[kbuild] arch/powerpc/net/bpf_jit_comp.c:225 bpf_int_jit_compile() error: uninitialized symbol 'pass'.

From: Dan Carpenter
Date: Fri Feb 04 2022 - 05:37:43 EST

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tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 88808fbbead481aedb46640a5ace69c58287f56a
commit: 51c66ad849a703d9bbfd7704c941827aed0fd9fd powerpc/bpf: Implement extended BPF on PPC32
config: powerpc-randconfig-m031-20220130 (https://download.01.org/0day-ci/archive/20220204/202202040124.7MMKaXXV-lkp@xxxxxxxxx/config )
compiler: powerpc-linux-gcc (GCC) 11.2.0

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

smatch warnings:
arch/powerpc/net/bpf_jit_comp.c:225 bpf_int_jit_compile() error: uninitialized symbol 'pass'.

vim +/pass +225 arch/powerpc/net/bpf_jit_comp.c

4ea76e90a97d22 Christophe Leroy 2021-03-22 88 struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
4ea76e90a97d22 Christophe Leroy 2021-03-22 89 {
4ea76e90a97d22 Christophe Leroy 2021-03-22 90 u32 proglen;
4ea76e90a97d22 Christophe Leroy 2021-03-22 91 u32 alloclen;
4ea76e90a97d22 Christophe Leroy 2021-03-22 92 u8 *image = NULL;
4ea76e90a97d22 Christophe Leroy 2021-03-22 93 u32 *code_base;
4ea76e90a97d22 Christophe Leroy 2021-03-22 94 u32 *addrs;
4ea76e90a97d22 Christophe Leroy 2021-03-22 95 struct powerpc64_jit_data *jit_data;
4ea76e90a97d22 Christophe Leroy 2021-03-22 96 struct codegen_context cgctx;
4ea76e90a97d22 Christophe Leroy 2021-03-22 97 int pass;
^^^^^^^^

4ea76e90a97d22 Christophe Leroy 2021-03-22 98 int flen;
4ea76e90a97d22 Christophe Leroy 2021-03-22 99 struct bpf_binary_header *bpf_hdr;
4ea76e90a97d22 Christophe Leroy 2021-03-22 100 struct bpf_prog *org_fp = fp;
4ea76e90a97d22 Christophe Leroy 2021-03-22 101 struct bpf_prog *tmp_fp;
4ea76e90a97d22 Christophe Leroy 2021-03-22 102 bool bpf_blinded = false;
4ea76e90a97d22 Christophe Leroy 2021-03-22 103 bool extra_pass = false;
4ea76e90a97d22 Christophe Leroy 2021-03-22 104
4ea76e90a97d22 Christophe Leroy 2021-03-22 105 if (!fp->jit_requested)
4ea76e90a97d22 Christophe Leroy 2021-03-22 106 return org_fp;
4ea76e90a97d22 Christophe Leroy 2021-03-22 107
4ea76e90a97d22 Christophe Leroy 2021-03-22 108 tmp_fp = bpf_jit_blind_constants(org_fp);
4ea76e90a97d22 Christophe Leroy 2021-03-22 109 if (IS_ERR(tmp_fp))
4ea76e90a97d22 Christophe Leroy 2021-03-22 110 return org_fp;
4ea76e90a97d22 Christophe Leroy 2021-03-22 111
4ea76e90a97d22 Christophe Leroy 2021-03-22 112 if (tmp_fp != org_fp) {
4ea76e90a97d22 Christophe Leroy 2021-03-22 113 bpf_blinded = true;
4ea76e90a97d22 Christophe Leroy 2021-03-22 114 fp = tmp_fp;
4ea76e90a97d22 Christophe Leroy 2021-03-22 115 }
4ea76e90a97d22 Christophe Leroy 2021-03-22 116
4ea76e90a97d22 Christophe Leroy 2021-03-22 117 jit_data = fp->aux->jit_data;
4ea76e90a97d22 Christophe Leroy 2021-03-22 118 if (!jit_data) {
4ea76e90a97d22 Christophe Leroy 2021-03-22 119 jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
4ea76e90a97d22 Christophe Leroy 2021-03-22 120 if (!jit_data) {
4ea76e90a97d22 Christophe Leroy 2021-03-22 121 fp = org_fp;
4ea76e90a97d22 Christophe Leroy 2021-03-22 122 goto out;
4ea76e90a97d22 Christophe Leroy 2021-03-22 123 }
4ea76e90a97d22 Christophe Leroy 2021-03-22 124 fp->aux->jit_data = jit_data;
4ea76e90a97d22 Christophe Leroy 2021-03-22 125 }
4ea76e90a97d22 Christophe Leroy 2021-03-22 126
4ea76e90a97d22 Christophe Leroy 2021-03-22 127 flen = fp->len;
4ea76e90a97d22 Christophe Leroy 2021-03-22 128 addrs = jit_data->addrs;
4ea76e90a97d22 Christophe Leroy 2021-03-22 129 if (addrs) {
4ea76e90a97d22 Christophe Leroy 2021-03-22 130 cgctx = jit_data->ctx;
4ea76e90a97d22 Christophe Leroy 2021-03-22 131 image = jit_data->image;
4ea76e90a97d22 Christophe Leroy 2021-03-22 132 bpf_hdr = jit_data->header;
4ea76e90a97d22 Christophe Leroy 2021-03-22 133 proglen = jit_data->proglen;
4ea76e90a97d22 Christophe Leroy 2021-03-22 134 alloclen = proglen + FUNCTION_DESCR_SIZE;
4ea76e90a97d22 Christophe Leroy 2021-03-22 135 extra_pass = true;
4ea76e90a97d22 Christophe Leroy 2021-03-22 136 goto skip_init_ctx;

Assume we hit this goto

4ea76e90a97d22 Christophe Leroy 2021-03-22 137 }
4ea76e90a97d22 Christophe Leroy 2021-03-22 138
4ea76e90a97d22 Christophe Leroy 2021-03-22 139 addrs = kcalloc(flen + 1, sizeof(*addrs), GFP_KERNEL);
4ea76e90a97d22 Christophe Leroy 2021-03-22 140 if (addrs == NULL) {
4ea76e90a97d22 Christophe Leroy 2021-03-22 141 fp = org_fp;
4ea76e90a97d22 Christophe Leroy 2021-03-22 142 goto out_addrs;
4ea76e90a97d22 Christophe Leroy 2021-03-22 143 }
4ea76e90a97d22 Christophe Leroy 2021-03-22 144
4ea76e90a97d22 Christophe Leroy 2021-03-22 145 memset(&cgctx, 0, sizeof(struct codegen_context));
4ea76e90a97d22 Christophe Leroy 2021-03-22 146
4ea76e90a97d22 Christophe Leroy 2021-03-22 147 /* Make sure that the stack is quadword aligned. */
4ea76e90a97d22 Christophe Leroy 2021-03-22 148 cgctx.stack_size = round_up(fp->aux->stack_depth, 16);
4ea76e90a97d22 Christophe Leroy 2021-03-22 149
4ea76e90a97d22 Christophe Leroy 2021-03-22 150 /* Scouting faux-generate pass 0 */
4ea76e90a97d22 Christophe Leroy 2021-03-22 151 if (bpf_jit_build_body(fp, 0, &cgctx, addrs, false)) {
4ea76e90a97d22 Christophe Leroy 2021-03-22 152 /* We hit something illegal or unsupported. */
4ea76e90a97d22 Christophe Leroy 2021-03-22 153 fp = org_fp;
4ea76e90a97d22 Christophe Leroy 2021-03-22 154 goto out_addrs;
4ea76e90a97d22 Christophe Leroy 2021-03-22 155 }
4ea76e90a97d22 Christophe Leroy 2021-03-22 156
4ea76e90a97d22 Christophe Leroy 2021-03-22 157 /*
4ea76e90a97d22 Christophe Leroy 2021-03-22 158 * If we have seen a tail call, we need a second pass.
4ea76e90a97d22 Christophe Leroy 2021-03-22 159 * This is because bpf_jit_emit_common_epilogue() is called
4ea76e90a97d22 Christophe Leroy 2021-03-22 160 * from bpf_jit_emit_tail_call() with a not yet stable ctx->seen.
4ea76e90a97d22 Christophe Leroy 2021-03-22 161 */
4ea76e90a97d22 Christophe Leroy 2021-03-22 162 if (cgctx.seen & SEEN_TAILCALL) {
4ea76e90a97d22 Christophe Leroy 2021-03-22 163 cgctx.idx = 0;
4ea76e90a97d22 Christophe Leroy 2021-03-22 164 if (bpf_jit_build_body(fp, 0, &cgctx, addrs, false)) {
4ea76e90a97d22 Christophe Leroy 2021-03-22 165 fp = org_fp;
4ea76e90a97d22 Christophe Leroy 2021-03-22 166 goto out_addrs;
4ea76e90a97d22 Christophe Leroy 2021-03-22 167 }
4ea76e90a97d22 Christophe Leroy 2021-03-22 168 }
4ea76e90a97d22 Christophe Leroy 2021-03-22 169
4ea76e90a97d22 Christophe Leroy 2021-03-22 170 /*
4ea76e90a97d22 Christophe Leroy 2021-03-22 171 * Pretend to build prologue, given the features we've seen. This will
4ea76e90a97d22 Christophe Leroy 2021-03-22 172 * update ctgtx.idx as it pretends to output instructions, then we can
4ea76e90a97d22 Christophe Leroy 2021-03-22 173 * calculate total size from idx.
4ea76e90a97d22 Christophe Leroy 2021-03-22 174 */
4ea76e90a97d22 Christophe Leroy 2021-03-22 175 bpf_jit_build_prologue(0, &cgctx);
4ea76e90a97d22 Christophe Leroy 2021-03-22 176 bpf_jit_build_epilogue(0, &cgctx);
4ea76e90a97d22 Christophe Leroy 2021-03-22 177
4ea76e90a97d22 Christophe Leroy 2021-03-22 178 proglen = cgctx.idx * 4;
4ea76e90a97d22 Christophe Leroy 2021-03-22 179 alloclen = proglen + FUNCTION_DESCR_SIZE;
4ea76e90a97d22 Christophe Leroy 2021-03-22 180
4ea76e90a97d22 Christophe Leroy 2021-03-22 181 bpf_hdr = bpf_jit_binary_alloc(alloclen, &image, 4, bpf_jit_fill_ill_insns);
4ea76e90a97d22 Christophe Leroy 2021-03-22 182 if (!bpf_hdr) {
4ea76e90a97d22 Christophe Leroy 2021-03-22 183 fp = org_fp;
4ea76e90a97d22 Christophe Leroy 2021-03-22 184 goto out_addrs;
4ea76e90a97d22 Christophe Leroy 2021-03-22 185 }
4ea76e90a97d22 Christophe Leroy 2021-03-22 186
4ea76e90a97d22 Christophe Leroy 2021-03-22 187 skip_init_ctx:
4ea76e90a97d22 Christophe Leroy 2021-03-22 188 code_base = (u32 *)(image + FUNCTION_DESCR_SIZE);
4ea76e90a97d22 Christophe Leroy 2021-03-22 189
4ea76e90a97d22 Christophe Leroy 2021-03-22 190 if (extra_pass) {
4ea76e90a97d22 Christophe Leroy 2021-03-22 191 /*
4ea76e90a97d22 Christophe Leroy 2021-03-22 192 * Do not touch the prologue and epilogue as they will remain
4ea76e90a97d22 Christophe Leroy 2021-03-22 193 * unchanged. Only fix the branch target address for subprog
4ea76e90a97d22 Christophe Leroy 2021-03-22 194 * calls in the body.
4ea76e90a97d22 Christophe Leroy 2021-03-22 195 *
4ea76e90a97d22 Christophe Leroy 2021-03-22 196 * This does not change the offsets and lengths of the subprog
4ea76e90a97d22 Christophe Leroy 2021-03-22 197 * call instruction sequences and hence, the size of the JITed
4ea76e90a97d22 Christophe Leroy 2021-03-22 198 * image as well.
4ea76e90a97d22 Christophe Leroy 2021-03-22 199 */
4ea76e90a97d22 Christophe Leroy 2021-03-22 200 bpf_jit_fixup_subprog_calls(fp, code_base, &cgctx, addrs);
4ea76e90a97d22 Christophe Leroy 2021-03-22 201
4ea76e90a97d22 Christophe Leroy 2021-03-22 202 /* There is no need to perform the usual passes. */
4ea76e90a97d22 Christophe Leroy 2021-03-22 203 goto skip_codegen_passes;

Goto before pass is inintialized

4ea76e90a97d22 Christophe Leroy 2021-03-22 204 }
4ea76e90a97d22 Christophe Leroy 2021-03-22 205
4ea76e90a97d22 Christophe Leroy 2021-03-22 206 /* Code generation passes 1-2 */
4ea76e90a97d22 Christophe Leroy 2021-03-22 207 for (pass = 1; pass < 3; pass++) {
^^^^^^^^
Here

4ea76e90a97d22 Christophe Leroy 2021-03-22 208 /* Now build the prologue, body code & epilogue for real. */
4ea76e90a97d22 Christophe Leroy 2021-03-22 209 cgctx.idx = 0;
4ea76e90a97d22 Christophe Leroy 2021-03-22 210 bpf_jit_build_prologue(code_base, &cgctx);
4ea76e90a97d22 Christophe Leroy 2021-03-22 211 bpf_jit_build_body(fp, code_base, &cgctx, addrs, extra_pass);
4ea76e90a97d22 Christophe Leroy 2021-03-22 212 bpf_jit_build_epilogue(code_base, &cgctx);
4ea76e90a97d22 Christophe Leroy 2021-03-22 213
4ea76e90a97d22 Christophe Leroy 2021-03-22 214 if (bpf_jit_enable > 1)
4ea76e90a97d22 Christophe Leroy 2021-03-22 215 pr_info("Pass %d: shrink = %d, seen = 0x%x\n", pass,
4ea76e90a97d22 Christophe Leroy 2021-03-22 216 proglen - (cgctx.idx * 4), cgctx.seen);
4ea76e90a97d22 Christophe Leroy 2021-03-22 217 }
4ea76e90a97d22 Christophe Leroy 2021-03-22 218
4ea76e90a97d22 Christophe Leroy 2021-03-22 219 skip_codegen_passes:
4ea76e90a97d22 Christophe Leroy 2021-03-22 220 if (bpf_jit_enable > 1)
4ea76e90a97d22 Christophe Leroy 2021-03-22 221 /*
4ea76e90a97d22 Christophe Leroy 2021-03-22 222 * Note that we output the base address of the code_base
4ea76e90a97d22 Christophe Leroy 2021-03-22 223 * rather than image, since opcodes are in code_base.
4ea76e90a97d22 Christophe Leroy 2021-03-22 224 */
4ea76e90a97d22 Christophe Leroy 2021-03-22 @225 bpf_jit_dump(flen, proglen, pass, code_base);
^^^^
Uninitialized.

4ea76e90a97d22 Christophe Leroy 2021-03-22 226

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