Ville Syrjälä 6f6060a5c9 x86/apm: Don't access __preempt_count with zeroed fs ... APM_DO_POP_SEGS does not restore fs/gs which were zeroed by APM_DO_ZERO_SEGS. Trying to access __preempt_count with zeroed fs doesn't really work. Move the ibrs call outside the APM_DO_SAVE_SEGS/APM_DO_RESTORE_SEGS invocations so that fs is actually restored before calling preempt_enable(). Fixes the following sort of oopses: [ 0.313581] general protection fault: 0000 [#1] PREEMPT SMP [ 0.313803] Modules linked in: [ 0.314040] CPU: 0 PID: 268 Comm: kapmd Not tainted 4.16.0-rc1-triton-bisect-00090-gdd84441a7971 #19 [ 0.316161] EIP: __apm_bios_call_simple+0xc8/0x170 [ 0.316161] EFLAGS: 00210016 CPU: 0 [ 0.316161] EAX: 00000102 EBX: 00000000 ECX: 00000102 EDX: 00000000 [ 0.316161] ESI: 0000530e EDI: dea95f64 EBP: dea95f18 ESP: dea95ef0 [ 0.316161] DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 [ 0.316161] CR0: 80050033 CR2: 00000000 CR3: 015d3000 CR4: 000006d0 [ 0.316161] Call Trace: [ 0.316161] ? cpumask_weight.constprop.15+0x20/0x20 [ 0.316161] on_cpu0+0x44/0x70 [ 0.316161] apm+0x54e/0x720 [ 0.316161] ? __switch_to_asm+0x26/0x40 [ 0.316161] ? __schedule+0x17d/0x590 [ 0.316161] kthread+0xc0/0xf0 [ 0.316161] ? proc_apm_show+0x150/0x150 [ 0.316161] ? kthread_create_worker_on_cpu+0x20/0x20 [ 0.316161] ret_from_fork+0x2e/0x38 [ 0.316161] Code: da 8e c2 8e e2 8e ea 57 55 2e ff 1d e0 bb 5d b1 0f 92 c3 5d 5f 07 1f 89 47 0c 90 8d b4 26 00 00 00 00 90 8d b4 26 00 00 00 00 90 <64> ff 0d 84 16 5c b1 74 7f 8b 45 dc 8e e0 8b 45 d8 8e e8 8b 45 [ 0.316161] EIP: __apm_bios_call_simple+0xc8/0x170 SS:ESP: 0068:dea95ef0 [ 0.316161] ---[ end trace 656253db2deaa12c ]--- Fixes: dd84441a79 ("x86/speculation: Use IBRS if available before calling into firmware") Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Cc: David Woodhouse <dwmw@amazon.co.uk> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Cc: David Woodhouse <dwmw@amazon.co.uk> Cc: "H. Peter Anvin" <hpa@zytor.com> Link: https://lkml.kernel.org/r/20180709133534.5963-1-ville.syrjala@linux.intel.com		2018-07-16 17:59:57 +02:00
..
asm	x86/apm: Don't access __preempt_count with zeroed fs	2018-07-16 17:59:57 +02:00
uapi/asm	Merge branch 'linus' into timers/2038	2018-05-19 13:55:40 +02:00