vmlinux.lds.h: Fix placement of '.data..decrypted' section

Commit d4c6399 ("vmlinux.lds.h: Avoid orphan section with !SMP")
fixed an orphan section warning by adding the '.data..decrypted' section
to the linker script under the PERCPU_DECRYPTED_SECTION define but that
placement introduced a panic with !SMP, as the percpu sections are not
instantiated with that configuration so attempting to access variables
defined with DEFINE_PER_CPU_DECRYPTED() will result in a page fault.

Move the '.data..decrypted' section to the DATA_MAIN define so that the
variables in it are properly instantiated at boot time with
CONFIG_SMP=n.

Cc: [email protected]
Fixes: d4c6399 ("vmlinux.lds.h: Avoid orphan section with !SMP")
Link: https://lore.kernel.org/[email protected]/
Debugged-by: Ard Biesheuvel <[email protected]>
Reported-by: Zhao Wenhui <[email protected]>
Tested-by: xiafukun <[email protected]>
Signed-off-by: Nathan Chancellor <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: nathanchance

include/asm-generic/vmlinux.lds.h

@@ -341,6 +341,7 @@
 #define DATA_DATA							\
 	*(.xiptext)							\
 	*(DATA_MAIN)							\
+	*(.data..decrypted)						\
 	*(.ref.data)							\
 	*(.data..shared_aligned) /* percpu related */			\
 	MEM_KEEP(init.data*)						\
@@ -989,7 +990,6 @@
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 #define PERCPU_DECRYPTED_SECTION					\
 	. = ALIGN(PAGE_SIZE);						\
-	*(.data..decrypted)						\
 	*(.data..percpu..decrypted)					\
 	. = ALIGN(PAGE_SIZE);
 #else