Messages in this thread | | | Subject | Re: [PATCH 1/3] arm64: kprobes: Move extable address check into arch_prepare_kprobe() | From | James Morse <> | Date | Fri, 11 Jan 2019 18:22:38 +0000 |
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Hi,
On 09/01/2019 02:05, Masami Hiramatsu wrote: > On Tue, 8 Jan 2019 17:13:36 +0000 > James Morse <james.morse@arm.com> wrote: >> On 08/01/2019 02:39, Masami Hiramatsu wrote: >>> On Thu, 3 Jan 2019 17:05:18 +0000 >>> James Morse <james.morse@arm.com> wrote: >>>> 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. >>> >>> Yes, more precisely, the code smaller than a function (symbol), it must be >>> rejected by arch_prepare_kprobe(), since blacklist is poplated based on >>> kallsyms. >> >> Ah, okay, so the pattern is the blacklist should only be for whole symbols, >> (which explains why its usually based on sections). > > Correct. Actually, the blacklist is generated based on the symbol info > from symbol address. > >> I see kprobe_add_ksym_blacklist() would go wrong if you give it something like: >> platform_drv_probe+0x50/0xb0, as it will log platform_drv_probe+0x50 as the >> start_addr and platform_drv_probe+0x50+0xb0 as the end. > > Yes, it expects given address is the entry of a symbol.
>> But how does anything from the arch code's blacklist get into the >> kprobe_blacklist list? > > It should be done via arch_populate_kprobe_blacklist().
>> We don't have an arch_populate_kprobe_blacklist(), so rely on >> within_kprobe_blacklist() calling arch_within_kprobe_blacklist() with the >> address, as well as walking kprobe_blacklist. >> >> Is this cleanup ahead of a series that does away with >> arch_within_kprobe_blacklist() so that debugfs list is always complete? > > Right, after this cleanup, I will send arch_populate_kprobe_blacklist() > patch for arm64 and others. My plan is to move all arch_within_kprobe_blacklist() > to arch_populate_kprobe_blacklist() so that user can get more precise blacklist > via debugfs.
Thanks, now it all makes sense!
Reviewed-by: James Morse <james.morse@arm.com>
Could you include a paragraph like that in the cover-letter or commit-message? The 'fix' in the cover-letter subject had me looking for the bug!
Thanks,
James
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