Commits
Shanker Donthineni committed ea6eac904f0
arm64: Avoid clobbering mm in erratum workaround on QDF2400
Commit 38fd94b0275c ("arm64: Work around Falkor erratum 1003") tried to
work around a hardware erratum, but actually caused a system crash of
its own during switch_mm:
cpu_do_switch_mm+0x20/0x40
efi_virtmap_load+0x34/0x40
virt_efi_get_next_variable+0x64/0xc8
efivar_init+0x8c/0x348
efisubsys_init+0xd4/0x270
do_one_initcall+0x80/0x110
kernel_init_freeable+0x19c/0x240
kernel_init+0x10/0x100
ret_from_fork+0x10/0x50
Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
In cpu_do_switch_mm, x1 contains the mm_struct pointer, which needs to
be preserved by the pre_ttbr0_update_workaround macro rather than passed
as a temporary.
This patch clobbers x2 and x3 instead, keeping the mm_struct intact
after the workaround has run.
Fixes: 38fd94b0275c ("arm64: Work around Falkor erratum 1003")
Tested-by: Manoj Iyer <manoj.iyer@canonical.com>
Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>