Re: [PATCH v2 06/27] x86/entry/64: Adapt assembly for PIE support
From: Peter Zijlstra <peterz@infradead.org>
Date: 2018-03-14 10:29:51
Also in:
kvm, linux-arch, linux-crypto, linux-pm, lkml
On Tue, Mar 13, 2018 at 01:59:24PM -0700, Thomas Garnier wrote:
quoted hunk
@@ -1576,7 +1578,9 @@ first_nmi: addq $8, (%rsp) /* Fix up RSP */ pushfq /* RFLAGS */ pushq $__KERNEL_CS /* CS */ - pushq $1f /* RIP */ + pushq %rax /* Support Position Independent Code */ + leaq 1f(%rip), %rax /* RIP */ + xchgq %rax, (%rsp) /* Restore RAX, put 1f */ iretq /* continues at repeat_nmi below */ UNWIND_HINT_IRET_REGS 1:
Urgh, xchg with a memop has an implicit LOCK prefix.