Changeset 4f205248 in mainline for uspace/lib/c/generic/rtld

Timestamp:

2018-04-23T18:50:40Z (7 years ago)

Author:

Jiří Zárevúcky <jiri.zarevucky@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

a2eb85d

Parents:

8d58fca

git-author:

Jiří Zárevúcky <jiri.zarevucky@…> (2018-04-23 17:47:09)

git-committer:

Jiří Zárevúcky <jiri.zarevucky@…> (2018-04-23 18:50:40)

Message:

Honor TLS alignment.

Location:

uspace/lib/c/generic/rtld

Files:

• module.c (modified) (4 diffs)
• rtld.c (modified) (3 diffs)

uspace/lib/c/generic/rtld/module.c

@@ -35 +35 @@
  */
 
+#include <align.h>
 #include <adt/list.h>
 #include <elf/elf_load.h>
@@ -42 +43 @@
 #include <stdlib.h>
 #include <str.h>
+#include <macros.h>
 
 #include <rtld/rtld.h>
@@ -72 +74 @@
         const elf_segment_header_t *tls =
             elf_get_phdr(__executable_start, PT_TLS);
-        uintptr_t bias = elf_get_bias(__executable_start);
-
-        module->tdata = (void *) (tls->p_vaddr + bias);
-        module->tdata_size = tls->p_filesz;
-        module->tbss_size = tls->p_memsz - tls->p_filesz;
-        module->tls_align = tls->p_align;
+
+        if (tls) {
+                uintptr_t bias = elf_get_bias(__executable_start);
+                module->tdata = (void *) (tls->p_vaddr + bias);
+                module->tdata_size = tls->p_filesz;
+                module->tbss_size = tls->p_memsz - tls->p_filesz;
+                module->tls_align = tls->p_align;
+        } else {
+                module->tdata = NULL;
+                module->tdata_size = 0;
+                module->tbss_size = 0;
+                module->tls_align = 1;
+        }
 
         list_append(&module->modules_link, &rtld->modules);
@@ -324 +333 @@
 {
 #ifdef CONFIG_TLS_VARIANT_1
-        list_foreach(rtld->modules, modules_link, module_t, m) {
-                m->ioffs = rtld->tls_size;
-                list_append(&m->imodules_link, &rtmd->imodules);
+        rtld->tls_size = sizeof(tcb_t);
+        rtld->tls_align = _Alignof(tcb_t);
+
+        list_foreach(rtld->modules, modules_link, module_t, m) {
+                list_append(&m->imodules_link, &rtld->imodules);
+                rtld->tls_align = max(rtld->tls_align, m->tls_align);
+
+                rtld->tls_size = ALIGN_UP(rtld->tls_size, m->tls_align);
+                m->tpoff = rtld->tls_size;
                 rtld->tls_size += m->tdata_size + m->tbss_size;
         }
-#else /* CONFIG_TLS_VARIANT_2 */
-        size_t offs;
-
-        list_foreach(rtld->modules, modules_link, module_t, m) {
+
+#else
+        rtld->tls_size = 0;
+        rtld->tls_align = _Alignof(tcb_t);
+
+        list_foreach(rtld->modules, modules_link, module_t, m) {
+                list_append(&m->imodules_link, &rtld->imodules);
+                rtld->tls_align = max(rtld->tls_align, m->tls_align);
+
+                /* We are allocating spans "backwards", here,
+                 * as described in U. Drepper's paper.
+                 */
                 rtld->tls_size += m->tdata_size + m->tbss_size;
-        }
-
-        offs = 0;
-        list_foreach(rtld->modules, modules_link, module_t, m) {
-                offs += m->tdata_size + m->tbss_size;
-                m->ioffs = rtld->tls_size - offs;
-                list_append(&m->imodules_link, &rtld->imodules);
-        }
+                rtld->tls_size = ALIGN_UP(rtld->tls_size, m->tls_align);
+                m->tpoff = -(ptrdiff_t) rtld->tls_size;
+        }
+
+        /* We are in negative offsets. In order for the alignments to
+         * be correct, "zero" offset (i.e. the total size) must be aligned
+         * to the strictest alignment present.
+         */
+        rtld->tls_size = ALIGN_UP(rtld->tls_size, rtld->tls_align);
+
+        /* Space for the TCB. */
+        rtld->tls_size += sizeof(tcb_t);
 #endif
 }

uspace/lib/c/generic/rtld/rtld.c

@@ -152 +152 @@
 tcb_t *rtld_tls_make(rtld_t *rtld)
 {
-        void *data;
         tcb_t *tcb;
-        size_t offset;
         void **dtv;
         size_t nmods;
         size_t i;
 
-        tcb = tls_alloc_arch(&data, rtld->tls_size);
+        tcb = tls_alloc_arch(rtld->tls_size, rtld->tls_align);
         if (tcb == NULL)
                 return NULL;
@@ -182 +180 @@
          */
 
-#ifdef CONFIG_TLS_VARIANT_1
-        /*
-         * Ascending addresses
-         */
-        offset = 0;
         i = 1;
         list_foreach(rtld->imodules, imodules_link, module_t, m) {
-                assert(i == m->id);
-                assert(offset + m->tdata_size + m->tbss_size <= rtld->tls_size);
-                dtv[i++] = data + offset;
-                memcpy(data + offset, m->tdata, m->tdata_size);
-                offset += m->tdata_size;
-                memset(data + offset, 0, m->tbss_size);
-                offset += m->tbss_size;
-        }
-#else /* CONFIG_TLS_VARIANT_2 */
-        /*
-         * Descending addresses
-         */
-        offset = 0;
-        i = 1;
-        list_foreach(rtld->imodules, imodules_link, module_t, m) {
-                assert(i == m->id);
-                assert(offset + m->tdata_size + m->tbss_size <= rtld->tls_size);
-                offset += m->tbss_size;
-                memset(data + rtld->tls_size - offset, 0, m->tbss_size);
-                offset += m->tdata_size;
-                memcpy(data + rtld->tls_size - offset, m->tdata, m->tdata_size);
-                dtv[i++] = data + rtld->tls_size - offset;
-        }
-#endif
+                assert(i++ == m->id);
+
+                dtv[m->id] = (void *) tcb + m->tpoff;
+
+                assert(((uintptr_t) dtv[m->id]) % m->tls_align == 0);
+
+                memcpy(dtv[m->id], m->tdata, m->tdata_size);
+                memset(dtv[m->id] + m->tdata_size, 0, m->tbss_size);
+        }
 
         tcb->dtv = dtv;
@@ -259 +237 @@
                 assert(!link_used(&m->imodules_link));
 
-                tls_block = malloc(m->tdata_size + m->tbss_size);
+                tls_block = memalign(m->tls_align, m->tdata_size + m->tbss_size);
                 /* XXX This can fail if OOM */
                 assert(tls_block != NULL);