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Tue, 16 Jan 2024 09:44:16 +0000 (GMT) From: Ilya Leoshkevich To: =?utf-8?q?Alex_Benn=C3=A9e?= , Riku Voipio Cc: =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , qemu-devel@nongnu.org, Ilya Leoshkevich Subject: [PATCH v2 1/2] gdbstub: Implement catching syscalls Date: Tue, 16 Jan 2024 10:41:53 +0100 Message-ID: <20240116094411.216665-2-iii@linux.ibm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240116094411.216665-1-iii@linux.ibm.com> References: <20240116094411.216665-1-iii@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 8LhwRgHf2rTT9PwwKSbdScRp1FLCC5M6 X-Proofpoint-ORIG-GUID: 8LhwRgHf2rTT9PwwKSbdScRp1FLCC5M6 X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-01-16_04,2024-01-15_03,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 suspectscore=0 malwarescore=0 lowpriorityscore=0 bulkscore=0 clxscore=1015 mlxlogscore=999 spamscore=0 priorityscore=1501 adultscore=0 impostorscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2401160077 Received-SPF: pass client-ip=148.163.158.5; envelope-from=iii@linux.ibm.com; helo=mx0b-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_H4=0.001, RCVD_IN_MSPIKE_WL=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 GDB supports stopping on syscall entry and exit using the "catch syscall" command. It relies on 3 packets, which are currently not supported by QEMU: * qSupported:QCatchSyscalls+ [1] * QCatchSyscalls: [2] * T05syscall_entry: and T05syscall_return: [3] Implement generation and handling of these packets. [1] https://sourceware.org/gdb/current/onlinedocs/gdb.html/General-Query-Packets.html#qSupported [2] https://sourceware.org/gdb/current/onlinedocs/gdb.html/General-Query-Packets.html#QCatchSyscalls [3] https://sourceware.org/gdb/current/onlinedocs/gdb.html/Stop-Reply-Packets.html Signed-off-by: Ilya Leoshkevich --- gdbstub/gdbstub.c | 9 +++ gdbstub/internals.h | 2 + gdbstub/user-target.c | 5 ++ gdbstub/user.c | 104 ++++++++++++++++++++++++++++++++++- include/gdbstub/user.h | 29 +++++++++- include/user/syscall-trace.h | 7 ++- 6 files changed, 151 insertions(+), 5 deletions(-) diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c index 46d752bbc2c..7e73e916bdc 100644 --- a/gdbstub/gdbstub.c +++ b/gdbstub/gdbstub.c @@ -1617,6 +1617,7 @@ static void handle_query_supported(GArray *params, void *user_ctx) if (gdbserver_state.c_cpu->opaque) { g_string_append(gdbserver_state.str_buf, ";qXfer:auxv:read+"); } + g_string_append(gdbserver_state.str_buf, ";QCatchSyscalls+"); #endif g_string_append(gdbserver_state.str_buf, ";qXfer:exec-file:read+"); #endif @@ -1810,6 +1811,14 @@ static const GdbCmdParseEntry gdb_gen_set_table[] = { .schema = "l0" }, #endif +#if defined(CONFIG_USER_ONLY) + { + .handler = gdb_handle_set_catch_syscalls, + .cmd = "CatchSyscalls:", + .cmd_startswith = 1, + .schema = "s0", + }, +#endif }; static void handle_gen_query(GArray *params, void *user_ctx) diff --git a/gdbstub/internals.h b/gdbstub/internals.h index 5c0c725e54c..56b7c13b750 100644 --- a/gdbstub/internals.h +++ b/gdbstub/internals.h @@ -136,6 +136,7 @@ void gdb_append_thread_id(CPUState *cpu, GString *buf); int gdb_get_cpu_index(CPUState *cpu); unsigned int gdb_get_max_cpus(void); /* both */ bool gdb_can_reverse(void); /* softmmu, stub for user */ +int gdb_target_sigtrap(void); /* user */ void gdb_create_default_process(GDBState *s); @@ -194,6 +195,7 @@ 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_set_catch_syscalls(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 c4bba4c72c7..b7d4c37cd81 100644 --- a/gdbstub/user-target.c +++ b/gdbstub/user-target.c @@ -418,3 +418,8 @@ void gdb_handle_query_xfer_exec_file(GArray *params, void *user_ctx) ts->bprm->filename + offset); gdb_put_strbuf(); } + +int gdb_target_sigtrap(void) +{ + return TARGET_SIGTRAP; +} diff --git a/gdbstub/user.c b/gdbstub/user.c index dbe1d9b8875..01dd7169258 100644 --- a/gdbstub/user.c +++ b/gdbstub/user.c @@ -10,6 +10,7 @@ */ #include "qemu/osdep.h" +#include "qemu/bitops.h" #include "qemu/cutils.h" #include "qemu/sockets.h" #include "exec/hwaddr.h" @@ -21,11 +22,25 @@ #include "trace.h" #include "internals.h" +enum GDBCatchSyscallsState { + GDB_CATCH_SYSCALLS_NONE, + GDB_CATCH_SYSCALLS_ALL, + GDB_CATCH_SYSCALLS_SELECTED, +}; +#define GDB_NR_SYSCALLS 1024 +typedef unsigned long GDBSyscallsMask[BITS_TO_LONGS(GDB_NR_SYSCALLS)]; + /* User-mode specific state */ typedef struct { int fd; char *socket_path; int running_state; + /* + * Store syscalls mask without memory allocation in order to avoid + * implementing synchronization. + */ + enum GDBCatchSyscallsState catch_syscalls_state; + GDBSyscallsMask catch_syscalls_mask; } GDBUserState; static GDBUserState gdbserver_user_state; @@ -121,7 +136,7 @@ void gdb_qemu_exit(int code) exit(code); } -int gdb_handlesig(CPUState *cpu, int sig) +int gdb_handlesig_reason(CPUState *cpu, int sig, const char *reason) { char buf[256]; int n; @@ -141,6 +156,9 @@ int gdb_handlesig(CPUState *cpu, int sig) "T%02xthread:", gdb_target_signal_to_gdb(sig)); gdb_append_thread_id(cpu, gdbserver_state.str_buf); g_string_append_c(gdbserver_state.str_buf, ';'); + if (reason) { + g_string_append(gdbserver_state.str_buf, reason); + } gdb_put_strbuf(); gdbserver_state.allow_stop_reply = false; } @@ -499,3 +517,87 @@ void gdb_syscall_handling(const char *syscall_packet) gdb_put_packet(syscall_packet); gdb_handlesig(gdbserver_state.c_cpu, 0); } + +static bool should_catch_syscall(int num) +{ + switch (gdbserver_user_state.catch_syscalls_state) { + case GDB_CATCH_SYSCALLS_NONE: + return false; + case GDB_CATCH_SYSCALLS_ALL: + return true; + case GDB_CATCH_SYSCALLS_SELECTED: + if (num < 0 || num >= GDB_NR_SYSCALLS) { + return false; + } else { + return test_bit(num, gdbserver_user_state.catch_syscalls_mask); + } + default: + g_assert_not_reached(); + } +} + +void gdb_syscall_entry(CPUState *cs, int num) +{ + char reason[32]; + + if (should_catch_syscall(num)) { + snprintf(reason, sizeof(reason), "syscall_entry:%x;", num); + gdb_handlesig_reason(cs, gdb_target_sigtrap(), reason); + } +} + +void gdb_syscall_return(CPUState *cs, int num) +{ + char reason[32]; + + if (should_catch_syscall(num)) { + snprintf(reason, sizeof(reason), "syscall_return:%x;", num); + gdb_handlesig_reason(cs, gdb_target_sigtrap(), reason); + } +} + +void gdb_handle_set_catch_syscalls(GArray *params, void *user_ctx) +{ + enum GDBCatchSyscallsState catch_syscalls_state; + const char *param = get_param(params, 0)->data; + GDBSyscallsMask catch_syscalls_mask; + bool catch_syscalls_none; + unsigned int num; + const char *p; + + catch_syscalls_none = strcmp(param, "0") == 0; + if (catch_syscalls_none || strcmp(param, "1") == 0) { + gdbserver_user_state.catch_syscalls_state = + catch_syscalls_none ? GDB_CATCH_SYSCALLS_NONE : + GDB_CATCH_SYSCALLS_ALL; + gdb_put_packet("OK"); + return; + } + + if (param[0] == '1' && param[1] == ';') { + catch_syscalls_state = GDB_CATCH_SYSCALLS_SELECTED; + memset(catch_syscalls_mask, 0, sizeof(catch_syscalls_mask)); + for (p = ¶m[2];; p++) { + if (qemu_strtoui(p, &p, 16, &num) || (*p && *p != ';')) { + goto err; + } + if (num >= GDB_NR_SYSCALLS) { + /* Fall back to reporting all syscalls. */ + catch_syscalls_state = GDB_CATCH_SYSCALLS_ALL; + } else { + set_bit(num, catch_syscalls_mask); + } + if (!*p) { + break; + } + } + gdbserver_user_state.catch_syscalls_state = catch_syscalls_state; + memcpy(gdbserver_user_state.catch_syscalls_mask, catch_syscalls_mask, + sizeof(catch_syscalls_mask)); + gdb_put_packet("OK"); + return; + } + +err: + gdb_put_packet("E00"); +} diff --git a/include/gdbstub/user.h b/include/gdbstub/user.h index d392e510c59..68b6534130c 100644 --- a/include/gdbstub/user.h +++ b/include/gdbstub/user.h @@ -10,9 +10,10 @@ #define GDBSTUB_USER_H /** - * gdb_handlesig() - yield control to gdb + * gdb_handlesig_reason() - yield control to gdb * @cpu: CPU * @sig: if non-zero, the signal number which caused us to stop + * @reason: stop reason for stop reply packet or NULL * * This function yields control to gdb, when a user-mode-only target * needs to stop execution. If @sig is non-zero, then we will send a @@ -24,7 +25,18 @@ * or 0 if no signal should be delivered, ie the signal that caused * us to stop should be ignored. */ -int gdb_handlesig(CPUState *, int); +int gdb_handlesig_reason(CPUState *, int, const char *); + +/** + * gdb_handlesig() - yield control to gdb + * @cpu CPU + * @sig: if non-zero, the signal number which caused us to stop + * @see gdb_handlesig_reason() + */ +static inline int gdb_handlesig(CPUState *cpu, int sig) +{ + return gdb_handlesig_reason(cpu, sig, NULL); +} /** * gdb_signalled() - inform remote gdb of sig exit @@ -39,5 +51,18 @@ void gdb_signalled(CPUArchState *as, int sig); */ void gdbserver_fork(CPUState *cs); +/** + * gdb_syscall_entry() - inform gdb of syscall entry and yield control to it + * @cs: CPU + * @num: syscall number + */ +void gdb_syscall_entry(CPUState *cs, int num); + +/** + * gdb_syscall_entry() - inform gdb of syscall return and yield control to it + * @cs: CPU + * @num: syscall number + */ +void gdb_syscall_return(CPUState *cs, int num); #endif /* GDBSTUB_USER_H */ diff --git a/include/user/syscall-trace.h b/include/user/syscall-trace.h index 557f881a79b..b48b2b2d0ae 100644 --- a/include/user/syscall-trace.h +++ b/include/user/syscall-trace.h @@ -11,6 +11,7 @@ #define SYSCALL_TRACE_H #include "exec/user/abitypes.h" +#include "gdbstub/user.h" #include "qemu/plugin.h" #include "trace/trace-root.h" @@ -20,7 +21,7 @@ * could potentially unify the -strace code here as well. */ -static inline void record_syscall_start(void *cpu, int num, +static inline void record_syscall_start(CPUState *cpu, int num, abi_long arg1, abi_long arg2, abi_long arg3, abi_long arg4, abi_long arg5, abi_long arg6, @@ -29,11 +30,13 @@ static inline void record_syscall_start(void *cpu, int num, qemu_plugin_vcpu_syscall(cpu, num, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8); + gdb_syscall_entry(cpu, num); } -static inline void record_syscall_return(void *cpu, int num, abi_long ret) +static inline void record_syscall_return(CPUState *cpu, int num, abi_long ret) { qemu_plugin_vcpu_syscall_ret(cpu, num, ret); + gdb_syscall_return(cpu, num); }