The following commit has been merged into the x86/urgent branch of tip: Commit-ID: d16e0b26672066035439b2f49887f6576c4a3689 Gitweb: https://git.kernel.org/tip/d16e0b26672066035439b2f49887f6576c4a3689 Author: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx> AuthorDate: Wed, 13 Jul 2022 21:58:08 +02:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Thu, 14 Jul 2022 09:45:12 +02:00 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 <alexandre.chartre@xxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Link: https://lore.kernel.org/r/35b0d50f-12d1-10c3-f5e8-d6c140486d4a@xxxxxxxxxx --- 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 285e043..9953d96 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 */
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