x86-32/asm/power: Create stack frames in hibernate_asm_32.S

swsusp_arch_suspend() is callable non-leaf function which doesn't
honor CONFIG_FRAME_POINTER, which can result in bad stack traces.
Also it's not annotated as ELF callable function which can confuse tooling.

Create a stack frame for it when CONFIG_FRAME_POINTER is enabled and
give it proper ELF function annotation.

Also in this patch introduces the restore_registers() symbol and
gives it ELF function annotation, thus to prepare for later register
restore.

Analogous changes were made for 64bit before in commit ef0f3ed5a4ac
(x86/asm/power: Create stack frames in hibernate_asm_64.S) and
commit 4ce827b4cc58 (x86/power/64: Fix hibernation return address
corruption).

Signed-off-by: Zhimin Gu <[e-mail]>
Signed-off-by: Chen Yu <[e-mail]>
Acked-by: Thomas Gleixner <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

arch/x86/include/asm/suspend_32.h

···
 	unsigned long return_address;
 } __attribute__((packed));
 
+/* routines for saving/restoring kernel state */
+extern char core_restore_code[];
+extern char restore_registers[];
+
 #endif /* _ASM_X86_SUSPEND_32_H */

arch/x86/power/hibernate_asm_32.S

···
 #include <asm/page_types.h>
 #include <asm/asm-offsets.h>
 #include <asm/processor-flags.h>
+#include <asm/frame.h>
 
 .text
 
···
 	pushfl
 	popl saved_context_eflags
 
+	FRAME_BEGIN
 	call swsusp_save
+	FRAME_END
 	ret
+ENDPROC(swsusp_arch_suspend)
 
 ENTRY(restore_image)
 	movl	mmu_cr4_features, %ecx
···
 	.p2align 4,,7
 
 done:
+
+	/* code below belongs to the image kernel */
+	.align PAGE_SIZE
+ENTRY(restore_registers)
 	/* go back to the original page tables */
 	movl	$swapper_pg_dir, %eax
 	subl	$__PAGE_OFFSET, %eax
···
 	xorl	%eax, %eax
 
 	ret
+ENDPROC(restore_registers)