From: Shanker Donthineni Date: Thu, 23 Feb 2017 03:10:48 +0000 (-0600) Subject: arm64: Avoid clobbering mm in erratum workaround on QDF2400 X-Git-Tag: Ubuntu-4.10.0-13.15~4 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=554c46d54fe9b4427485f0c305c180fc833efe92;p=mirror_ubuntu-zesty-kernel.git arm64: Avoid clobbering mm in erratum workaround on QDF2400 BugLink: http://bugs.launchpad.net/bugs/1671602 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 Signed-off-by: Shanker Donthineni Signed-off-by: Will Deacon (cherry picked from commit ea6eac904f0a5a0c223bcfb133ec880ba9c70ae3) Signed-off-by: dann frazier Signed-off-by: Seth Forshee --- diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index cd4d53d7e458..877d42fb0df6 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -138,7 +138,7 @@ ENDPROC(cpu_do_resume) * - pgd_phys - physical address of new TTB */ ENTRY(cpu_do_switch_mm) - pre_ttbr0_update_workaround x0, x1, x2 + pre_ttbr0_update_workaround x0, x2, x3 mmid x1, x1 // get mm->context.id bfi x0, x1, #48, #16 // set the ASID msr ttbr0_el1, x0 // set TTBR0