The following commit has been merged into the perf/core branch of tip: Commit-ID: 78ff2733ff352175eb7f4418a34654346e1b6cd2 Gitweb: https://git.kernel.org/tip/78ff2733ff352175eb7f4418a34654346e1b6cd2 Author: Masami Hiramatsu <mhiramat@xxxxxxxxxx> AuthorDate: Wed, 28 Oct 2020 23:31:10 +09:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Wed, 09 Dec 2020 17:08:57 +01:00 x86/kprobes: Restore BTF if the single-stepping is cancelled 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 <mhiramat@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/160389546985.106936.12727996109376240993.stgit@devnote2 --- 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 547c7ab..39f7d8c 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,
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