This is a note to let you know that I've just added the patch titled x86/boot/32: Fix UP boot on Quark and possibly other platforms to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: x86-boot-32-fix-up-boot-on-quark-and-possibly-other-platforms.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From d2b6dc61a8dd3c429609b993778cb54e75a5c5f0 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski <luto@xxxxxxxxxx> 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@xxxxxxxxxx> 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@xxxxxxxxxxx> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx> Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Brian Gerst <brgerst@xxxxxxxxx> Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Cc: Juergen Gross <jgross@xxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Garnier <thgarnie@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: linux-efi@xxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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, Patches currently in stable-queue which might be from luto@xxxxxxxxxx are queue-4.9/perf-tools-make-perf_event__synthesize_mmap_events-scale.patch queue-4.9/x86-mm-make-mmap-map_32bit-work-correctly.patch queue-4.9/x86-boot-32-defer-resyncing-initial_page_table-until-per-cpu-is-set-up.patch queue-4.9/x86-boot-32-fix-up-boot-on-quark-and-possibly-other-platforms.patch