From mboxrd@z Thu Jan 1 00:00:00 1970 From: Masami Hiramatsu Subject: Re: [PATCH 2/4] arm64: kprobe: Always blacklist the KVM world-switch code Date: Tue, 22 Jan 2019 11:47:46 +0900 Message-ID: <20190122114746.437af5a57eb9bcf706916cf3@kernel.org> References: <20190121170404.142966-1-james.morse@arm.com> <20190121170404.142966-3-james.morse@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190121170404.142966-3-james.morse@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: James Morse Cc: Marc Zyngier , Catalin Marinas , Will Deacon , Christoffer Dall , Masami Hiramatsu , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org List-Id: kvmarm@lists.cs.columbia.edu On Mon, 21 Jan 2019 17:04:02 +0000 James Morse wrote: > On systems with VHE the kernel and KVM's world-switch code run at the > same exception level. Code that is only used on a VHE system does not > need to be annotated as __hyp_text as it can reside anywhere in the > kernel text. > > __hyp_text was also used to prevent kprobes from patching breakpoint > instructions into this region, as this code runs at a different > exception level. While this is no longer true with VHE, KVM still > switches VBAR_EL1, meaning a kprobe's breakpoint executed in the > world-switch code will cause a hyp-panic. > > Move the __hyp_text check in the kprobes blacklist so it applies on > VHE systems too, to cover the common code and guest enter/exit > assembly. > Looks good to me! Acked-by: Masami Hiramatsu Thank you, > Signed-off-by: James Morse > Fixes: 888b3c8720e0 ("arm64: Treat all entry code as non-kprobe-able") > --- > arch/arm64/kernel/probes/kprobes.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c > index 2a5b338b2542..f17afb99890c 100644 > --- a/arch/arm64/kernel/probes/kprobes.c > +++ b/arch/arm64/kernel/probes/kprobes.c > @@ -478,13 +478,13 @@ bool arch_within_kprobe_blacklist(unsigned long addr) > addr < (unsigned long)__entry_text_end) || > (addr >= (unsigned long)__idmap_text_start && > addr < (unsigned long)__idmap_text_end) || > + (addr >= (unsigned long)__hyp_text_start && > + addr < (unsigned long)__hyp_text_end) || > !!search_exception_tables(addr)) > return true; > > if (!is_kernel_in_hyp_mode()) { > - if ((addr >= (unsigned long)__hyp_text_start && > - addr < (unsigned long)__hyp_text_end) || > - (addr >= (unsigned long)__hyp_idmap_text_start && > + if ((addr >= (unsigned long)__hyp_idmap_text_start && > addr < (unsigned long)__hyp_idmap_text_end)) > return true; > } > -- > 2.20.1 > -- Masami Hiramatsu