diff options
authorAnton Blanchard <anton@samba.org>2006-06-07 16:10:19 +1000
committerPaul Mackerras <paulus@samba.org>2006-06-09 21:24:13 +1000
commit651d765d0b2c72d33430487c8b6ef64c60cd2134 (patch)
parent[PATCH] powerpc: Add udbg-immortal kernel option (diff)
[PATCH] Add a prctl to change the endianness of a process.
This new prctl is intended for changing the execution mode of the processor, on processors that support both a little-endian mode and a big-endian mode. It is intended for use by programs such as instruction set emulators (for example an x86 emulator on PowerPC), which may find it convenient to use the processor in an alternate endianness mode when executing translated instructions. Note that this does not imply the existence of a fully-fledged ABI for both endiannesses, or of compatibility code for converting system calls done in the non-native endianness mode. The program is expected to arrange for all of its system call arguments to be presented in the native endianness. Switching between big and little-endian mode will require some care in constructing the instruction sequence for the switch. Generally the instructions up to the instruction that invokes the prctl system call will have to be in the old endianness, and subsequent instructions will have to be in the new endianness. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to '')
2 files changed, 20 insertions, 0 deletions
diff --git a/include/linux/prctl.h b/include/linux/prctl.h
index bf022c43a18e..52a9be41250d 100644
--- a/include/linux/prctl.h
+++ b/include/linux/prctl.h
@@ -52,4 +52,11 @@
#define PR_SET_NAME 15 /* Set process name */
#define PR_GET_NAME 16 /* Get process name */
+/* Get/set process endian */
+#define PR_GET_ENDIAN 19
+#define PR_SET_ENDIAN 20
+# define PR_ENDIAN_BIG 0
+# define PR_ENDIAN_LITTLE 1 /* True little endian mode */
+# define PR_ENDIAN_PPC_LITTLE 2 /* "PowerPC" pseudo little endian */
#endif /* _LINUX_PRCTL_H */
diff --git a/kernel/sys.c b/kernel/sys.c
index 0b6ec0e7936f..12d2d753dc3b 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -57,6 +57,12 @@
# define GET_FPEXC_CTL(a,b) (-EINVAL)
+#ifndef GET_ENDIAN
+# define GET_ENDIAN(a,b) (-EINVAL)
+#ifndef SET_ENDIAN
+# define SET_ENDIAN(a,b) (-EINVAL)
* this is where the system-wide overflow UID and GID are defined, for
@@ -2057,6 +2063,13 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
return -EFAULT;
return 0;
+ error = GET_ENDIAN(current, arg2);
+ break;
+ error = SET_ENDIAN(current, arg2);
+ break;
error = -EINVAL;