From mboxrd@z Thu Jan 1 00:00:00 1970 From: james.morse@arm.com (James Morse) Date: Mon, 16 Nov 2015 18:22:07 +0000 Subject: [PATCH v7 3/3] arm64: Add do_softirq_own_stack() and enable irq_stacks In-Reply-To: <1447698128-8490-1-git-send-email-james.morse@arm.com> References: <1447698128-8490-1-git-send-email-james.morse@arm.com> Message-ID: <1447698128-8490-4-git-send-email-james.morse@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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-enabled interrupts to process softirqs. This patch adds the dummy stack frame and data needed by the previous stack tracing patches. Signed-off-by: James Morse --- arch/arm64/include/asm/irq.h | 2 ++ arch/arm64/kernel/entry.S | 30 ++++++++++++++++++++++++++++++ arch/arm64/kernel/irq.c | 34 ++++++++++++++++++++++++++++++++++ 3 files changed, 66 insertions(+) diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h index bf823c5f8cbd..04aae95dee8d 100644 --- a/arch/arm64/include/asm/irq.h +++ b/arch/arm64/include/asm/irq.h @@ -6,6 +6,8 @@ #include #include +#define __ARCH_HAS_DO_SOFTIRQ + struct pt_regs; DECLARE_PER_CPU(unsigned long, irq_stack_ptr); diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 1971da98dfad..45473838fe21 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -175,6 +175,34 @@ alternative_endif mrs \rd, sp_el0 .endm + .macro irq_stack_entry + mov x19, sp // preserve the original sp + adr_l x25, irq_count // incremented by do_softirq_own_stack() + mrs x26, tpidr_el1 + add x25, x25, x26 + ldr w25, [x25] + cbnz w25, 1f // recursive use? + + /* switch to the irq stack */ + adr_l x25, irq_stack_ptr + add x25, x25, x26 + ldr x25, [x25] + mov sp, x25 + + /* Add a dummy stack frame */ + stp x29, x22, [sp, #-16]! // dummy stack frame + mov x29, sp + stp xzr, x19, [sp, #-16]! +1: + .endm + + /* + * x19 is 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. @@ -192,7 +220,9 @@ tsk .req x28 // current thread_info .macro irq_handler ldr_l x1, handle_arch_irq mov x0, sp + irq_stack_entry blr x1 + irq_stack_exit .endm .text diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c index da752bb18bfb..838541cf5e5d 100644 --- a/arch/arm64/kernel/irq.c +++ b/arch/arm64/kernel/irq.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include @@ -34,6 +35,13 @@ unsigned long irq_err_count; DEFINE_PER_CPU(unsigned long [IRQ_STACK_SIZE/sizeof(long)], irq_stack) __aligned(16); DEFINE_PER_CPU(unsigned long, irq_stack_ptr); +/* + * irq_count is used to detect recursive use of the irq_stack, it is lazily + * incremented very late, by do_softirq_own_stack(), which is called on the + * irq_stack, before re-enabling interrupts to process softirqs. + */ +DEFINE_PER_CPU(unsigned int, irq_count); + int arch_show_interrupts(struct seq_file *p, int prec) { show_ipi_list(p, prec); @@ -66,3 +74,29 @@ void init_irq_stack(unsigned int cpu) per_cpu(irq_stack_ptr, cpu) = stack + IRQ_STACK_START_SP; } + +/* + * 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)) { + per_cpu(irq_count, cpu)++; + __do_softirq(); + per_cpu(irq_count, cpu)--; + } else { + __do_softirq(); + } +} -- 2.1.4