Selected by
   - BCM47XX_SSB && BCM47XX


vim +/mips_insn +1127 arch/mips/kernel/ptrace.c

  1111	
  1112	static void ptrace_set_bpt(struct task_struct *child)
  1113	{
  1114		union mips_instruction mips_insn;
  1115		struct pt_regs *regs;
  1116		unsigned long pc;
  1117		unsigned int insn;
  1118		int i, ret, nsaved = 0;
  1119	
  1120		regs = task_pt_regs(child);
  1121		pc = regs->cp0_epc;
  1122	
  1123		ret = read_insn(child, pc, &insn);
  1124		if (ret < 0)
  1125			return;
  1126	
> 1127		if (insn_has_delayslot(mips_insn)) {
  1128			pr_info("executing branch insn\n");
  1129			ret = __compute_return_epc(regs);
  1130			if (ret < 0)
  1131				return;
  1132			task_thread_info(child)->bpt_addr[nsaved++] = regs->cp0_epc;
  1133		} else {
  1134			pr_info("executing normal insn\n");
  1135			task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
  1136		}
  1137	
  1138		/* install breakpoints */
  1139		for (i = 0; i < nsaved; i++) {
  1140			ret = read_insn(child, task_thread_info(child)->bpt_addr[i], &insn);
  1141			if (ret < 0)
  1142				return;
  1143	
  1144			task_thread_info(child)->bpt_insn[i] = insn;
  1145	
  1146			ret = write_insn(child, task_thread_info(child)->bpt_addr[i], BREAKINST);
  1147			if (ret < 0)
  1148				return;
  1149		}
  1150	
  1151		task_thread_info(child)->bpt_nsaved = nsaved;
  1152	}
  1153	

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

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