Messages in this thread Patch in this message | | | From | Lai Jiangshan <> | Subject | [PATCH 2/4] x86/entry: Call paranoid_exit() in asm_exc_nmi() | Date | Mon, 13 Dec 2021 23:03:38 +0800 |
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From: Lai Jiangshan <laijs@linux.alibaba.com>
The code between "call exc_nmi" and nmi_restore is as the same as paranoid_exit(), so we can just use paranoid_exit() instead of the open duplicated code.
No functional change intended.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com> --- arch/x86/entry/entry_64.S | 34 +++++----------------------------- 1 file changed, 5 insertions(+), 29 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 3dc3cec03425..47ff4abd87b5 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -920,8 +920,7 @@ SYM_CODE_END(paranoid_entry) /* * "Paranoid" exit path from exception stack. This is invoked - * only on return from non-NMI IST interrupts that came - * from kernel space. + * only on return from IST interrupts that came from kernel space. * * We may be returning to very strange contexts (e.g. very early * in syscall entry), so checking for preemption here would @@ -1354,11 +1353,7 @@ end_repeat_nmi: pushq $-1 /* ORIG_RAX: no syscall to restart */ /* - * Use paranoid_entry to handle SWAPGS, but no need to use paranoid_exit - * as we should not be calling schedule in NMI context. - * Even with normal interrupts enabled. An NMI should not be - * setting NEED_RESCHED or anything that normal interrupts and - * exceptions might do. + * Use paranoid_entry to handle SWAPGS and CR3. */ call paranoid_entry UNWIND_HINT_REGS @@ -1367,31 +1362,12 @@ end_repeat_nmi: movq $-1, %rsi call exc_nmi - /* Always restore stashed CR3 value (see paranoid_entry) */ - RESTORE_CR3 scratch_reg=%r15 save_reg=%r14 - /* - * The above invocation of paranoid_entry stored the GSBASE - * related information in R/EBX depending on the availability - * of FSGSBASE. - * - * If FSGSBASE is enabled, restore the saved GSBASE value - * unconditionally, otherwise take the conditional SWAPGS path. + * Use paranoid_exit to handle SWAPGS and CR3, but no need to use + * restore_regs_and_return_to_kernel as we must handle nested NMI. */ - ALTERNATIVE "jmp nmi_no_fsgsbase", "", X86_FEATURE_FSGSBASE - - wrgsbase %rbx - jmp nmi_restore - -nmi_no_fsgsbase: - /* EBX == 0 -> invoke SWAPGS */ - testl %ebx, %ebx - jnz nmi_restore - -nmi_swapgs: - swapgs + call paranoid_exit -nmi_restore: POP_REGS /* -- 2.19.1.6.gb485710b
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