4.10-stable review patch. If anyone has any objections, please let me know.
------------------ From: Ard Biesheuvel <ard.biesheu...@linaro.org> commit d1eb98143c56f24fef125f5bbed49ae0b52fb7d6 upstream. On ARM and arm64, we use a dedicated mm_struct to map the UEFI Runtime Services regions, which allows us to map those regions on demand, and in a way that is guaranteed to be compatible with incoming kernels across kexec. As it turns out, we don't fully initialize the mm_struct in the same way as process mm_structs are initialized on fork(), which results in the following crash on ARM if CONFIG_CPUMASK_OFFSTACK=y is enabled: ... EFI Variables Facility v0.08 2004-May-17 Unable to handle kernel NULL pointer dereference at virtual address 00000000 [...] Process swapper/0 (pid: 1) ... __memzero() check_and_switch_context() virt_efi_get_next_variable() efivar_init() efivars_sysfs_init() do_one_initcall() ... This is due to a missing call to mm_init_cpumask(), so add it. Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Matt Fleming <m...@codeblueprint.co.uk> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: linux-...@vger.kernel.org Link: http://lkml.kernel.org/r/1488395154-29786-1-git-send-email-ard.biesheu...@linaro.org Signed-off-by: Ingo Molnar <mi...@kernel.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- drivers/firmware/efi/arm-runtime.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/firmware/efi/arm-runtime.c +++ b/drivers/firmware/efi/arm-runtime.c @@ -65,6 +65,7 @@ static bool __init efi_virtmap_init(void bool systab_found; efi_mm.pgd = pgd_alloc(&efi_mm); + mm_init_cpumask(&efi_mm); init_new_context(NULL, &efi_mm); systab_found = false;
