From: Will Deacon <will.deacon@arm.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Pratyush Anand <panand@redhat.com>,
linux-arm-kernel@lists.infradead.org, linux@arm.linux.org.uk,
catalin.marinas@arm.com, linux-kernel@vger.kernel.org,
wcohen@redhat.com, dave.long@linaro.org, steve.capper@linaro.org,
srikar@linux.vnet.ibm.com, vijaya.kumar@caviumnetworks.com,
Shi Yang <yang.shi@linaro.org>,
Andre Przywara <andre.przywara@arm.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Ashok Kumar <ashoks@broadcom.com>,
James Morse <james.morse@arm.com>,
Jungseok Lee <jungseoklee85@gmail.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Mark Rutland <mark.rutland@arm.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com>,
Shaokun Zhang <zhangshaokun@hisilicon.com>,
"Suzuki K. Poulose" <suzuki.poulose@arm.com>,
Vladimir Murzin <vladimir.murzin@arm.com>
Subject: Re: [PATCH 5/5] arm64: Add uprobe support
Date: Wed, 24 Aug 2016 16:56:50 +0100 [thread overview]
Message-ID: <20160824155649.GG16944@arm.com> (raw)
In-Reply-To: <20160824154711.GA25531@redhat.com>
On Wed, Aug 24, 2016 at 05:47:11PM +0200, Oleg Nesterov wrote:
> On 08/24, Pratyush Anand wrote:
> >
> > > I don't think we want user_{enable,disable{_single_step in the long term,
> > > please look at 9bd1190a11c9d2 "uprobes/x86: Do not (ab)use TIF_SINGLESTEP
> > > /user_*_single_step() for single-stepping". it seems that ARM64 sets/clears
> > > TIF_SINGLESTEP. You can also lool at saved_tf logic, probably ARM64 needs
> > > the same.
> >
> > IIUC, then you mean that TIF_SINGLESTEP is a per task flag,
>
> Yes, and nobody but ptrace should use it, otherwise ptrace/uprobes can confuse
> each other. And uprobes simply doesn't need to set/clear it.
We're already using it for kprobes, hw_breakpoint and kgdb as well as
ptrace, so I'd rather uprobes either followed existing practice, or we
converted everybody off the current code.
In what way do things get confused?
> > while
> > arch_uprobe_pre/post_xol() should enable/disable single stepping using a per
> > uprobe_task,
>
> I can't really answer since I know nothing about arm. x86 just needs to set
> X86_EFLAGS_TF, I guess arm needs to modify some register too?
We have {user,kernel}_{enable,disable}_single_step for managing the various
registers controlling the single-step state machine on arm64.
Will
next prev parent reply other threads:[~2016-08-24 15:56 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-02 5:30 [PATCH 0/5] ARM64: Uprobe support added Pratyush Anand
2016-08-02 5:30 ` [PATCH 1/5] arm64: kprobe: protect/rename few definitions to be reused by uprobe Pratyush Anand
2016-08-02 5:30 ` [PATCH 2/5] arm64: kgdb_step_brk_fn: ignore other's exception Pratyush Anand
2016-08-02 5:30 ` [PATCH 3/5] arm64: Handle TRAP_HWBRKPT for user mode as well Pratyush Anand
2016-09-06 16:11 ` Catalin Marinas
2016-09-06 21:36 ` David Long
2016-09-07 4:47 ` Pratyush Anand
2016-09-07 13:41 ` Catalin Marinas
2016-08-02 5:30 ` [PATCH 4/5] arm64: Handle TRAP_BRKPT " Pratyush Anand
2016-09-06 16:34 ` Catalin Marinas
2016-08-02 5:30 ` [PATCH 5/5] arm64: Add uprobe support Pratyush Anand
2016-08-09 18:49 ` Oleg Nesterov
2016-08-24 7:13 ` Pratyush Anand
2016-08-24 15:47 ` Oleg Nesterov
2016-08-24 15:56 ` Will Deacon [this message]
2016-08-25 13:33 ` Oleg Nesterov
2016-09-20 16:59 ` Catalin Marinas
2016-09-21 11:00 ` Pratyush Anand
2016-09-21 17:04 ` Catalin Marinas
2016-09-22 3:23 ` Pratyush Anand
2016-09-22 16:50 ` Catalin Marinas
2016-09-23 4:12 ` Pratyush Anand
2016-09-23 13:05 ` Catalin Marinas
2016-09-25 17:02 ` Pratyush Anand
2016-09-26 11:01 ` Catalin Marinas
2016-09-26 13:03 ` Pratyush Anand
2016-09-27 13:51 ` Catalin Marinas
2016-09-27 15:03 ` Pratyush Anand
2016-09-28 17:12 ` Catalin Marinas
2016-08-24 7:26 ` [PATCH 0/5] ARM64: Uprobe support added Pratyush Anand
2016-09-20 2:51 ` Pratyush Anand
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