From d16e0b26672066035439b2f49887f6576c4a3689 Mon Sep 17 00:00:00 2001 From: Alexandre Chartre Date: Wed, 13 Jul 2022 21:58:08 +0200 Subject: x86/entry: Remove UNTRAIN_RET from native_irq_return_ldt UNTRAIN_RET is not needed in native_irq_return_ldt because RET untraining has already been done at this point. In addition, when the RETBleed mitigation is IBPB, UNTRAIN_RET clobbers several registers (AX, CX, DX) so here it trashes user values which are in these registers. Signed-off-by: Alexandre Chartre Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/35b0d50f-12d1-10c3-f5e8-d6c140486d4a@oracle.com --- arch/x86/entry/entry_64.S | 1 - 1 file changed, 1 deletion(-) (limited to 'arch') diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 285e043a3e40..9953d966d124 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -727,7 +727,6 @@ native_irq_return_ldt: pushq %rdi /* Stash user RDI */ swapgs /* to kernel GS */ SWITCH_TO_KERNEL_CR3 scratch_reg=%rdi /* to kernel CR3 */ - UNTRAIN_RET movq PER_CPU_VAR(espfix_waddr), %rdi movq %rax, (0*8)(%rdi) /* user RAX */ -- cgit v1.2.3