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[192.155.81.56]) by smtp.gmail.com with ESMTPSA id b4sm799990pfl.101.2022.01.12.17.38.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Jan 2022 17:38:53 -0800 (PST) From: Jeff Xie To: rostedt@goodmis.org Cc: mhiramat@kernel.org, mingo@redhat.com, zanussi@kernel.org, linux-kernel@vger.kernel.org, Jeff Xie Subject: [PATCH v7 2/4] trace/objtrace: get the value of the object Date: Thu, 13 Jan 2022 09:38:33 +0800 Message-Id: <20220113013835.503285-3-xiehuan09@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220113013835.503285-1-xiehuan09@gmail.com> References: <20220113013835.503285-1-xiehuan09@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Using objtrace trigger to get the value of the object which from the kernel function parameter. Syntax: objtrace:add:obj[,offset][:type][:count][if ] Usage: # echo 'p bio_add_page arg1=$arg1' > ./kprobe_events # gdb vmlinux (gdb) p &(((struct bio *)0)->bi_iter.bi_size) $1 = (unsigned int *) 0x28 # echo 'objtrace:add:arg1,0x28:u32:1 if comm == "cat"' > ./events/kprobes/ \ p_bio_add_page_0/trigger # cat /test.txt Signed-off-by: Jeff Xie --- kernel/trace/trace.c | 2 +- kernel/trace/trace_entries.h | 5 +- kernel/trace/trace_object.c | 190 +++++++++++++++++++++++++++++------ kernel/trace/trace_output.c | 6 +- 4 files changed, 169 insertions(+), 34 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 0b627963e343..d5332ece4c67 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5591,7 +5591,7 @@ static const char readme_msg[] = "\t disable_hist::\n" #endif #ifdef CONFIG_TRACE_OBJECT - "\t objtrace:add:obj[:count][if ]\n" + "\t objtrace:add:obj[,offset][:type][:count][if ]\n" #endif #ifdef CONFIG_STACKTRACE "\t\t stacktrace\n" diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h index bb120d9498a9..2407c45a568c 100644 --- a/kernel/trace/trace_entries.h +++ b/kernel/trace/trace_entries.h @@ -413,8 +413,9 @@ FTRACE_ENTRY(object, trace_object_entry, __field( unsigned long, ip ) __field( unsigned long, parent_ip ) __field( unsigned long, object ) + __field( unsigned long, value ) ), - F_printk(" %ps <-- %ps object:%lx\n", - (void *)__entry->ip, (void *)__entry->parent_ip, __entry->object) + F_printk(" %ps <-- %ps object:%lx value:%lx\n", (void *)__entry->ip, + (void *)__entry->parent_ip, __entry->object, __entry->value) ); diff --git a/kernel/trace/trace_object.c b/kernel/trace/trace_object.c index 4af1c117cbfa..774a9dff4d0a 100644 --- a/kernel/trace/trace_object.c +++ b/kernel/trace/trace_object.c @@ -11,7 +11,6 @@ #define MAX_TRACED_OBJECT 5 static DEFINE_RAW_SPINLOCK(trace_obj_lock); static struct trace_event_file event_trace_file; -static const int max_args_num = 6; static atomic_t trace_object_ref; static atomic_t num_traced_obj; static int exit_trace_object(void); @@ -19,8 +18,22 @@ static int init_trace_object(void); static struct object_instance { void *obj; + int obj_type_size; } traced_obj[MAX_TRACED_OBJECT]; +/* objtrace private data */ +struct objtrace_trigger_data { + struct ftrace_event_field *field; + int offset; + int obj_type_size; +}; + +/* get the type size for the special object */ +struct objtrace_fetch_type { + char *name; + int type_size; +}; + static bool object_exist(void *obj) { int i, max; @@ -39,7 +52,7 @@ static bool object_empty(void) return !atomic_read(&num_traced_obj); } -static void set_trace_object(void *obj) +static void set_trace_object(void *obj, int obj_type_size) { unsigned long flags; @@ -59,6 +72,7 @@ static void set_trace_object(void *obj) goto out; } traced_obj[atomic_read(&num_traced_obj)].obj = obj; + traced_obj[atomic_read(&num_traced_obj)].obj_type_size = obj_type_size; /* make sure the num_traced_obj update always appears after traced_obj update */ smp_wmb(); atomic_inc(&num_traced_obj); @@ -67,7 +81,7 @@ static void set_trace_object(void *obj) } static void submit_trace_object(unsigned long ip, unsigned long parent_ip, - unsigned long object) + unsigned long object, unsigned long value) { struct trace_buffer *buffer; @@ -84,18 +98,66 @@ static void submit_trace_object(unsigned long ip, unsigned long parent_ip, entry->ip = ip; entry->parent_ip = parent_ip; entry->object = object; + entry->value = value; event_trigger_unlock_commit(&event_trace_file, buffer, event, entry, pc); } +static inline long get_object_value(unsigned long *val, void *obj, int type_size) +{ + long ret = 0; + + switch (type_size) { + case 1: { + u8 tmp; + + ret = copy_from_kernel_nofault(&tmp, obj, sizeof(tmp)); + if (ret) + goto out; + *val = tmp; + break; + } + case 2: { + u16 tmp; + + ret = copy_from_kernel_nofault(&tmp, obj, sizeof(tmp)); + if (ret) + goto out; + *val = tmp; + break; + } + case 4: { + u32 tmp; + + ret = copy_from_kernel_nofault(&tmp, obj, sizeof(tmp)); + if (ret) + goto out; + *val = tmp; + break; + } + case 8: { + u64 tmp; + + ret = copy_from_kernel_nofault(&tmp, obj, sizeof(tmp)); + if (ret) + goto out; + *val = tmp; + break; + } + default: + return -EINVAL; + } +out: + return ret; +} + static void trace_object_events_call(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, struct ftrace_regs *fregs) { - struct pt_regs *pt_regs = ftrace_get_regs(fregs); - unsigned long obj; - int bit, n; + unsigned long val = 0; + int bit, n, max; bit = ftrace_test_recursion_trylock(ip, parent_ip); if (bit < 0) @@ -104,11 +166,12 @@ trace_object_events_call(unsigned long ip, unsigned long parent_ip, if (object_empty()) goto out; - for (n = 0; n < max_args_num; n++) { - obj = regs_get_kernel_argument(pt_regs, n); - if (object_exist((void *)obj)) - submit_trace_object(ip, parent_ip, obj); - /* The parameters of a function may match multiple objects */ + max = atomic_read(&num_traced_obj); + smp_rmb(); + for (n = 0; n < max; n++) { + if (get_object_value(&val, traced_obj[n].obj, traced_obj[n].obj_type_size)) + goto out; + submit_trace_object(ip, parent_ip, (unsigned long)traced_obj[n].obj, val); } out: ftrace_test_recursion_unlock(bit); @@ -124,12 +187,15 @@ trace_object_trigger(struct event_trigger_data *data, struct trace_buffer *buffer, void *rec, struct ring_buffer_event *event) { + struct objtrace_trigger_data *obj_data = data->private_data; + struct ftrace_event_field *field; + void *obj, *val = NULL; - struct ftrace_event_field *field = data->private_data; - void *obj = NULL; - - memcpy(&obj, rec + field->offset, sizeof(obj)); - set_trace_object(obj); + field = obj_data->field; + memcpy(&val, rec + field->offset, sizeof(val)); + /* get the final object */ + obj = val + obj_data->offset; + set_trace_object(obj, obj_data->obj_type_size); } static void @@ -140,8 +206,10 @@ trace_object_trigger_free(struct event_trigger_ops *ops, return; data->ref--; - if (!data->ref) + if (!data->ref) { + kfree(data->private_data); trigger_data_free(data); + } } static void @@ -276,6 +344,22 @@ static void unregister_object_trigger(char *glob, struct event_trigger_ops *ops, } } +static const struct objtrace_fetch_type objtrace_fetch_types[] = { + {"u8", 1}, + {"s8", 1}, + {"x8", 1}, + {"u16", 2}, + {"s16", 2}, + {"x16", 2}, + {"u32", 4}, + {"s32", 4}, + {"x32", 4}, + {"u64", 8}, + {"s64", 8}, + {"x64", 8}, + {} +}; + static int event_object_trigger_callback(struct event_command *cmd_ops, struct trace_event_file *file, @@ -283,19 +367,22 @@ event_object_trigger_callback(struct event_command *cmd_ops, { struct event_trigger_data *trigger_data; struct event_trigger_ops *trigger_ops; + struct objtrace_trigger_data *obj_data; struct trace_event_call *call; struct ftrace_event_field *field; - char *objtrace_cmd; - char *trigger = NULL; - char *arg; - char *number; - int ret; + char *type, *tr, *obj, *tmp, *trigger = NULL; + char *number, *objtrace_cmd; + int ret, i, def_type_size, obj_type_size = 0; + long offset = 0; ret = -EINVAL; if (!param) goto out; - /* separate the trigger from the filter (c:a:n [if filter]) */ + /* + * separate the trigger from the filter: + * objtrace:add:OBJ[,OFFS][:TYPE][:COUNT] [if filter] + */ trigger = strsep(¶m, " \t"); if (!trigger) goto out; @@ -309,33 +396,79 @@ event_object_trigger_callback(struct event_command *cmd_ops, if (!objtrace_cmd || strcmp(objtrace_cmd, "add")) goto out; - arg = strsep(&trigger, ":"); - if (!arg) + obj = strsep(&trigger, ":"); + if (!obj) goto out; + + tr = strchr(obj, ','); + if (!tr) + offset = 0; + else { + *tr++ = '\0'; + ret = kstrtol(tr, 0, &offset); + if (ret) + goto out; + } + + ret = -EINVAL; call = file->event_call; - field = trace_find_event_field(call, arg); + field = trace_find_event_field(call, obj); if (!field) goto out; if (field->size != sizeof(void *)) goto out; + def_type_size = sizeof(void *); + if (!trigger) { + obj_type_size = def_type_size; + goto skip_get_type; + } + tmp = trigger; + type = strsep(&trigger, ":"); + if (!type) + obj_type_size = def_type_size; + else if (isdigit(type[0])) { + obj_type_size = def_type_size; + trigger = tmp; + } else { + for (i = 0; objtrace_fetch_types[i].name; i++) { + if (strcmp(objtrace_fetch_types[i].name, type) == 0) { + obj_type_size = objtrace_fetch_types[i].type_size; + break; + } + } + } + if (!obj_type_size) + goto out; +skip_get_type: trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger); ret = -ENOMEM; + obj_data = kzalloc(sizeof(*obj_data), GFP_KERNEL); + if (!obj_data) + goto out; + + obj_data->field = field; + obj_data->offset = offset; + obj_data->obj_type_size = obj_type_size; + trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL); - if (!trigger_data) + if (!trigger_data) { + kfree(obj_data); goto out; + } trigger_data->count = -1; trigger_data->ops = trigger_ops; trigger_data->cmd_ops = cmd_ops; - trigger_data->private_data = field; + trigger_data->private_data = obj_data; INIT_LIST_HEAD(&trigger_data->list); INIT_LIST_HEAD(&trigger_data->named_list); if (glob[0] == '!') { cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file); + kfree(obj_data); kfree(trigger_data); ret = 0; goto out; @@ -390,6 +523,7 @@ event_object_trigger_callback(struct event_command *cmd_ops, out_free: if (cmd_ops->set_filter) cmd_ops->set_filter(NULL, trigger_data, NULL); + kfree(obj_data); kfree(trigger_data); goto out; } diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index d747aed27104..12a971927d8c 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -1553,6 +1553,7 @@ static enum print_line_t trace_object_print(struct trace_iterator *iter, int fla trace_assign_type(field, iter->ent); print_fn_trace(s, field->ip, field->parent_ip, flags); trace_seq_printf(s, " object:0x%lx", field->object); + trace_seq_printf(s, " value:0x%lx", field->value); trace_seq_putc(s, '\n'); return trace_handle_return(s); @@ -1565,9 +1566,8 @@ static enum print_line_t trace_object_raw(struct trace_iterator *iter, int flags trace_assign_type(field, iter->ent); - trace_seq_printf(&iter->seq, "%lx %lx\n", - field->ip, - field->parent_ip); + trace_seq_printf(&iter->seq, "%lx %lx %lx %lx\n", field->ip, + field->parent_ip, field->object, field->value); return trace_handle_return(&iter->seq); } -- 2.25.1