Did this patch fall through the cracks?
-- Steve
On Wed, 28 Oct 2020 23:31:10 +0900
Masami Hiramatsu <mhira...@kernel.org> wrote:
> Fix to restore BTF if single-stepping causes a page fault and
> it is cancelled.
>
> Usually the BTF flag was restored when the single stepping is done
> (in resume_execution()). However, if a page fault happens on the
> single stepping instruction, the fault handler is invoked and
> the single stepping is cancelled. Thus, the BTF flag is not
> restored.
>
> Fixes: 1ecc798c6764 ("x86: debugctlmsr kprobes")
> Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
> ---
> arch/x86/kernel/kprobes/core.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
> index 547c7abb39f5..39f7d8c3c064 100644
> --- a/arch/x86/kernel/kprobes/core.c
> +++ b/arch/x86/kernel/kprobes/core.c
> @@ -937,6 +937,11 @@ int kprobe_fault_handler(struct pt_regs *regs, int
> trapnr)
> * So clear it by resetting the current kprobe:
> */
> regs->flags &= ~X86_EFLAGS_TF;
> + /*
> + * Since the single step (trap) has been cancelled,
> + * we need to restore BTF here.
> + */
> + restore_btf();
>
> /*
> * If the TF flag was set before the kprobe hit,
