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SubjectRe: x86: Spurious vectors not handled robustly
On Mon, 24 Jun 2019, Thomas Gleixner wrote:
>
> +#ifdef CONFIG_X86_LOCAL_APIC
> + .align 8
> +ENTRY(spurious_entries_start)
> + vector=FIRST_SYSTEM_VECTOR
> + .rept (NR_VECTORS - FIRST_SYSTEM_VECTOR)
> + pushl $(~vector+0x80) /* Note: always in signed byte range */
> + vector=vector+1
> + jmp common_spurious_vector

Moo. Not syncing the compile machine and the laptop! That should obviously be

+ jmp common_spurious

> + .align 8
> + .endr
> +END(spurious_entries_start)
> +
> +common_spurious:
> + ASM_CLAC
> + addl $-0x80, (%esp) /* Adjust vector into the [-256, -1] range */
> + SAVE_ALL switch_stacks=1
> + ENCODE_FRAME_POINTER
> + TRACE_IRQS_OFF
> + movl %esp, %eax
> + call smp_spurious_interrupt
> + jmp ret_from_intr
> +ENDPROC(common_interrupt)
> +#endif
> +
> /*
> * the CPU automatically disables interrupts when executing an IRQ vector,
> * so IRQ-flags tracing has to follow that:
> --- a/arch/x86/entry/entry_64.S
> +++ b/arch/x86/entry/entry_64.S
> @@ -375,6 +375,18 @@ ENTRY(irq_entries_start)
> .endr
> END(irq_entries_start)
>
> + .align 8
> +ENTRY(spurious_entries_start)
> + vector=FIRST_SYSTEM_VECTOR
> + .rept (NR_VECTORS - FIRST_SYSTEM_VECTOR)
> + UNWIND_HINT_IRET_REGS
> + pushq $(~vector+0x80) /* Note: always in signed byte range */
> + jmp common_spurious
> + .align 8
> + vector=vector+1
> + .endr
> +END(spurious_entries_start)
> +
> .macro DEBUG_ENTRY_ASSERT_IRQS_OFF
> #ifdef CONFIG_DEBUG_ENTRY
> pushq %rax
> @@ -571,10 +583,20 @@ END(interrupt_entry)
>
> /* Interrupt entry/exit. */
>
> - /*
> - * The interrupt stubs push (~vector+0x80) onto the stack and
> - * then jump to common_interrupt.
> - */
> +/*
> + * The interrupt stubs push (~vector+0x80) onto the stack and
> + * then jump to common_spurious/interrupt.
> + */
> +common_spurious:
> + addq $-0x80, (%rsp) /* Adjust vector to [-256, -1] range */
> + call interrupt_entry
> + UNWIND_HINT_REGS indirect=1
> + call smp_spurious_interrupt /* rdi points to pt_regs */
> + jmp ret_from_intr
> +END(common_spurious)
> +_ASM_NOKPROBE(common_spurious)
> +
> +/* common_interrupt is a hotpath. Align it */
> .p2align CONFIG_X86_L1_CACHE_SHIFT
> common_interrupt:
> addq $-0x80, (%rsp) /* Adjust vector to [-256, -1] range */
> --- a/arch/x86/include/asm/hw_irq.h
> +++ b/arch/x86/include/asm/hw_irq.h
> @@ -150,6 +150,8 @@ extern char irq_entries_start[];
> #define trace_irq_entries_start irq_entries_start
> #endif
>
> +extern char spurious_entries_start[];
> +
> #define VECTOR_UNUSED NULL
> #define VECTOR_RETRIGGERED ((void *)~0UL)
>
> --- a/arch/x86/kernel/idt.c
> +++ b/arch/x86/kernel/idt.c
> @@ -319,7 +319,8 @@ void __init idt_setup_apic_and_irq_gates
> #ifdef CONFIG_X86_LOCAL_APIC
> for_each_clear_bit_from(i, system_vectors, NR_VECTORS) {
> set_bit(i, system_vectors);
> - set_intr_gate(i, spurious_interrupt);
> + entry = spurious_entries_start + 8 * (i - FIRST_SYSTEM_VECTOR);
> + set_intr_gate(i, entry);
> }
> #endif
> }
>

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