TLS (GNU/C11 thread-local storage) support for static-linked programs

the design for TLS in dynamic-linked programs is mostly complete too,
but I have not yet implemented it. cost is nonzero but still low for
programs which do not use TLS and/or do not use threads (a few hundred
bytes of new code, plus dependency on memcpy). i believe it can be
made smaller at some point by merging __init_tls and __init_security
into __libc_start_main and avoiding duplicate auxv-parsing code.

at the same time, I've also slightly changed the logic pthread_create
uses to allocate guard pages to ensure that guard pages are not
counted towards commit charge.

1 files changed, 10 insertions, 0 deletions

diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index 960e0898..1447e205 100644
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -17,6 +17,9 @@
 #include <pthread.h>
 #include <ctype.h>
 #include <dlfcn.h>
+#include "pthread_impl.h"
+#include "libc.h"
+#undef libc
 
 static int errflag;
 static char errbuf[128];
@@ -788,6 +791,8 @@ void *__dynlink(int argc, char **argv)
 	debug.state = 0;
 	_dl_debug_state();
 
+	/* Stand-in until real TLS support is added to dynamic linker */
+	__libc.tls_size = sizeof(struct pthread) + 4*sizeof(size_t);
 	if (ssp_used) __init_ssp(auxv);
 
 	do_init_fini(tail);
@@ -802,6 +807,11 @@ void *__dynlink(int argc, char **argv)
 	return (void *)aux[AT_ENTRY];
 }
 
+void *__copy_tls(unsigned char *mem, size_t cnt)
+{
+	return mem;
+}
+
 void *dlopen(const char *file, int mode)
 {
 	struct dso *volatile p, *orig_tail = tail, *next;