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charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.2 (3.54.2-1.fc41) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2025-01-15 at 21:51 -0800, Yonghong Song wrote: > Add both asm-based and C-based tests which have 'may_goto 0' insns. >=20 > For the following code in C-based test, > int i, tmp[3]; > for (i =3D 0; i < 3 && can_loop; i++) > tmp[i] =3D 0; >=20 > The clang compiler (clang 19 and 20) generates > may_goto 2 > may_goto 1 > may_goto 0 > r1 =3D 0 > r2 =3D 0 > r3 =3D 0 >=20 > The above asm codes are due to llvm pass SROAPass. This ensures the > successful verification since tmp[0-2] are initialized. Otherwise, > the code without SROAPass like > may_goto 5 > r1 =3D 0 > may_goto 3 > r2 =3D 0 > may_goto 1 > r3 =3D 0 > will have verification failure. >=20 > Although from the source code C-based test should have verification > failure, clang compiler optimization generates code with successful > verification. If gcc generates different asm codes than clang, the > following code can be used for gcc: > int i, tmp[3]; > for (i =3D 0; i < 3; i++) > tmp[i] =3D 0; >=20 > Signed-off-by: Yonghong Song > --- Acked-by: Eduard Zingerman [...] > +SEC("raw_tp") > +__description("may_goto batch with offsets 2/1/0") > +__arch_x86_64 > +__xlated("0: r0 =3D 1") > +__xlated("1: exit") > +__success > +__naked void may_goto_batch_1(void) > +{ > + asm volatile ( > + ".8byte %[may_goto1];" > + ".8byte %[may_goto2];" > + ".8byte %[may_goto3];" > + "r0 =3D 1;" > + ".8byte %[may_goto1];" > + ".8byte %[may_goto2];" > + ".8byte %[may_goto3];" > + "exit;" > + : > + : __imm_insn(may_goto1, BPF_RAW_INSN(BPF_JMP | BPF_JCOND, 0, 0, 2 /* of= fset */, 0)), > + __imm_insn(may_goto2, BPF_RAW_INSN(BPF_JMP | BPF_JCOND, 0, 0, 1 /* of= fset */, 0)), > + __imm_insn(may_goto3, BPF_RAW_INSN(BPF_JMP | BPF_JCOND, 0, 0, 0 /* of= fset */, 0)) Rant: may_goto3 that does +0 jump is a bit confusing :) > + : __clobber_all); > +} [...]