4 Jul
2018
4 Jul
'18
3:55 p.m.
Implement _start: compute parameters for __self_reloc, and give
control to the user program.
* ldso/ldso/arm/dl-startup.h: Implement _start for __FDPIC__.
Signed-off-by: Mickaël Guêné <mickael.guene(a)st.com>
Signed-off-by: Christophe Lyon <christophe.lyon(a)st.com>
diff --git a/ldso/ldso/arm/dl-startup.h b/ldso/ldso/arm/dl-startup.h
index d15264f..b5f7d73 100644
--- a/ldso/ldso/arm/dl-startup.h
+++ b/ldso/ldso/arm/dl-startup.h
@@ -8,6 +8,71 @@
#include <features.h>
#include <bits/arm_bx.h>
+#if defined(__FDPIC__)
+#if !defined(__thumb__) || defined(__thumb2__)
+__asm__(
+ " .arm\n"
+ " .text\n"
+ " .globl _start\n"
+ " .type _start,%function\n"
+ "_start:\n"
+ /* We compute the parameters for __self_reloc:
+ - r0 is a pointer to the loadmap (either from r8 or r7 if rtld is
+ lauched in standalone mode)
+ - r1 is a pointer to the start of .rofixup section
+ - r2 is a pointer to the last word of .rofixup section
+
+ __self_reloc will fix indirect addresses in .rofixup
+ section and will return the relocated GOT value.
+ */
+ " sub r4, pc, #8\n"
+ " ldr r1, .L__ROFIXUP_LIST__\n"
+ " add r1, r1, r4\n"
+ " ldr r2, .L__ROFIXUP_END__\n"
+ " add r2, r2, r4\n"
+ " movs r0, r8\n"
+ " moveq r0, r7\n"
+ " push {r7, r8, r9, r10}\n"
+ " bl __self_reloc;\n"
+ " pop {r7, r8, r9, r10}\n"
+ /* We compute the parameters for dl_start(). See DL_START()
+ macro below. The address of the user entry point is
+ returned in dl_main_funcdesc (on stack). */
+ " mov r1, r7\n"
+ " mov r2, r8\n"
+ " mov r3, r9\n"
+ " mov r4, sp\n"
+ " sub r5, sp, #8\n"
+ " sub sp, sp, #16\n"
+ " str r4, [sp, #4]\n"
+ " str r5, [sp, #0]\n"
+ " mov r9, r0\n"
+ /* Save r9 into r4, to preserve the GOT pointer. */
+ " mov r4, r9\n"
+ " bl _dl_start;\n"
+ /* Now compute parameters for entry point according to FDPIC ABI. */
+ " ldr r10, .L_dl_fini_gotofffuncdesc\n"
+ /* Save GOT value from r4. */
+ " add r10, r10, r4\n"
+ " ldr r5, [sp, #8]\n"
+ " ldr r9, [sp, #12]\n"
+ " add sp, sp, #16\n"
+ " bx r5\n"
+ ".loopforever:\n"
+ " b .loopforever\n"
+ ".L__ROFIXUP_LIST__:\n"
+ " .word __ROFIXUP_LIST__ - _start\n"
+ ".L__ROFIXUP_END__:\n"
+ " .word __ROFIXUP_END__ - _start\n"
+ ".L_dl_fini_gotofffuncdesc:\n"
+ " .word _dl_fini(GOTOFFFUNCDESC)\n"
+ " .size _start,.-_start\n"
+ " .previous\n"
+);
+#else /* !defined(__thumb__) */
+#error Thumb-1 is not supported
+#endif /* !defined(__thumb__) */
+#else /* defined(__FDPIC__) */
#if !defined(__thumb__)
__asm__(
" .text\n"
@@ -121,7 +186,7 @@ __asm__(
".previous\n"
);
#endif
-
+#endif /* defined(__FDPIC__) */
/* Get a pointer to the argv array. On many platforms this can be just
* the address of the first argument, on other platforms we need to
--
2.6.3