From: Masami Hiramatsu Date: Wed, 28 Oct 2020 14:31:10 +0000 (+0900) Subject: x86/kprobes: Restore BTF if the single-stepping is cancelled X-Git-Tag: v4.4.249~53 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2bfd3bc1b78e2ce92de1b710158b89df3a0edf63;p=thirdparty%2Fkernel%2Fstable.git x86/kprobes: Restore BTF if the single-stepping is cancelled [ Upstream commit 78ff2733ff352175eb7f4418a34654346e1b6cd2 ] 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 Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/160389546985.106936.12727996109376240993.stgit@devnote2 Signed-off-by: Sasha Levin --- diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 5a6cb30b1c621..ebd4da00a56ea 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -1014,6 +1014,11 @@ 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,