arm64: mm: Defer remap of linear alias of data/bss

Marking the linear alias of data/bss invalid involves calling
set_memory_valid(), which calls split_kernel_leaf_mapping() under the
hood.

On BBML2_NOABORT capable systems, this may result in the need to
allocate page tables at a time when the generic memory allocation APIs
are not yet available, resulting in a splat like

   WARNING: arch/arm64/mm/mmu.c:821 at split_kernel_leaf_mapping+0x15c/0x170, CPU#0: swapper/0
   Modules linked in:
   CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 7.1.0-rc6 #1 PREEMPT(undef)
   pstate: a04000c9 (NzCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
   pc : split_kernel_leaf_mapping+0x15c/0x170
   lr : update_range_prot+0x40/0x128
   sp : ffffc99ad3863c80
   ...
   Call trace:
    split_kernel_leaf_mapping+0x15c/0x170 (P)
    update_range_prot+0x40/0x128
    set_memory_valid+0x94/0xe0
    mark_linear_data_alias_valid+0x54/0x68
    map_mem+0x1fc/0x240
    paging_init+0x48/0x210
    setup_arch+0x274/0x338
    start_kernel+0x98/0x538
    __primary_switched+0x88/0x98

as reported by CKI automated testing.

So defer the boot-time call to mark_linear_data_alias_valid() to a later
time when page allocations can be made normally.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>

0 files changed, 0 insertions, 0 deletions