releases/4.4.133/arm-8769-1-kprobes-fix-to-use-get_kprobe_ctlblk-after-irq-disabed.patch

   1 From 69af7e23a6870df2ea6fa79ca16493d59b3eebeb Mon Sep 17 00:00:00 2001
   2 From: Masami Hiramatsu <mhiramat@kernel.org>
   3 Date: Sun, 13 May 2018 05:03:54 +0100
   4 Subject: ARM: 8769/1: kprobes: Fix to use get_kprobe_ctlblk after irq-disabed
   5
   6 From: Masami Hiramatsu <mhiramat@kernel.org>
   7
   8 commit 69af7e23a6870df2ea6fa79ca16493d59b3eebeb upstream.
   9
  10 Since get_kprobe_ctlblk() uses smp_processor_id() to access
  11 per-cpu variable, it hits smp_processor_id sanity check as below.
  12
  13 [    7.006928] BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1
  14 [    7.007859] caller is debug_smp_processor_id+0x20/0x24
  15 [    7.008438] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.16.0-rc1-00192-g4eb17253e4b5 #1
  16 [    7.008890] Hardware name: Generic DT based system
  17 [    7.009917] [<c0313f0c>] (unwind_backtrace) from [<c030e6d8>] (show_stack+0x20/0x24)
  18 [    7.010473] [<c030e6d8>] (show_stack) from [<c0c64694>] (dump_stack+0x84/0x98)
  19 [    7.010990] [<c0c64694>] (dump_stack) from [<c071ca5c>] (check_preemption_disabled+0x138/0x13c)
  20 [    7.011592] [<c071ca5c>] (check_preemption_disabled) from [<c071ca80>] (debug_smp_processor_id+0x20/0x24)
  21 [    7.012214] [<c071ca80>] (debug_smp_processor_id) from [<c03335e0>] (optimized_callback+0x2c/0xe4)
  22 [    7.013077] [<c03335e0>] (optimized_callback) from [<bf0021b0>] (0xbf0021b0)
  23
  24 To fix this issue, call get_kprobe_ctlblk() right after
  25 irq-disabled since that disables preemption.
  26
  27 Fixes: 0dc016dbd820 ("ARM: kprobes: enable OPTPROBES for ARM 32")
  28 Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
  29 Cc: stable@vger.kernel.org
  30 Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
  31 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  32
  33 ---
  34  arch/arm/probes/kprobes/opt-arm.c |    3 ++-
  35  1 file changed, 2 insertions(+), 1 deletion(-)
  36
  37 --- a/arch/arm/probes/kprobes/opt-arm.c
  38 +++ b/arch/arm/probes/kprobes/opt-arm.c
  39 @@ -165,13 +165,14 @@ optimized_callback(struct optimized_kpro
  40  {
  41         unsigned long flags;
  42         struct kprobe *p = &op->kp;
  43 -       struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
  44 +       struct kprobe_ctlblk *kcb;
  45
  46         /* Save skipped registers */
  47         regs->ARM_pc = (unsigned long)op->kp.addr;
  48         regs->ARM_ORIG_r0 = ~0UL;
  49
  50         local_irq_save(flags);
  51 +       kcb = get_kprobe_ctlblk();
  52
  53         if (kprobe_running()) {
  54                 kprobes_inc_nmissed_count(&op->kp);