From: Masami Hiramatsu <mhiramat@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
tglx@linutronix.de, luto@kernel.org, me@kylehuey.com,
x86@kernel.org, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, rocallahan@gmail.com,
alexandre.chartre@oracle.com, paulmck@kernel.org,
frederic@kernel.org, pbonzini@redhat.com,
sean.j.christopherson@intel.com, pmladek@suse.com,
joel@joelfernandes.org, rostedt@goodmis.org,
boris.ostrovsky@oracle.com, jgross@suse.com, brgerst@gmail.com,
jpoimboe@redhat.com, daniel.thompson@linaro.org,
julliard@winehq.org, pgofman@codeweavers.com
Subject: [PATCH] x86/kprobes: Restore BTF if the single-stepping is cancelled
Date: Wed, 28 Oct 2020 23:31:10 +0900 [thread overview]
Message-ID: <160389546985.106936.12727996109376240993.stgit@devnote2> (raw)
In-Reply-To: <20201028211109.a25f52fa6fb0412e3a65ea52@kernel.org>
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@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,
next prev parent reply other threads:[~2020-10-28 22:20 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-27 9:15 [PATCH 0/3] x86/debug: Fixes Peter Zijlstra
2020-10-27 9:15 ` [PATCH 1/3] x86/debug: Fix BTF handling Peter Zijlstra
2020-10-27 19:41 ` Peter Zijlstra
2020-10-28 9:20 ` Masami Hiramatsu
2020-10-28 9:59 ` Peter Zijlstra
2020-10-28 12:11 ` Masami Hiramatsu
2020-10-28 14:31 ` Masami Hiramatsu [this message]
2020-12-07 23:22 ` [PATCH] x86/kprobes: Restore BTF if the single-stepping is cancelled Steven Rostedt
2020-12-09 18:44 ` [tip: perf/core] " tip-bot2 for Masami Hiramatsu
2020-10-27 22:19 ` [tip: x86/urgent] x86/debug: Fix BTF handling tip-bot2 for Peter Zijlstra
2020-10-27 9:15 ` [PATCH 2/3] x86/debug: Only clear/set ->virtual_dr6 for userspace #DB Peter Zijlstra
2020-10-27 22:19 ` [tip: x86/urgent] " tip-bot2 for Peter Zijlstra
2020-10-27 9:15 ` [PATCH 3/3] x86/debug: Fix PTRACE_{BLOCK,SINGLE}STEP vs ptrace_get_debugreg(6) Peter Zijlstra
2020-10-27 17:22 ` Kyle Huey
2020-10-27 18:33 ` [PATCH v2 3/3] Fix DR_STEP " Peter Zijlstra
2020-10-27 22:19 ` [tip: x86/urgent] x86/debug: " tip-bot2 for Peter Zijlstra
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