added strace pid filtering feature

doc/user-getting-started.md

@@ -114,6 +114,11 @@ Options:
                             from the output. Can be used in conjunction with any of the above filters 
                             E.g: To filter by tid=101, specify - 
                             --strace-filter-tid '101'
+    --strace-filter-pid 'pid1:pid2...'
+                         -- Specify a set of process IDs to be traced, all others are excluded 
+                            from the output. Can be used in conjunction with any of the above filters 
+                            E.g: To filter by pid=101, specify - 
+                            --strace-filter-pid=101
 ```
 
 You can also specify many other parameters in a configuration file, conventionally called `config.json`, you will also use this configuration file to package your application.

include/myst/kernel.h

@@ -91,6 +91,15 @@ typedef struct _myst_strace_config
     */
     long tid_trace[MYST_MAX_IDS];
 
+    /* If the pid filter is enabled, this will store the number of pids to
+     * filter by */
+    int pid_filter_num;
+
+    /*
+        If pid filter is enabled, stores the list of pids to include.
+    */
+    long pid_trace[MYST_MAX_IDS];
+
 } myst_strace_config_t;
 
 typedef struct myst_kernel_args

kernel/syscall.c

@@ -225,6 +225,23 @@ static bool _trace_syscall(long n)
             // tid filter is specified, but no match in filter
             return false;
         }
+        if (__myst_kernel_args.strace_config.pid_filter_num > 0)
+        {
+            // Check if thread filtering is enabled & follow filter
+            myst_process_t* self = myst_process_self();
+            pid_t current_pid = self->pid;
+
+            for (int i = 0; i < __myst_kernel_args.strace_config.pid_filter_num;
+                 i++)
+            {
+                if ((long)current_pid ==
+                    __myst_kernel_args.strace_config.pid_trace[i])
+                    return true;
+            }
+
+            // pid filter is specified, but no match in filter
+            return false;
+        }
 
         // syscall filtering is enabled & syscall is to be traversed
         return true;

tests/strace/.gitignore

@@ -14,4 +14,10 @@
 14
 15
 16
+17
+18
+19
+20
+21
+22
 test*.txt

tests/strace/14test.expected.txt

@@ -0,0 +1,2 @@
+Tid file is invalid. Must be a positive number.
+Aborted (core dumped)

tests/strace/Makefile

@@ -22,7 +22,7 @@ endif
 
 OPTS += --thread-stack-size=1048576
 
-__TESTS=1 2 3 4 5 6 7 8 9 10 11 12 13
+__TESTS=1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
 .PHONY: $(__TESTS)
 
 tests: $(__TESTS)
@@ -91,6 +91,25 @@ test13:
 	$(RUNTEST) test ! -s test13.txt || (cat test13.txt | grep -E '(tid=|SYS_)' > 15 && cat test13.txt | grep 'tid=101' | grep -v 'SYS_mmap' > 16 && $(RUNTEST) diff 15 16)
 	echo  "=== test13 passed"
 
+test14:
+	$(MYST_EXEC) rootfs /bin/strace --strace-filter-pid=file $(OPTS) 2> test14.txt || $(RUNTEST) diff test14.txt 10test.expected.txt
+	echo "=== test14 passed"
+
+test15:
+	$(MYST_EXEC) rootfs /bin/strace --strace-filter-pid=101 $(OPTS) 2> test15.txt
+	$(RUNTEST) test ! -s test15.txt || (cat test15.txt | grep "pid=" > 17 && cat test15.txt | grep 'pid=101' > 18 && $(RUNTEST) diff 17 18)
+	echo "=== test15 passed"
+
+test16:
+	$(MYST_EXEC) rootfs /bin/strace --strace-filter=SYS_mmap --strace-filter-pid 101 $(OPTS) 2> test16.txt
+	$(RUNTEST) test ! -s test16.txt || (cat test16.txt | grep -E '(pid=|SYS_)' > 19 && cat test16.txt | grep -E '(pid=101|SYS_mmap)' > 20 && $(RUNTEST) diff 19 20)
+	echo  "=== test16 passed"
+
+test17:
+	$(MYST_EXEC) rootfs /bin/strace --strace-exclude-filter=SYS_mmap --strace-filter-pid 101 $(OPTS) 2> test17.txt
+	$(RUNTEST) test ! -s test17.txt || (cat test17.txt | grep -E '(pid=|SYS_)' > 21 && cat test17.txt | grep 'pid=101' | grep -v 'SYS_mmap' > 22 && $(RUNTEST) diff 21 22)
+	echo  "=== test17 passed"
+
 myst:
 	$(MAKE) -C $(TOP)/tools/myst
 

tools/myst/host/exec.c

@@ -420,6 +420,11 @@ Options:\n\
                             from the output. Can be used in conjunction with any of the above filters \n\
                             E.g: To filter by tid=101, specify - \n\
                             --strace-filter-tid '101'\n\
+    --strace-filter-pid 'pid1:pid2...'\n\
+                         -- Specify a set of process IDs to be traced, all others are excluded \n\
+                            from the output. Can be used in conjunction with any of the above filters \n\
+                            E.g: To filter by pid=101, specify - \n\
+                            --strace-filter-pid=101\n\
 \n"
 
 int exec_action(int argc, const char* argv[], const char* envp[])
@@ -460,16 +465,13 @@ int exec_action(int argc, const char* argv[], const char* envp[])
             cli_getopt(&argc, argv, "--strace", NULL) == 0)
         {
             options.strace_config.trace_syscalls = true;
-            // fprintf(stderr, "Failed to  final options\n");
         }
 
         if (myst_strace_parse_config(&argc, argv, &options.strace_config) == 0)
         {
             options.strace_config.trace_syscalls = true;
-            // fprintf(stderr, "Failed to determine final options\n");
         }
 
-        // fprintf(stderr, " to determine final options\n");
         /* Get --trace option */
         if (cli_getopt(&argc, argv, "--trace-errors", NULL) == 0 ||
             cli_getopt(&argc, argv, "--etrace", NULL) == 0)

tools/myst/host/exec_linux.c

@@ -117,6 +117,11 @@ Options:\n\
                             from the output. Can be used in conjunction with any of the above filters \n\
                             E.g: To filter by tid=101, specify - \n\
                             --strace-filter-tid '101'\n\
+    --strace-filter-pid 'pid1:pid2...'\n\
+                         -- Specify a set of process IDs to be traced, all others are excluded \n\
+                            from the output. Can be used in conjunction with any of the above filters \n\
+                            E.g: To filter by pid=101, specify - \n\
+                            --strace-filter-pid=101\n\
 \n\
 "
 

tools/myst/host/strace.c

@@ -91,14 +91,73 @@ int myst_set_strace_filter(
     return 0;
 }
 
+int myst_set_strace_id_filter(
+    const char* id_filter,
+    myst_strace_config_t* strace_config,
+    bool tid)
+{
+    char** tokens = NULL;
+    size_t num_tokens = 0;
+    int ret = -1;
+
+    if (myst_strsplit(id_filter, ":", &tokens, &num_tokens) != 0)
+    {
+        fprintf(
+            stderr,
+            "Invalid strace-filter-tid or strace-filter-pid option '%s' "
+            "specified.\n",
+            id_filter);
+        abort();
+    }
+
+    for (size_t i = 0; i < num_tokens; ++i)
+    {
+        long id;
+        const char* _id = tokens[i];
+
+        ret = myst_str2long(_id, &id);
+
+        if (id <= 0)
+        {
+            fprintf(
+                stderr,
+                "tid or pid%s is invalid. Must be a positive number.\n",
+                _id);
+            abort();
+        }
+
+        if (tid)
+            strace_config->tid_trace[i] = id;
+        else
+            strace_config->pid_trace[i] = id;
+
+        if (i >= MYST_MAX_IDS)
+        {
+            fprintf(
+                stderr,
+                "Tid %s exceeds trace array. Fix "
+                "myst_syscall_config_t\n",
+                _id);
+            abort();
+        }
+    }
+
+    if (tid)
+        strace_config->tid_filter_num = num_tokens;
+    else
+        strace_config->pid_filter_num = num_tokens;
+
+    return ret;
+}
+
 int myst_strace_parse_config(
     int* argc,
     const char** argv,
     myst_strace_config_t* strace_config)
 {
     int ret = -1;
     const char* filter = NULL;
-    const char* tid_filter = NULL;
+    const char* id_filter = NULL;
     char** tokens = NULL;
     size_t num_tokens = 0;
     bool filter_flag = 0;
@@ -145,48 +204,10 @@ int myst_strace_parse_config(
         ret = myst_set_strace_filter(num_tokens, tokens, strace_config, 1);
     }
 
-    if (cli_getopt(argc, argv, "--strace-filter-tid", &tid_filter) == 0 &&
-        tid_filter)
+    if (cli_getopt(argc, argv, "--strace-filter-tid", &id_filter) == 0 &&
+        id_filter)
     {
-        if (myst_strsplit(tid_filter, ":", &tokens, &num_tokens) != 0)
-        {
-            fprintf(
-                stderr,
-                "Invalid strace-filter-tid option '%s' specified.\n",
-                tid_filter);
-            abort();
-        }
-
-        for (size_t i = 0; i < num_tokens; ++i)
-        {
-            long tid;
-            const char* _tid = tokens[i];
-
-            ret = myst_str2long(_tid, &tid);
-
-            if (tid <= 0)
-            {
-                fprintf(
-                    stderr,
-                    "Tid %s is invalid. Must be a positive number.\n",
-                    _tid);
-                abort();
-            }
-
-            strace_config->tid_trace[i] = tid;
-
-            if (i >= MYST_MAX_IDS)
-            {
-                fprintf(
-                    stderr,
-                    "Tid %s exceeds trace array. Fix "
-                    "myst_syscall_config_t\n",
-                    _tid);
-                abort();
-            }
-        }
-
-        strace_config->tid_filter_num = num_tokens;
+        myst_set_strace_id_filter(id_filter, strace_config, true);
     }
     else
     {
@@ -195,6 +216,18 @@ int myst_strace_parse_config(
         ret = 0;
     }
 
+    if (cli_getopt(argc, argv, "--strace-filter-pid", &id_filter) == 0 &&
+        id_filter)
+    {
+        ret = myst_set_strace_id_filter(id_filter, strace_config, false);
+    }
+    else
+    {
+        // tid filter is not enabled
+        strace_config->pid_filter_num = 0;
+        ret = 0;
+    }
+
     if (tokens)
         free(tokens);