inmates: Clear bss during initialization

Stop relying on the Jailhouse loader to clear call memory and perform
the required bss initialization to zero on our own.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

inmates/header.S

@@ -62,6 +62,11 @@ start32:
 start64:
 	mov $stack_top,%rsp
 
+	xor %rax,%rax
+	mov $bss_start,%rdi
+	mov $bss_qwords,%rcx
+	rep stosq
+
 	mov $inmate_main,%rax
 	jmpq *%rax
 

inmates/inmate.lds

@@ -22,10 +22,15 @@ SECTIONS
 		. = ALIGN(16);
 	}
 
-	/* 32-bit sections */
+	/* 32/64-bit sections */
 	. = 0xe0000;
 	stack_top = .;
-	.bss		: { *(.bss) }
+	bss_start = .;
+	.bss		: {
+		*(.bss)
+		. = ALIGN(8);
+	}
+	bss_qwords = SIZEOF(.bss) / 8;
 
 	. = 0xf0000 + SIZEOF(.startup);
 	.text		: AT (ADDR(.text) & 0xffff) {