[PATCH 13/24] arm64: introduce binfmt_elf32.c

[Yury Norov]

As we support more than one compat formats, it looks more reasonable
to not use fs/compat_binfmt.c. Custom binfmt_elf32.c allows to move aarch32
specific definitions there and make code more maintainable and readable.

Signed-off-by: Yury Norov <ynorov at caviumnetworks.com>
---
 arch/arm64/Kconfig               |  1 -
 arch/arm64/include/asm/elf.h     | 26 +++---------------------
 arch/arm64/include/asm/hwcap.h   |  2 --
 arch/arm64/kernel/Makefile       |  2 +-
 arch/arm64/kernel/binfmt_elf32.c | 35 ++++++++++++++++++++++++++++++++
 5 files changed, 39 insertions(+), 27 deletions(-)
 create mode 100644 arch/arm64/kernel/binfmt_elf32.c

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a16916be20f5..0685754a9f7b 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1232,7 +1232,6 @@ config AARCH32_EL0
 	bool "Kernel support for 32-bit EL0"
 	def_bool y
 	depends on ARM64_4K_PAGES || EXPERT
-	select COMPAT_BINFMT_ELF if BINFMT_ELF
 	select HAVE_UID16
 	select OLD_SIGSUSPEND3
 	select COMPAT_OLD_SIGACTION
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 023b2fbc1454..f04b27bd9bb6 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -175,36 +175,16 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm,
 
 /* PIE load location for compat arm. Must match ARM ELF_ET_DYN_BASE. */
 #define COMPAT_ELF_ET_DYN_BASE		0x000400000UL
+#endif /*CONFIG_COMPAT */
 
+#ifdef CONFIG_AARCH32_EL0
 /* AArch32 registers. */
 #define COMPAT_ELF_NGREG		18
 typedef unsigned int			compat_elf_greg_t;
 typedef compat_elf_greg_t		compat_elf_gregset_t[COMPAT_ELF_NGREG];
-
-/* AArch32 EABI. */
-#define EF_ARM_EABI_MASK		0xff000000
-#define compat_elf_check_arch(x)	(system_supports_32bit_el0() && \
-					 ((x)->e_machine == EM_ARM) && \
-					 ((x)->e_flags & EF_ARM_EABI_MASK))
-
-#define compat_start_thread		compat_start_thread
-/*
- * Unlike the native SET_PERSONALITY macro, the compat version maintains
- * READ_IMPLIES_EXEC across an execve() since this is the behaviour on
- * arch/arm/.
- */
-#define COMPAT_SET_PERSONALITY(ex)					\
-({									\
-	clear_thread_flag(TIF_32BIT_AARCH64);				\
-	set_thread_flag(TIF_32BIT);					\
- })
-#define COMPAT_ARCH_DLINFO
 extern int aarch32_setup_vectors_page(struct linux_binprm *bprm,
 				      int uses_interp);
-#define compat_arch_setup_additional_pages \
-					aarch32_setup_vectors_page
-
-#endif /* CONFIG_COMPAT */
+#endif /* CONFIG_AARCH32_EL0 */
 
 #endif /* !__ASSEMBLY__ */
 
diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
index 2c7fc5d89813..99dfd9277559 100644
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h
@@ -47,8 +47,6 @@
 #define ELF_HWCAP		(elf_hwcap)
 
 #ifdef CONFIG_AARCH32_EL0
-#define COMPAT_ELF_HWCAP	(compat_elf_hwcap)
-#define COMPAT_ELF_HWCAP2	(compat_elf_hwcap2)
 extern unsigned int compat_elf_hwcap, compat_elf_hwcap2;
 #endif
 
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index cff1a78bdf4c..c63e0164fc12 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -27,7 +27,7 @@ $(obj)/%.stub.o: $(obj)/%.o FORCE
 	$(call if_changed,objcopy)
 
 arm64-obj-$(CONFIG_AARCH32_EL0)		+= sys32.o kuser32.o signal32.o 	\
-					   sys_compat.o entry32.o
+					   sys_compat.o entry32.o binfmt_elf32.o
 arm64-obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o entry-ftrace.o
 arm64-obj-$(CONFIG_MODULES)		+= arm64ksyms.o module.o
 arm64-obj-$(CONFIG_ARM64_MODULE_PLTS)	+= module-plts.o
diff --git a/arch/arm64/kernel/binfmt_elf32.c b/arch/arm64/kernel/binfmt_elf32.c
new file mode 100644
index 000000000000..440fa84f62b3
--- /dev/null
+++ b/arch/arm64/kernel/binfmt_elf32.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/*
+ * Support for AArch32 Linux ELF binaries.
+ */
+
+/* AArch32 EABI. */
+#define EF_ARM_EABI_MASK		0xff000000
+
+#define compat_start_thread		compat_start_thread
+/*
+ * Unlike the native SET_PERSONALITY macro, the compat version inherits
+ * READ_IMPLIES_EXEC across a fork() since this is the behaviour on
+ * arch/arm/.
+ */
+#define COMPAT_SET_PERSONALITY(ex)					\
+({									\
+	clear_thread_flag(TIF_32BIT_AARCH64);				\
+	set_thread_flag(TIF_32BIT);					\
+})
+
+#define COMPAT_ARCH_DLINFO
+#define COMPAT_ELF_HWCAP		(compat_elf_hwcap)
+#define COMPAT_ELF_HWCAP2		(compat_elf_hwcap2)
+
+#define compat_arch_setup_additional_pages \
+					aarch32_setup_vectors_page
+
+/* AArch32 EABI. */
+#define compat_elf_check_arch(x)	(system_supports_32bit_el0() && \
+					 ((x)->e_machine == EM_ARM) && \
+					 ((x)->e_flags & EF_ARM_EABI_MASK))
+
+
+#include "../../../fs/compat_binfmt_elf.c"
-- 
2.17.0