markers: export pointer array instead of struct marker

Ensures we don't end up running in gcc/linker structure alignment problems by
exporting an array of pointers instead of the structures per se.

Same fix as done for tracepoints for the mainline kernel.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/include/ust/marker.h b/include/ust/marker.h
index ef3c1bd8acfd7fb30f1eeccccf4016d2364d6063..cac71ffc59fe641ade37b47c8daa0a66dbc57275 100644 (file)
--- a/include/ust/marker.h
+++ b/include/ust/marker.h
@@ -75,11 +75,7 @@ struct marker {
        const char *tp_name;    /* Optional tracepoint name */
        void *tp_cb;            /* Optional tracepoint callback */
        void *location;         /* Address of marker in code */
-} __attribute__((aligned(128)));/*
-                                * Aligned on 128 bytes because it is
-                                * globally visible and gcc happily
-                                * align these on the structure size.
-                                */
+};
 
 #define GET_MARKER(channel, name)      (__mark_##channel##_##name)
 
@@ -111,7 +107,6 @@ struct marker {
                asm volatile (                                                                  \
                        /*".section __markers\n\t"*/ \
                        ".section __markers,\"aw\",@progbits\n\t"                                       \
-                       ".balign 128\n\t"                                                               \
                        "2:\n\t" \
                        _ASM_PTR "(__mstrtab_" __stringify(channel) "_" __stringify(name) "_channel_" __stringify(unique) ")\n\t" /* channel string */ \
                        _ASM_PTR "(__mstrtab_" __stringify(channel) "_" __stringify(name) "_name_" __stringify(unique) ")\n\t" /* name string */ \
@@ -129,7 +124,12 @@ struct marker {
                        _ASM_PTR "0\n\t" /* tp_cb */                                            \
                        _ASM_PTR "(1f)\n\t" /* location */                                              \
                        ".previous\n\t"                                                         \
-                       "1:\n\t"                                                                        \
+                       /*".section __markers_ptrs\n\t"*/ \
+                       ".section __markers_ptrs,\"a\",@progbits\n\t"                           \
+                       ".balign 8\n\t"                                                         \
+                       _ASM_PTR "(2b)\n\t"                                                     \
+                       ".previous\n\t"                                                         \
+                       "1:\n\t"                                                                \
                        ARCH_COPY_ADDR("%[outptr]")                                             \
                : [outptr] "=r" (m) );                                                          \
                                                                                                \
@@ -147,13 +147,16 @@ struct marker {
                __attribute__((section("__markers_strings")))           \
                = #channel "\0" #name "\0" format;                      \
                static struct marker GET_MARKER(channel, name)          \
-               __attribute__((section("__markers"), aligned(128))) =   \
+               __attribute__((section("__markers"))) =                 \
                { __mstrtab_##channel##_##name,                         \
                        &__mstrtab_##channel##_##name[sizeof(#channel)],        \
                        &__mstrtab_##channel##_##name[sizeof(#channel) + sizeof(#name)],                \
                        0, 0, 0, 0, marker_probe_cb,                            \
                        { __mark_empty_function, NULL},                 \
-                       NULL, tp_name_str, tp_cb }
+                       NULL, tp_name_str, tp_cb };                     \
+               static struct marker * const __mark_ptr_##channel##_##name      \
+                       __attribute__((used, section("__markers_ptrs"))) =      \
+                       &GET_MARKER(channel, name);
 
 /*
  * Make sure the alignment of the structure in the __markers section will
@@ -198,8 +201,8 @@ struct marker {
                        call_private, &regs, ## args);                          \
        } while (0)
 
-extern void marker_update_probe_range(struct marker *begin,
-       struct marker *end);
+extern void marker_update_probe_range(struct marker * const *begin,
+       struct marker * const *end);
 
 /**
  * trace_mark - Marker using code patching
@@ -302,15 +305,15 @@ extern void *marker_get_private_data(const char *channel, const char *name,
 struct marker_iter {
 //ust//        struct module *module;
        struct lib *lib;
-       struct marker *marker;
+       struct marker * const *marker;
 };
 
 extern void marker_iter_start(struct marker_iter *iter);
 extern void marker_iter_next(struct marker_iter *iter);
 extern void marker_iter_stop(struct marker_iter *iter);
 extern void marker_iter_reset(struct marker_iter *iter);
-extern int marker_get_iter_range(struct marker **marker, struct marker *begin,
-       struct marker *end);
+extern int marker_get_iter_range(struct marker * const **marker, struct marker * const *begin,
+       struct marker * const *end);
 
 extern void marker_update_process(void);
 extern int is_marker_enabled(const char *channel, const char *name);
@@ -329,7 +332,7 @@ struct marker_addr {
 };
 
 struct lib {
-       struct marker *markers_start;
+       struct marker * const *markers_start;
 #ifdef CONFIG_UST_GDB_INTEGRATION
        struct marker_addr *markers_addr_start;
 #endif
@@ -337,16 +340,18 @@ struct lib {
        struct cds_list_head list;
 };
 
-extern int marker_register_lib(struct marker *markers_start, int markers_count);
-extern int marker_unregister_lib(struct marker *markers_start);
+extern int marker_register_lib(struct marker * const *markers_start, int markers_count);
+extern int marker_unregister_lib(struct marker * const *markers_start);
 
 #define MARKER_LIB                                                     \
-       extern struct marker __start___markers[] __attribute__((weak, visibility("hidden"))); \
-       extern struct marker __stop___markers[] __attribute__((weak, visibility("hidden"))); \
+       extern struct marker * const __start___markers[] __attribute__((weak, visibility("hidden"))); \
+       extern struct marker * const __stop___markers[] __attribute__((weak, visibility("hidden"))); \
                                                                        \
        static void __attribute__((constructor)) __markers__init(void)  \
        {                                                               \
-               marker_register_lib(__start___markers, (((long)__stop___markers)-((long)__start___markers))/sizeof(struct marker)); \
+               marker_register_lib(__start___markers,                  \
+                       (((long)__stop___markers) - ((long)__start___markers))  \
+                               / sizeof(*__start___markers));          \
        } \
        \
        static void __attribute__((destructor)) __markers__destroy(void)        \

diff --git a/libust/marker.c b/libust/marker.c
index 7a32351bd59d1e2038d3a77613f6ce6a1edfb8db..664f59c61c6495229ba4661206e267b5e5a7635c 100644 (file)
--- a/libust/marker.c
+++ b/libust/marker.c
@@ -35,8 +35,8 @@
 __thread long ust_reg_stack[500];
 volatile __thread long *ust_reg_stack_ptr = (long *) 0;
 
-extern struct marker __start___markers[] __attribute__((visibility("hidden")));
-extern struct marker __stop___markers[] __attribute__((visibility("hidden")));
+extern struct marker * const __start___markers[] __attribute__((visibility("hidden")));
+extern struct marker * const __stop___markers[] __attribute__((visibility("hidden")));
 
 /* Set to 1 to enable marker debug output */
 static const int marker_debug;
@@ -677,17 +677,17 @@ int is_marker_enabled(const char *channel, const char *name)
  *
  * Updates the probe callback corresponding to a range of markers.
  */
-void marker_update_probe_range(struct marker *begin,
-       struct marker *end)
+void marker_update_probe_range(struct marker * const *begin,
+       struct marker * const *end)
 {
-       struct marker *iter;
+       struct marker * const *iter;
        struct marker_entry *mark_entry;
 
        pthread_mutex_lock(&markers_mutex);
        for (iter = begin; iter < end; iter++) {
-               mark_entry = get_marker(iter->channel, iter->name);
+               mark_entry = get_marker((*iter)->channel, (*iter)->name);
                if (mark_entry) {
-                       set_marker(mark_entry, iter, !!mark_entry->refcount);
+                       set_marker(mark_entry, *iter, !!mark_entry->refcount);
                        /*
                         * ignore error, continue
                         */
@@ -702,11 +702,11 @@ void marker_update_probe_range(struct marker *begin,
                                   "channel %s name %s event_id %hu "
                                   "int #1u%zu long #1u%zu pointer #1u%zu "
                                   "size_t #1u%zu alignment #1u%u",
-                                  iter->channel, iter->name, mark_entry->event_id,
+                                  (*iter)->channel, (*iter)->name, mark_entry->event_id,
                                   sizeof(int), sizeof(long), sizeof(void *),
                                   sizeof(size_t), ltt_get_alignment());
                } else {
-                       disable_marker(iter);
+                       disable_marker(*iter);
                }
        }
        pthread_mutex_unlock(&markers_mutex);
@@ -1114,8 +1114,9 @@ int lib_get_iter_markers(struct marker_iter *iter)
  * Returns whether a next marker has been found (1) or not (0).
  * Will return the first marker in the range if the input marker is NULL.
  */
-int marker_get_iter_range(struct marker **marker, struct marker *begin,
-       struct marker *end)
+int marker_get_iter_range(struct marker * const **marker,
+       struct marker * const *begin,
+       struct marker * const *end)
 {
        if (!*marker && begin != end) {
                *marker = begin;
@@ -1351,17 +1352,17 @@ void marker_set_new_marker_cb(void (*cb)(struct marker *))
        new_marker_cb = cb;
 }
 
-static void new_markers(struct marker *start, struct marker *end)
+static void new_markers(struct marker * const *start, struct marker * const *end)
 {
-       if(new_marker_cb) {
-               struct marker *m;
+       if (new_marker_cb) {
+               struct marker * const *m;
                for(m=start; m < end; m++) {
-                       new_marker_cb(m);
+                       new_marker_cb(*m);
                }
        }
 }
 
-int marker_register_lib(struct marker *markers_start, int markers_count)
+int marker_register_lib(struct marker * const *markers_start, int markers_count)
 {
        struct lib *pl;
 
@@ -1385,7 +1386,7 @@ int marker_register_lib(struct marker *markers_start, int markers_count)
        return 0;
 }
 
-int marker_unregister_lib(struct marker *markers_start)
+int marker_unregister_lib(struct marker * const *markers_start)
 {
        struct lib *lib;
 
@@ -1415,7 +1416,9 @@ static int initialized = 0;
 void __attribute__((constructor)) init_markers(void)
 {
        if(!initialized) {
-               marker_register_lib(__start___markers, (((long)__stop___markers)-((long)__start___markers))/sizeof(struct marker));
+               marker_register_lib(__start___markers,
+                       (((long)__stop___markers) - ((long)__start___markers))
+                               / sizeof(*__start___markers));
                initialized = 1;
        }
 }

diff --git a/libust/tracectl.c b/libust/tracectl.c
index 25f84ccd0f033f2ec4ec38f40a589dae6cb05bc2..233a460d6163bdaa3ff7d61d100b646a91c763c1 100644 (file)
--- a/libust/tracectl.c
+++ b/libust/tracectl.c
@@ -100,11 +100,11 @@ static void print_markers(FILE *fp)
 
        while (iter.marker) {
                fprintf(fp, "marker: %s/%s %d \"%s\" %p\n",
-                       iter.marker->channel,
-                       iter.marker->name,
-                       (int)imv_read(iter.marker->state),
-                       iter.marker->format,
-                       iter.marker->location);
+                       (*iter.marker)->channel,
+                       (*iter.marker)->name,
+                       (int)imv_read((*iter.marker)->state),
+                       (*iter.marker)->format,
+                       (*iter.marker)->location);
                marker_iter_next(&iter);
        }
        unlock_markers();
@@ -1314,8 +1314,8 @@ static void __attribute__((constructor)) init()
 
                DBG("now iterating on markers already registered");
                while (iter.marker) {
-                       DBG("now iterating on marker %s", iter.marker->name);
-                       auto_probe_connect(iter.marker);
+                       DBG("now iterating on marker %s", (*iter.marker)->name);
+                       auto_probe_connect(*iter.marker);
                        marker_iter_next(&iter);
                }
        }