From 318f5a2a672152328c9fb4dead504b89ec738a43 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Wed, 3 Aug 2011 09:31:53 -0400 Subject: 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 --- arch/x86/include/asm/paravirt_types.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'arch/x86/include/asm/paravirt_types.h') diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h index 82885099c869..96a0f80407b8 100644 --- a/arch/x86/include/asm/paravirt_types.h +++ b/arch/x86/include/asm/paravirt_types.h @@ -41,6 +41,7 @@ #include #include +#include struct page; struct thread_struct; @@ -63,6 +64,11 @@ struct paravirt_callee_save { struct pv_info { unsigned int kernel_rpl; int shared_kernel_pmd; + +#ifdef CONFIG_X86_64 + u16 extra_user_64bit_cs; /* __USER_CS if none */ +#endif + int paravirt_enabled; const char *name; }; -- cgit v1.2.3-55-g7522