arch/riscv/kernel/elf_kexec.c:185:16: warning: variable 'kernel_start' set but not used

From: kernel test robot
Date: Tue Mar 28 2023 - 16:40:32 EST


Hi Li,

FYI, the error/warning still remains.

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 3a93e40326c8f470e71d20b4c42d36767450f38f
commit: 838b3e28488f702e2b5477b393f009b2639d2b1a RISC-V: Load purgatory in kexec_file
date: 10 months ago
config: riscv-randconfig-r042-20230329 (https://download.01.org/0day-ci/archive/20230329/202303290418.XvYFwNe4-lkp@xxxxxxxxx/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project 67409911353323ca5edf2049ef0df54132fa1ca7)
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 riscv cross compiling tool for clang build
# apt-get install binutils-riscv64-linux-gnu
# 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=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang 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@xxxxxxxxx>
| Link: https://lore.kernel.org/oe-kbuild-all/202303290418.XvYFwNe4-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

>> arch/riscv/kernel/elf_kexec.c:185:16: warning: variable 'kernel_start' set but not used [-Wunused-but-set-variable]
unsigned long kernel_start;
^
1 warning generated.


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

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests