Replace macro "ARCH_HAVE_EXTRA_ELF_NOTES" with kconfig

"ARCH_HAVE_EXTRA_ELF_NOTES" enables an extra note section in the
core dump. Kconfig variable is preferred over ARCH_HAVE_* macro.

Co-developed-by: Jini Susan George <[e-mail]>
Signed-off-by: Jini Susan George <[e-mail]>
Signed-off-by: Vignesh Balasubramanian <[e-mail]>
Acked-by: Michael Ellerman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Kees Cook <[e-mail]>

arch/Kconfig

···
 config ARCH_HAVE_NMI_SAFE_CMPXCHG
 	bool
 
+config ARCH_HAVE_EXTRA_ELF_NOTES
+	bool
+	help
+	  An architecture should select this in order to enable adding an
+	  arch-specific ELF note section to core files. It must provide two
+	  functions: elf_coredump_extra_notes_size() and
+	  elf_coredump_extra_notes_write() which are invoked by the ELF core
+	  dumper.
+
 config ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
 	bool
 

arch/powerpc/Kconfig

···
 	select ARCH_HAS_UACCESS_FLUSHCACHE
 	select ARCH_HAS_UBSAN
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
+	select ARCH_HAVE_EXTRA_ELF_NOTES        if SPU_BASE
 	select ARCH_KEEP_MEMBLOCK
 	select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE	if PPC_RADIX_MMU
 	select ARCH_MIGHT_HAVE_PC_PARPORT

arch/powerpc/include/asm/elf.h

···
 /* Notes used in ET_CORE. Note name is "SPU/<fd>/<filename>". */
 #define NT_SPU		1
 
-#define ARCH_HAVE_EXTRA_ELF_NOTES
-
 #endif /* CONFIG_SPU_BASE */
 
 #ifdef CONFIG_PPC64

include/linux/elf.h

···
 struct file;
 struct coredump_params;
 
-#ifndef ARCH_HAVE_EXTRA_ELF_NOTES
+#ifndef CONFIG_ARCH_HAVE_EXTRA_ELF_NOTES
 static inline int elf_coredump_extra_notes_size(void) { return 0; }
 static inline int elf_coredump_extra_notes_write(struct coredump_params *cprm) { return 0; }
 #else