kernel: backport MIPS changes introducing a separate IRQ stack

[openwrt/staging/chunkeey.git] / target / linux / generic / patches-4.4 / 062-02-MIPS-Stack-unwinding-while-on-IRQ-stack.patch

diff --git a/target/linux/generic/patches-4.4/062-02-MIPS-Stack-unwinding-while-on-IRQ-stack.patch b/target/linux/generic/patches-4.4/062-02-MIPS-Stack-unwinding-while-on-IRQ-stack.patch
new file mode 100644 (file)
index 0000000..513e904
--- /dev/null
+++ b/target/linux/generic/patches-4.4/062-02-MIPS-Stack-unwinding-while-on-IRQ-stack.patch
@@ -0,0 +1,42 @@
+From: Matt Redfearn <matt.redfearn@imgtec.com>
+Date: Mon, 19 Dec 2016 14:20:57 +0000
+Subject: [PATCH] MIPS: Stack unwinding while on IRQ stack
+
+Within unwind stack, check if the stack pointer being unwound is within
+the CPU's irq_stack and if so use that page rather than the task's stack
+page.
+
+Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
+---
+
+--- a/arch/mips/kernel/process.c
++++ b/arch/mips/kernel/process.c
+@@ -32,6 +32,7 @@
+ #include <asm/cpu.h>
+ #include <asm/dsp.h>
+ #include <asm/fpu.h>
++#include <asm/irq.h>
+ #include <asm/msa.h>
+ #include <asm/pgtable.h>
+ #include <asm/mipsregs.h>
+@@ -507,7 +508,19 @@ EXPORT_SYMBOL(unwind_stack_by_address);
+ unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
+                          unsigned long pc, unsigned long *ra)
+ {
+-      unsigned long stack_page = (unsigned long)task_stack_page(task);
++      unsigned long stack_page = 0;
++      int cpu;
++
++      for_each_possible_cpu(cpu) {
++              if (on_irq_stack(cpu, *sp)) {
++                      stack_page = (unsigned long)irq_stack[cpu];
++                      break;
++              }
++      }
++
++      if (!stack_page)
++              stack_page = (unsigned long)task_stack_page(task);
++
+       return unwind_stack_by_address(stack_page, sp, pc, ra);
+ }
+ #endif