From: Andy Lutomirski Date: Wed, 3 Aug 2011 13:31:53 +0000 (-0400) Subject: x86-64: Add user_64bit_mode paravirt op X-Git-Tag: v3.1-rc2~16^2~4 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=318f5a2a672152328c9fb4dead504b89ec738a43;p=pandora-kernel.git x86-64: Add user_64bit_mode paravirt op Three places in the kernel assume that the only long mode CPL 3 selector is __USER_CS. This is not true on Xen -- Xen's sysretq changes cs to the magic value 0xe033. Two of the places are corner cases, but as of "x86-64: Improve vsyscall emulation CS and RIP handling" (c9712944b2a12373cb6ff8059afcfb7e826a6c54), vsyscalls will segfault if called with Xen's extra CS selector. This causes a panic when older init builds die. It seems impossible to make Xen use __USER_CS reliably without taking a performance hit on every system call, so this fixes the tests instead with a new paravirt op. It's a little ugly because ptrace.h can't include paravirt.h. Signed-off-by: Andy Lutomirski Link: http://lkml.kernel.org/r/f4fcb3947340d9e96ce1054a432f183f9da9db83.1312378163.git.luto@mit.edu Reported-by: Konrad Rzeszutek Wilk Signed-off-by: H. Peter Anvin --- Reading git-diff-tree failed