From mboxrd@z Thu Jan 1 00:00:00 1970 From: ard.biesheuvel@linaro.org (Ard Biesheuvel) Date: Mon, 24 Jul 2017 12:26:20 +0100 Subject: [PATCH 1/4] arm64: avoid percpu indirection for irq stack ops In-Reply-To: <20170724112623.26109-1-ard.biesheuvel@linaro.org> References: <20170724112623.26109-1-ard.biesheuvel@linaro.org> Message-ID: <20170724112623.26109-2-ard.biesheuvel@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Mark Rutland Our IRQ_STACK_PTR() and on_irq_stack() helpers both take a cpu argument, used to generate a percpu address. In all cases, they are passed {raw_,}smp_processor_id(), so this parameter is redundant. Since {raw_,}smp_processor_id() use a percpu variable internally, this approach means we generate a percpu offset to find the current cpu, then use this to index an array of percpu offsets, which we then use to find the current CPU's IRQ stack pointer. Thus, most of the work is redundant. Instead, we can consistently use raw_cpu_ptr() to generate the CPU's irq_stack pointer by simply adding the percpu offset to the irq_stack address, which is simpler in both respects. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: James Morse Cc: Will Deacon Signed-off-by: Ard Biesheuvel --- arch/arm64/include/asm/irq.h | 4 ++-- arch/arm64/kernel/ptrace.c | 2 +- arch/arm64/kernel/stacktrace.c | 4 ++-- arch/arm64/kernel/traps.c | 2 +- 4 files changed, 6 insertions(+), 6 deletions(-) diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h index b77197d941fc..c01a912fbb1e 100644 --- a/arch/arm64/include/asm/irq.h +++ b/arch/arm64/include/asm/irq.h @@ -47,10 +47,10 @@ static inline int nr_legacy_irqs(void) return 0; } -static inline bool on_irq_stack(unsigned long sp, int cpu) +static inline bool on_irq_stack(unsigned long sp) { /* variable names the same as kernel/stacktrace.c */ - unsigned long low = (unsigned long)per_cpu(irq_stack, cpu); + unsigned long low = (unsigned long)raw_cpu_ptr(irq_stack); unsigned long high = low + IRQ_STACK_START_SP; return (low <= sp && sp <= high); diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 1b38c0150aec..baf0838205c7 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -127,7 +127,7 @@ static bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr) { return ((addr & ~(THREAD_SIZE - 1)) == (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1))) || - on_irq_stack(addr, raw_smp_processor_id()); + on_irq_stack(addr); } /** diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index 09d37d66b630..6ffb965be641 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -54,13 +54,13 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) * non-preemptible context. */ if (tsk == current && !preemptible()) - irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id()); + irq_stack_ptr = IRQ_STACK_PTR(); else irq_stack_ptr = 0; low = frame->sp; /* irq stacks are not THREAD_SIZE aligned */ - if (on_irq_stack(frame->sp, raw_smp_processor_id())) + if (on_irq_stack(frame->sp)) high = irq_stack_ptr; else high = ALIGN(low, THREAD_SIZE) - 0x20; diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index c7c7088097be..7ba80f2a6177 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -159,7 +159,7 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) * non-preemptible context. */ if (tsk == current && !preemptible()) - irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id()); + irq_stack_ptr = IRQ_STACK_PTR(); else irq_stack_ptr = 0; -- 2.9.3