Messages in this thread Patch in this message | | | From | Alexandre Chartre <> | Subject | [PATCH] x86/entry: Remove UNTRAIN_RET from native_irq_return_ldt | Date | Wed, 13 Jul 2022 21:58:08 +0200 |
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UNTRAIN_RET is not needed in native_irq_return_ldt because ret untrain has already be 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 <alexandre.chartre@oracle.com> --- arch/x86/entry/entry_64.S | 1 - 1 file changed, 1 deletion(-)
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 */ -- 2.31.1
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