From: James Morse <james.morse@arm.com>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Pratyush Anand <panand@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
"David A . Long" <dave.long@linaro.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/3] arm64: kprobes: Move extable address check into arch_prepare_kprobe()
Date: Thu, 3 Jan 2019 17:05:18 +0000 [thread overview]
Message-ID: <aec51c10-d744-df0f-1216-d3372e779cb1@arm.com> (raw)
In-Reply-To: <154502884653.30629.3172839440883293817.stgit@devbox>
Hi!
On 17/12/2018 06:40, Masami Hiramatsu wrote:
> Move extable address check into arch_prepare_kprobe() from
> arch_within_kprobe_blacklist().
I'm trying to work out the pattern for what should go in the blacklist, and what
should be rejected by the arch code.
It seems address-ranges should be blacklisted as the contents don't matter.
easy-example: the idmap text.
The arch code should also reject instructions that can't be probed from
arch_prepare_kprobe(). easy-example: exclusive load or store.
> Please do not blacklisting instructions on exception_table,
> since it is a kind of architectural unsupported instruction.
This doesn't fit the pattern, ... what should it be?
The instructions in the exception_table don't matter, its the address that
indicates there is a fixup for page-faults that occur here. We don't need to
look at the instruction to determine this, why can't we treated these as a
blacklisted range?
Thanks,
James
> diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
> index 2a5b338b2542..b2d4b7428ebc 100644
> --- a/arch/arm64/kernel/probes/kprobes.c
> +++ b/arch/arm64/kernel/probes/kprobes.c
> @@ -102,6 +102,10 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
>
> if (in_exception_text(probe_addr))
> return -EINVAL;
> +
> + if (search_exception_tables(probe_addr))
> + return -EINVAL;
> +
> if (probe_addr >= (unsigned long) __start_rodata &&
> probe_addr <= (unsigned long) __end_rodata)
> return -EINVAL;
> @@ -477,8 +481,7 @@ bool arch_within_kprobe_blacklist(unsigned long addr)
> (addr >= (unsigned long)__entry_text_start &&
> addr < (unsigned long)__entry_text_end) ||
> (addr >= (unsigned long)__idmap_text_start &&
> - addr < (unsigned long)__idmap_text_end) ||
> - !!search_exception_tables(addr))
> + addr < (unsigned long)__idmap_text_end))
> return true;
>
> if (!is_kernel_in_hyp_mode()) {
>
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next prev parent reply other threads:[~2019-01-03 17:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-17 6:40 [PATCH 0/3] arm64: kprobes: Fix blacklist checking on arm64 Masami Hiramatsu
2018-12-17 6:40 ` [PATCH 1/3] arm64: kprobes: Move extable address check into arch_prepare_kprobe() Masami Hiramatsu
2019-01-03 17:05 ` James Morse [this message]
2019-01-08 2:39 ` Masami Hiramatsu
2019-01-08 17:13 ` James Morse
2019-01-09 2:05 ` Masami Hiramatsu
2019-01-11 18:22 ` James Morse
2019-01-15 5:49 ` Masami Hiramatsu
2018-12-17 6:41 ` [PATCH 2/3] arm64: kprobes: Remove unneeded RODATA check Masami Hiramatsu
2019-01-03 17:07 ` James Morse
2018-12-17 6:41 ` [PATCH 3/3] arm64: kprobes: Move exception_text check in blacklist Masami Hiramatsu
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