Fix SH ldso sequence startup.

Pass via r4 the rtld finalizer
_dl_fini to the user application. This will be the 6^ arg of
__uClibc_main and will be registered with 'atexit'.
In this way the dynamic linker will be able to call destructors
defined within the loaded DSOs.

Signed-off-by: Carmelo Amoroso <carmelo.amoroso@st.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>

Add missing 7th arg "stack_end".
add comment of undocumented usage of r4.
fix comment of expected __uClibc_main() prototype.

Signed-off-by: Yoshii Takashi <yoshii.takashi@renesas.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>

ldso/ldso/sh/dl-startup.h

@@ -12,10 +12,20 @@ __asm__(
     "	bsrf    r0\n"
     "	add	#4, r4\n"
     ".jmp_loc:\n"
-    "	jmp	@r0\n"
-    "	mov    #0, r4 	!call _start with arg == 0\n"
+    "	mov     r0, r8        ! Save the user entry point address in r8\n"
+    "	mov.l   .L_got, r12   ! Load the GOT on r12\n"
+    "	mova    .L_got, r0\n"
+    "	add     r0, r12\n"
+    "	mov.l   .L_dl_fini, r0\n"
+    "	mov.l   @(r0,r12), r4 ! Pass the finalizer in r4\n"
+    "	jmp     @r8\n"
+    "	nop\n"
     ".L_dl_start:\n"
     "	.long   _dl_start-.jmp_loc\n"
+    ".L_dl_fini:\n"
+    "	.long	_dl_fini@GOT\n"
+    ".L_got:\n"
+    "	.long _GLOBAL_OFFSET_TABLE_\n"
     "	.size	_start,.-_start\n"
     "	.previous\n"
 );

libc/sysdeps/linux/sh/crt1.S

@@ -24,6 +24,11 @@
 
 	At this entry point, most registers' values are unspecified, except:
 
+   r4	Contains a function pointer to be registered with `atexit'.
+		This is how the dynamic linker arranges to have DT_FINI
+		functions called for shared libraries that have been loaded
+		before this code runs.
+
    sp		The stack contains the arguments and environment:
    		0(sp)			argc
 		4(sp)			argv[0]
@@ -48,7 +53,8 @@ _start:
 	mov.l @r15+,r5
 	mov r15, r6
 
-	/* Push the fini func onto the stack */
+	/* Push the stack_end, rtld_fini and fini func onto the stack */
+	mov.l r6,@-r15
 	mov.l r4,@-r15
 	mov.l L_fini,r0
 	mov.l r0,@-r15
@@ -57,7 +63,7 @@ _start:
 	mov.l L_main,r4
 	mov.l L_init,r7
 
-	/* __uClibc_main (main, argc, argv, init, fini) */
+	/* __uClibc_main (main, argc, argv, init, fini, rtld_fini, stack_end) */
 
 	/* Let the libc call main and exit with its return code.  */
 	mov.l L_uClibc_main,r1