[Pal/Linux,Linux-SGX] Make sure g_debug_map is complete

After this change, `g_debug_map` contains all loaded executables, even
the ones that were loaded by the system (such as main Gramine executable
or protobuf).

This is not necessary for GDB integration, but will help add features
such as crash location reporting (and it already helped simplify the SGX
profiling system).

Signed-off-by: Paweł Marczewski <pawel@invisiblethingslab.com>

Pal/include/host/Linux-common/debug_map.h

@@ -28,4 +28,8 @@ void debug_map_update_debugger(void);
 int debug_map_add(const char* name, void* addr);
 int debug_map_remove(void* addr);
 
+/* Initialize `g_debug_map` with executable files already loaded by the system (main program, and
+ * dynamic libraries). Processes `/proc/self/maps`. */
+int debug_map_init_from_proc_maps(void);
+
 #endif /* DEBUG_MAP_H */

Pal/src/host/Linux-SGX/meson.build

@@ -174,7 +174,6 @@ executable('loader',
     'sgx_platform.c',
     'sgx_process.c',
     'sgx_profile.c',
-    'sgx_profile_glibc.c',
     'sgx_syscall.c',
     'sgx_thread.c',
     pal_linux_common_sources_urts,

Pal/src/host/Linux-SGX/sgx_internal.h

@@ -181,9 +181,6 @@ void sgx_profile_sample_ocall_outer(void* ocall_func);
 
 /* Record a new mapped ELF */
 void sgx_profile_report_elf(const char* filename, void* addr);
-
-/* Record all ELFs from outer PAL */
-void sgx_profile_report_urts_elfs(void);
 #endif
 
 /* perf.data output (sgx_perf_data.h) */

Pal/src/host/Linux-SGX/sgx_main.c

@@ -258,6 +258,13 @@ static int initialize_enclave(struct pal_enclave* enclave, const char* manifest_
         ret = sgx_profile_init();
         if (ret < 0)
             goto out;
+
+        /* Report all ELFs that are already loaded (URTS and dynamic libraries used by it) */
+        struct debug_map* map = g_debug_map;
+        while (map) {
+            sgx_profile_report_elf(map->name, map->addr);
+            map = map->next;
+        }
     }
 #endif
 
@@ -559,9 +566,6 @@ static int initialize_enclave(struct pal_enclave* enclave, const char* manifest_
 
     debug_map_add(enclave->libpal_uri + URI_PREFIX_FILE_LEN, (void*)pal_area->addr);
     sgx_profile_report_elf(enclave->libpal_uri + URI_PREFIX_FILE_LEN, (void*)pal_area->addr);
-
-    /* Report outer PAL maps to profiler, so that we can record samples pointing to outer PAL. */
-    sgx_profile_report_urts_elfs();
 #endif
 
     ret = 0;
@@ -1100,6 +1104,14 @@ int main(int argc, char* argv[], char* envp[]) {
     setup_asan();
 #endif
 
+#ifdef DEBUG
+    ret = debug_map_init_from_proc_maps();
+    if (ret < 0) {
+        log_error("Failed to init debug maps");
+        return unix_to_pal_error(ret);
+    }
+#endif
+
     force_linux_to_grow_stack();
 
     if (argc < 4)

Pal/src/host/Linux-common/debug_map.c

@@ -3,16 +3,17 @@
  *                    Paweł Marczewski <pawel@invisiblethingslab.com>
  */
 
-#include "debug_map.h"
-
 #include <asm/errno.h>
+#include <asm/mman.h>
 
+#include "debug_map.h"
+#include "linux_utils.h"
 #include "spinlock.h"
 
 struct debug_map* _Atomic g_debug_map = NULL;
 
-/* Lock for modifying g_debug_map on our end. Even though the list can be read at any
- * time, we need to prevent concurrent modification. */
+/* Lock for modifying g_debug_map on our end. Even though the list can be read by GDB at any time,
+ * we need to prevent concurrent modification. */
 static spinlock_t g_debug_map_lock = INIT_SPINLOCK_UNLOCKED;
 
 static struct debug_map* debug_map_new(const char* name, void* addr) {
@@ -38,12 +39,26 @@ __attribute__((__noinline__)) void debug_map_update_debugger(void) {
 }
 
 int debug_map_add(const char* name, void* addr) {
-    struct debug_map* map = debug_map_new(name, addr);
-    if (!map)
-        return -ENOMEM;
-
     spinlock_lock(&g_debug_map_lock);
 
+    struct debug_map* map = g_debug_map;
+    while (map) {
+        if (map->addr == addr) {
+            bool name_matches = !strcmp(name, map->name);
+            spinlock_unlock(&g_debug_map_lock);
+            /* If the exact same map is already there, skip adding it and report success: this can
+             * happen when we encounter two executable ranges for the same file. */
+            return name_matches ? 0 : -EEXIST;
+        }
+        map = map->next;
+    }
+
+    map = debug_map_new(name, addr);
+    if (!map) {
+        spinlock_unlock(&g_debug_map_lock);
+        return -ENOMEM;
+    }
+
     map->next = g_debug_map;
     g_debug_map = map;
 
@@ -84,3 +99,31 @@ int debug_map_remove(void* addr) {
 
     return 0;
 }
+
+/* Find a range that (likely) corresponds to a mapped executable file, and add it to debug maps. */
+static int debug_map_init_callback(struct proc_maps_range* r, void* arg) {
+    __UNUSED(arg);
+
+    /* not executable */
+    if (!(r->prot & PROT_EXEC))
+        return 0;
+
+    /* no name */
+    if (!r->name)
+        return 0;
+
+    /* [vvar], [vdso] etc. */
+    if (r->name[0] != '/')
+        return 0;
+
+    /* /dev/sgx etc. */
+    if (strstartswith(r->name, "/dev/"))
+        return 0;
+
+    void* addr = (void*)(r->start - r->offset);
+    return debug_map_add(r->name, addr);
+}
+
+int debug_map_init_from_proc_maps(void) {
+    return parse_proc_maps("/proc/self/maps", debug_map_init_callback, /*arg=*/NULL);
+}

Pal/src/host/Linux/db_main.c

@@ -13,6 +13,7 @@
 
 #include "api.h"
 #include "asan.h"
+#include "debug_map.h"
 #include "elf/elf.h"
 #include "linux_utils.h"
 #include "pal.h"
@@ -236,6 +237,12 @@ noreturn void pal_linux_main(void* initial_rsp, void* fini_callback) {
 
     init_slab_mgr();
 
+#ifdef DEBUG
+    ret = debug_map_init_from_proc_maps();
+    if (ret < 0)
+        INIT_FAIL(-unix_to_pal_error(ret), "failed to init debug maps");
+#endif
+
     g_pal_loader_path = get_main_exec_path();
     g_libpal_path = strdup(argv[1]);
     if (!g_pal_loader_path || !g_libpal_path) {