Dave Hansen 8a09317b89 x86/mm/pti: Prepare the x86/entry assembly code for entry/exit CR3 switching ... PAGE_TABLE_ISOLATION needs to switch to a different CR3 value when it enters the kernel and switch back when it exits. This essentially needs to be done before leaving assembly code. This is extra challenging because the switching context is tricky: the registers that can be clobbered can vary. It is also hard to store things on the stack because there is an established ABI (ptregs) or the stack is entirely unsafe to use. Establish a set of macros that allow changing to the user and kernel CR3 values. Interactions with SWAPGS: Previous versions of the PAGE_TABLE_ISOLATION code relied on having per-CPU scratch space to save/restore a register that can be used for the CR3 MOV. The %GS register is used to index into our per-CPU space, so SWAPGS *had* to be done before the CR3 switch. That scratch space is gone now, but the semantic that SWAPGS must be done before the CR3 MOV is retained. This is good to keep because it is not that hard to do and it allows to do things like add per-CPU debugging information. What this does in the NMI code is worth pointing out. NMIs can interrupt *any* context and they can also be nested with NMIs interrupting other NMIs. The comments below ".Lnmi_from_kernel" explain the format of the stack during this situation. Changing the format of this stack is hard. Instead of storing the old CR3 value on the stack, this depends on the *regular* register save/restore mechanism and then uses %r14 to keep CR3 during the NMI. It is callee-saved and will not be clobbered by the C NMI handlers that get called. [ PeterZ: ESPFIX optimization ] Based-on-code-from: Andy Lutomirski <luto@kernel.org> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Borislav Petkov <bp@suse.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar <mingo@kernel.org>		2017-12-23 21:12:59 +01:00
..
syscalls	Merge branch 'x86/build' into x86/asm, to fix up conflicts	2017-11-07 10:54:30 +01:00
vdso	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
vsyscall	x86/vsyscall/64: Warn and fail vsyscall emulation in NATIVE mode	2017-12-22 20:13:01 +01:00
calling.h	x86/mm/pti: Prepare the x86/entry assembly code for entry/exit CR3 switching	2017-12-23 21:12:59 +01:00
common.c	x86/syscalls: Check address limit on user-mode return	2017-07-08 14:05:32 +02:00
entry_32.S	x86/entry: Rename SYSENTER_stack to CPU_ENTRY_AREA_entry_stack	2017-12-22 20:13:02 +01:00
entry_64_compat.S	x86/mm/pti: Prepare the x86/entry assembly code for entry/exit CR3 switching	2017-12-23 21:12:59 +01:00
entry_64.S	x86/mm/pti: Prepare the x86/entry assembly code for entry/exit CR3 switching	2017-12-23 21:12:59 +01:00
Makefile	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
syscall_32.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
syscall_64.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
thunk_32.S	x86: move exports to actual definitions	2016-08-07 23:47:15 -04:00
thunk_64.S	x86: move exports to actual definitions	2016-08-07 23:47:15 -04:00