![Mathias Krause](/assets/img/avatar_default.png)
This patch restores the changes of commitdff38e3e93
"x86: Use inline assembler instead of global register variable to get sp". They got lost in commit198d208df4
"x86: Keep thread_info on thread stack in x86_32" while moving the code to arch/x86/kernel/irq_32.c. Quoting Andi from commitdff38e3e93
: """ LTO in gcc 4.6/47. has trouble with global register variables. They were used to read the stack pointer. Use a simple inline assembler statement with a mov instead. This also helps LLVM/clang, which does not support global register variables. """ Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Brian Gerst <brgerst@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Mathias Krause <minipli@googlemail.com> Link: http://lkml.kernel.org/r/1394178752-18047-1-git-send-email-minipli@googlemail.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
183 lines
4.5 KiB
C
183 lines
4.5 KiB
C
/*
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* Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
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*
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* This file contains the lowest level x86-specific interrupt
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* entry, irq-stacks and irq statistics code. All the remaining
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* irq logic is done by the generic kernel/irq/ code and
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* by the x86-specific irq controller code. (e.g. i8259.c and
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* io_apic.c.)
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*/
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#include <linux/module.h>
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#include <linux/seq_file.h>
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#include <linux/interrupt.h>
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#include <linux/kernel_stat.h>
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#include <linux/notifier.h>
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#include <linux/cpu.h>
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#include <linux/delay.h>
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#include <linux/uaccess.h>
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#include <linux/percpu.h>
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#include <linux/mm.h>
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#include <asm/apic.h>
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DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
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EXPORT_PER_CPU_SYMBOL(irq_stat);
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DEFINE_PER_CPU(struct pt_regs *, irq_regs);
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EXPORT_PER_CPU_SYMBOL(irq_regs);
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#ifdef CONFIG_DEBUG_STACKOVERFLOW
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int sysctl_panic_on_stackoverflow __read_mostly;
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/* Debugging check for stack overflow: is there less than 1KB free? */
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static int check_stack_overflow(void)
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{
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long sp;
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__asm__ __volatile__("andl %%esp,%0" :
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"=r" (sp) : "0" (THREAD_SIZE - 1));
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return sp < (sizeof(struct thread_info) + STACK_WARN);
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}
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static void print_stack_overflow(void)
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{
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printk(KERN_WARNING "low stack detected by irq handler\n");
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dump_stack();
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if (sysctl_panic_on_stackoverflow)
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panic("low stack detected by irq handler - check messages\n");
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}
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#else
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static inline int check_stack_overflow(void) { return 0; }
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static inline void print_stack_overflow(void) { }
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#endif
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DEFINE_PER_CPU(struct irq_stack *, hardirq_stack);
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DEFINE_PER_CPU(struct irq_stack *, softirq_stack);
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static void call_on_stack(void *func, void *stack)
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{
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asm volatile("xchgl %%ebx,%%esp \n"
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"call *%%edi \n"
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"movl %%ebx,%%esp \n"
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: "=b" (stack)
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: "0" (stack),
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"D"(func)
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: "memory", "cc", "edx", "ecx", "eax");
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}
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/* how to get the current stack pointer from C */
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#define current_stack_pointer ({ \
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unsigned long sp; \
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asm("mov %%esp,%0" : "=g" (sp)); \
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sp; \
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})
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static inline void *current_stack(void)
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{
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return (void *)(current_stack_pointer & ~(THREAD_SIZE - 1));
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}
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static inline int
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execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq)
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{
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struct irq_stack *curstk, *irqstk;
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u32 *isp, *prev_esp, arg1, arg2;
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curstk = (struct irq_stack *) current_stack();
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irqstk = __this_cpu_read(hardirq_stack);
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/*
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* this is where we switch to the IRQ stack. However, if we are
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* already using the IRQ stack (because we interrupted a hardirq
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* handler) we can't do that and just have to keep using the
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* current stack (which is the irq stack already after all)
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*/
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if (unlikely(curstk == irqstk))
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return 0;
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isp = (u32 *) ((char *)irqstk + sizeof(*irqstk));
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/* Save the next esp at the bottom of the stack */
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prev_esp = (u32 *)irqstk;
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*prev_esp = current_stack_pointer;
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if (unlikely(overflow))
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call_on_stack(print_stack_overflow, isp);
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asm volatile("xchgl %%ebx,%%esp \n"
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"call *%%edi \n"
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"movl %%ebx,%%esp \n"
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: "=a" (arg1), "=d" (arg2), "=b" (isp)
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: "0" (irq), "1" (desc), "2" (isp),
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"D" (desc->handle_irq)
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: "memory", "cc", "ecx");
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return 1;
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}
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/*
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* allocate per-cpu stacks for hardirq and for softirq processing
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*/
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void irq_ctx_init(int cpu)
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{
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struct irq_stack *irqstk;
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if (per_cpu(hardirq_stack, cpu))
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return;
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irqstk = page_address(alloc_pages_node(cpu_to_node(cpu),
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THREADINFO_GFP,
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THREAD_SIZE_ORDER));
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per_cpu(hardirq_stack, cpu) = irqstk;
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irqstk = page_address(alloc_pages_node(cpu_to_node(cpu),
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THREADINFO_GFP,
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THREAD_SIZE_ORDER));
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per_cpu(softirq_stack, cpu) = irqstk;
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printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n",
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cpu, per_cpu(hardirq_stack, cpu), per_cpu(softirq_stack, cpu));
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}
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void do_softirq_own_stack(void)
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{
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struct thread_info *curstk;
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struct irq_stack *irqstk;
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u32 *isp, *prev_esp;
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curstk = current_stack();
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irqstk = __this_cpu_read(softirq_stack);
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/* build the stack frame on the softirq stack */
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isp = (u32 *) ((char *)irqstk + sizeof(*irqstk));
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/* Push the previous esp onto the stack */
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prev_esp = (u32 *)irqstk;
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*prev_esp = current_stack_pointer;
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call_on_stack(__do_softirq, isp);
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}
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bool handle_irq(unsigned irq, struct pt_regs *regs)
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{
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struct irq_desc *desc;
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int overflow;
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overflow = check_stack_overflow();
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desc = irq_to_desc(irq);
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if (unlikely(!desc))
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return false;
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if (user_mode_vm(regs) || !execute_on_irq_stack(overflow, desc, irq)) {
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if (unlikely(overflow))
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print_stack_overflow();
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desc->handle_irq(irq, desc);
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}
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return true;
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}
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