Commit f8818559 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86-urgent-2020-09-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 fixes from Thomas Gleixner:
 "Two fixes for the x86 interrupt code:

   - Unbreak the magic 'search the timer interrupt' logic in IO/APIC
     code which got wreckaged when the core interrupt code made the
     state tracking logic stricter.

     That caused the interrupt line to stay masked after switching from
     IO/APIC to PIC delivery mode, which obviously prevents interrupts
     from being delivered.

   - Make run_on_irqstack_code() typesafe. The function argument is a
     void pointer which is then cast to 'void (*fun)(void *).

     This breaks Control Flow Integrity checking in clang. Use proper
     helper functions for the three variants reuqired"

* tag 'x86-urgent-2020-09-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/ioapic: Unbreak check_timer()
  x86/irq: Make run_on_irqstack_cond() typesafe
parents ba25f057 86a82ae0

arch/x86/entry/common.c

+1 −1
Original line number Diff line number Diff line
@@ -299,7 +299,7 @@ __visible noinstr void xen_pv_evtchn_do_upcall(struct pt_regs *regs) 
	old_regs = set_irq_regs(regs);



	instrumentation_begin();

	run_on_irqstack_cond(__xen_pv_evtchn_do_upcall, NULL, regs);

	run_on_irqstack_cond(__xen_pv_evtchn_do_upcall, regs);

	instrumentation_begin();



	set_irq_regs(old_regs);

arch/x86/entry/entry_64.S

+2 −0
Original line number Diff line number Diff line
@@ -682,6 +682,8 @@ SYM_CODE_END(.Lbad_gs) 
 * rdx: Function argument (can be NULL if none)

 */

SYM_FUNC_START(asm_call_on_stack)

SYM_INNER_LABEL(asm_call_sysvec_on_stack, SYM_L_GLOBAL)

SYM_INNER_LABEL(asm_call_irq_on_stack, SYM_L_GLOBAL)

	/*

	 * Save the frame pointer unconditionally. This allows the ORC

	 * unwinder to handle the stack switch.

arch/x86/include/asm/idtentry.h

+1 −1
Original line number Diff line number Diff line
@@ -242,7 +242,7 @@ __visible noinstr void func(struct pt_regs *regs) \ 
	instrumentation_begin();					\

	irq_enter_rcu();						\

	kvm_set_cpu_l1tf_flush_l1d();					\

	run_on_irqstack_cond(__##func, regs, regs);			\

	run_sysvec_on_irqstack_cond(__##func, regs);			\

	irq_exit_rcu();							\

	instrumentation_end();						\

	irqentry_exit(regs, state);					\

arch/x86/include/asm/irq_stack.h

+61 −8
Original line number Diff line number Diff line
@@ -12,20 +12,50 @@ static __always_inline bool irqstack_active(void) 
	return __this_cpu_read(irq_count) != -1;

}



void asm_call_on_stack(void *sp, void *func, void *arg);

void asm_call_on_stack(void *sp, void (*func)(void), void *arg);

void asm_call_sysvec_on_stack(void *sp, void (*func)(struct pt_regs *regs),

			      struct pt_regs *regs);

void asm_call_irq_on_stack(void *sp, void (*func)(struct irq_desc *desc),

			   struct irq_desc *desc);



static __always_inline void __run_on_irqstack(void *func, void *arg)

static __always_inline void __run_on_irqstack(void (*func)(void))

{

	void *tos = __this_cpu_read(hardirq_stack_ptr);



	__this_cpu_add(irq_count, 1);

	asm_call_on_stack(tos - 8, func, arg);

	asm_call_on_stack(tos - 8, func, NULL);

	__this_cpu_sub(irq_count, 1);

}



static __always_inline void

__run_sysvec_on_irqstack(void (*func)(struct pt_regs *regs),

			 struct pt_regs *regs)

{

	void *tos = __this_cpu_read(hardirq_stack_ptr);



	__this_cpu_add(irq_count, 1);

	asm_call_sysvec_on_stack(tos - 8, func, regs);

	__this_cpu_sub(irq_count, 1);

}



static __always_inline void

__run_irq_on_irqstack(void (*func)(struct irq_desc *desc),

		      struct irq_desc *desc)

{

	void *tos = __this_cpu_read(hardirq_stack_ptr);



	__this_cpu_add(irq_count, 1);

	asm_call_irq_on_stack(tos - 8, func, desc);

	__this_cpu_sub(irq_count, 1);

}



#else /* CONFIG_X86_64 */

static inline bool irqstack_active(void) { return false; }

static inline void __run_on_irqstack(void *func, void *arg) { }

static inline void __run_on_irqstack(void (*func)(void)) { }

static inline void __run_sysvec_on_irqstack(void (*func)(struct pt_regs *regs),

					    struct pt_regs *regs) { }

static inline void __run_irq_on_irqstack(void (*func)(struct irq_desc *desc),

					 struct irq_desc *desc) { }

#endif /* !CONFIG_X86_64 */



static __always_inline bool irq_needs_irq_stack(struct pt_regs *regs)
@@ -37,17 +67,40 @@ static __always_inline bool irq_needs_irq_stack(struct pt_regs *regs) 
	return !user_mode(regs) && !irqstack_active();

}



static __always_inline void run_on_irqstack_cond(void *func, void *arg,



static __always_inline void run_on_irqstack_cond(void (*func)(void),

						 struct pt_regs *regs)

{

	void (*__func)(void *arg) = func;

	lockdep_assert_irqs_disabled();



	if (irq_needs_irq_stack(regs))

		__run_on_irqstack(func);

	else

		func();

}



static __always_inline void

run_sysvec_on_irqstack_cond(void (*func)(struct pt_regs *regs),

			    struct pt_regs *regs)

{

	lockdep_assert_irqs_disabled();



	if (irq_needs_irq_stack(regs))

		__run_sysvec_on_irqstack(func, regs);

	else

		func(regs);

}



static __always_inline void

run_irq_on_irqstack_cond(void (*func)(struct irq_desc *desc), struct irq_desc *desc,

			 struct pt_regs *regs)

{

	lockdep_assert_irqs_disabled();



	if (irq_needs_irq_stack(regs))

		__run_on_irqstack(__func, arg);

		__run_irq_on_irqstack(func, desc);

	else

		__func(arg);

		func(desc);

}



#endif

arch/x86/kernel/apic/io_apic.c

+1 −0
Original line number Diff line number Diff line
@@ -2243,6 +2243,7 @@ static inline void __init check_timer(void) 
	legacy_pic->init(0);

	legacy_pic->make_irq(0);

	apic_write(APIC_LVT0, APIC_DM_EXTINT);

	legacy_pic->unmask(0);



	unlock_ExtINT_logic();

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