Messages in this thread Patch in this message | | | From | Lai Jiangshan <> | Subject | [PATCH V7 5/6] x86/entry: Don't call error_entry() for XENPV | Date | Tue, 3 May 2022 11:21:06 +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 the CR3.
So there is no reason to call error_entry() in XENPV.
Cc: Juergen Gross <jgross@suse.com> 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 ab6ab6d3dab5..062aa9d95961 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -336,8 +336,17 @@ SYM_CODE_END(push_and_clear_regs) call push_and_clear_regs UNWIND_HINT_REGS - call error_entry - movq %rax, %rsp /* switch to the task stack if from userspace */ + /* + * Call error_entry() and switch to the task stack if from userspace. + * + * 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 the 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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