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Wed, 10 May 2023 20:27:07 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D4CC020063; Wed, 10 May 2023 20:27:06 +0000 (GMT) Received: from heavy.boeblingen.de.ibm.com (unknown [9.171.51.237]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 10 May 2023 20:27:06 +0000 (GMT) From: Ilya Leoshkevich To: =?utf-8?q?Alex_Benn=C3=A9e?= , =?utf-8?q?Philipp?= =?utf-8?q?e_Mathieu-Daud=C3=A9?= , Laurent Vivier Cc: "Dominik 'Disconnect3d' Czarnota" , Christian Borntraeger , Andreas Arnez , qemu-devel@nongnu.org, Ilya Leoshkevich Subject: [PATCH RESEND 4/6] gdbstub: Add support for info proc mappings Date: Wed, 10 May 2023 22:26:52 +0200 Message-Id: <20230510202654.225689-5-iii@linux.ibm.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230510202654.225689-1-iii@linux.ibm.com> References: <20230510202654.225689-1-iii@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 2nYY3gIvJ6T5aRW5_8hoySzXqqsCZlNO X-Proofpoint-GUID: dBIGikKBqw1c3IxKBRrDiaYCMF6iLEtM X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-05-10_04,2023-05-05_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 mlxscore=0 suspectscore=0 bulkscore=0 adultscore=0 impostorscore=0 lowpriorityscore=0 mlxlogscore=999 priorityscore=1501 clxscore=1015 malwarescore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2304280000 definitions=main-2305100163 Received-SPF: pass client-ip=148.163.156.1; envelope-from=iii@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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 Currently the GDB's generate-core-file command doesn't work well with qemu-user: the resulting dumps are huge [1] and at the same time incomplete (argv and envp are missing). The reason is that GDB has no access to proc mappings and therefore has to fall back to using heuristics for discovering them. This is, in turn, because qemu-user does not implement the Host I/O feature of the GDB Remote Serial Protocol. Implement vFile:{open,close,pread,readlink} and also qXfer:exec-file:read+. With that, generate-core-file begins to work on aarch64 and s390x, albeit with two deficiencies: * GDB still tries to dump the host mappings, because QEMU does not fake /proc/$PID/smaps (as opposed to /proc/$PID/maps). The user-visible effect is only a bunch of warnings. * PT_LOAD segments lack PF_X flags (I have not debugged this). The impact of these issues on usability is fairly low, so they can be resolved later. [1] https://sourceware.org/pipermail/gdb-patches/2023-May/199432.html Co-developed-by: Dominik 'Disconnect3d' Czarnota Signed-off-by: Ilya Leoshkevich --- gdbstub/gdbstub.c | 45 +++++++++++++- gdbstub/internals.h | 5 ++ gdbstub/user-target.c | 139 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 187 insertions(+), 2 deletions(-) diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c index 003db59b1b2..c4112d6eacd 100644 --- a/gdbstub/gdbstub.c +++ b/gdbstub/gdbstub.c @@ -1326,6 +1326,36 @@ static const GdbCmdParseEntry gdb_v_commands_table[] = { .cmd = "Kill;", .cmd_startswith = 1 }, +#ifdef CONFIG_USER_ONLY + /* + * Host I/O Packets. See [1] for details. + * [1] https://sourceware.org/gdb/onlinedocs/gdb/Host-I_002fO-Packets.html + */ + { + .handler = gdb_handle_v_file_open, + .cmd = "File:open:", + .cmd_startswith = 1, + .schema = "s,L,L0" + }, + { + .handler = gdb_handle_v_file_close, + .cmd = "File:close:", + .cmd_startswith = 1, + .schema = "l0" + }, + { + .handler = gdb_handle_v_file_pread, + .cmd = "File:pread:", + .cmd_startswith = 1, + .schema = "l,L,L0" + }, + { + .handler = gdb_handle_v_file_readlink, + .cmd = "File:readlink:", + .cmd_startswith = 1, + .schema = "s0" + }, +#endif }; static void handle_v_commands(GArray *params, void *user_ctx) @@ -1471,11 +1501,14 @@ static void handle_query_supported(GArray *params, void *user_ctx) ";ReverseStep+;ReverseContinue+"); } -#if defined(CONFIG_USER_ONLY) && defined(CONFIG_LINUX) +#if defined(CONFIG_USER_ONLY) +#if defined(CONFIG_LINUX) if (gdbserver_state.c_cpu->opaque) { g_string_append(gdbserver_state.str_buf, ";qXfer:auxv:read+"); } #endif + g_string_append(gdbserver_state.str_buf, ";qXfer:exec-file:read+"); +#endif if (params->len && strstr(get_param(params, 0)->data, "multiprocess+")) { @@ -1614,13 +1647,21 @@ static const GdbCmdParseEntry gdb_gen_query_table[] = { .cmd_startswith = 1, .schema = "s:l,l0" }, -#if defined(CONFIG_USER_ONLY) && defined(CONFIG_LINUX) +#if defined(CONFIG_USER_ONLY) +#if defined(CONFIG_LINUX) { .handler = gdb_handle_query_xfer_auxv, .cmd = "Xfer:auxv:read::", .cmd_startswith = 1, .schema = "l,l0" }, +#endif + { + .handler = gdb_handle_query_xfer_exec_file, + .cmd = "Xfer:exec-file:read:", + .cmd_startswith = 1, + .schema = "l:l,l0" + }, #endif { .handler = gdb_handle_query_attached, diff --git a/gdbstub/internals.h b/gdbstub/internals.h index 235f2551bd4..c1217337812 100644 --- a/gdbstub/internals.h +++ b/gdbstub/internals.h @@ -184,6 +184,11 @@ typedef union GdbCmdVariant { void gdb_handle_query_rcmd(GArray *params, void *user_ctx); /* softmmu */ void gdb_handle_query_offsets(GArray *params, void *user_ctx); /* user */ void gdb_handle_query_xfer_auxv(GArray *params, void *user_ctx); /*user */ +void gdb_handle_v_file_open(GArray *params, void *user_ctx); /* user */ +void gdb_handle_v_file_close(GArray *params, void *user_ctx); /* user */ +void gdb_handle_v_file_pread(GArray *params, void *user_ctx); /* user */ +void gdb_handle_v_file_readlink(GArray *params, void *user_ctx); /* user */ +void gdb_handle_query_xfer_exec_file(GArray *params, void *user_ctx); /* user */ void gdb_handle_query_attached(GArray *params, void *user_ctx); /* both */ diff --git a/gdbstub/user-target.c b/gdbstub/user-target.c index fa0e59ec9a5..09df05b5526 100644 --- a/gdbstub/user-target.c +++ b/gdbstub/user-target.c @@ -11,6 +11,10 @@ #include "exec/gdbstub.h" #include "qemu.h" #include "internals.h" +#ifdef CONFIG_LINUX +#include "linux-user/loader.h" +#include "linux-user/qemu.h" +#endif /* * Map target signal numbers to GDB protocol signal numbers and vice @@ -281,3 +285,138 @@ void gdb_handle_query_xfer_auxv(GArray *params, void *user_ctx) gdbserver_state.str_buf->len, true); } #endif + +static const char *get_filename_param(GArray *params, int i) +{ + const char *hex_filename = get_param(params, i)->data; + gdb_hextomem(gdbserver_state.mem_buf, hex_filename, + strlen(hex_filename) / 2); + g_byte_array_append(gdbserver_state.mem_buf, (const guint8 *)"", 1); + return (const char *)gdbserver_state.mem_buf->data; +} + +static void hostio_reply_with_data(const void *buf, size_t n) +{ + g_string_printf(gdbserver_state.str_buf, "F%lx;", n); + gdb_memtox(gdbserver_state.str_buf, buf, n); + gdb_put_packet_binary(gdbserver_state.str_buf->str, + gdbserver_state.str_buf->len, true); +} + +void gdb_handle_v_file_open(GArray *params, void *user_ctx) +{ + const char *filename = get_filename_param(params, 0); + uint64_t flags = get_param(params, 1)->val_ull; + uint64_t mode = get_param(params, 2)->val_ull; + +#ifdef CONFIG_LINUX + int fd = do_guest_openat(gdbserver_state.g_cpu->env_ptr, 0, filename, + flags, mode); +#else + int fd = open(filename, flags, mode); +#endif + if (fd < 0) { + g_string_printf(gdbserver_state.str_buf, "F-1,%d", errno); + } else { + g_string_printf(gdbserver_state.str_buf, "F%d", fd); + } + gdb_put_strbuf(); +} + +void gdb_handle_v_file_close(GArray *params, void *user_ctx) +{ + int fd = get_param(params, 0)->val_ul; + + if (close(fd) == -1) { + g_string_printf(gdbserver_state.str_buf, "F-1,%d", errno); + gdb_put_strbuf(); + return; + } + + gdb_put_packet("F00"); +} + +#define BUFSIZ 8192 + +void gdb_handle_v_file_pread(GArray *params, void *user_ctx) +{ + int fd = get_param(params, 0)->val_ul; + size_t count = get_param(params, 1)->val_ull; + off_t offset = get_param(params, 2)->val_ull; + + size_t bufsiz = MIN(count, BUFSIZ); + g_autofree char *buf = g_try_malloc(bufsiz); + if (buf == NULL) { + gdb_put_packet("E12"); + return; + } + + ssize_t n = pread(fd, buf, bufsiz, offset); + if (n < 0) { + g_string_printf(gdbserver_state.str_buf, "F-1,%d", errno); + gdb_put_strbuf(); + return; + } + hostio_reply_with_data(buf, n); +} + +void gdb_handle_v_file_readlink(GArray *params, void *user_ctx) +{ + const char *filename = get_filename_param(params, 0); + + g_autofree char *buf = g_try_malloc(BUFSIZ); + if (buf == NULL) { + gdb_put_packet("E12"); + return; + } + +#ifdef CONFIG_LINUX + ssize_t n = do_guest_readlink(filename, buf, BUFSIZ); +#else + ssize_t n = readlink(filename, buf, BUFSIZ); +#endif + if (n < 0) { + g_string_printf(gdbserver_state.str_buf, "F-1,%d", errno); + gdb_put_strbuf(); + return; + } + hostio_reply_with_data(buf, n); +} + +void gdb_handle_query_xfer_exec_file(GArray *params, void *user_ctx) +{ + uint32_t pid = get_param(params, 0)->val_ul; + uint32_t offset = get_param(params, 1)->val_ul; + uint32_t length = get_param(params, 2)->val_ul; + + GDBProcess *process = gdb_get_process(pid); + if (!process) { + gdb_put_packet("E00"); + return; + } + + CPUState *cpu = gdb_get_first_cpu_in_process(process); + if (!cpu) { + gdb_put_packet("E00"); + return; + } + + TaskState *ts = cpu->opaque; + if (!ts || !ts->bprm || !ts->bprm->filename) { + gdb_put_packet("E00"); + return; + } + + size_t total_length = strlen(ts->bprm->filename); + if (offset > total_length) { + gdb_put_packet("E00"); + return; + } + if (offset + length > total_length) { + length = total_length - offset; + } + + g_string_printf(gdbserver_state.str_buf, "l%.*s", length, + ts->bprm->filename + offset); + gdb_put_strbuf(); +}