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Besides asking vmalloc memory to be executable via the prot argument of
__vmalloc_node_range() (see the previous patch), the kernel can skip that
bit and instead mark memory as executable via set_memory_x().

Once tag-based KASAN modes start tagging vmalloc allocations, executing
code from such allocations will lead to the PC register getting a tag,
which is not tolerated by the kernel.

Generic kernel code typically allocates memory via module_alloc() if it
intends to mark memory as executable.  (On arm64 module_alloc() uses
__vmalloc_node_range() without setting the executable bit).

Thus, reset pointer tags of pointers returned from module_alloc().

However, on arm64 there's an exception: the eBPF subsystem.  Instead of
using module_alloc(), it uses vmalloc() (via bpf_jit_alloc_exec()) to
allocate its JIT region.

Thus, reset pointer tags of pointers returned from bpf_jit_alloc_exec().

Resetting tags for these pointers results in untagged pointers...