Commit
84e6ffb2c4 ("arm: add support for folded p4d page tables")
updated create_mapping_late() to take folded P4Ds into account when
creating mappings, but inverted the p4d_alloc() failure test, resulting
in no mapping to be created at all.
When the EFI rtc driver subsequently tries to invoke the EFI GetTime()
service, the memory regions covering the EFI data structures are missing
from the page tables, resulting in a crash like
Unable to handle kernel paging request at virtual address 5ae0cf28
pgd = (ptrval)
[5ae0cf28] *pgd=80000040205003, *pmd=00000000
Internal error: Oops: 207 [#1] SMP THUMB2
Modules linked in:
CPU: 0 PID: 7 Comm: kworker/u32:0 Not tainted 5.7.0+ #92
Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
Workqueue: efi_rts_wq efi_call_rts
PC is at efi_call_rts+0x94/0x294
LR is at efi_call_rts+0x83/0x294
pc : [<c0b4f098>] lr : [<c0b4f087>] psr: 30000033
sp : e6219ef0 ip : 00000000 fp : ffffe000
r10: 00000000 r9 : 00000000 r8 : 30000013
r7 : e6201dd0 r6 : e6201ddc r5 : 00000000 r4 : c181f264
r3 : 5ae0cf10 r2 : 00000001 r1 : e6201dd0 r0 : e6201ddc
Flags: nzCV IRQs on FIQs on Mode SVC_32 ISA Thumb Segment none
Control: 70c5383d Table: 661cc840 DAC: 00000001
Process kworker/u32:0 (pid: 7, stack limit = 0x(ptrval))
...
[<c0b4f098>] (efi_call_rts) from [<c0448219>] (process_one_work+0x16d/0x3d8)
[<c0448219>] (process_one_work) from [<c0448581>] (worker_thread+0xfd/0x408)
[<c0448581>] (worker_thread) from [<c044ca7b>] (kthread+0x103/0x104)
...
Fixes: 84e6ffb2c4 ("arm: add support for folded p4d page tables")
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
5c6360ee4a