Messages in this thread Patch in this message | | | From | Lai Jiangshan <> | Subject | [PATCH V4 5/7] x86/entry: Don't call error_entry for XENPV | Date | Fri, 18 Mar 2022 22:30:14 +0800 |
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From: Lai Jiangshan <jiangshan.ljs@antgroup.com>
When in XENPV, it is already in the task stack, and it can't fault for native_iret() nor native_load_gs_index() since XENPV uses its own pvops for iret and load_gs_index(). And it doesn't need to switch CR3. So there is no reason to call error_entry() in XENPV.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.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 8121b9f3fceb..e9fe9f00d17c 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -328,8 +328,17 @@ 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 + * for native_iret() nor native_load_gs_index() 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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