4.4-stable review patch. If anyone has any objections, please let me know.
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From: Masami Hiramatsu mhiramat@kernel.org
commit 69af7e23a6870df2ea6fa79ca16493d59b3eebeb upstream.
Since get_kprobe_ctlblk() uses smp_processor_id() to access per-cpu variable, it hits smp_processor_id sanity check as below.
[ 7.006928] BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1 [ 7.007859] caller is debug_smp_processor_id+0x20/0x24 [ 7.008438] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.16.0-rc1-00192-g4eb17253e4b5 #1 [ 7.008890] Hardware name: Generic DT based system [ 7.009917] [<c0313f0c>] (unwind_backtrace) from [<c030e6d8>] (show_stack+0x20/0x24) [ 7.010473] [<c030e6d8>] (show_stack) from [<c0c64694>] (dump_stack+0x84/0x98) [ 7.010990] [<c0c64694>] (dump_stack) from [<c071ca5c>] (check_preemption_disabled+0x138/0x13c) [ 7.011592] [<c071ca5c>] (check_preemption_disabled) from [<c071ca80>] (debug_smp_processor_id+0x20/0x24) [ 7.012214] [<c071ca80>] (debug_smp_processor_id) from [<c03335e0>] (optimized_callback+0x2c/0xe4) [ 7.013077] [<c03335e0>] (optimized_callback) from [<bf0021b0>] (0xbf0021b0)
To fix this issue, call get_kprobe_ctlblk() right after irq-disabled since that disables preemption.
Fixes: 0dc016dbd820 ("ARM: kprobes: enable OPTPROBES for ARM 32") Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Russell King rmk+kernel@armlinux.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/arm/probes/kprobes/opt-arm.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/arm/probes/kprobes/opt-arm.c +++ b/arch/arm/probes/kprobes/opt-arm.c @@ -165,13 +165,14 @@ optimized_callback(struct optimized_kpro { unsigned long flags; struct kprobe *p = &op->kp; - struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + struct kprobe_ctlblk *kcb;
/* Save skipped registers */ regs->ARM_pc = (unsigned long)op->kp.addr; regs->ARM_ORIG_r0 = ~0UL;
local_irq_save(flags); + kcb = get_kprobe_ctlblk();
if (kprobe_running()) { kprobes_inc_nmissed_count(&op->kp);