elfcore: Replace CONFIG_{IA64, UML} checks with a new option

As arm64 is about to introduce MTE-specific phdrs in the core dump, add
a common CONFIG_ARCH_BINFMT_ELF_EXTRA_PHDRS option currently selectable
by UML_X86 and IA64.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Link: https://lore.kernel.org/r/20220131165456.2160675-2-catalin.marinas@arm.comSigned-off-by: Will Deacon <will@kernel.org>

arch/ia64/Kconfig

@@ -8,6 +8,7 @@ menu "Processor type and features"
 
 config IA64
 	bool
+	select ARCH_BINFMT_ELF_EXTRA_PHDRS
 	select ARCH_HAS_DMA_MARK_CLEAN
 	select ARCH_HAS_STRNCPY_FROM_USER
 	select ARCH_HAS_STRNLEN_USER

arch/x86/um/Kconfig

@@ -8,6 +8,7 @@ endmenu
 
 config UML_X86
 	def_bool y
+	select ARCH_BINFMT_ELF_EXTRA_PHDRS if X86_32
 
 config 64BIT
 	bool "64-bit kernel" if "$(SUBARCH)" = "x86"

fs/Kconfig.binfmt

@@ -36,6 +36,9 @@ config COMPAT_BINFMT_ELF
 config ARCH_BINFMT_ELF_STATE
 	bool
 
+config ARCH_BINFMT_ELF_EXTRA_PHDRS
+	bool
+
 config ARCH_HAVE_ELF_PROT
 	bool
 

include/linux/elfcore.h

@@ -114,7 +114,7 @@ static inline int elf_core_copy_task_fpregs(struct task_struct *t, struct pt_reg
 #endif
 }
 
-#if (defined(CONFIG_UML) && defined(CONFIG_X86_32)) || defined(CONFIG_IA64)
+#ifdef CONFIG_ARCH_BINFMT_ELF_EXTRA_PHDRS
 /*
  * These functions parameterize elf_core_dump in fs/binfmt_elf.c to write out
  * extra segments containing the gate DSO contents.  Dumping its
@@ -149,6 +149,6 @@ static inline size_t elf_core_extra_data_size(void)
 {
 	return 0;
 }
-#endif
+#endif /* CONFIG_ARCH_BINFMT_ELF_EXTRA_PHDRS */
 
 #endif /* _LINUX_ELFCORE_H */