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arm64: Add do_softirq_own_stack() and enable irq_stacks

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entry.S is modified to switch to the per_cpu irq_stack during el{0,1}_irq.
irq_count is used to detect recursive interrupts on the irq_stack, it is
updated late by do_softirq_own_stack(), when called on the irq_stack, before
__do_softirq() re-enables interrupts to process softirqs.

do_softirq_own_stack() is added by this patch, but does not yet switch
stack.

This patch adds the dummy stack frame and data needed by the previous
stack tracing patches.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
James Morse 2015-12-04 11:02:27 +00:00 committed by Will Deacon
parent 132cd887b5
commit 8e23dacd12
3 changed files with 79 additions and 3 deletions
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2
arch/arm64/include/asm/irq.h
View File

@ -11,6 +11,8 @@
#include <asm-generic/irq.h>
#include <asm/thread_info.h>
#define __ARCH_HAS_DO_SOFTIRQ
struct pt_regs;
DECLARE_PER_CPU(unsigned long [IRQ_STACK_SIZE/sizeof(long)], irq_stack);

42
arch/arm64/kernel/entry.S
View File

@ -27,6 +27,7 @@
#include <asm/cpufeature.h>
#include <asm/errno.h>
#include <asm/esr.h>
#include <asm/irq.h>
#include <asm/thread_info.h>
#include <asm/unistd.h>
@ -175,6 +176,42 @@ alternative_endif
mrs \rd, sp_el0
.endm
.macro irq_stack_entry, dummy_lr
mov x19, sp // preserve the original sp
adr_l x25, irq_stack
mrs x26, tpidr_el1
add x25, x25, x26
/*
* Check the lowest address on irq_stack for the irq_count value,
* incremented by do_softirq_own_stack if we have re-enabled irqs
* while on the irq_stack.
*/
ldr x26, [x25]
cbnz x26, 9998f // recursive use?
/* switch to the irq stack */
mov x26, #IRQ_STACK_START_SP
add x26, x25, x26
mov sp, x26
/* Add a dummy stack frame */
stp x29, \dummy_lr, [sp, #-16]! // dummy stack frame
mov x29, sp
stp xzr, x19, [sp, #-16]!
9998:
.endm
/*
* x19 should be preserved between irq_stack_entry and
* irq_stack_exit.
*/
.macro irq_stack_exit
mov sp, x19
.endm
/*
* These are the registers used in the syscall handler, and allow us to
* have in theory up to 7 arguments to a function - x0 to x6.
@ -190,10 +227,11 @@ tsk .req x28 // current thread_info
* Interrupt handling.
*/
.macro irq_handler
adrp x1, handle_arch_irq
ldr x1, [x1, #:lo12:handle_arch_irq]
ldr_l x1, handle_arch_irq
mov x0, sp
irq_stack_entry x22
blr x1
irq_stack_exit
.endm
.text

38
arch/arm64/kernel/irq.c
View File

@ -25,14 +25,24 @@
#include <linux/irq.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irqchip.h>
#include <linux/seq_file.h>
unsigned long irq_err_count;
/* irq stack only needs to be 16 byte aligned - not IRQ_STACK_SIZE aligned */
/*
* irq stack only needs to be 16 byte aligned - not IRQ_STACK_SIZE aligned.
* irq_stack[0] is used as irq_count, a non-zero value indicates the stack
* is in use, and el?_irq() shouldn't switch to it. This is used to detect
* recursive use of the irq_stack, it is lazily updated by
* do_softirq_own_stack(), which is called on the irq_stack, before
* re-enabling interrupts to process softirqs.
*/
DEFINE_PER_CPU(unsigned long [IRQ_STACK_SIZE/sizeof(long)], irq_stack) __aligned(16);
#define IRQ_COUNT() (*per_cpu(irq_stack, smp_processor_id()))
int arch_show_interrupts(struct seq_file *p, int prec)
{
show_ipi_list(p, prec);
@ -56,3 +66,29 @@ void __init init_IRQ(void)
if (!handle_arch_irq)
panic("No interrupt controller found.");
}
/*
* do_softirq_own_stack() is called from irq_exit() before __do_softirq()
* re-enables interrupts, at which point we may re-enter el?_irq(). We
* increase irq_count here so that el1_irq() knows that it is already on the
* irq stack.
*
* Called with interrupts disabled, so we don't worry about moving cpu, or
* being interrupted while modifying irq_count.
*
* This function doesn't actually switch stack.
*/
void do_softirq_own_stack(void)
{
int cpu = smp_processor_id();
WARN_ON_ONCE(!irqs_disabled());
if (on_irq_stack(current_stack_pointer, cpu)) {
IRQ_COUNT()++;
__do_softirq();
IRQ_COUNT()--;
} else {
__do_softirq();
}
}