[18/25] arm64: ilp32: introduce binfmt_ilp32.c

Commit Message

Yury Norov April 5, 2016, 10:08 p.m. UTC

to handle ILP32 binaries

Signed-off-by: Yury Norov <[e-mail]>
---
 arch/arm64/kernel/Makefile       |  1 +
 arch/arm64/kernel/binfmt_ilp32.c | 91 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 92 insertions(+)
 create mode 100644 arch/arm64/kernel/binfmt_ilp32.c

Comments

Catalin Marinas April 22, 2016, 4:51 p.m. UTC | #1

On Wed, Apr 06, 2016 at 01:08:40AM +0300, Yury Norov wrote:
> --- /dev/null
> +++ b/arch/arm64/kernel/binfmt_ilp32.c

[...]

> +#include "../../../fs/binfmt_elf.c"

How different is this new binfmt_ilp32.c file from the first part of
compat_binfmt_elf.c? I wonder whether we could include the latter here
instead and make this similar to binfmt_elf32.c introduced by the
previous patch.

Arnd Bergmann April 22, 2016, 5:41 p.m. UTC | #2

On Friday 22 April 2016 17:51:30 Catalin Marinas wrote:
> On Wed, Apr 06, 2016 at 01:08:40AM +0300, Yury Norov wrote:
> > --- /dev/null
> > +++ b/arch/arm64/kernel/binfmt_ilp32.c
> 
> [...]
> 
> > +#include "../../../fs/binfmt_elf.c"
> 
> How different is this new binfmt_ilp32.c file from the first part of
> compat_binfmt_elf.c? I wonder whether we could include the latter here
> instead and make this similar to binfmt_elf32.c introduced by the
> previous patch.

That is how the earlier versions did it, and I thought it ended up 
too ugly with lots of runtime checks instead of compile-time checks.

The current version is how I asked it to be done. A slight
variation would be to keep using fs/compat_binfmt_elf.c for one
of the two compat modes (today it is used for aarch32) and have
a separate file include "../../../fs/binfmt_elf.c" for the other
mode (as this patch does for ilp32). I think that is what I asked
for, but there was probably a good reason for having two files
in the same directory. The result is basically the same.

	Arnd

Patch

diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 6bc9738..9dfdf86 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -28,6 +28,7 @@  $(obj)/%.stub.o: $(obj)/%.o FORCE
 arm64-obj-$(CONFIG_AARCH32_EL0)		+= sys32.o kuser32.o signal32.o 	\
 					   sys_compat.o entry32.o		\
 					   ../../arm/kernel/opcodes.o binfmt_elf32.o
+arm64-obj-$(CONFIG_ARM64_ILP32)		+= binfmt_ilp32.o
 arm64-obj-$(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_ilp32.c b/arch/arm64/kernel/binfmt_ilp32.c
new file mode 100644
index 0000000..a934fd4
--- /dev/null
+++ b/arch/arm64/kernel/binfmt_ilp32.c
@@ -0,0 +1,91 @@ 
+/*
+ * Support for ILP32 Linux/aarch64 ELF binaries.
+ */
+
+#include <linux/elfcore-compat.h>
+#include <linux/time.h>
+
+#undef	ELF_CLASS
+#define ELF_CLASS	ELFCLASS32
+
+#undef	elfhdr
+#undef	elf_phdr
+#undef	elf_shdr
+#undef	elf_note
+#undef	elf_addr_t
+#define elfhdr		elf32_hdr
+#define elf_phdr	elf32_phdr
+#define elf_shdr	elf32_shdr
+#define elf_note	elf32_note
+#define elf_addr_t	Elf32_Addr
+
+/*
+ * Some data types as stored in coredump.
+ */
+#define user_long_t		compat_long_t
+#define user_siginfo_t		compat_siginfo_t
+#define copy_siginfo_to_user	copy_siginfo_to_user32
+
+/*
+ * The machine-dependent core note format types are defined in elfcore-compat.h,
+ * which requires asm/elf.h to define compat_elf_gregset_t et al.
+ */
+#define elf_prstatus	compat_elf_prstatus
+#define elf_prpsinfo	compat_elf_prpsinfo
+
+/*
+ * Compat version of cputime_to_compat_timeval, perhaps this
+ * should be an inline in <linux/compat.h>.
+ */
+static void cputime_to_compat_timeval(const cputime_t cputime,
+				      struct compat_timeval *value)
+{
+	struct timeval tv;
+	cputime_to_timeval(cputime, &tv);
+	value->tv_sec = tv.tv_sec;
+	value->tv_usec = tv.tv_usec;
+}
+
+#undef cputime_to_timeval
+#define cputime_to_timeval cputime_to_compat_timeval
+
+/* AARCH64 ILP32 EABI. */
+#undef elf_check_arch
+#define elf_check_arch(x)		(((x)->e_machine == EM_AARCH64)	\
+					&& (x)->e_ident[EI_CLASS] == ELFCLASS32)
+
+#undef SET_PERSONALITY
+#define SET_PERSONALITY(ex)						\
+do {									\
+	set_thread_flag(TIF_32BIT_AARCH64);				\
+	clear_thread_flag(TIF_32BIT);					\
+} while (0)
+
+#undef ARCH_DLINFO
+#define ARCH_DLINFO							\
+do {									\
+	NEW_AUX_ENT(AT_SYSINFO_EHDR,					\
+		    (elf_addr_t)(long)current->mm->context.vdso);	\
+} while (0)
+
+#ifdef __AARCH64EB__
+#define COMPAT_ELF_PLATFORM		("aarch64_be:ilp32")
+#else
+#define COMPAT_ELF_PLATFORM		("aarch64:ilp32")
+#endif
+
+#undef ELF_HWCAP
+#undef ELF_HWCAP2
+#define ELF_HWCAP			((u32) elf_hwcap)
+#define ELF_HWCAP2			((u32) (elf_hwcap >> 32))
+
+/*
+ * Rename a few of the symbols that binfmt_elf.c will define.
+ * These are all local so the names don't really matter, but it
+ * might make some debugging less confusing not to duplicate them.
+ */
+#define elf_format		compat_elf_format
+#define init_elf_binfmt		init_compat_elf_binfmt
+#define exit_elf_binfmt		exit_compat_elf_binfmt
+
+#include "../../../fs/binfmt_elf.c"