runtime: mark runtime functions used by other TUs as `__attribute__((…

…visibility("default")))` * Fixes #442. Making the visibility explicit for these allows projects to be compiled with `-fvisibility=hidden`, which sets the default (not `default`) to `hidden`.
immunant · Oct 14, 2024 · 6c97b60 · 6c97b60
1 parent 0177cc4
commit 6c97b60
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Showing 3 changed files with 13 additions and 13 deletions.
diff --git a/runtime/libia2/include/ia2_compartment_init.inc b/runtime/libia2/include/ia2_compartment_init.inc
@@ -37,7 +37,7 @@ __attribute__((used)) void COMPARTMENT_IDENT(ia2_compartment_destructor)(void) {
 
 #else
 
-__thread void *COMPARTMENT_IDENT(ia2_stackptr) __attribute__((used));
+__attribute__((visibility("default"))) __thread void *COMPARTMENT_IDENT(ia2_stackptr) __attribute__((used));
 
 /*
 ** Initializes a compartment with protection key `n`. Called automatically as a
@@ -113,7 +113,7 @@ __attribute__((constructor)) static void COMPARTMENT_IDENT(init_pkey)() {
   }
 }
 
-void COMPARTMENT_IDENT(init_tls)(void) {
+__attribute__((visibility("default"))) void COMPARTMENT_IDENT(init_tls)(void) {
   struct PhdrSearchArgs args = {
       .pkey = IA2_COMPARTMENT,
       .address = &COMPARTMENT_IDENT(init_tls),
@@ -137,7 +137,7 @@ static volatile struct FinalizerInfo finalizers
 
 extern void COMPARTMENT_IDENT(__wrap_ia2_compartment_destructor)(void);
 
-__attribute__((no_sanitize("undefined"))) __attribute__((used)) void
+__attribute__((visibility("default"))) __attribute__((no_sanitize("undefined"))) __attribute__((used)) void
 COMPARTMENT_IDENT(ia2_compartment_destructor)(void) {
   static bool ran_destructors = false;
   if (ran_destructors)
@@ -169,7 +169,7 @@ static inline uint32_t ubsan_access_phdr_type(Elf64_Phdr *phdr, int i) {
     return phdr[i].p_type;
 }
 
-void COMPARTMENT_IDENT(ia2_setup_destructors)(void) {
+__attribute__((visibility("default"))) void COMPARTMENT_IDENT(ia2_setup_destructors)(void) {
   int res = 0;
   Elf64_Ehdr *ehdr = &__ehdr_start;
   Elf64_Phdr *phdr = (Elf64_Phdr *)((uint8_t *)ehdr + __ehdr_start.e_phoff);

diff --git a/runtime/libia2/include/ia2_internal.h b/runtime/libia2/include/ia2_internal.h
@@ -175,7 +175,7 @@ asm(".macro movz_shifted_tag_x18 tag\n"
 /* Allocate and protect the stack for this thread's i'th compartment. */
 #define ALLOCATE_COMPARTMENT_STACK_AND_SETUP_TLS(i)                            \
   {                                                                            \
-    __IA2_UNUSED extern __thread void *ia2_stackptr_##i;                       \
+    __IA2_UNUSED __attribute__((visibility ("default"))) extern __thread void *ia2_stackptr_##i;                       \
                                                                                \
     register void *stack asm("rax") = allocate_stack(i);                       \
                                                                                \
@@ -292,9 +292,9 @@ always fail because it maps a non-page-aligned addr with MAP_FIXED, so it
 works as a reasonable signpost no-op. */
 #define mark_init_finished() (void)mmap((void *)IA2_FINISH_INIT_MAGIC, 0, 0, MAP_FIXED, -1, 0)
 
-#define declare_init_tls_fn(n) void init_tls_##n(void);
+#define declare_init_tls_fn(n) __attribute__((visibility("default"))) void init_tls_##n(void);
 #define setup_destructors_for_compartment(n)                                   \
-  void ia2_setup_destructors_##n(void);                                        \
+  __attribute__((visibility("default"))) void ia2_setup_destructors_##n(void);                                        \
   ia2_setup_destructors_##n();
 
 #if defined(__aarch64__)
@@ -316,20 +316,20 @@ void ensure_pkeys_allocated(int *n_to_alloc);
 __attribute__((__noreturn__)) void ia2_reinit_stack_err(int i);
 
 #define _IA2_INIT_RUNTIME(n)                                                   \
-  int ia2_n_pkeys_to_alloc = n;                                                \
-  __thread void *ia2_stackptr_0[PAGE_SIZE / sizeof(void *)]                    \
+  __attribute__((visibility("default"))) int ia2_n_pkeys_to_alloc = n;                                                \
+  __attribute__((visibility("default"))) __thread void *ia2_stackptr_0[PAGE_SIZE / sizeof(void *)]                    \
       __attribute__((aligned(4096)));                                          \
                                                                                \
   REPEATB(n, declare_init_tls_fn, nop_macro);                                  \
                                                                                \
   /* Returns `&ia2_stackptr_N` given a pkru value for the Nth compartment. */  \
-  void **ia2_stackptr_for_pkru(uint32_t pkru) {                                \
+  __attribute__((visibility("default"))) void **ia2_stackptr_for_pkru(uint32_t pkru) {                                \
     REPEATB(n, return_stackptr_if_compartment,                                 \
             return_stackptr_if_compartment);                                   \
     return NULL;                                                               \
   }                                                                            \
                                                                                \
-  __attribute__((weak)) void init_stacks_and_setup_tls(void) {                 \
+  __attribute__((visibility("default"))) __attribute__((weak)) void init_stacks_and_setup_tls(void) {                 \
     verify_tls_padding();                                                      \
     REPEATB(n, ALLOCATE_COMPARTMENT_STACK_AND_SETUP_TLS, nop_macro);           \
     /* allocate an unprotected stack for the untrusted compartment */          \

diff --git a/runtime/libia2/threads.c b/runtime/libia2/threads.c
@@ -4,8 +4,8 @@
 
 #include "ia2.h"
 
-void init_stacks_and_setup_tls(void);
-void **ia2_stackptr_for_pkru(uint32_t pkey);
+__attribute__((visibility("default"))) void init_stacks_and_setup_tls(void);
+__attribute__((visibility("default"))) void **ia2_stackptr_for_pkru(uint32_t pkey);
 
 struct ia2_thread_thunk {
   void *(*fn)(void *);