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Date: Thu, 20 May 2021 14:09:06 +1000
From: Jordan Niethe <jniethe5@...il.com>
To: kernel test robot <lkp@...el.com>
Cc: kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org,
Michael Ellerman <mpe@...erman.id.au>,
Alistair Popple <alistair@...ple.id.au>
Subject: Re: arch/powerpc/lib/sstep.c:1172:21: error: variable 'suffix' set
but not used
On Thu, May 20, 2021 at 5:01 AM kernel test robot <lkp@...el.com> wrote:
>
> Hi Jordan,
>
> FYI, the error/warning still remains.
>
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: c3d0e3fd41b7f0f5d5d5b6022ab7e813f04ea727
> commit: 650b55b707fdfa764e9f2b81314d3eb4216fb962 powerpc: Add prefixed instructions to instruction data type
> date: 1 year ago
> config: powerpc-klondike_defconfig (attached as .config)
> compiler: powerpc-linux-gcc (GCC) 9.3.0
> 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=650b55b707fdfa764e9f2b81314d3eb4216fb962
> git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> git fetch --no-tags linus master
> git checkout 650b55b707fdfa764e9f2b81314d3eb4216fb962
> # save the attached .config to linux build tree
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=powerpc
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@...el.com>
>
> All errors (new ones prefixed by >>):
>
> arch/powerpc/lib/sstep.c: In function 'analyse_instr':
> >> arch/powerpc/lib/sstep.c:1172:21: error: variable 'suffix' set but not used [-Werror=unused-but-set-variable]
> 1172 | unsigned int word, suffix;
Yeah, we should only need suffix if we have prefixed instructions.
> | ^~~~~~
> arch/powerpc/lib/sstep.c:1168:31: error: variable 'rc' set but not used [-Werror=unused-but-set-variable]
> 1168 | unsigned int opcode, ra, rb, rc, rd, spr, u;
> | ^~
> cc1: all warnings being treated as errors
>
>
> vim +/suffix +1172 arch/powerpc/lib/sstep.c
>
> 1153
> 1154 /*
> 1155 * Decode an instruction, and return information about it in *op
> 1156 * without changing *regs.
> 1157 * Integer arithmetic and logical instructions, branches, and barrier
> 1158 * instructions can be emulated just using the information in *op.
> 1159 *
> 1160 * Return value is 1 if the instruction can be emulated just by
> 1161 * updating *regs with the information in *op, -1 if we need the
> 1162 * GPRs but *regs doesn't contain the full register set, or 0
> 1163 * otherwise.
> 1164 */
> 1165 int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
> 1166 struct ppc_inst instr)
> 1167 {
> 1168 unsigned int opcode, ra, rb, rc, rd, spr, u;
> 1169 unsigned long int imm;
> 1170 unsigned long int val, val2;
> 1171 unsigned int mb, me, sh;
> > 1172 unsigned int word, suffix;
> 1173 long ival;
> 1174
> 1175 word = ppc_inst_val(instr);
> 1176 suffix = ppc_inst_suffix(instr);
> 1177
> 1178 op->type = COMPUTE;
> 1179
> 1180 opcode = ppc_inst_primary_opcode(instr);
> 1181 switch (opcode) {
> 1182 case 16: /* bc */
> 1183 op->type = BRANCH;
> 1184 imm = (signed short)(word & 0xfffc);
> 1185 if ((word & 2) == 0)
> 1186 imm += regs->nip;
> 1187 op->val = truncate_if_32bit(regs->msr, imm);
> 1188 if (word & 1)
> 1189 op->type |= SETLK;
> 1190 if (branch_taken(word, regs, op))
> 1191 op->type |= BRTAKEN;
> 1192 return 1;
> 1193 #ifdef CONFIG_PPC64
> 1194 case 17: /* sc */
> 1195 if ((word & 0xfe2) == 2)
> 1196 op->type = SYSCALL;
> 1197 else
> 1198 op->type = UNKNOWN;
> 1199 return 0;
> 1200 #endif
> 1201 case 18: /* b */
> 1202 op->type = BRANCH | BRTAKEN;
> 1203 imm = word & 0x03fffffc;
> 1204 if (imm & 0x02000000)
> 1205 imm -= 0x04000000;
> 1206 if ((word & 2) == 0)
> 1207 imm += regs->nip;
> 1208 op->val = truncate_if_32bit(regs->msr, imm);
> 1209 if (word & 1)
> 1210 op->type |= SETLK;
> 1211 return 1;
> 1212 case 19:
> 1213 switch ((word >> 1) & 0x3ff) {
> 1214 case 0: /* mcrf */
> 1215 op->type = COMPUTE + SETCC;
> 1216 rd = 7 - ((word >> 23) & 0x7);
> 1217 ra = 7 - ((word >> 18) & 0x7);
> 1218 rd *= 4;
> 1219 ra *= 4;
> 1220 val = (regs->ccr >> ra) & 0xf;
> 1221 op->ccval = (regs->ccr & ~(0xfUL << rd)) | (val << rd);
> 1222 return 1;
> 1223
> 1224 case 16: /* bclr */
> 1225 case 528: /* bcctr */
> 1226 op->type = BRANCH;
> 1227 imm = (word & 0x400)? regs->ctr: regs->link;
> 1228 op->val = truncate_if_32bit(regs->msr, imm);
> 1229 if (word & 1)
> 1230 op->type |= SETLK;
> 1231 if (branch_taken(word, regs, op))
> 1232 op->type |= BRTAKEN;
> 1233 return 1;
> 1234
> 1235 case 18: /* rfid, scary */
> 1236 if (regs->msr & MSR_PR)
> 1237 goto priv;
> 1238 op->type = RFI;
> 1239 return 0;
> 1240
> 1241 case 150: /* isync */
> 1242 op->type = BARRIER | BARRIER_ISYNC;
> 1243 return 1;
> 1244
> 1245 case 33: /* crnor */
> 1246 case 129: /* crandc */
> 1247 case 193: /* crxor */
> 1248 case 225: /* crnand */
> 1249 case 257: /* crand */
> 1250 case 289: /* creqv */
> 1251 case 417: /* crorc */
> 1252 case 449: /* cror */
> 1253 op->type = COMPUTE + SETCC;
> 1254 ra = (word >> 16) & 0x1f;
> 1255 rb = (word >> 11) & 0x1f;
> 1256 rd = (word >> 21) & 0x1f;
> 1257 ra = (regs->ccr >> (31 - ra)) & 1;
> 1258 rb = (regs->ccr >> (31 - rb)) & 1;
> 1259 val = (word >> (6 + ra * 2 + rb)) & 1;
> 1260 op->ccval = (regs->ccr & ~(1UL << (31 - rd))) |
> 1261 (val << (31 - rd));
> 1262 return 1;
> 1263 }
> 1264 break;
> 1265 case 31:
> 1266 switch ((word >> 1) & 0x3ff) {
> 1267 case 598: /* sync */
> 1268 op->type = BARRIER + BARRIER_SYNC;
> 1269 #ifdef __powerpc64__
> 1270 switch ((word >> 21) & 3) {
> 1271 case 1: /* lwsync */
> 1272 op->type = BARRIER + BARRIER_LWSYNC;
> 1273 break;
> 1274 case 2: /* ptesync */
> 1275 op->type = BARRIER + BARRIER_PTESYNC;
> 1276 break;
> 1277 }
> 1278 #endif
> 1279 return 1;
> 1280
> 1281 case 854: /* eieio */
> 1282 op->type = BARRIER + BARRIER_EIEIO;
> 1283 return 1;
> 1284 }
> 1285 break;
> 1286 }
> 1287
> 1288 /* Following cases refer to regs->gpr[], so we need all regs */
> 1289 if (!FULL_REGS(regs))
> 1290 return -1;
> 1291
> 1292 rd = (word >> 21) & 0x1f;
> 1293 ra = (word >> 16) & 0x1f;
> 1294 rb = (word >> 11) & 0x1f;
> 1295 rc = (word >> 6) & 0x1f;
> 1296
> 1297 switch (opcode) {
> 1298 #ifdef __powerpc64__
> 1299 case 2: /* tdi */
> 1300 if (rd & trap_compare(regs->gpr[ra], (short) word))
> 1301 goto trap;
> 1302 return 1;
> 1303 #endif
> 1304 case 3: /* twi */
> 1305 if (rd & trap_compare((int)regs->gpr[ra], (short) word))
> 1306 goto trap;
> 1307 return 1;
> 1308
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
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