Hi, kernel test robot noticed the following build warnings:
[auto build test WARNING on bpf-next/master] [also build test WARNING on bpf/master powerpc/next linus/master v7.0-rc1 next-20260224] [cannot apply to bpf-next/net powerpc/fixes] [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#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/adubey-linux-ibm-com/selftests-bpf-Enable-private-stack-tests-for-powerpc64/20260225-184532 base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master patch link: https://lore.kernel.org/r/20260225153950.15331-1-adubey%40linux.ibm.com patch subject: [PATCH v2 1/2] powerpc64/bpf: Implement JIT support for private stack config: powerpc-randconfig-r123-20260225 (https://download.01.org/0day-ci/archive/20260226/[email protected]/config) compiler: clang version 23.0.0git (https://github.com/llvm/llvm-project 9a109fbb6e184ec9bcce10615949f598f4c974a9) reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260226/[email protected]/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 <[email protected]> | Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/ All warnings (new ones prefixed by >>): >> arch/powerpc/net/bpf_jit_comp.c:222:7: warning: variable 'addrs' is used >> uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] 222 | if (!priv_stack_ptr) { | ^~~~~~~~~~~~~~~ arch/powerpc/net/bpf_jit_comp.c:370:9: note: uninitialized use occurs here 370 | kfree(addrs); | ^~~~~ arch/powerpc/net/bpf_jit_comp.c:222:3: note: remove the 'if' if its condition is always false 222 | if (!priv_stack_ptr) { | ^~~~~~~~~~~~~~~~~~~~~~ 223 | fp = org_fp; | ~~~~~~~~~~~~ 224 | goto out_priv_stack; | ~~~~~~~~~~~~~~~~~~~~ 225 | } | ~ arch/powerpc/net/bpf_jit_comp.c:171:12: note: initialize the variable 'addrs' to silence this warning 171 | u32 *addrs; | ^ | = NULL 1 warning generated. vim +222 arch/powerpc/net/bpf_jit_comp.c 164 165 struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) 166 { 167 u32 proglen; 168 u32 alloclen; 169 u8 *image = NULL; 170 u32 *code_base; 171 u32 *addrs; 172 struct powerpc_jit_data *jit_data; 173 struct codegen_context cgctx; 174 int pass; 175 int flen; 176 int priv_stack_alloc_size; 177 void __percpu *priv_stack_ptr = NULL; 178 struct bpf_binary_header *fhdr = NULL; 179 struct bpf_binary_header *hdr = NULL; 180 struct bpf_prog *org_fp = fp; 181 struct bpf_prog *tmp_fp; 182 bool bpf_blinded = false; 183 bool extra_pass = false; 184 u8 *fimage = NULL; 185 u32 *fcode_base; 186 u32 extable_len; 187 u32 fixup_len; 188 189 if (!fp->jit_requested) 190 return org_fp; 191 192 tmp_fp = bpf_jit_blind_constants(org_fp); 193 if (IS_ERR(tmp_fp)) 194 return org_fp; 195 196 if (tmp_fp != org_fp) { 197 bpf_blinded = true; 198 fp = tmp_fp; 199 } 200 201 jit_data = fp->aux->jit_data; 202 if (!jit_data) { 203 jit_data = kzalloc_obj(*jit_data); 204 if (!jit_data) { 205 fp = org_fp; 206 goto out; 207 } 208 fp->aux->jit_data = jit_data; 209 } 210 211 priv_stack_ptr = fp->aux->priv_stack_ptr; 212 if (!priv_stack_ptr && fp->aux->jits_use_priv_stack) { 213 /* 214 * Allocate private stack of size equivalent to 215 * verifier-calculated stack size plus two memory 216 * guard regions to detect private stack overflow 217 * and underflow. 218 */ 219 priv_stack_alloc_size = round_up(fp->aux->stack_depth, 16) + 220 2 * PRIV_STACK_GUARD_SZ; 221 priv_stack_ptr = __alloc_percpu_gfp(priv_stack_alloc_size, 16, GFP_KERNEL); > 222 if (!priv_stack_ptr) { 223 fp = org_fp; 224 goto out_priv_stack; 225 } 226 227 priv_stack_init_guard(priv_stack_ptr, priv_stack_alloc_size); 228 fp->aux->priv_stack_ptr = priv_stack_ptr; 229 } 230 231 flen = fp->len; 232 addrs = jit_data->addrs; 233 if (addrs) { 234 cgctx = jit_data->ctx; 235 /* 236 * JIT compiled to a writable location (image/code_base) first. 237 * It is then moved to the readonly final location (fimage/fcode_base) 238 * using instruction patching. 239 */ 240 fimage = jit_data->fimage; 241 fhdr = jit_data->fhdr; 242 proglen = jit_data->proglen; 243 hdr = jit_data->hdr; 244 image = (void *)hdr + ((void *)fimage - (void *)fhdr); 245 extra_pass = true; 246 /* During extra pass, ensure index is reset before repopulating extable entries */ 247 cgctx.exentry_idx = 0; 248 goto skip_init_ctx; 249 } 250 251 addrs = kcalloc(flen + 1, sizeof(*addrs), GFP_KERNEL); 252 if (addrs == NULL) { 253 fp = org_fp; 254 goto out_addrs; 255 } 256 257 memset(&cgctx, 0, sizeof(struct codegen_context)); 258 bpf_jit_init_reg_mapping(&cgctx); 259 260 /* Make sure that the stack is quadword aligned. */ 261 cgctx.stack_size = round_up(fp->aux->stack_depth, 16); 262 cgctx.arena_vm_start = bpf_arena_get_kern_vm_start(fp->aux->arena); 263 cgctx.user_vm_start = bpf_arena_get_user_vm_start(fp->aux->arena); 264 cgctx.is_subprog = bpf_is_subprog(fp); 265 cgctx.exception_boundary = fp->aux->exception_boundary; 266 cgctx.exception_cb = fp->aux->exception_cb; 267 cgctx.priv_sp = priv_stack_ptr; 268 269 /* Scouting faux-generate pass 0 */ 270 if (bpf_jit_build_body(fp, NULL, NULL, &cgctx, addrs, 0, false)) { 271 /* We hit something illegal or unsupported. */ 272 fp = org_fp; 273 goto out_addrs; 274 } 275 276 /* 277 * If we have seen a tail call, we need a second pass. 278 * This is because bpf_jit_emit_common_epilogue() is called 279 * from bpf_jit_emit_tail_call() with a not yet stable ctx->seen. 280 * We also need a second pass if we ended up with too large 281 * a program so as to ensure BPF_EXIT branches are in range. 282 */ 283 if (cgctx.seen & SEEN_TAILCALL || !is_offset_in_branch_range((long)cgctx.idx * 4)) { 284 cgctx.idx = 0; 285 if (bpf_jit_build_body(fp, NULL, NULL, &cgctx, addrs, 0, false)) { 286 fp = org_fp; 287 goto out_addrs; 288 } 289 } 290 291 bpf_jit_realloc_regs(&cgctx); 292 /* 293 * Pretend to build prologue, given the features we've seen. This will 294 * update ctgtx.idx as it pretends to output instructions, then we can 295 * calculate total size from idx. 296 */ 297 bpf_jit_build_prologue(NULL, &cgctx); 298 addrs[fp->len] = cgctx.idx * 4; 299 bpf_jit_build_epilogue(NULL, &cgctx); 300 301 fixup_len = fp->aux->num_exentries * BPF_FIXUP_LEN * 4; 302 extable_len = fp->aux->num_exentries * sizeof(struct exception_table_entry); 303 304 proglen = cgctx.idx * 4; 305 alloclen = proglen + FUNCTION_DESCR_SIZE + fixup_len + extable_len; 306 307 fhdr = bpf_jit_binary_pack_alloc(alloclen, &fimage, 4, &hdr, &image, 308 bpf_jit_fill_ill_insns); 309 if (!fhdr) { 310 fp = org_fp; 311 goto out_addrs; 312 } 313 314 if (extable_len) 315 fp->aux->extable = (void *)fimage + FUNCTION_DESCR_SIZE + proglen + fixup_len; 316 317 skip_init_ctx: 318 code_base = (u32 *)(image + FUNCTION_DESCR_SIZE); 319 fcode_base = (u32 *)(fimage + FUNCTION_DESCR_SIZE); 320 321 /* Code generation passes 1-2 */ 322 for (pass = 1; pass < 3; pass++) { 323 /* Now build the prologue, body code & epilogue for real. */ 324 cgctx.idx = 0; 325 cgctx.alt_exit_addr = 0; 326 bpf_jit_build_prologue(code_base, &cgctx); 327 if (bpf_jit_build_body(fp, code_base, fcode_base, &cgctx, addrs, pass, 328 extra_pass)) { 329 bpf_arch_text_copy(&fhdr->size, &hdr->size, sizeof(hdr->size)); 330 bpf_jit_binary_pack_free(fhdr, hdr); 331 fp = org_fp; 332 goto out_addrs; 333 } 334 bpf_jit_build_epilogue(code_base, &cgctx); 335 336 if (bpf_jit_enable > 1) 337 pr_info("Pass %d: shrink = %d, seen = 0x%x\n", pass, 338 proglen - (cgctx.idx * 4), cgctx.seen); 339 } 340 341 if (bpf_jit_enable > 1) 342 /* 343 * Note that we output the base address of the code_base 344 * rather than image, since opcodes are in code_base. 345 */ 346 bpf_jit_dump(flen, proglen, pass, code_base); 347 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
