From 651d765d0b2c72d33430487c8b6ef64c60cd2134 Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Wed, 7 Jun 2006 16:10:19 +1000 Subject: [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 Signed-off-by: Paul Mackerras --- include/linux/prctl.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/linux') 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 */ -- cgit v1.2.3 From 1e92a550e80fef01ebcc0bcd0896109cdb986c72 Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Thu, 15 Jun 2006 14:11:22 +1000 Subject: [POWERPC] Fix mdelay badness on shared processor partitions On partitioned PPC64 systems where a partition is given 1/10 of a processor, we have seen mdelay() delaying for 10 times longer than it should. The reason is that the generic mdelay(n) does n delays of 1 millisecond each. However, with 1/10 of a processor, we only get a one-millisecond timeslice every 10ms. Thus each 1 millisecond delay loop ends up taking 10ms elapsed time. The solution is just to use the PPC64 udelay function, which uses the timebase to ensure that the delay is based on elapsed time rather than how much processing time the partition has been given. (Yes, the generic mdelay uses the PPC64 udelay, but the problem is that the start time gets reset every millisecond, and each time it gets reset we lose another 9ms.) Signed-off-by: Anton Blanchard Signed-off-by: Paul Mackerras Acked-by: Andrew Morton --- include/asm-powerpc/delay.h | 13 +++++++++++++ include/linux/delay.h | 5 +---- 2 files changed, 14 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/asm-powerpc/delay.h b/include/asm-powerpc/delay.h index 057a60955474..f9200a65c632 100644 --- a/include/asm-powerpc/delay.h +++ b/include/asm-powerpc/delay.h @@ -17,5 +17,18 @@ extern void __delay(unsigned long loops); extern void udelay(unsigned long usecs); +/* + * On shared processor machines the generic implementation of mdelay can + * result in large errors. While each iteration of the loop inside mdelay + * is supposed to take 1ms, the hypervisor could sleep our partition for + * longer (eg 10ms). With the right timing these errors can add up. + * + * Since there is no 32bit overflow issue on 64bit kernels, just call + * udelay directly. + */ +#ifdef CONFIG_PPC64 +#define mdelay(n) udelay((n) * 1000) +#endif + #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_DELAY_H */ diff --git a/include/linux/delay.h b/include/linux/delay.h index acb74865b973..17ddb55430ae 100644 --- a/include/linux/delay.h +++ b/include/linux/delay.h @@ -25,10 +25,7 @@ extern unsigned long loops_per_jiffy; #define MAX_UDELAY_MS 5 #endif -#ifdef notdef -#define mdelay(n) (\ - {unsigned long __ms=(n); while (__ms--) udelay(1000);}) -#else +#ifndef mdelay #define mdelay(n) (\ (__builtin_constant_p(n) && (n)<=MAX_UDELAY_MS) ? udelay((n)*1000) : \ ({unsigned long __ms=(n); while (__ms--) udelay(1000);})) -- cgit v1.2.3