[PATCH] Add a.out support for x86-64

From: Andi Kleen <ak@muc.de>

Add 32bit a.out support for x86-64.

Not exactly an important bug fix, but maybe it will help someone.  This
should increase the current 98% compatibility to i386 to perhaps 98.1% @)

I tested an old a.out SuSE 4.2 installation in chroot and it worked.  It
also ran some very old linux binaries from '92 found on ftp.funet.fi.  The
only program that didn't was the SuSE a.out GNU emacs, but I was too lazy
to track that down.  Core dumps are not supported.

arch/x86_64/Kconfig

@@ -371,6 +371,12 @@ config IA32_EMULATION
 	  turn this on, unless you're 100% sure that you don't have any 32-bit programs
 	  left.
 
+config IA32_AOUT
+       bool "IA32 a.out support"
+       depends on IA32_EMULATION
+       help
+         Support old a.out binaries in the 32bit emulation.
+
 config COMPAT
 	bool
 	depends on IA32_EMULATION

arch/x86_64/ia32/Makefile

@@ -6,6 +6,8 @@ obj-$(CONFIG_IA32_EMULATION) := ia32entry.o sys_ia32.o ia32_ioctl.o \
 	ia32_signal.o tls32.o \
 	ia32_binfmt.o fpu32.o ptrace32.o ipc32.o syscall32.o
 
+obj-$(CONFIG_IA32_AOUT) += ia32_aout.o
+
 $(obj)/syscall32.o: $(src)/syscall32.c $(obj)/vsyscall.so
 
 # Teach kbuild about targets

arch/x86_64/ia32/ia32entry.S

@@ -221,7 +221,7 @@ ia32_sys_call_table:
 	.quad sys_chmod		/* 15 */
 	.quad sys_lchown16
 	.quad ni_syscall			/* old break syscall holder */
-	.quad ni_syscall	/* (old)stat */ 
+	.quad sys_stat
 	.quad sys32_lseek
 	.quad sys_getpid		/* 20 */
 	.quad sys_mount	/* mount  */
@@ -231,7 +231,7 @@ ia32_sys_call_table:
 	.quad sys_stime		/* stime */		/* 25 */
 	.quad sys32_ptrace	/* ptrace */
 	.quad sys_alarm		/* XXX sign extension??? */ 
-	.quad ni_syscall	/* (old)fstat */
+	.quad sys_fstat	/* (old)fstat */
 	.quad sys_pause
 	.quad compat_sys_utime	/* 30 */
 	.quad ni_syscall	/* old stty syscall holder */
@@ -287,7 +287,7 @@ ia32_sys_call_table:
 	.quad sys_setgroups16
 	.quad sys32_old_select
 	.quad sys_symlink
-	.quad ni_syscall	/* (old)lstat */
+	.quad sys_lstat
 	.quad sys_readlink		/* 85 */
 	.quad sys_uselib
 	.quad sys_swapon

fs/stat.c

@@ -106,7 +106,7 @@ int vfs_fstat(unsigned int fd, struct kstat *stat)
 EXPORT_SYMBOL(vfs_fstat);
 
 #if !defined(__alpha__) && !defined(__sparc__) && !defined(__ia64__) \
-  && !defined(CONFIG_ARCH_S390) && !defined(__hppa__) && !defined(__x86_64__) \
+  && !defined(CONFIG_ARCH_S390) && !defined(__hppa__) \
   && !defined(__arm__) && !defined(CONFIG_V850) && !defined(__powerpc64__)
 
 /*

include/asm-x86_64/a.out.h

 #ifndef __X8664_A_OUT_H__
 #define __X8664_A_OUT_H__
 
-
-/* Note: a.out is not supported in 64bit mode. This is just here to 
-   still let some old things compile. */ 
+/* 32bit a.out */
 
 struct exec
 {
-  unsigned long a_info;		/* Use macros N_MAGIC, etc for access */
+  unsigned int a_info;		/* Use macros N_MAGIC, etc for access */
   unsigned a_text;		/* length of text, in bytes */
   unsigned a_data;		/* length of data, in bytes */
   unsigned a_bss;		/* length of uninitialized data area for file, in bytes */
@@ -23,7 +21,7 @@ struct exec
 
 #ifdef __KERNEL__
 
-#define STACK_TOP	TASK_SIZE
+#define STACK_TOP	0xc0000000
 
 #endif
 

include/asm-x86_64/stat.h

@@ -26,4 +26,19 @@ struct stat {
   	long		__unused[3];
 };
 
+/* For 32bit emulation */
+struct __old_kernel_stat {
+	unsigned short st_dev;
+	unsigned short st_ino;
+	unsigned short st_mode;
+	unsigned short st_nlink;
+	unsigned short st_uid;
+	unsigned short st_gid;
+	unsigned short st_rdev;
+	unsigned int  st_size;
+	unsigned int  st_atime;
+	unsigned int  st_mtime;
+	unsigned int  st_ctime;
+};
+
 #endif