--- /dev/null
+From d2b6dc61a8dd3c429609b993778cb54e75a5c5f0 Mon Sep 17 00:00:00 2001
+From: Andy Lutomirski <luto@kernel.org>
+Date: Mon, 8 May 2017 17:09:10 -0700
+Subject: x86/boot/32: Fix UP boot on Quark and possibly other platforms
+
+From: Andy Lutomirski <luto@kernel.org>
+
+commit d2b6dc61a8dd3c429609b993778cb54e75a5c5f0 upstream.
+
+This partially reverts commit:
+
+ 23b2a4ddebdd17f ("x86/boot/32: Defer resyncing initial_page_table until per-cpu is set up")
+
+That commit had one definite bug and one potential bug. The
+definite bug is that setup_per_cpu_areas() uses a differnet generic
+implementation on UP kernels, so initial_page_table never got
+resynced. This was fine for access to percpu data (it's in the
+identity map on UP), but it breaks other users of
+initial_page_table. The potential bug is that helpers like
+efi_init() would be called before the tables were synced.
+
+Avoid both problems by just syncing the page tables in setup_arch()
+*and* setup_per_cpu_areas().
+
+Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
+Signed-off-by: Andy Lutomirski <luto@kernel.org>
+Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
+Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
+Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
+Cc: Borislav Petkov <bp@alien8.de>
+Cc: Brian Gerst <brgerst@gmail.com>
+Cc: Denys Vlasenko <dvlasenk@redhat.com>
+Cc: Josh Poimboeuf <jpoimboe@redhat.com>
+Cc: Juergen Gross <jgross@suse.com>
+Cc: Linus Torvalds <torvalds@linux-foundation.org>
+Cc: Matt Fleming <matt@codeblueprint.co.uk>
+Cc: Peter Zijlstra <peterz@infradead.org>
+Cc: Thomas Garnier <thgarnie@google.com>
+Cc: Thomas Gleixner <tglx@linutronix.de>
+Cc: linux-efi@vger.kernel.org
+Signed-off-by: Ingo Molnar <mingo@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/x86/kernel/setup.c | 15 +++++++++++++++
+ arch/x86/kernel/setup_percpu.c | 10 +++++-----
+ 2 files changed, 20 insertions(+), 5 deletions(-)
+
+--- a/arch/x86/kernel/setup.c
++++ b/arch/x86/kernel/setup.c
+@@ -1200,6 +1200,21 @@ void __init setup_arch(char **cmdline_p)
+
+ kasan_init();
+
++#ifdef CONFIG_X86_32
++ /* sync back kernel address range */
++ clone_pgd_range(initial_page_table + KERNEL_PGD_BOUNDARY,
++ swapper_pg_dir + KERNEL_PGD_BOUNDARY,
++ KERNEL_PGD_PTRS);
++
++ /*
++ * sync back low identity map too. It is used for example
++ * in the 32-bit EFI stub.
++ */
++ clone_pgd_range(initial_page_table,
++ swapper_pg_dir + KERNEL_PGD_BOUNDARY,
++ min(KERNEL_PGD_PTRS, KERNEL_PGD_BOUNDARY));
++#endif
++
+ tboot_probe();
+
+ map_vsyscall();
+--- a/arch/x86/kernel/setup_percpu.c
++++ b/arch/x86/kernel/setup_percpu.c
+@@ -290,11 +290,11 @@ void __init setup_per_cpu_areas(void)
+
+ #ifdef CONFIG_X86_32
+ /*
+- * Sync back kernel address range. We want to make sure that
+- * all kernel mappings, including percpu mappings, are available
+- * in the smpboot asm. We can't reliably pick up percpu
+- * mappings using vmalloc_fault(), because exception dispatch
+- * needs percpu data.
++ * Sync back kernel address range again. We already did this in
++ * setup_arch(), but percpu data also needs to be available in
++ * the smpboot asm. We can't reliably pick up percpu mappings
++ * using vmalloc_fault(), because exception dispatch needs
++ * percpu data.
+ */
+ clone_pgd_range(initial_page_table + KERNEL_PGD_BOUNDARY,
+ swapper_pg_dir + KERNEL_PGD_BOUNDARY,