| From | Lai Jiangshan <> | Subject | [PATCH V6 21/49] x86/entry: Don't call error_entry for XENPV | Date | Fri, 26 Nov 2021 18:11:41 +0800 |
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From: Lai Jiangshan <laijs@linux.alibaba.com>
When in XENPV, it is already in the task stack, and it can't fault at native_irq_return_iret nor asm_load_gs_index_gs_change since XENPV uses its own pvops for iret and load_gs_index(). And it doesn't need to switch CR3. So it can skip invoking error_entry().
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com> --- arch/x86/entry/entry_64.S | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 09bd77e49249..c09e5a4dfbbf 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -325,8 +325,17 @@ SYM_CODE_END(ret_from_fork) PUSH_AND_CLEAR_REGS ENCODE_FRAME_POINTER - call error_entry - movq %rax, %rsp /* switch stack settled by sync_regs() */ + /* + * Call error_entry and switch stack settled by sync_regs(). + * + * When in XENPV, it is already in the task stack, and it can't fault + * at native_irq_return_iret nor asm_load_gs_index_gs_change since + * XENPV uses its own pvops for iret and load_gs_index(). And it + * doesn't need to switch CR3. So it can skip invoking error_entry(). + */ + ALTERNATIVE "call error_entry; movq %rax, %rsp", \ + "", X86_FEATURE_XENPV + ENCODE_FRAME_POINTER UNWIND_HINT_REGS -- 2.19.1.6.gb485710b
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