kasan: dynamically allocate stack ring entries

kasan: dynamically allocate stack ring entries

Instead of using a large static array, allocate the stack ring dynamically
via memblock_alloc().

The size of the stack ring is controlled by a new kasan.stack_ring_size
command-line parameter.  When kasan.stack_ring_size is not provided, the
default value of 32 << 10 is used.

When the stack trace collection is disabled via kasan.stacktrace=off, the
stack ring is not allocated.

Link: https://lkml.kernel.org/r/03b82ab60db53427e9818e0b0c1971baa10c3cbc.1662411800.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>