From: Dave Martin <Dave.Martin@arm.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
sahara <keun-o.park@windriver.com>,
Keun-O Park <kpark3469@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH 19/19] [INCOMPLETE] ARM: make return_address available for ARM_UNWIND
Date: Tue, 7 Jan 2014 16:36:29 +0000 [thread overview]
Message-ID: <20140107163629.GC3350@e103592.cambridge.arm.com> (raw)
In-Reply-To: <4325142.7drL5ndxN9@wuerfel>
On Tue, Jan 07, 2014 at 03:48:25PM +0000, Arnd Bergmann wrote:
> On Tuesday 07 January 2014 14:41:30 Russell King - ARM Linux wrote:
> > On Tue, Jan 07, 2014 at 03:33:34PM +0100, Arnd Bergmann wrote:
> > >
> > >
> > > It's been almost a year since we last discussed the patches that were
> > > posted by Dave and sahara, but nothing has changed in the mainline kernel.
> > >
> > > Any chance that someone could be motivated to pick this work up again
> > > and finally fix return_address().
> >
> > I thought that we had _actively_ decided that we would not use the
> > unwinder for these paths - that it was too expensive for these paths,
> > and you had to use frame pointers instead.
>
> I don't remember that discussion, but it may well be. What does
> that mean for the #warning in return_address.c then? Can we
> just use the frame pointer version based on CONFIG_FRAME_POINTER
> and ignore whether CONFIG_ARM_UNWIND is set as the patch below,
> or did I misunderstand?
For an ARM kernel this may work, but I thought that for THUMB2_KERNEL
there just isn't usable a framepointer at all.
If so, the only choices are to use the unwinder and accept the cost, or
to decide that return_address() will never work without
CONFIG_FRAMEPOINTER and remove the build-time warning.
My other concern was that we might end up in a recursive trace due to
the use of non-notrace core functions in the unwinder. But I seem to
remember Steve Rostedt saying the the tracer guards against recursive
invocation nowadays -- if so, that shouldn't be a problem.
Cheers
---Dave
next prev parent reply other threads:[~2014-01-07 16:37 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-25 14:14 [PATCH 00/19] ARM: common warning fixes Arnd Bergmann
2013-01-25 14:14 ` [PATCH 01/19] ARM: shmobile: fix defconfig warning on CONFIG_USB Arnd Bergmann
2013-01-25 14:14 ` [PATCH 02/19] ARM: disable virt_to_bus/virt_to_bus almost everywhere Arnd Bergmann
2013-01-25 14:14 ` [PATCH 03/19] ARM: msm: proc_comm_boot_wait should not be __init Arnd Bergmann
2013-01-25 18:16 ` David Brown
2013-02-12 1:42 ` Olof Johansson
2013-01-25 14:14 ` [PATCH 04/19] oss/dmabuf: use dma_map_single Arnd Bergmann
2013-01-25 14:14 ` [PATCH 05/19] sched: warnings in kernel/sched/fair.c Arnd Bergmann
2013-01-25 16:00 ` Paul Turner
2013-01-26 12:17 ` [tip:sched/urgent] sched: Fix warning " tip-bot for Arnd Bergmann
2013-01-25 14:14 ` [PATCH 06/19] sched/debug: fix format string for 32 bit platforms Arnd Bergmann
2013-01-25 16:01 ` Paul Turner
2013-01-26 12:19 ` [tip:sched/urgent] sched/debug: Fix format string for 32-bit platforms tip-bot for Arnd Bergmann
2013-01-25 14:14 ` [PATCH 07/19] scripts/sortextable: silence script output Arnd Bergmann
2013-01-25 23:06 ` David Daney
2013-01-25 14:14 ` [PATCH 08/19] lockdep: avoid warning about unused variables Arnd Bergmann
2013-01-25 14:14 ` [PATCH 09/19] mfd/twl4030: don't warn about uninitialized return code Arnd Bergmann
2013-01-25 14:25 ` Peter Ujfalusi
2013-01-25 14:34 ` Arnd Bergmann
2013-01-25 14:35 ` Amit Kucheria
2013-01-25 14:14 ` [PATCH 10/19] watchdog: at91sam9: at91_wdt_dt_ids cannot be __init Arnd Bergmann
2013-01-25 14:14 ` [PATCH 11/19] regmap: avoid undefined return from regmap_read_debugfs Arnd Bergmann
2013-01-26 4:42 ` Mark Brown
2013-01-26 4:52 ` Mark Brown
2013-01-26 9:17 ` Arnd Bergmann
2013-01-26 9:49 ` Mark Brown
2013-01-26 9:59 ` Russell King - ARM Linux
2013-01-26 10:03 ` Mark Brown
2013-01-26 10:07 ` Russell King - ARM Linux
2013-01-26 11:45 ` [PATCH 11/19] regmap: regmap: avoid spurious warning in regmap_read_debugfs Arnd Bergmann
2013-01-27 2:51 ` Mark Brown
2013-01-25 14:14 ` [PATCH 12/19] pinctrl: exynos: don't mark probing functions as __init Arnd Bergmann
2013-01-25 17:51 ` Kukjin Kim
2013-01-29 22:08 ` Linus Walleij
2013-01-25 14:14 ` [PATCH 13/19] pinctrl: nomadik: nmk_prcm_gpiocr_get_mode may be unused Arnd Bergmann
2013-01-29 22:11 ` Linus Walleij
2013-01-25 14:14 ` [PATCH 14/19] spi/atmel: remove incorrect __exit_p() Arnd Bergmann
2013-02-05 13:34 ` Grant Likely
2013-01-25 14:14 ` [PATCH 15/19] sunrpc: don't warn for unused variable 'buf' Arnd Bergmann
2013-01-25 14:14 ` [PATCH 16/19] mac80211: avoid a build warning Arnd Bergmann
2013-01-25 14:17 ` Johannes Berg
2013-01-25 14:14 ` [PATCH 17/19] input/joystick: use get_cycles on ARM Arnd Bergmann
2013-01-25 14:14 ` [PATCH 18/19] ARM: at91: suspend both memory controllers on at91sam9263 Arnd Bergmann
2013-01-25 15:42 ` Jean-Christophe PLAGNIOL-VILLARD
2013-01-25 15:57 ` Arnd Bergmann
2013-01-25 14:14 ` [PATCH 19/19] [INCOMPLETE] ARM: make return_address available for ARM_UNWIND Arnd Bergmann
2013-01-25 16:26 ` Dave Martin
2013-01-25 16:44 ` Steven Rostedt
2013-01-25 16:59 ` Dave Martin
2013-01-25 17:08 ` Steven Rostedt
2013-01-25 17:22 ` Dave Martin
2013-01-26 0:45 ` Arnd Bergmann
2013-01-28 2:33 ` Keun-O Park
2013-01-28 12:50 ` Dave Martin
2013-01-29 2:13 ` Keun-O Park
2014-01-07 14:33 ` Arnd Bergmann
2014-01-07 14:41 ` Russell King - ARM Linux
2014-01-07 15:48 ` Arnd Bergmann
2014-01-07 16:36 ` Dave Martin [this message]
2014-01-07 18:31 ` Steven Rostedt
2013-01-25 22:43 ` [PATCHv2 00/19] ARM: common warning fixes Arnd Bergmann
2013-01-25 22:44 ` [PATCH 01/19] ARM: shmobile: fix defconfig warning on CONFIG_USB Arnd Bergmann
2013-01-28 0:21 ` Simon Horman
2013-01-25 22:44 ` [PATCH 02/19] ARM: disable virt_to_bus/virt_to_bus almost everywhere Arnd Bergmann
2013-01-25 22:44 ` [PATCH 03/19] ARM: msm: proc_comm_boot_wait should not be __init Arnd Bergmann
2013-01-25 22:44 ` [PATCH 04/19] oss/dmabuf: use dma_map_single Arnd Bergmann
2013-01-25 22:44 ` [PATCH 05/19] sched: warnings in kernel/sched/fair.c Arnd Bergmann
2013-01-25 22:44 ` [PATCH 06/19] sched/debug: fix format string for 32 bit platforms Arnd Bergmann
2013-01-25 22:44 ` [PATCH 07/19] scripts/sortextable: silence script output Arnd Bergmann
2013-01-25 22:44 ` [PATCH 08/19] lockdep: avoid warning about unused variables Arnd Bergmann
2013-01-25 22:44 ` [PATCH 09/19] mfd/twl4030: don't warn about uninitialized return code Arnd Bergmann
2013-01-27 0:42 ` Samuel Ortiz
2013-01-25 22:44 ` [PATCH 10/19] watchdog: at91sam9: at91_wdt_dt_ids cannot be __init Arnd Bergmann
2013-01-28 8:32 ` Nicolas Ferre
2013-01-28 10:19 ` Fabio Porcedda
2013-01-28 9:49 ` Fabio Porcedda
2013-01-30 19:31 ` Wim Van Sebroeck
2013-01-25 22:44 ` [PATCH 11/19] regmap: avoid undefined return from regmap_read_debugfs Arnd Bergmann
2013-01-25 22:44 ` [PATCH 12/19] pinctrl: exynos: don't mark probing functions as __init Arnd Bergmann
2013-01-25 22:44 ` [PATCH 13/19] pinctrl: nomadik: nmk_prcm_gpiocr_get_mode may be unused Arnd Bergmann
2013-01-25 22:44 ` [PATCH 14/19] spi/atmel: remove incorrect __exit_p() Arnd Bergmann
2013-01-28 8:33 ` Nicolas Ferre
2013-01-25 22:44 ` [PATCH 15/19] sunrpc: don't warn for unused variable 'buf' Arnd Bergmann
2013-01-25 23:04 ` Myklebust, Trond
2013-01-25 23:45 ` Arnd Bergmann
2013-01-26 11:03 ` Russell King - ARM Linux
2013-01-26 13:34 ` Arnd Bergmann
2013-01-28 23:18 ` J. Bruce Fields
2013-01-25 22:44 ` [PATCH 16/19] ARM: sa1100: don't warn about mach/ide.h Arnd Bergmann
2013-01-25 22:44 ` [PATCH 17/19] input/joystick: use get_cycles on ARM Arnd Bergmann
2013-01-25 22:44 ` [PATCH 18/19] ARM: at91: suspend both memory controllers on at91sam9263 Arnd Bergmann
2013-04-18 13:45 ` Nicolas Ferre
2013-04-18 14:15 ` Arnd Bergmann
2013-04-18 14:19 ` Nicolas Ferre
2013-04-18 14:20 ` Arnd Bergmann
2013-04-18 14:32 ` Daniel Lezcano
2013-01-25 22:44 ` [PATCH 19/19] [INCOMPLETE] ARM: make return_address available for ARM_UNWIND Arnd Bergmann
2013-01-26 10:05 ` [PATCHv2 00/19] ARM: common warning fixes Russell King - ARM Linux
2013-01-26 13:31 ` Arnd Bergmann
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