Commit dda45f70 authored by Matt Redfearn's avatar Matt Redfearn Committed by Ralf Baechle
Browse files

MIPS: Switch to the irq_stack in interrupts 



When enterring interrupt context via handle_int or except_vec_vi, switch
to the irq_stack of the current CPU if it is not already in use.

The current stack pointer is masked with the thread size and compared to
the base or the irq stack. If it does not match then the stack pointer
is set to the top of that stack, otherwise this is a nested irq being
handled on the irq stack so the stack pointer should be left as it was.

The in-use stack pointer is placed in the callee saved register s1. It
will be saved to the stack when plat_irq_dispatch is invoked and can be
restored once control returns here.

Signed-off-by: default avatarMatt Redfearn <matt.redfearn@imgtec.com>
Acked-by: default avatarJason A. Donenfeld <jason@zx2c4.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14743/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 510d8636

arch/mips/kernel/genex.S

+76 −5
Original line number Diff line number Diff line
@@ -187,9 +187,44 @@ NESTED(handle_int, PT_SIZE, sp) 


	LONG_L	s0, TI_REGS($28)

	LONG_S	sp, TI_REGS($28)

	PTR_LA	ra, ret_from_irq

	PTR_LA	v0, plat_irq_dispatch

	jr	v0



	/*

	 * SAVE_ALL ensures we are using a valid kernel stack for the thread.

	 * Check if we are already using the IRQ stack.

	 */

	move	s1, sp # Preserve the sp



	/* Get IRQ stack for this CPU */

	ASM_CPUID_MFC0	k0, ASM_SMP_CPUID_REG

#if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)

	lui	k1, %hi(irq_stack)

#else

	lui	k1, %highest(irq_stack)

	daddiu	k1, %higher(irq_stack)

	dsll	k1, 16

	daddiu	k1, %hi(irq_stack)

	dsll	k1, 16

#endif

	LONG_SRL	k0, SMP_CPUID_PTRSHIFT

	LONG_ADDU	k1, k0

	LONG_L	t0, %lo(irq_stack)(k1)



	# Check if already on IRQ stack

	PTR_LI	t1, ~(_THREAD_SIZE-1)

	and	t1, t1, sp

	beq	t0, t1, 2f



	/* Switch to IRQ stack */

	li	t1, _IRQ_STACK_SIZE

	PTR_ADD sp, t0, t1



2:

	jal	plat_irq_dispatch



	/* Restore sp */

	move	sp, s1



	j	ret_from_irq

#ifdef CONFIG_CPU_MICROMIPS

	nop

#endif
@@ -262,8 +297,44 @@ NESTED(except_vec_vi_handler, 0, sp) 


	LONG_L	s0, TI_REGS($28)

	LONG_S	sp, TI_REGS($28)

	PTR_LA	ra, ret_from_irq

	jr	v0



	/*

	 * SAVE_ALL ensures we are using a valid kernel stack for the thread.

	 * Check if we are already using the IRQ stack.

	 */

	move	s1, sp # Preserve the sp



	/* Get IRQ stack for this CPU */

	ASM_CPUID_MFC0	k0, ASM_SMP_CPUID_REG

#if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)

	lui	k1, %hi(irq_stack)

#else

	lui	k1, %highest(irq_stack)

	daddiu	k1, %higher(irq_stack)

	dsll	k1, 16

	daddiu	k1, %hi(irq_stack)

	dsll	k1, 16

#endif

	LONG_SRL	k0, SMP_CPUID_PTRSHIFT

	LONG_ADDU	k1, k0

	LONG_L	t0, %lo(irq_stack)(k1)



	# Check if already on IRQ stack

	PTR_LI	t1, ~(_THREAD_SIZE-1)

	and	t1, t1, sp

	beq	t0, t1, 2f



	/* Switch to IRQ stack */

	li	t1, _IRQ_STACK_SIZE

	PTR_ADD sp, t0, t1



2:

	jal	plat_irq_dispatch



	/* Restore sp */

	move	sp, s1



	j	ret_from_irq

	END(except_vec_vi_handler)



/*

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