[PATCH 09/18] arm64: introduce binfmt_elf32.c

On Mon, Dec 05, 2016 at 03:10:19PM +0000, Catalin Marinas wrote:

On Fri, Oct 21, 2016 at 11:33:08PM +0300, Yury Norov wrote:

quoted

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.

Can you remind me why we need this patch (rather than using the default
fs/compat_binfmt_elf.c which you include here anyway)?

https://patchwork.kernel.org/patch/8756121/

This is mostly to avoid runtime checks and hide some re-definitions
for aarch32 from ilp32, to avoid re-re-definition.

quoted

--- /dev/null
+++ b/arch/arm64/kernel/binfmt_elf32.c

@@ -0,0 +1,31 @@
+/*
+ * Support for AArch32 Linux ELF binaries.
+ */
+
+/* AArch32 EABI. */
+#define EF_ARM_EABI_MASK		0xff000000
+
+#define compat_start_thread		compat_start_thread
+#define COMPAT_SET_PERSONALITY(ex)		\
+do {						\
+	clear_thread_flag(TIF_32BIT_AARCH64);	\
+	set_thread_flag(TIF_32BIT);		\
+} while (0)

You introduce this here but it seems to still be present in asm/elf.h.

Hmm... Maybe chunk that delete it from asm/elf.h was dropped at some
rebase. Thank you for the catch. I'll check it again.

Yury