From: Pratyush Anand <panand@redhat.com>
To: David Long <dave.long@linaro.org>
Cc: William Cohen <wcohen@redhat.com>,
systemtap@sourceware.org, Mark Brown <broonie@linaro.org>
Subject: Re: exercising current aarch64 kprobe support with systemtap
Date: Fri, 10 Jun 2016 13:43:00 -0000 [thread overview]
Message-ID: <20160610134251.GA15590@dhcppc6> (raw)
In-Reply-To: <575A54D6.2070801@linaro.org>
On 10/06/2016:01:49:10 AM, David Long wrote:
> Attached are incremental diffs I hope will fix the latest systemtap
> failures, without abandoning atomic sequence checking. I'm trying to avoid
> the hex constants but I don't think the insn.c functions help in this case.
It will save us from current problem by checking "stp x29,x30,[sp,...]"
instruction and returning false if matches. However, we will have to find some
way to recognize .word instructions.
* An assembly function may not start with "stp x29,x30,[sp,...]", e.g.
__dma_map_area(), _cpu_resume etc. However, it could be least likely that a
.word instruction exists before start of assembly function and that too
contains a word value which could be misleading.
* But major issue is, what if someone instruments a kprobe at an address which
contains .word values. Instruction will never hit, so probe function will not
be called, but when real code reads that .word value, it reads a wrong value.
Can GCC provide some compiler option where .word values are located into a
specific area?
~Pratyush
>
> -dl
>
> diff --git a/arch/arm64/kernel/kprobes-arm64.c b/arch/arm64/kernel/kprobes-arm64.c
> index 28b9c5b..36b4ea5 100644
> --- a/arch/arm64/kernel/kprobes-arm64.c
> +++ b/arch/arm64/kernel/kprobes-arm64.c
> @@ -127,7 +127,9 @@ is_probed_address_atomic(kprobe_opcode_t *scan_start, kprobe_opcode_t *scan_end)
> * atomic region starts from exclusive load and ends with
> * exclusive store.
> */
> - if (aarch64_insn_is_store_ex(le32_to_cpu(*scan_start)))
> + if ((le32_to_cpu(*scan_start) & 0xffc07fff) == 0xa9807bfd)
> + return false;
> + else if (aarch64_insn_is_store_ex(le32_to_cpu(*scan_start)))
> return false;
> else if (aarch64_insn_is_load_ex(le32_to_cpu(*scan_start)))
> return true;
next prev parent reply other threads:[~2016-06-10 13:43 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-09 16:17 William Cohen
2016-06-09 19:52 ` William Cohen
2016-06-10 3:42 ` David Long
2016-06-10 5:49 ` David Long
2016-06-10 13:43 ` Pratyush Anand [this message]
2016-06-10 14:03 ` William Cohen
2016-06-10 14:37 ` David Long
2016-06-10 15:27 ` William Cohen
2016-06-10 14:20 ` David Long
2016-06-10 15:11 ` William Cohen
2016-06-10 17:07 ` Pratyush Anand
2016-07-12 14:33 ` William Cohen
2016-07-13 18:26 ` David Long
2016-07-13 18:47 ` Pratyush Anand
2016-07-13 19:45 ` William Cohen
2016-06-10 21:28 ` William Cohen
2016-06-10 21:37 ` William Cohen
2016-06-13 4:28 ` Pratyush Anand
2016-06-13 13:42 ` William Cohen
2016-06-22 20:24 ` William Cohen
2016-06-23 3:19 ` David Long
2016-06-23 13:42 ` William Cohen
2016-06-23 13:47 ` David Smith
2016-06-23 15:49 ` William Cohen
2016-06-23 18:26 ` David Long
2016-06-23 19:22 ` William Cohen
2016-06-27 2:57 ` David Long
2016-06-27 14:18 ` Pratyush Anand
2016-06-28 3:20 ` William Cohen
2016-07-04 12:46 ` Pratyush Anand
2016-07-07 19:05 ` David Long
2016-07-07 19:58 ` Frank Ch. Eigler
2016-08-03 13:13 ` Pratyush Anand
2016-08-03 14:51 ` William Cohen
2016-08-03 15:11 ` David Long
2016-08-03 17:40 ` William Cohen
2016-08-03 20:00 ` Lastest kprobes64 patch David Long
2016-08-03 20:01 ` Frank Ch. Eigler
2016-08-03 20:08 ` David Long
2016-08-04 5:03 ` Pratyush Anand
2016-08-04 13:07 ` David Long
2016-08-04 4:42 ` exercising current aarch64 kprobe support with systemtap Pratyush Anand
2016-08-04 13:57 ` William Cohen
2016-08-04 14:36 ` Pratyush Anand
2016-08-04 14:50 ` William Cohen
2016-08-04 20:51 ` William Cohen
2016-08-17 14:36 ` William Cohen
2016-08-17 18:04 ` David Smith
2016-08-17 18:28 ` William Cohen
2016-08-18 15:07 ` David Smith
2016-08-18 15:16 ` William Cohen
2016-08-18 15:39 ` David Smith
2016-08-18 14:55 ` Pratyush Anand
2016-06-13 16:11 ` William Cohen
2016-06-13 16:15 ` William Cohen
2016-06-14 4:27 ` Pratyush Anand
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