From: Michael Ellerman Date: Sat, 28 Mar 2015 10:35:16 +0000 (+1100) Subject: powerpc: Add a proper syscall for switching endianness X-Git-Tag: omap-for-v4.1/fixes-rc1~126^2~66 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=529d235a0e190ded1d21ccc80a73e625ebcad09b;p=pandora-kernel.git powerpc: Add a proper syscall for switching endianness We currently have a "special" syscall for switching endianness. This is syscall number 0x1ebe, which is handled explicitly in the 64-bit syscall exception entry. That has a few problems, firstly the syscall number is outside of the usual range, which confuses various tools. For example strace doesn't recognise the syscall at all. Secondly it's handled explicitly as a special case in the syscall exception entry, which is complicated enough without it. As a first step toward removing the special syscall, we need to add a regular syscall that implements the same functionality. The logic is simple, it simply toggles the MSR_LE bit in the userspace MSR. This is the same as the special syscall, with the caveat that the special syscall clobbers fewer registers. This version clobbers r9-r12, XER, CTR, and CR0-1,5-7. Signed-off-by: Michael Ellerman --- Reading git-diff-tree failed