s390/vmlinux.lds.S: Prevent thunk functions from getting placed with normal text

The s390 indirect thunks are placed in the .text.__s390_indirect_jump_*
sections.

Certain config options which enable -ffunction-sections have a custom
version of the TEXT_TEXT macro:

  .text.[0-9a-zA-Z_]*

That unintentionally matches the thunk sections, causing them to get
grouped with normal text rather than being handled by their intended
rule later in the script:

  *(.text.*_indirect_*)

Fix that by adding another period to the thunk section names, following
the kernel's general convention for distinguishing code-generated text
sections from compiler-generated ones.

Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

arch/s390/include/asm/nospec-insn.h

@@ -19,7 +19,7 @@
 #ifdef CONFIG_EXPOLINE_EXTERN
 	SYM_CODE_START(\name)
 #else
-	.pushsection .text.\name,"axG",@progbits,\name,comdat
+	.pushsection .text..\name,"axG",@progbits,\name,comdat
 	.globl \name
 	.hidden \name
 	.type \name,@function

arch/s390/kernel/vmlinux.lds.S

@@ -51,7 +51,7 @@ SECTIONS
 		IRQENTRY_TEXT
 		SOFTIRQENTRY_TEXT
 		FTRACE_HOTPATCH_TRAMPOLINES_TEXT
-		*(.text.*_indirect_*)
+		*(.text..*_indirect_*)
 		*(.gnu.warning)
 		. = ALIGN(PAGE_SIZE);
 		_etext = .;		/* End of text section */