target/linux/generic/patches-4.9/040-02-MIPS-Stack-unwinding-while-on-IRQ-stack.patch

   1 From: Matt Redfearn <matt.redfearn@imgtec.com>
   2 Date: Mon, 19 Dec 2016 14:20:57 +0000
   3 Subject: [PATCH] MIPS: Stack unwinding while on IRQ stack
   4
   5 Within unwind stack, check if the stack pointer being unwound is within
   6 the CPU's irq_stack and if so use that page rather than the task's stack
   7 page.
   8
   9 Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
  10 ---
  11
  12 --- a/arch/mips/kernel/process.c
  13 +++ b/arch/mips/kernel/process.c
  14 @@ -33,6 +33,7 @@
  15  #include <asm/dsemul.h>
  16  #include <asm/dsp.h>
  17  #include <asm/fpu.h>
  18 +#include <asm/irq.h>
  19  #include <asm/msa.h>
  20  #include <asm/pgtable.h>
  21  #include <asm/mipsregs.h>
  22 @@ -556,7 +557,19 @@ EXPORT_SYMBOL(unwind_stack_by_address);
  23  unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
  24                            unsigned long pc, unsigned long *ra)
  25  {
  26 -       unsigned long stack_page = (unsigned long)task_stack_page(task);
  27 +       unsigned long stack_page = 0;
  28 +       int cpu;
  29 +
  30 +       for_each_possible_cpu(cpu) {
  31 +               if (on_irq_stack(cpu, *sp)) {
  32 +                       stack_page = (unsigned long)irq_stack[cpu];
  33 +                       break;
  34 +               }
  35 +       }
  36 +
  37 +       if (!stack_page)
  38 +               stack_page = (unsigned long)task_stack_page(task);
  39 +
  40         return unwind_stack_by_address(stack_page, sp, pc, ra);
  41  }
  42  #endif