add rcrt1 start file for fully static-linked PIE

static-linked PIE files need startup code to relocate themselves, much
like the dynamic linker does. rcrt1.c reuses the code in dlstart.c,
stage 1 of the dynamic linker, which in turn reuses crt_arch.h, to
achieve static PIE with no new code. only relative relocations are
supported.

existing toolchains that don't yet support static PIE directly can be
repurposed by passing "-shared -Wl,-Bstatic -Wl,-Bsymbolic" instead of
"-static -pie" and substituting rcrt1.o in place of crt1.o.

all libraries being linked must be built as PIC/PIE; TEXTRELs are not
supported at this time.

1 files changed, 15 insertions, 0 deletions

diff --git a/crt/rcrt1.c b/crt/rcrt1.c
new file mode 100644
index 00000000..5ac612db
--- /dev/null
+++ b/crt/rcrt1.c
@@ -0,0 +1,15 @@
+#define SHARED
+#define START "_start"
+#define _dlstart_c _start_c
+#include "../src/ldso/dlstart.c"
+
+int main();
+void _init() __attribute__((weak));
+void _fini() __attribute__((weak));
+_Noreturn int __libc_start_main(int (*)(), int, char **,
+	void (*)(), void(*)(), void(*)());
+
+_Noreturn void __dls2(unsigned char *base, size_t *sp)
+{
+	__libc_start_main(main, *sp, (void *)(sp+1), _init, _fini, 0);
+}