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Sun, 21 Sep 2025 09:46:07 -0700 (PDT) Received: from draig.lan ([185.126.160.19]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3f61703b206sm6133953f8f.6.2025.09.21.09.46.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 21 Sep 2025 09:46:06 -0700 (PDT) Received: from draig (localhost [IPv6:::1]) by draig.lan (Postfix) with ESMTP id 9A2465F87D; Sun, 21 Sep 2025 17:46:05 +0100 (BST) From: =?utf-8?Q?Alex_Benn=C3=A9e?= To: Julian Ganz Cc: qemu-devel@nongnu.org, Pierrick Bouvier , Alexandre Iooss , Mahmoud Mandour Subject: Re: [PATCH v6 23/25] tests: add plugin asserting correctness of discon event's to_pc In-Reply-To: <073cad7dd8ae509ff64a2835fd146833b60c1f60.1757018626.git.neither@nut.email> (Julian Ganz's message of "Thu, 4 Sep 2025 22:48:58 +0200") References: <073cad7dd8ae509ff64a2835fd146833b60c1f60.1757018626.git.neither@nut.email> User-Agent: mu4e 1.12.12; emacs 30.1 Date: Sun, 21 Sep 2025 17:46:05 +0100 Message-ID: <87segf69f6.fsf@draig.linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=2a00:1450:4864:20::42b; envelope-from=alex.bennee@linaro.org; helo=mail-wr1-x42b.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Julian Ganz writes: > We recently introduced plugin API for the registration of callbacks for > discontinuity events, specifically for interrupts, exceptions and host > call events. The callback receives various bits of information, > including the VCPU index and PCs. > > This change introduces a test plugin asserting the correctness of that > behaviour in cases where this is possible with reasonable effort. > > Reviewed-by: Pierrick Bouvier > Signed-off-by: Julian Ganz > --- > tests/tcg/plugins/discons.c | 210 ++++++++++++++++++++++++++++++++++ > tests/tcg/plugins/meson.build | 2 +- > 2 files changed, 211 insertions(+), 1 deletion(-) > create mode 100644 tests/tcg/plugins/discons.c > > diff --git a/tests/tcg/plugins/discons.c b/tests/tcg/plugins/discons.c > new file mode 100644 > index 0000000000..f185e3948b > --- /dev/null > +++ b/tests/tcg/plugins/discons.c > @@ -0,0 +1,210 @@ > +/* > + * SPDX-License-Identifier: GPL-2.0-or-later > + * Copyright (C) 2025, Julian Ganz > + * > + * This plugin exercises the discontinuity plugin API and asserts some > + * of its behaviour regarding reported program counters. > + */ > +#include > + > +#include > + > +QEMU_PLUGIN_EXPORT int qemu_plugin_version =3D QEMU_PLUGIN_VERSION; > + > +struct cpu_state { > + uint64_t last_pc; > + uint64_t from_pc; > + uint64_t next_pc; > + uint64_t has_from; > + bool has_next; > + enum qemu_plugin_discon_type next_type; > +}; > + > +struct insn_data { > + uint64_t addr; > + uint64_t next_pc; > + bool next_valid; > +}; > + > +static struct qemu_plugin_scoreboard *states; > + > +static qemu_plugin_u64 last_pc; > +static qemu_plugin_u64 from_pc; > +static qemu_plugin_u64 has_from; > + > +static bool abort_on_mismatch; > +static bool trace_all_insns; > + > +static bool addr_eq(uint64_t a, uint64_t b) > +{ > + if (a =3D=3D b) { > + return true; > + } > + > + uint64_t a_hw; > + uint64_t b_hw; > + if (!qemu_plugin_translate_vaddr(a, &a_hw) || > + !qemu_plugin_translate_vaddr(b, &b_hw)) > + { > + return false; > + } > + > + return a_hw =3D=3D b_hw; > +} > + > +static void report_mismatch(const char *pc_name, unsigned int vcpu_index, > + enum qemu_plugin_discon_type type, uint64_t = last, > + uint64_t expected, uint64_t encountered) > +{ > + GString *report; This could be: g_autoptr(GString) buf =3D g_string_new(NULL); > + const char *discon_type_name =3D "unknown"; > + > + if (addr_eq(expected, encountered)) { > + return; > + } > + > + switch (type) { > + case QEMU_PLUGIN_DISCON_INTERRUPT: > + discon_type_name =3D "interrupt"; > + break; > + case QEMU_PLUGIN_DISCON_EXCEPTION: > + discon_type_name =3D "exception"; > + break; > + case QEMU_PLUGIN_DISCON_HOSTCALL: > + discon_type_name =3D "hostcall"; > + break; > + default: > + break; > + } > + > + report =3D g_string_new(NULL); > + g_string_append_printf(report, > + "Discon %s PC mismatch on VCPU %d\nExpected: = %" > + PRIx64"\nEncountered: %"PRIx64"\nExecuted L= ast: %" > + PRIx64"\nEvent type: %s\n", > + pc_name, vcpu_index, expected, encountered, l= ast, > + discon_type_name); > + qemu_plugin_outs(report->str); I think we might want to flush here because > + if (abort_on_mismatch) { > + g_abort(); > + } This is firing on: =F0=9F=95=9917:35:50 alex@draig:tests/tcg/i386-linux-user on =EE=82=A0 r= eview/tcg-discon-v6 [$!?]=20 =E2=9E=9C make run-plugin-catch-syscalls-with-libdiscons.so V=3D1 timeout -s KILL --foreground 120 env QEMU=3D/home/alex/lsrc/qemu.git/bui= lds/sanitisers/qemu-i386 /home/alex/lsrc/qemu.git/builds/sanitisers/qemu-i3= 86 -plugin ../plugins/libdiscons.so -d plugin -D catch-syscalls-with-libdi= scons.so.pout catch-syscalls > run-plugin-catch-syscalls-with-libdiscons.s= o.out Aborted make: *** [Makefile:226: run-plugin-catch-syscalls-with-libdiscons.so] Er= ror 134 =F0=9F=95=9917:35:52 alex@draig:tests/tcg/i386-linux-user on =EE=82=A0 r= eview/tcg-discon-v6 [$!?] [=F0=9F=94=B4 USAGE]=20 =E2=9C=97 although it never gets to the point of reporting what failed: Thread 1 "qemu-i386" hit Breakpoint 1, __GI_abort () at ./stdlib/abort.c:= 72 warning: 72 ./stdlib/abort.c: No such file or directory (gdb) bt #0 __GI_abort () at ./stdlib/abort.c:72 #1 0x00007ffff630874d in report_mismatch (pc_name=3D0x7ffff630a220 "targ= et", vcpu_index=3D0, type=3DQEMU_PLUGIN_DISCON_EXCEPTION, last=3D134574955,= expected=3D134574953,=20 encountered=3D134574955) at ../../tests/tcg/plugins/discons.c:89 #2 0x00007ffff6308c0d in insn_exec (vcpu_index=3D0, userdata=3D0x0) at .= ./../tests/tcg/plugins/discons.c:132 #3 0x00007fffea431114 in code_gen_buffer () #4 0x000055555577b0a6 in cpu_tb_exec (cpu=3D0x529000005200, itb=3D0x7fff= ea431000 , tb_exit=3D0x7ffff49c9530) at ../../accel= /tcg/cpu-exec.c:438 #5 0x000055555577c92f in cpu_loop_exec_tb (cpu=3D0x529000005200, tb=3D0x= 7fffea431000 , pc=3D134574955, last_tb=3D0x7ffff49c= 9540, tb_exit=3D0x7ffff49c9530) at ../../accel/tcg/cpu-exec.c:871 #6 0x000055555577d151 in cpu_exec_loop (cpu=3D0x529000005200, sc=3D0x7ff= ff483a740) at ../../accel/tcg/cpu-exec.c:981 #7 0x000055555577d2fe in cpu_exec_setjmp (cpu=3D0x529000005200, sc=3D0x7= ffff483a740) at ../../accel/tcg/cpu-exec.c:998 #8 0x000055555577d4c8 in cpu_exec (cpu=3D0x529000005200) at ../../accel/= tcg/cpu-exec.c:1024 #9 0x00005555557bfc83 in cpu_loop (env=3D0x529000007dd0) at ../../linux-= user/i386/cpu_loop.c:215 #10 0x00005555558ee3e1 in main (argc=3D4, argv=3D0x7fffffffe688, envp=3D0= x7fffffffe6b0) at ../../linux-user/main.c:1038 (gdb) f 1 #1 0x00007ffff630874d in report_mismatch (pc_name=3D0x7ffff630a220 "targ= et", vcpu_index=3D0, type=3DQEMU_PLUGIN_DISCON_EXCEPTION, last=3D134574955,= expected=3D134574953,=20 encountered=3D134574955) at ../../tests/tcg/plugins/discons.c:89 89 g_abort(); (gdb) p report $1 =3D (GString *) 0x50300002bf00 (gdb) p report->Str There is no member named Str. (gdb) p report->str $2 =3D (gchar *) 0x51100001fbc0 "Discon target PC mismatch on VCPU 0\nExp= ected: 8057369\nEncountered: 805736b\nExecuted Last: 805736b\nEvent = type: exception\n" (gdb)=20 I think this is where it is going wrong: IN: _dl_early_allocate 0x0805736b: 89 c2 movl %eax, %edx 0x0805736d: 8d 1c 28 leal (%eax, %ebp), %ebx 0x08057370: 89 c8 movl %ecx, %eax 0x08057372: cd 80 int $0x80 > + g_string_free(report, true); so we could drop this... or.. > +} > + > +static void vcpu_discon(qemu_plugin_id_t id, unsigned int vcpu_index, > + enum qemu_plugin_discon_type type, uint64_t from= _pc, > + uint64_t to_pc) > +{ > + struct cpu_state *state =3D qemu_plugin_scoreboard_find(states, vcpu= _index); > + > + if (type =3D=3D QEMU_PLUGIN_DISCON_EXCEPTION && > + addr_eq(state->last_pc, from_pc)) > + { > + /* > + * For some types of exceptions, insn_exec will be called for the > + * instruction that caused the exception. This is valid behaviou= r and > + * does not need to be reported. > + */ > + } else if (state->has_next) { > + /* > + * We may encounter discontinuity chains without any instructions > + * being executed in between. > + */ > + report_mismatch("source", vcpu_index, type, state->last_pc, > + state->next_pc, from_pc); > + } else if (state->has_from) { > + report_mismatch("source", vcpu_index, type, state->last_pc, > + state->from_pc, from_pc); > + } > + > + state->has_from =3D false; > + > + state->next_pc =3D to_pc; > + state->next_type =3D type; > + state->has_next =3D true; > +} > + > +static void insn_exec(unsigned int vcpu_index, void *userdata) > +{ > + struct cpu_state *state =3D qemu_plugin_scoreboard_find(states, vcpu= _index); > + > + if (state->has_next) { > + report_mismatch("target", vcpu_index, state->next_type, state->l= ast_pc, > + state->next_pc, state->last_pc); > + state->has_next =3D false; > + } > + > + if (trace_all_insns) { > + g_autoptr(GString) report =3D g_string_new(NULL); > + g_string_append_printf(report, "Exec insn at %"PRIx64" on VCPU %= d\n", > + state->last_pc, vcpu_index); > + qemu_plugin_outs(report->str); > + } > +} > + > +static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb) > +{ > + size_t n_insns =3D qemu_plugin_tb_n_insns(tb); > + for (size_t i =3D 0; i < n_insns; i++) { > + struct qemu_plugin_insn *insn =3D qemu_plugin_tb_get_insn(tb, i); > + uint64_t pc =3D qemu_plugin_insn_vaddr(insn); > + uint64_t next_pc =3D pc + qemu_plugin_insn_size(insn); > + uint64_t has_next =3D (i + 1) < n_insns; > + > + qemu_plugin_register_vcpu_insn_exec_inline_per_vcpu(insn, > + QEMU_PLUGIN_= INLINE_STORE_U64, > + last_pc, pc); > + qemu_plugin_register_vcpu_insn_exec_inline_per_vcpu(insn, > + QEMU_PLUGIN_= INLINE_STORE_U64, > + from_pc, nex= t_pc); > + qemu_plugin_register_vcpu_insn_exec_inline_per_vcpu(insn, > + QEMU_PLUGIN_= INLINE_STORE_U64, > + has_from, ha= s_next); > + qemu_plugin_register_vcpu_insn_exec_cb(insn, insn_exec, > + QEMU_PLUGIN_CB_NO_REGS, N= ULL); > + } > +} > + > +QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id, > + const qemu_info_t *info, > + int argc, char **argv) > +{ > + /* Set defaults */ > + abort_on_mismatch =3D true; > + trace_all_insns =3D false; > + > + for (int i =3D 0; i < argc; i++) { > + char *opt =3D argv[i]; > + g_auto(GStrv) tokens =3D g_strsplit(opt, "=3D", 2); > + if (g_strcmp0(tokens[0], "abort") =3D=3D 0) { > + if (!qemu_plugin_bool_parse(tokens[0], tokens[1], > + &abort_on_mismatch)) { > + fprintf(stderr, "boolean argument parsing failed: %s\n",= opt); > + return -1; > + } > + } else if (g_strcmp0(tokens[0], "trace-all") =3D=3D 0) { > + if (!qemu_plugin_bool_parse(tokens[0], tokens[1], > + &trace_all_insns)) { > + fprintf(stderr, "boolean argument parsing failed: %s\n",= opt); > + return -1; > + } > + } else { > + fprintf(stderr, "option parsing failed: %s\n", opt); > + return -1; > + } > + } > + > + states =3D qemu_plugin_scoreboard_new(sizeof(struct cpu_state)); > + last_pc =3D qemu_plugin_scoreboard_u64_in_struct(states, struct cpu_= state, > + last_pc); > + from_pc =3D qemu_plugin_scoreboard_u64_in_struct(states, struct cpu_= state, > + from_pc); > + has_from =3D qemu_plugin_scoreboard_u64_in_struct(states, struct cpu= _state, > + has_from); > + > + qemu_plugin_register_vcpu_discon_cb(id, QEMU_PLUGIN_DISCON_ALL, > + vcpu_discon); > + qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans); > + > + return 0; > +} > diff --git a/tests/tcg/plugins/meson.build b/tests/tcg/plugins/meson.build > index 61a007d9e7..561584159e 100644 > --- a/tests/tcg/plugins/meson.build > +++ b/tests/tcg/plugins/meson.build > @@ -1,6 +1,6 @@ > t =3D [] > if get_option('plugins') > - foreach i : ['bb', 'empty', 'inline', 'insn', 'mem', 'reset', 'syscall= ', 'patch'] > + foreach i : ['bb', 'discons', 'empty', 'inline', 'insn', 'mem', 'reset= ', 'syscall', 'patch'] > if host_os =3D=3D 'windows' > t +=3D shared_module(i, files(i + '.c') + '../../../contrib/plugin= s/win32_linker.c', > include_directories: '../../../include/qemu', --=20 Alex Benn=C3=A9e Virtualisation Tech Lead @ Linaro