linux-kernel - arch/riscv/kernel/elf_kexec.c:185:23: warning: variable 'kernel

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Date:   Thu, 22 Sep 2022 13:02:39 +0800
From:   kernel test robot <lkp@...el.com>
To:     Li Zhengyu <lizhengyu3@...wei.com>
Cc:     kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org,
        Palmer Dabbelt <palmer@...osinc.com>
Subject: arch/riscv/kernel/elf_kexec.c:185:23: warning: variable
 'kernel_start' set but not used

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   dc164f4fb00a0abebdfff132f8bc7291a28f5401
commit: 838b3e28488f702e2b5477b393f009b2639d2b1a RISC-V: Load purgatory in kexec_file
date:   4 months ago
config: riscv-randconfig-r032-20220922 (https://download.01.org/0day-ci/archive/20220922/202209221201.YBE0WYnK-lkp@intel.com/config)
compiler: riscv64-linux-gcc (GCC) 12.1.0
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
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=838b3e28488f702e2b5477b393f009b2639d2b1a
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 838b3e28488f702e2b5477b393f009b2639d2b1a
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash arch/riscv/kernel/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

   arch/riscv/kernel/elf_kexec.c: In function 'elf_kexec_load':
>> arch/riscv/kernel/elf_kexec.c:185:23: warning: variable 'kernel_start' set but not used [-Wunused-but-set-variable]
     185 |         unsigned long kernel_start;
         |                       ^~~~~~~~~~~~


vim +/kernel_start +185 arch/riscv/kernel/elf_kexec.c

   174	
   175	static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
   176				    unsigned long kernel_len, char *initrd,
   177				    unsigned long initrd_len, char *cmdline,
   178				    unsigned long cmdline_len)
   179	{
   180		int ret;
   181		unsigned long old_kernel_pbase = ULONG_MAX;
   182		unsigned long new_kernel_pbase = 0UL;
   183		unsigned long initrd_pbase = 0UL;
   184		unsigned long headers_sz;
 > 185		unsigned long kernel_start;
   186		void *fdt, *headers;
   187		struct elfhdr ehdr;
   188		struct kexec_buf kbuf;
   189		struct kexec_elf_info elf_info;
   190		char *modified_cmdline = NULL;
   191	
   192		ret = kexec_build_elf_info(kernel_buf, kernel_len, &ehdr, &elf_info);
   193		if (ret)
   194			return ERR_PTR(ret);
   195	
   196		ret = elf_find_pbase(image, kernel_len, &ehdr, &elf_info,
   197				     &old_kernel_pbase, &new_kernel_pbase);
   198		if (ret)
   199			goto out;
   200		kernel_start = image->start;
   201		pr_notice("The entry point of kernel at 0x%lx\n", image->start);
   202	
   203		/* Add the kernel binary to the image */
   204		ret = riscv_kexec_elf_load(image, &ehdr, &elf_info,
   205					   old_kernel_pbase, new_kernel_pbase);
   206		if (ret)
   207			goto out;
   208	
   209		kbuf.image = image;
   210		kbuf.buf_min = new_kernel_pbase + kernel_len;
   211		kbuf.buf_max = ULONG_MAX;
   212	
   213		/* Add elfcorehdr */
   214		if (image->type == KEXEC_TYPE_CRASH) {
   215			ret = prepare_elf_headers(&headers, &headers_sz);
   216			if (ret) {
   217				pr_err("Preparing elf core header failed\n");
   218				goto out;
   219			}
   220	
   221			kbuf.buffer = headers;
   222			kbuf.bufsz = headers_sz;
   223			kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
   224			kbuf.memsz = headers_sz;
   225			kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
   226			kbuf.top_down = true;
   227	
   228			ret = kexec_add_buffer(&kbuf);
   229			if (ret) {
   230				vfree(headers);
   231				goto out;
   232			}
   233			image->elf_headers = headers;
   234			image->elf_load_addr = kbuf.mem;
   235			image->elf_headers_sz = headers_sz;
   236	
   237			pr_debug("Loaded elf core header at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
   238				 image->elf_load_addr, kbuf.bufsz, kbuf.memsz);
   239	
   240			/* Setup cmdline for kdump kernel case */
   241			modified_cmdline = setup_kdump_cmdline(image, cmdline,
   242							       cmdline_len);
   243			if (!modified_cmdline) {
   244				pr_err("Setting up cmdline for kdump kernel failed\n");
   245				ret = -EINVAL;
   246				goto out;
   247			}
   248			cmdline = modified_cmdline;
   249		}
   250	

-- 
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