UPSTREAM: arm64: when walking onto the task stack, check sp & fp are in current-...

UPSTREAM: arm64: when walking onto the task stack, check sp & fp are in current->stack

When unwind_frame() reaches the bottom of the irq_stack, the last fp
points to the original task stack. unwind_frame() uses
IRQ_STACK_TO_TASK_STACK() to find the sp value. If either values is
wrong, we may end up walking a corrupt stack.

Check these values are sane by testing if they are both on the stack
pointed to by current->stack.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Bug: 30369029
Patchset: per-cpu-irq-stack

(cherry picked from commit 1ffe199b1c9b72a8e752a9ae2a7af10128ab2ca1)
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Change-Id: I2e5bf1ce899a1018f1c5b8ccb4f7c816d61bba21