openwrt/target/linux/generic/patches-4.4/062-02-MIPS-Stack-unwinding-while-on-IRQ-stack.patch
Felix Fietkau 1708644f19 kernel: backport MIPS changes introducing a separate IRQ stack
Prevents crashes when IRQs arrive when the current kernel stack context
already contains deeply nested function calls, e.g. when stacking lots
of network devices on top of each other

Signed-off-by: Felix Fietkau <nbd@nbd.name>
2017-01-15 18:25:54 +01:00

43 lines
1.1 KiB
Diff

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