From: Christoffer Dall <christoffer.dall@arm.com>
To: James Morse <james.morse@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 2/4] arm64: kprobe: Always blacklist the KVM world-switch code
Date: Thu, 31 Jan 2019 09:08:49 +0100 [thread overview]
Message-ID: <20190131080849.GL13482@e113682-lin.lund.arm.com> (raw)
In-Reply-To: <20190124163257.233929-3-james.morse@arm.com>
On Thu, Jan 24, 2019 at 04:32:55PM +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.
>
> Fixes: 888b3c8720e0 ("arm64: Treat all entry code as non-kprobe-able")
> Signed-off-by: James Morse <james.morse@arm.com>
> Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
> ---
> 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
>
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next prev parent reply other threads:[~2019-01-31 8:09 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-24 16:32 [PATCH v2 0/4] Fix some KVM/HYP interactions with kprobes James Morse
2019-01-24 16:32 ` [PATCH v2 1/4] KVM: arm64: Forbid kprobing of the VHE world-switch code James Morse
2019-01-25 1:28 ` Masami Hiramatsu
2019-01-31 8:08 ` Christoffer Dall
2019-01-31 18:53 ` James Morse
2019-02-01 8:04 ` Christoffer Dall
2019-02-01 13:34 ` Marc Zyngier
2019-01-24 16:32 ` [PATCH v2 2/4] arm64: kprobe: Always blacklist the KVM " James Morse
2019-01-31 8:08 ` Christoffer Dall [this message]
2019-01-24 16:32 ` [PATCH v2 3/4] arm64: hyp-stub: Forbid kprobing of the hyp-stub James Morse
2019-01-31 8:04 ` Christoffer Dall
2019-02-01 12:02 ` James Morse
2019-01-24 16:32 ` [PATCH v2 4/4] arm64: hibernate: Clean the __hyp_text to PoC after resume James Morse
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