* [RFC v2 1/7] sections.h: add sections header to collect all section info
2016-02-19 13:45 [RFC v2 0/7] linux: add linker tables Luis R. Rodriguez
@ 2016-02-19 13:45 ` Luis R. Rodriguez
2016-02-19 16:23 ` Greg KH
2016-02-19 13:45 ` [RFC v2 2/7] tables.h: add linker table support Luis R. Rodriguez
` (6 subsequent siblings)
7 siblings, 1 reply; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-19 13:45 UTC (permalink / raw)
To: hpa, tglx, mingo, bp
Cc: benh, ming.lei, masami.hiramatsu.pt, linux-arch, xen-devel,
linux, x86, anil.s.keshavamurthy, arnd, rusty, jbaron,
boris.ostrovsky, andriy.shevchenko, mcb30, jgross, ananth,
gregkh, linux-kernel, luto, Luis R. Rodriguez, david.vrabel,
dwmw2, davem
Linux makes extensive use of custom ELF header sections,
documentation for these are well scatterred. Unify this
documentation in a central place.
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
Documentation/DocBook/Makefile | 3 +-
Documentation/DocBook/sections.tmpl | 99 ++++++++++++++++
include/linux/sections.h | 224 ++++++++++++++++++++++++++++++++++++
3 files changed, 325 insertions(+), 1 deletion(-)
create mode 100644 Documentation/DocBook/sections.tmpl
create mode 100644 include/linux/sections.h
diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile
index d70f9b68174e..f2dfd46bf30a 100644
--- a/Documentation/DocBook/Makefile
+++ b/Documentation/DocBook/Makefile
@@ -15,7 +15,8 @@ DOCBOOKS := z8530book.xml device-drivers.xml \
80211.xml debugobjects.xml sh.xml regulator.xml \
alsa-driver-api.xml writing-an-alsa-driver.xml \
tracepoint.xml gpu.xml media_api.xml w1.xml \
- writing_musb_glue_layer.xml crypto-API.xml iio.xml
+ writing_musb_glue_layer.xml crypto-API.xml iio.xml \
+ sections.xml
include Documentation/DocBook/media/Makefile
diff --git a/Documentation/DocBook/sections.tmpl b/Documentation/DocBook/sections.tmpl
new file mode 100644
index 000000000000..96d8d88c1b93
--- /dev/null
+++ b/Documentation/DocBook/sections.tmpl
@@ -0,0 +1,99 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE set PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
+ "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
+<set>
+ <setinfo>
+ <title>Linux ELF sections</title>
+ <subtitle>
+ Explains Linux ELF sections
+ </subtitle>
+
+ <copyright>
+ <year>2016</year>
+ <holder>Luis R. Rodriguez</holder>
+ </copyright>
+
+ <authorgroup>
+ <author>
+ <firstname>Luis</firstname>
+ <surname>Rodriguez</surname>
+ <affiliation>
+ <address><email>mcgrof@kernel.org</email></address>
+ </affiliation>
+ </author>
+ </authorgroup>
+
+ <legalnotice>
+ <para>
+ This documentation is free software; you can redistribute
+ it and/or modify it under the terms of the GNU General Public
+ License version 2 as published by the Free Software Foundation.
+ </para>
+ <para>
+ This documentation is distributed in the hope that it will be
+ useful, but WITHOUT ANY WARRANTY; without even the implied
+ warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ See the GNU General Public License for more details.
+ </para>
+ <para>
+ You should have received a copy of the GNU General Public
+ License along with this documentation; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ MA 02111-1307 USA
+ </para>
+ <para>
+ For more details see the file COPYING in the source
+ distribution of Linux.
+ </para>
+ </legalnotice>
+
+ <abstract>
+ <para>
+ This book documents the different custom ELF sections used on the Linux
+ kernel and defined on Linux's custom linker script.
+ </para>
+ </abstract>
+ </setinfo>
+ <book id="linux-elf-sections">
+ <bookinfo>
+ <title>Linux kernel ELF sections</title>
+
+ <abstract>
+!Pinclude/linux/sections.h Introduction
+ </abstract>
+ </bookinfo>
+
+ <chapter>
+ <title>Core Linux kernel sections</title>
+!Pinclude/linux/sections.h Core Linux kernel sections
+!Finclude/linux/sections.h SECTION_RODATA
+!Pinclude/linux/sections.h SECTION_TEXT
+!Pinclude/linux/sections.h SECTION_DATA
+ </chapter>
+
+ <chapter>
+ <title>Linux .init* sections</title>
+!Pinclude/linux/sections.h Linux init sections
+!Finclude/linux/sections.h SECTION_INIT_DATA
+!Finclude/linux/sections.h SECTION_INIT_RODATA
+!Finclude/linux/sections.h SECTION_INIT_CALL
+ </chapter>
+
+ <chapter>
+ <title>Linux .exit* sections</title>
+!Pinclude/linux/sections.h Linux exit sections
+!Finclude/linux/sections.h SECTION_EXIT
+!Finclude/linux/sections.h SECTION_EXIT_DATA
+!Finclude/linux/sections.h SECTION_EXIT_CALL
+ </chapter>
+
+ <chapter>
+ <title>Linux .ref* sections</title>
+!Pinclude/linux/sections.h Linux references to init sections
+!Finclude/linux/sections.h SECTION_REF
+!Finclude/linux/sections.h SECTION_REF_DATA
+!Finclude/linux/sections.h SECTION_REF_RODATA
+ </chapter>
+
+ </book>
+</set>
diff --git a/include/linux/sections.h b/include/linux/sections.h
new file mode 100644
index 000000000000..7b47bea4956a
--- /dev/null
+++ b/include/linux/sections.h
@@ -0,0 +1,224 @@
+#ifndef _LINUX_SECTIONS_H
+#define _LINUX_SECTIONS_H
+/*
+ * Linux ELF sections
+ *
+ * Copyright (C) 2016 Luis R. Rodriguez <mcgrof@kernel.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Due to this file being licensed under the GPL there is controversy over
+ * whether this permits you to write a module that #includes this file
+ * without placing your module under the GPL. Please consult a lawyer for
+ * advice before doing this.
+ */
+
+/**
+ * DOC: Introduction
+ *
+ * The Linux vmlinux binary uses a custom linker script which adds
+ * some custom specialized ELF sections. This aims to document those
+ * sections. Each section must document the goal of the section, and
+ * address concurrency considerations when applicable.
+ */
+
+/**
+ * DOC: Core Linux kernel sections
+ *
+ * These are the core Linux kernel sections.
+ */
+
+/**
+ * SECTION_RODATA - read only data
+ *
+ * Macro name for code which must be protected from write access.
+ */
+#define SECTION_RODATA .rodata
+
+/**
+ * SECTION_TEXT - kernel code execution section, read-only
+ *
+ * Macro name used to annotate code (functions) used during regular
+ * kernel run time. This is combined with SECTION_RODATA, only this
+ * section also gets execution allowed.
+ *
+ */
+#define SECTION_TEXT .text
+
+/**
+ * SECTION_DATA - for read-write data
+ *
+ * Macro name for read-write data.
+ */
+#define SECTION_DATA .data
+
+/**
+ * DOC: Linux init sections
+ *
+ * These sections are used for code and data structures used during boot or
+ * module initialization. On architectures that support it (x86, x86_64), all
+ * this code is freed up by the kernel right before the fist userspace init
+ * process is called when built-in to the kernel, and if modular it is freed
+ * after module initialization. Since the code is freed so early, in theory
+ * there should be no races against freeing this code with other CPUs. Init
+ * section code and data structures should never be exported with
+ * EXPORT_SYMBOL*() as the code will quickly become unavailable to the kernel
+ * after bootup.
+ */
+
+/**
+ * SECTION_INIT - boot initialization code
+ *
+ * Macro name used to annotate code (functions) used only during boot or driver
+ * initialization.
+ *
+ */
+#define SECTION_INIT .init.text
+
+/**
+ * SECTION_INIT_DATA - boot initialization data
+ *
+ * Macro name used to annotate data structures used only during boot or driver
+ * initialization.
+ */
+#define SECTION_INIT_DATA .init.data
+
+/**
+ * SECTION_INIT_RODATA - boot read-only initialization data
+ *
+ * Macro name used to annotate read-only code (functions) used only during boot
+ * or driver initialization.
+ */
+#define SECTION_INIT_RODATA .init.rodata
+
+/**
+ * SECTION_INIT_CALL - special init call
+ *
+ * Special macro name used to annotate subsystem init call. These calls are
+ * are now grouped by functionality into separate subsections. Ordering inside
+ * the subsections is determined by link order.
+ */
+#define SECTION_INIT_CALL .initcall
+
+/**
+ * DOC: Linux exit sections
+ *
+ * These sections are used to declare a functions and data structures which
+ * are only required on exit, the function or data structure will be dropped
+ * if the code declaring this section is not compiled as a module on
+ * architectures that support this (x86, x86_64). There is no special case
+ * handling for this code when built-in to the kernel.
+ */
+
+/**
+ * SECTION_EXIT - module exit code
+ *
+ * Macro name used to annotate code (functions) used only during module
+ * unload.
+ */
+#define SECTION_EXIT .exit.text
+
+/**
+ * SECTION_EXIT_DATA - module exit data structures
+ *
+ * Macro name used to annotate data structures used only during module
+ * unload.
+ */
+#define SECTION_EXIT_DATA .exit.data
+
+/**
+ * SECTION_EXIT_CALL - special exit call
+ *
+ * Special macro name used to annotate an exit exit routine, order
+ * is important and maintained by link order.
+ */
+#define SECTION_EXIT_CALL .exitcall.exit
+
+/**
+ * DOC: Linux references to init sections
+ *
+ * These sections are used to teach modpost to not warn about possible
+ * misuses of init section code from other sections. If you use this
+ * your use case should document why you are certain such use of init
+ * sectioned code is valid. For more details refer to include/linux/init.h
+ * __ref, __refdata, and __refconst documentation.
+ */
+
+/**
+ * SECTION_REF - code referencing init is valid
+ *
+ * Macro name used to annotate that code (functions) declared with this section
+ * has been vetteed as valid for its reference or use of other code (functions)
+ * or data structures which are part of the init sections.
+ */
+#define SECTION_REF .ref.text
+
+/**
+ * SECTION_REF_DATA - reference data structure are valid
+ *
+ * Macro name used to annotate data structures declared with this section have
+ * been vetteed for its reference or use of other code (functions) or data
+ * structures part of the init sections.
+ */
+#define SECTION_REF_DATA .ref.data
+
+/**
+ * SECTION_REF_RODATA - const code or data structure referencing init is valid
+ *
+ * Macro name used to annotate const code (functions) const data structures which
+ * has been vetteed for its reference or use of other code (functions) or data
+ * structures part of the init sections.
+ */
+#define SECTION_REF_RODATA .ref.rodata
+
+/**
+ * DOC: Custom Linux sections
+ *
+ * These are very custom Linux sections.
+ */
+
+#ifndef __ASSEMBLY__
+
+/*
+ * Without this you end up with the section macro
+ * as part of the name
+ */
+#define __SECTION_TBL(section, name, level) \
+ #section ".tbl." #name "." #level
+
+/**
+ * SECTION_TBL - Linux linker table section
+ *
+ * @section: respective section
+ * @name: used to describe the use case
+ * @level: the order-level for the linker table
+ *
+ * Macro name used to annotate a linker table. For more details refer to
+ * include/linux/tables.h. Linker tables use standard Linux sections defined
+ * in this file.
+ */
+#define SECTION_TBL(section, name, level) \
+ __SECTION_TBL(section, name, level)
+
+/*
+ * For use on linker scripts and helpers
+ */
+#define ___SECTION_TBL(section, name) \
+ section##.tbl.##name
+/**
+ * SECTION_TBL_ALL - glob to capture all linker table uses for this section
+ *
+ * @section: respective section
+ *
+ * Macro name used by linker script to capture all linker tables uses for
+ * the given section. This is used by include/asm-generic/vmlinux.lds.h
+ */
+#define SECTION_TBL_ALL(section) \
+ ___SECTION_TBL(section,*)
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _LINUX_SECTIONS_H */
--
2.7.0
^ permalink raw reply related [flat|nested] 46+ messages in thread* Re: [RFC v2 1/7] sections.h: add sections header to collect all section info
2016-02-19 13:45 ` [RFC v2 1/7] sections.h: add sections header to collect all section info Luis R. Rodriguez
@ 2016-02-19 16:23 ` Greg KH
2016-02-19 20:06 ` Luis R. Rodriguez
0 siblings, 1 reply; 46+ messages in thread
From: Greg KH @ 2016-02-19 16:23 UTC (permalink / raw)
To: Luis R. Rodriguez
Cc: hpa, tglx, mingo, bp, x86, linux-kernel, luto, boris.ostrovsky,
rusty, david.vrabel, konrad.wilk, mcb30, jgross, ming.lei, arnd,
linux-arch, linux, benh, jbaron, ananth, anil.s.keshavamurthy,
davem, masami.hiramatsu.pt, andriy.shevchenko, dwmw2, xen-devel
On Fri, Feb 19, 2016 at 05:45:53AM -0800, Luis R. Rodriguez wrote:
> Linux makes extensive use of custom ELF header sections,
> documentation for these are well scatterred. Unify this
> documentation in a central place.
Minor questions:
> + <para>
> + You should have received a copy of the GNU General Public
> + License along with this documentation; if not, write to the Free
> + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
> + MA 02111-1307 USA
> + </para>
Unless you are willing to personally track the office moves of the FSF
for the next 20+ years, just drop this paragraph please :)
> +++ b/include/linux/sections.h
> @@ -0,0 +1,224 @@
> +#ifndef _LINUX_SECTIONS_H
> +#define _LINUX_SECTIONS_H
> +/*
> + * Linux ELF sections
> + *
> + * Copyright (C) 2016 Luis R. Rodriguez <mcgrof@kernel.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
Do you really mean "any later version"?
> + * Due to this file being licensed under the GPL there is controversy over
> + * whether this permits you to write a module that #includes this file
> + * without placing your module under the GPL. Please consult a lawyer for
> + * advice before doing this.
Interesting wording, I don't think there's any "controversy" here, so
I'd drop that word if at all possible.
thanks,
greg k-h
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 1/7] sections.h: add sections header to collect all section info
2016-02-19 16:23 ` Greg KH
@ 2016-02-19 20:06 ` Luis R. Rodriguez
2016-02-19 21:25 ` Greg KH
0 siblings, 1 reply; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-19 20:06 UTC (permalink / raw)
To: Greg KH
Cc: Luis R. Rodriguez, hpa, tglx, mingo, bp, x86, linux-kernel, luto,
boris.ostrovsky, rusty, david.vrabel, konrad.wilk, mcb30, jgross,
ming.lei, arnd, linux-arch, linux, benh, jbaron, ananth,
anil.s.keshavamurthy, davem, masami.hiramatsu.pt,
andriy.shevchenko, dwmw2, xen-devel
On Fri, Feb 19, 2016 at 08:23:29AM -0800, Greg KH wrote:
> On Fri, Feb 19, 2016 at 05:45:53AM -0800, Luis R. Rodriguez wrote:
> > Linux makes extensive use of custom ELF header sections,
> > documentation for these are well scatterred. Unify this
> > documentation in a central place.
>
> Minor questions:
>
> > + <para>
> > + You should have received a copy of the GNU General Public
> > + License along with this documentation; if not, write to the Free
> > + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
> > + MA 02111-1307 USA
> > + </para>
>
> Unless you are willing to personally track the office moves of the FSF
> for the next 20+ years, just drop this paragraph please :)
Sure.
> > +++ b/include/linux/sections.h
> > @@ -0,0 +1,224 @@
> > +#ifndef _LINUX_SECTIONS_H
> > +#define _LINUX_SECTIONS_H
> > +/*
> > + * Linux ELF sections
> > + *
> > + * Copyright (C) 2016 Luis R. Rodriguez <mcgrof@kernel.org>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License as published by
> > + * the Free Software Foundation; either version 2 of the License, or
> > + * (at your option) any later version.
>
> Do you really mean "any later version"?
Yes.
> > + * Due to this file being licensed under the GPL there is controversy over
> > + * whether this permits you to write a module that #includes this file
> > + * without placing your module under the GPL. Please consult a lawyer for
> > + * advice before doing this.
>
> Interesting wording,
This was copied from security.h.
> I don't think there's any "controversy" here, so I'd drop that word if at all
> possible.
Change it for something else? Any preference?
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 1/7] sections.h: add sections header to collect all section info
2016-02-19 20:06 ` Luis R. Rodriguez
@ 2016-02-19 21:25 ` Greg KH
2016-02-19 21:59 ` Luis R. Rodriguez
0 siblings, 1 reply; 46+ messages in thread
From: Greg KH @ 2016-02-19 21:25 UTC (permalink / raw)
To: Luis R. Rodriguez
Cc: Luis R. Rodriguez, hpa, tglx, mingo, bp, x86, linux-kernel, luto,
boris.ostrovsky, rusty, david.vrabel, konrad.wilk, mcb30, jgross,
ming.lei, arnd, linux-arch, linux, benh, jbaron, ananth,
anil.s.keshavamurthy, davem, masami.hiramatsu.pt,
andriy.shevchenko, dwmw2, xen-devel
On Fri, Feb 19, 2016 at 09:06:03PM +0100, Luis R. Rodriguez wrote:
> On Fri, Feb 19, 2016 at 08:23:29AM -0800, Greg KH wrote:
> > On Fri, Feb 19, 2016 at 05:45:53AM -0800, Luis R. Rodriguez wrote:
> > > + * Due to this file being licensed under the GPL there is controversy over
> > > + * whether this permits you to write a module that #includes this file
> > > + * without placing your module under the GPL. Please consult a lawyer for
> > > + * advice before doing this.
> >
> > Interesting wording,
>
> This was copied from security.h.
Ah, and look, I wrote that, nevermind then :)
sorry for the noise,
greg k-h
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 1/7] sections.h: add sections header to collect all section info
2016-02-19 21:25 ` Greg KH
@ 2016-02-19 21:59 ` Luis R. Rodriguez
0 siblings, 0 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-19 21:59 UTC (permalink / raw)
To: Greg KH
Cc: Luis R. Rodriguez, hpa, tglx, mingo, bp, x86, linux-kernel, luto,
boris.ostrovsky, rusty, david.vrabel, konrad.wilk, mcb30, jgross,
ming.lei, arnd, linux-arch, linux, benh, jbaron, ananth,
anil.s.keshavamurthy, davem, masami.hiramatsu.pt,
andriy.shevchenko, dwmw2, xen-devel
On Fri, Feb 19, 2016 at 01:25:22PM -0800, Greg KH wrote:
> On Fri, Feb 19, 2016 at 09:06:03PM +0100, Luis R. Rodriguez wrote:
> > On Fri, Feb 19, 2016 at 08:23:29AM -0800, Greg KH wrote:
> > > On Fri, Feb 19, 2016 at 05:45:53AM -0800, Luis R. Rodriguez wrote:
> > > > + * Due to this file being licensed under the GPL there is controversy over
> > > > + * whether this permits you to write a module that #includes this file
> > > > + * without placing your module under the GPL. Please consult a lawyer for
> > > > + * advice before doing this.
> > >
> > > Interesting wording,
> >
> > This was copied from security.h.
>
> Ah, and look, I wrote that, nevermind then :)
>
> sorry for the noise,
Heh, thanks I'll leave it as-is and modify that pesky address to a URL.
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread
* [RFC v2 2/7] tables.h: add linker table support
2016-02-19 13:45 [RFC v2 0/7] linux: add linker tables Luis R. Rodriguez
2016-02-19 13:45 ` [RFC v2 1/7] sections.h: add sections header to collect all section info Luis R. Rodriguez
@ 2016-02-19 13:45 ` Luis R. Rodriguez
2016-02-19 20:25 ` H. Peter Anvin
2016-02-19 20:33 ` H. Peter Anvin
2016-02-19 13:45 ` [RFC v2 3/7] firmware: port built-in section to linker table Luis R. Rodriguez
` (5 subsequent siblings)
7 siblings, 2 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-19 13:45 UTC (permalink / raw)
To: hpa, tglx, mingo, bp
Cc: benh, ming.lei, masami.hiramatsu.pt, linux-arch, xen-devel,
linux, x86, anil.s.keshavamurthy, arnd, rusty, jbaron,
boris.ostrovsky, andriy.shevchenko, mcb30, jgross, ananth,
gregkh, linux-kernel, luto, Luis R. Rodriguez, david.vrabel,
dwmw2, davem
A linker table is a data structure that is stitched together from items
in multiple object files. Linux has historically implicitly used linker
tables for ages, however they were all built in an adhoc manner which
requires linker script modifications, per architecture. This adds a
general linker table solution so that a new linker table can be
implemented by changing C code only. The Linux linker table was
originally based on Michael Brown's iPXE's linker table solution but
has been significantly modified to fit Linux's use in its integration.
The same philosoph is borrowed, extended and further simplified:
Linker tables enable an extremely light weight linker build time
solution for feature ordering and selection, this can help to both
simplify init sequences in a generic fashion and helps avoiding code
bit-rotting when desirable.
Bit rotting avoidance is enabled by *granting the option* to force
compilation of code and only enable linking object code in when
specific features have been enabled. It accomplishes this by using
linker sections, the lightweight feature ordering of code is enabled
by taking advantage of the old binutils ld SORT() on features
specific sections.
Contrary to iPXE's solution, which strives to force compilation
of all features, Linux' solution strives to encourage usage of linker
tables to force compilation of code *only on designated code*. Linker
tables can be used without requiring one to force code compilation
of features that use it though, to take advantage of the simplification
of init sequences.
Linux code that uses linker tables *and* wishes to always require
compilation but selectively linking must use new kbuild target object
that helps accomplishes this, table-y. Linux code that uses linker
tables but does not want to require forcing compilation can use the
good 'ol obj-y targets.
Used commit 67a10ef000cb7 from iPXE upstream [0] as the starting point
for development and evaluation of Linux's integration, further changes
made and evaluation of different linker table options for Linux are
available on the linker-table userspace tree [1].
[0] git://git.ipxe.org/ipxe.git
[1] https://git.kernel.org/cgit/linux/kernel/git/mcgrof/linker-tables.git/
v2:
- modified completely to match feedback by community, made equivalent
modifications to userspace solution. This is pretty much a complete
rewrite of how we present and use linker tables. By using standard
sections we no longer have to make custom linker script extensions
for each new linker table solution, you just pick a linker table
type by section type.
- extend documention considerably, including use of kdoc
- drop ICC hacks per popular request to ignore such issues for now
- use sections.h - this lets us streamline a clean use case of
well documented sections. To help further with this make use of
SECTION_TBL() to allow use of these in code and SECTION_TBL_ALL()
on linker scripts, as well as SECTION_TBL_ALL_STR() on relocs.c
when needed.
Cc: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
Documentation/DocBook/Makefile | 2 +-
Documentation/DocBook/linker-tables.tmpl | 169 ++++++++
Documentation/kbuild/makefiles.txt | 19 +
arch/x86/tools/relocs.c | 3 +
include/asm-generic/vmlinux.lds.h | 15 +-
include/linux/sections.h | 4 +-
include/linux/tables.h | 696 +++++++++++++++++++++++++++++++
scripts/Makefile.build | 4 +-
scripts/Makefile.clean | 1 +
scripts/Makefile.lib | 12 +
tools/include/linux/sections.h | 13 +
11 files changed, 929 insertions(+), 9 deletions(-)
create mode 100644 Documentation/DocBook/linker-tables.tmpl
create mode 100644 include/linux/tables.h
create mode 100644 tools/include/linux/sections.h
diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile
index f2dfd46bf30a..57ff543f4d38 100644
--- a/Documentation/DocBook/Makefile
+++ b/Documentation/DocBook/Makefile
@@ -16,7 +16,7 @@ DOCBOOKS := z8530book.xml device-drivers.xml \
alsa-driver-api.xml writing-an-alsa-driver.xml \
tracepoint.xml gpu.xml media_api.xml w1.xml \
writing_musb_glue_layer.xml crypto-API.xml iio.xml \
- sections.xml
+ sections.xml linker-tables.xml
include Documentation/DocBook/media/Makefile
diff --git a/Documentation/DocBook/linker-tables.tmpl b/Documentation/DocBook/linker-tables.tmpl
new file mode 100644
index 000000000000..1256d3e3cd4d
--- /dev/null
+++ b/Documentation/DocBook/linker-tables.tmpl
@@ -0,0 +1,169 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE set PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
+ "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
+<set>
+ <setinfo>
+ <title>Linux linker tables</title>
+ <subtitle>
+ Explains Linux' linker tables work.
+ </subtitle>
+
+ <copyright>
+ <year>2015-2016</year>
+ <holder>Luis R. Rodriguez</holder>
+ </copyright>
+
+ <authorgroup>
+ <author>
+ <firstname>Luis</firstname>
+ <surname>Rodriguez</surname>
+ <affiliation>
+ <address><email>mcgrof@kernel.org</email></address>
+ </affiliation>
+ </author>
+ </authorgroup>
+
+ <legalnotice>
+ <para>
+ This documentation is free software; you can redistribute
+ it and/or modify it under the terms of the GNU General Public
+ License version 2 as published by the Free Software Foundation.
+ </para>
+ <para>
+ This documentation is distributed in the hope that it will be
+ useful, but WITHOUT ANY WARRANTY; without even the implied
+ warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ See the GNU General Public License for more details.
+ </para>
+ <para>
+ You should have received a copy of the GNU General Public
+ License along with this documentation; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ MA 02111-1307 USA
+ </para>
+ <para>
+ For more details see the file COPYING in the source
+ distribution of Linux.
+ </para>
+ </legalnotice>
+
+ <abstract>
+ <para>
+ This book documents the Linux' use of linker tables, how you can
+ use them and how they work.
+ </para>
+ </abstract>
+ </setinfo>
+ <book id="linux-linux-tables">
+ <bookinfo>
+ <title>Linux linker tables</title>
+
+ <abstract>
+!Pinclude/linux/tables.h Introduction
+ </abstract>
+ </bookinfo>
+
+ <chapter>
+ <title>About Linker tables</title>
+
+ <sect1>
+ <title>Linker table provenance and userspace testing</title>
+!Pinclude/linux/tables.h Linker table provenance and userspace testing
+ </sect1>
+
+ <sect1>
+ <title>The code bit-rot problem</title>
+!Pinclude/linux/tables.h The code bit-rot problem
+ </sect1>
+
+ <sect1>
+ <title>Avoiding the code bit-rot problem when desirable</title>
+!Pinclude/linux/tables.h Avoiding the code bit-rot problem when desirable
+ </sect1>
+ </chapter>
+
+ <chapter>
+ <title>Using linker tables in Linux</title>
+
+ <sect1>
+ <title>Using target table-y and table-n</title>
+!Pinclude/linux/tables.h Using target table-y and table-n
+ </sect1>
+
+ <sect1>
+ <title>Opting out of forcing compilation</title>
+!Pinclude/linux/tables.h Opting out of forcing compilation
+ </sect1>
+
+ <sect1>
+ <title>How linker tables simplify inits</title>
+!Pinclude/linux/tables.h How linker tables simplify inits
+ </sect1>
+
+ </chapter>
+
+ <chapter>
+ <title>Linker table helpers</title>
+!Pinclude/linux/tables.h LINKTABLE_ALIGNMENT
+!Finclude/linux/tables.h LINKTABLE_SIZE
+!Finclude/linux/tables.h LINKTABLE_EMPTY
+!Finclude/linux/tables.h LINKTABLE_START
+!Finclude/linux/tables.h LINKTABLE_END
+!Finclude/linux/tables.h LINKTABLE_ADDR_WITHIN
+ </chapter>
+
+ <chapter>
+ <title>Constructing Linker tables</title>
+!Pinclude/linux/tables.h Constructing linker tables
+
+ <sect1>
+ <title>Weak linker tables constructors</title>
+!Pinclude/linux/tables.h Weak linker tables constructors
+!Finclude/linux/tables.h LINKTABLE_TEXT_WEAK
+!Finclude/linux/tables.h LINKTABLE_DATA_WEAK
+!Finclude/linux/tables.h LINKTABLE_RO_WEAK
+!Finclude/linux/tables.h LINKTABLE_INIT_WEAK
+!Finclude/linux/tables.h LINKTABLE_INIT_DATA_WEAK
+ </sect1>
+
+ <sect1>
+ <title>Regular linker linker table constructors</title>
+!Pinclude/linux/tables.h Regular linker linker table constructors
+!Finclude/linux/tables.h LINKTABLE_TEXT
+!Finclude/linux/tables.h LINKTABLE_DATA
+!Finclude/linux/tables.h LINKTABLE_RO
+!Finclude/linux/tables.h LINKTABLE_INIT
+!Finclude/linux/tables.h LINKTABLE_INIT_DATA
+ </sect1>
+ </chapter>
+
+ <chapter>
+ <title>Declaring Linker tables</title>
+!Pinclude/linux/tables.h Declaring Linker tables
+!Finclude/linux/tables.h DECLARE_LINKTABLE_TEXT
+!Finclude/linux/tables.h DECLARE_LINKTABLE_DATA
+!Finclude/linux/tables.h DECLARE_LINKTABLE_RO
+!Finclude/linux/tables.h DECLARE_LINKTABLE_INIT
+!Finclude/linux/tables.h DECLARE_LINKTABLE_INIT_DATA
+ </chapter>
+
+ <chapter>
+ <title>Defining Linker tables</title>
+!Pinclude/linux/tables.h Defining Linker tables
+!Finclude/linux/tables.h DEFINE_LINKTABLE_TEXT
+!Finclude/linux/tables.h DEFINE_LINKTABLE_DATA
+!Finclude/linux/tables.h DEFINE_LINKTABLE_RO
+!Finclude/linux/tables.h DEFINE_LINKTABLE_INIT
+!Finclude/linux/tables.h DEFINE_LINKTABLE_INIT_DATA
+ </chapter>
+
+ <chapter>
+ <title>Iterating over Linker tables</title>
+!Pinclude/linux/tables.h Iterating over Linker tables
+!Finclude/linux/tables.h LINKTABLE_FOR_EACH
+!Finclude/linux/tables.h LINKTABLE_RUN_ALL
+!Finclude/linux/tables.h LINKTABLE_RUN_ERR
+ </chapter>
+
+ </book>
+</set>
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 13f888a02a3d..a0a35445d968 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -1088,6 +1088,25 @@ When kbuild executes, the following steps are followed (roughly):
In this example, extra-y is used to list object files that
shall be built, but shall not be linked as part of built-in.o.
+ table-y table-m and table-
+
+ To avoid code bit-rot you may wish to avoid using #ifdefs on your
+ code. Bit-rot is possible if certain features may not be enabled
+ on certain build environments. The table-y, specifies targets which you
+ always wish to force compilation on, but wish to only enable linking in
+ if the feature is enabled, these are features taking advantage of
+ Linux's linker tables. For details on how to implement a feature using
+ linker tablesrefer to include/linux/tables.h. Use of table-m is not
+ yet supported.
+
+ Example:
+ table-$(CONFIG-FEATURE_FOO) += foo.o
+
+ An alternative to using table-y, is to use extra-y followed by the
+ respective obj-y:
+
+ extra-y += foo.o
+ obj-$(CONFIG-FEATURE_FOO) += foo.o
--- 6.7 Commands useful for building a boot image
diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
index 0c2fae8d929d..07b335c67139 100644
--- a/arch/x86/tools/relocs.c
+++ b/arch/x86/tools/relocs.c
@@ -1,4 +1,5 @@
/* This is included from relocs_32/64.c */
+#include <linux/sections.h>
#define ElfW(type) _ElfW(ELF_BITS, type)
#define _ElfW(bits, type) __ElfW(bits, type)
@@ -68,6 +69,8 @@ static const char * const sym_regex_kernel[S_NSYMTYPES] = {
"__end_rodata|"
"__initramfs_start|"
"(jiffies|jiffies_64)|"
+ SECTION_TBL_ALL_STR(SECTION_RODATA) "|"
+ SECTION_TBL_ALL_STR(SECTION_INIT) "|"
#if ELF_BITS == 64
"__per_cpu_load|"
"init_per_cpu__.*|"
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index c4bd0e2c173c..eb23738ef4bd 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -55,6 +55,7 @@
#endif
#include <linux/export.h>
+#include <linux/sections.h>
/* Align . to a 8 byte boundary equals to maximum function alignment. */
#define ALIGN_FUNCTION() . = ALIGN(8)
@@ -199,7 +200,8 @@
/* .data section */
#define DATA_DATA \
- *(.data) \
+ *(SECTION_DATA) \
+ *(SORT(SECTION_TBL_ALL(SECTION_DATA))) \
*(.ref.data) \
*(.data..shared_aligned) /* percpu related */ \
MEM_KEEP(init.data) \
@@ -255,7 +257,9 @@
. = ALIGN((align)); \
.rodata : AT(ADDR(.rodata) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start_rodata) = .; \
- *(.rodata) *(.rodata.*) \
+ *(.rodata) \
+ *(SORT(SECTION_TBL_ALL(SECTION_RODATA))) \
+ *(.rodata.*) \
*(__vermagic) /* Kernel version magic */ \
. = ALIGN(8); \
VMLINUX_SYMBOL(__start___tracepoints_ptrs) = .; \
@@ -422,7 +426,8 @@
* during second ld run in second ld pass when generating System.map */
#define TEXT_TEXT \
ALIGN_FUNCTION(); \
- *(.text.hot .text .text.fixup .text.unlikely) \
+ *(.text.hot SECTION_TEXT .text.fixup .text.unlikely) \
+ *(SORT(SECTION_TBL_ALL(SECTION_TEXT))) \
*(.ref.text) \
MEM_KEEP(init.text) \
MEM_KEEP(exit.text) \
@@ -507,7 +512,8 @@
/* init and exit section handling */
#define INIT_DATA \
- *(.init.data) \
+ *(SECTION_INIT_DATA) \
+ *(SORT(SECTION_TBL_ALL(SECTION_INIT_DATA))) \
MEM_DISCARD(init.data) \
KERNEL_CTORS() \
MCOUNT_REC() \
@@ -531,6 +537,7 @@
#define INIT_TEXT \
*(.init.text) \
+ *(SORT(SECTION_TBL_ALL(SECTION_INIT))) \
MEM_DISCARD(init.text)
#define EXIT_DATA \
diff --git a/include/linux/sections.h b/include/linux/sections.h
index 7b47bea4956a..53de435e0056 100644
--- a/include/linux/sections.h
+++ b/include/linux/sections.h
@@ -203,6 +203,8 @@
#define SECTION_TBL(section, name, level) \
__SECTION_TBL(section, name, level)
+#endif /* __ASSEMBLY__ */
+
/*
* For use on linker scripts and helpers
*/
@@ -219,6 +221,4 @@
#define SECTION_TBL_ALL(section) \
___SECTION_TBL(section,*)
-#endif /* __ASSEMBLY__ */
-
#endif /* _LINUX_SECTIONS_H */
diff --git a/include/linux/tables.h b/include/linux/tables.h
new file mode 100644
index 000000000000..292b704f2b4d
--- /dev/null
+++ b/include/linux/tables.h
@@ -0,0 +1,696 @@
+#ifndef _LINUX_LINKER_TABLES_H
+#define _LINUX_LINKER_TABLES_H
+
+#include <linux/sections.h>
+
+/*
+ * Linux linker tables
+ *
+ * Copyright (C) 2005-2009 Michael Brown <mcb30@ipxe.org>
+ * Copyright (C) 2015-2016 Luis R. Rodriguez <mcgrof@kernel.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Due to this file being licensed under the GPL there is controversy over
+ * whether this permits you to write a module that #includes this file
+ * without placing your module under the GPL. Please consult a lawyer for
+ * advice before doing this.
+ */
+
+/**
+ * DOC: Introduction
+ *
+ * A linker table is a data structure that is stitched together from items
+ * in multiple object files. Linux has historically implicitly used linker
+ * tables for ages, however they were all built in an adhoc manner which
+ * requires linker script modifications, per architecture. This linker table
+ * solution provides a general linker table facility so that a new linker table
+ * can be implemented by changing C code only.
+ *
+ * Linker tables help you simplify init sequences by using ELF sections, linker
+ * build time selective sorting (disabled options get ignored), and can
+ * optionally also be used to help you avoid code bit-rot due to #ifdery
+ * collateral.
+ */
+
+/**
+ * DOC: Linker table provenance and userspace testing
+ *
+ * The Linux implementation of linker tables is derivative of iPXE linker
+ * table's solution (iPXE commit 67a10ef000cb7 [0]). To see how this code
+ * evolved or to extend and test and use this code in userspace refer to the
+ * userspace linker-table tree [1]. This repository can be used for ease of
+ * testing of extensions and sampling of changes prior to inclusion into Linux,
+ * it is intended to be kept up to date to match Linux's solution. Contrary to
+ * iPXE's solution, which strives to force compilation of everything using
+ * linker tables, Linux's solution allows for developers to be selective over
+ * where one wishes to force compilation, this then is just an optional feature
+ * for the Linux linker table solution.
+ *
+ * [0] git://git.ipxe.org/ipxe.git
+ *
+ * [1] https://git.kernel.org/cgit/linux/kernel/git/mcgrof/linker-tables.git/
+ */
+
+/**
+ * DOC: The code bit-rot problem
+ *
+ * Overuse of C #ifdefs can be problematic for certain types of code. Linux
+ * provides a rich array of features, but all these features take up valuable
+ * space in a kernel image. The traditional solution to this problem has been
+ * for each feature to have its own Kconfig entry and for the respective code
+ * to be wrapped around #ifdefs, allowing the feature to be compiled in only
+ * if desired.
+ *
+ * The problem with this is that over time it becomes very difficult and time
+ * consuming to compile, let alone test, all possible versions of Linux. Code
+ * that is not typically used tends to suffer from bit-rot over time. It can
+ * become difficult to predict which combinations of compile-time options will
+ * result in code that can compile and link correctly.
+ */
+
+/**
+ * DOC: Avoiding the code bit-rot problem when desirable
+ *
+ * To solve the code bit-rot problem linker tables can be used on Linux, it
+ * enables you to always force compiling of select features that one wishes to
+ * avoid bit-rot while still enabling you to disable linking feature code into
+ * the final kernel image if the features have been disabled via Kconfig.
+ * Linux's linker tables allows for developers to be selective over where one
+ * wishes to take advantage of the optional feature of forcing compilation and
+ * only linking in enabled features.
+ *
+ * To use linker tables and to optionally take advantage of avoiding code
+ * bit-rot, feature code should be implemented in separate C files, and should
+ * be designed to always be compiled -- they should not be guarded with a C
+ * code #ifdef CONFIG_FOO statements, consideration must also be taken for
+ * sub-features which depend on the main CONFIG_FOO option, as they will be
+ * disabled if they depend on CONFIG_FOO and therefore not compiled. To force
+ * compilation and only link when features are needed a new optional target
+ * table-y can be used on Makefiles, documented below.
+ *
+ * Currently only built-in features are supported, modular support is not
+ * yet supported, however you can make use of sub-features for modules
+ * if they are independent and can simply be linked into modules.
+ */
+
+/**
+ * DOC: Using target table-y and table-n
+ *
+ * Let's assume we want to always force compilation of feature FOO in the
+ * kernel but avoid linking it. When you enable the FOO feature via Kconfig
+ * you'd end up with:
+ *
+ * #define CONFIG_FOO 1
+ *
+ * You typically would then just use this on your Makefile to selectively
+ * compile and link the feature:
+ *
+ * obj-$(CONFIG_FOO) += foo.o
+ *
+ * You could instead optionally use the new linker table object:
+ *
+ * table-$(CONFIG_FOO) += foo.o
+ *
+ * Alternatively, this would be the equivalent of listing:
+ *
+ * extra += foo.o
+ * obj-$(CONFIG_FOO) += foo.o
+ *
+ * Both are mechanisms which can be used to take advantage of forcing
+ * compilation with linker tables, however making use of table-$(CONFIG_FOO)
+ * is encouraged as it helps with annotating linker tables clearly where
+ * compilation is forced.
+ */
+
+/**
+ * DOC: Opting out of forcing compilation
+ *
+ * If you want to opt-out of forcing compilation you would use the typical
+ * obj-$(CONFIG_FOO) += foo.o and foo.o will only be compiled and linked
+ * in when enabled. Using both table-$(CONFIG_FOO) and obj-($CONFIG_FOO)
+ * will result with the feature on your binary only if you've enabled
+ * CONFIG_FOO, however using table-$(CONFIG_FOO) will always force compilation,
+ * this is why avoiding code bit-rot is an optional fature for Linux linker
+ * tables.
+ */
+
+/**
+ * DOC: How linker tables simplify inits
+ *
+ * Traditionally, we would implement features in C code as follows:
+ *
+ * foo_init();
+ *
+ * You'd then have a foo.h which would have:
+ *
+ * #ifdef CONFIG_FOO
+ * #else
+ * static inline void foo(void) { }
+ * #endif
+ *
+ * With linker tables this is no longer necessary as your init routines would
+ * be implicit, you'd instead call:
+ *
+ * call_init_fns();
+ *
+ * call_init_fns() would call all functions present in your init table and if
+ * and only if foo.o gets linked in, then its initialisation function will be
+ * called, whether you use obj-$(CONFIG_FOO) or table-$(CONFIG_FOO).
+ *
+ * The linker script takes care of assembling the tables for us. All of our
+ * table sections have names of the format SECTION_NAME*.tbl.NAME.N. Here
+ * SECTION_NAME is one of the standard sections in include/linux/sections.h,
+ * and NAME designates the specific use case for the linker table, the table.
+ * N is a digit decimal number used to impose an "order level" upon the tables
+ * if required. NN= (empty string) is reserved for the symbol indicating "table
+ * start", and N=~ is reserved for the symbol indicating "table end". In order
+ * for the call_init_fns() to work behind the scenes the custom linker script
+ * would need to define the beginning of the table, the end of the table, and
+ * in between it should use SORT() to give order-level effect. Now, typically
+ * such type of requirements would require custom linker script modifications
+ * but Linux's linker tables builds on top of already existing standard Linux
+ * ELF sections, each with different purposes. This lets you build and add
+ * new tables without needing custom linker script modifications. This is
+ * also done to support all architectures. All that is needed then is to
+ * ensure a respective common linker table entry is added to the shared
+ * include/asm-generic/vmlinux.lds.h. There should be a respective:
+ *
+ * *(SORT(SECTION_TBL_ALL(SECTION_NAME)))
+ *
+ * entry for each type of supported section there. If your SECTION_NAME
+ * is not yet supported, consider adding support for it.
+ *
+ * The order-level is really only a helper, if only one order level is
+ * used, the next contributing factor to order is the order of the code
+ * in the C file, and the order of the objects in the Makefile. Using
+ * an order level then should not really be needed in most cases, its
+ * use however enables to compartamentalize code into tables where ordering
+ * through C file or through the Makefile would otherwise be very difficult
+ * or if one wanted to enable very specific initialization semantics.
+ *
+ * As an example, suppose that we want to create a "frobnicator"
+ * feature framework, and allow for several independent modules to
+ * provide frobnicating services. Then we would create a frob.h
+ * header file containing e.g.
+ *
+ * struct frobnicator {
+ * const char *name;
+ * void (*frob) (void);
+ * };
+ *
+ * DECLARE_LINKTABLE_INIT(struct frobnicator, frobnicator_fns);
+ *
+ * Any module providing frobnicating services would look something
+ * like
+ *
+ * #include "frob.h"
+ * static void my_frob(void) {
+ * ... Do my frobnicating
+ * }
+ * LINKTABLE(frobnicator_fns, all) my_frobnicator = {
+ * .name = "my_frob",
+ * .frob = my_frob,
+ * };
+ *
+ * The central frobnicator code (frob.c) would use the frobnicating
+ * modules as follows
+ *
+ * #include "frob.h"
+ *
+ * void frob_all(void) {
+ * struct frob *frob;
+ *
+ * LINKTABLE_FOR_EACH(frob, frobnicator_fns) {
+ * pr_info("Calling frobnicator \"%s\"\n", frob->name);
+ * frob->frob();
+ * }
+ * }
+ */
+
+/**
+ * DOC: Linker table helpers
+ *
+ * These are helpers for linker tables.
+ */
+
+/**
+ * LINKTABLE_ALIGNMENT - get linker table alignment
+ *
+ * @name: linker table
+ *
+ * Gives you the linker table alignment.
+ */
+#define LINKTABLE_ALIGNMENT(name) __alignof__(__typeof__(name[0]))
+
+/**
+ * LINKTABLE_SIZE - get number of entries in linker table
+ *
+ * @name: linker table
+ *
+ * This gives you the number of entries in linker table.
+ * Example usage:
+ *
+ * unsigned int num_frobs = LINKTABLE_SIZE(frobnicator_fns);
+ */
+#define LINKTABLE_SIZE(name) ((name##__end) - (name))
+
+/**
+ * LINKTABLE_EMPTY - check if link table is empty
+ *
+ * @name: linker table
+ *
+ * Returns true if link table is emtpy.
+ *
+ * bool is_empty = LINKTABLE_EMPTY(frobnicator_fns);
+ */
+#define LINKTABLE_EMPTY(name) (LINKTABLE_SIZE(name) == 0)
+
+/**
+ * LINKTABLE_START - get address of start of linker table.
+ *
+ * @tbl: linker table
+ *
+ * This gives you the start address of the linker table.
+ * This should give you the address of the first entry.
+ *
+ */
+#define LINKTABLE_START(tbl) tbl
+
+/**
+ * LINKTABLE_END - get address of endd of linker table.
+ *
+ * @tbl: linker table
+ *
+ * This gives you the end address of the linker table.
+ * This should give you the address of the end of the
+ * linker table. This will match the start address if the
+ * linker table is empty.
+ */
+#define LINKTABLE_END(tbl) tbl##__end
+
+/**
+ * LINKTABLE_ADDR_WITHIN - returns true if address is in range
+ *
+ * @tbl: linker table
+ * @address: address to query for
+ *
+ * Returns true if the address is part of the linker table.
+ */
+#define LINKTABLE_ADDR_WITHIN(tbl, addr) \
+ (addr >= (unsigned long) LINKTABLE_START(tbl) && \
+ addr < (unsigned long) LINKTABLE_END(tbl))
+
+/**
+ * DOC: Constructing linker tables
+ *
+ * Linker tables constructors are used to build an entry into a linker table.
+ * Linker table constructors exist for each type of supported section.
+ *
+ * You have weak and regular type of link table entry constructors.
+ */
+
+/**
+ * DOC: Weak linker tables constructors
+ *
+ * The weak attribute is desirable if you want an entry you can replace at
+ * link time. A very special use case for linker tables is the first entry.
+ * A weak attribute is used for the first entry to ensure that this entry's
+ * address matches the end address of the table when the linker table is
+ * emtpy, but will also point to the first real entry of the table once not
+ * empty. When the first entry is linked in, it takes place of the first entry.
+ */
+
+/**
+ * LINKTABLE_DATA_WEAK - Constructs a weak linker table entry for data
+ *
+ * @name: linker table name
+ * @level: order level
+ *
+ * Constructs a weak linker table which we data.
+ */
+#define LINKTABLE_DATA_WEAK(name, level) \
+ __typeof__(name[0]) \
+ __attribute__((used, \
+ weak, \
+ __aligned__(LINKTABLE_ALIGNMENT(name)), \
+ section(SECTION_TBL(SECTION_DATA, name, level))))
+
+/**
+ * LINKTABLE_TEXT_WEAK - Constructs a weak linker table entry for execution
+ *
+ * @name: linker table name
+ * @level: order level
+ *
+ * Constructs a weak linker table which we for execution. These will be
+ * read-only.
+ */
+#define LINKTABLE_TEXT_WEAK(name, level) \
+ __typeof__(name[0]) \
+ __attribute__((used, \
+ weak, \
+ __aligned__(LINKTABLE_ALIGNMENT(name)), \
+ section(SECTION_TBL(SECTION_TEXT, name, level))))
+
+
+/**
+ * LINKTABLE_RO_WEAK - Constructs a weak read-only linker table entry
+ *
+ * @name: linker table name
+ * @level: order level
+ *
+ * Constructs a weak linker table which we know only requires read-only access.
+ */
+#define LINKTABLE_RO_WEAK(name, level) \
+ const __typeof__(name[0]) \
+ __attribute__((used, \
+ weak, \
+ __aligned__(LINKTABLE_ALIGNMENT(name)), \
+ section(SECTION_TBL(SECTION_RODATA, name, level))))
+
+/**
+ * LINKTABLE_INIT_WEAK - Constructs a weak linker table entry for init code
+ *
+ * @name: linker table name
+ * @level: order level
+ *
+ * Constructs a weak linker table which will need at init for execution.
+ */
+#define LINKTABLE_INIT_WEAK(name, level) \
+ __typeof__(name[0]) \
+ __attribute__((used, \
+ weak, \
+ __aligned__(LINKTABLE_ALIGNMENT(name)), \
+ section(SECTION_TBL(SECTION_INIT, name, level))))
+
+/**
+ * LINKTABLE_INIT_DATA_WEAK - Constructs a weak linker table entry for initdata
+ *
+ * @name: linker table name
+ * @level: order level
+ *
+ * Constructs a weak linker table which will need at init for data.
+ */
+#define LINKTABLE_INIT_DATA_WEAK(name, level) \
+ __typeof__(name[0]) \
+ __attribute__((used, \
+ weak, \
+ __aligned__(LINKTABLE_ALIGNMENT(name)), \
+ section(SECTION_TBL(SECTION_INIT_DATA, name, level))))
+
+/**
+ * DOC: Regular linker linker table constructors
+ *
+ * Regular constructors are expected to be used for valid linker table entries.
+ * Valid uses of weak entries other than the beginning and is currently
+ * untested but should in theory work.
+ */
+
+/**
+ * LINKTABLE_TEXT - Declares a linker table entry for execution
+ *
+ * @name: linker table name
+ * @level: order level
+ *
+ * Declares a linker table to be used for execution.
+ */
+#define LINKTABLE_TEXT(name, level) \
+ __typeof__(name[0]) \
+ __attribute__((used, \
+ __aligned__(LINKTABLE_ALIGNMENT(name)), \
+ section(SECTION_TBL(SECTION_TEXT, name, level))))
+
+/**
+ * LINKTABLE_DATA - Declares a data linker table entry
+ *
+ * @name: linker table name
+ * @level: order level
+ *
+ * Declares a data linker table entry. These are read-write.
+ */
+#define LINKTABLE_DATA(name, level) \
+ __typeof__(name[0]) \
+ __attribute__((used, \
+ __aligned__(LINKTABLE_ALIGNMENT(name)), \
+ section(SECTION_TBL(SECTION_DATA, name, level))))
+/**
+ * LINKTABLE_RO - Declares a read-only linker table entry.
+ *
+ * @name: linker table name
+ * @level: order level
+ *
+ * Declares a linker table which we know only requires read-only access.
+ */
+#define LINKTABLE_RO(name, level) \
+ const __typeof__(name[0]) \
+ __attribute__((used, \
+ __aligned__(LINKTABLE_ALIGNMENT(name)), \
+ section(SECTION_TBL(SECTION_RODATA, name, level))))
+
+/**
+ * LINKTABLE_INIT - Declares a linker table entry to be used on init.
+ *
+ * @name: linker table name
+ * @level: order level
+ *
+ * Declares a linker table entry which we will use during init for execution.
+ */
+#define LINKTABLE_INIT(name, level) \
+ __typeof__(name[0]) \
+ __attribute__((used, \
+ __aligned__(LINKTABLE_ALIGNMENT(name)), \
+ section(SECTION_TBL(SECTION_INIT, name, level))))
+/**
+ * LINKTABLE_INIT_DATA - Declares a linker table entry to be used on init data.
+ *
+ * @name: linker table name
+ * @level: order level
+ *
+ * Declares a linker table entry which we will use during init for data.
+ */
+#define LINKTABLE_INIT_DATA(name, level) \
+ __typeof__(name[0]) \
+ __attribute__((used, \
+ __aligned__(LINKTABLE_ALIGNMENT(name)), \
+ section(SECTION_TBL(SECTION_INIT_DATA, name, level))))
+
+
+/**
+ * DOC: Declaring Linker tables
+ *
+ * Declarers are used to help code access the linker tables. Typically
+ * header files for subsystems would declare the linker tables to enable
+ * easy access to add new entries, and to iterate over the list of table.
+ */
+
+/**
+ * DECLARE_LINKTABLE_TEXT - Declares linker table entry for exectuion
+ *
+ * @type: data type
+ * @name: table name
+ *
+ * Declares a linker table entry for execution.
+ */
+#define DECLARE_LINKTABLE_TEXT(type, name) \
+ extern type name[], name##__end[];
+
+/**
+ * DECLARE_LINKTABLE_DATA - Declares a data linker table entry
+ *
+ * @type: data type
+ * @name: table name
+ *
+ * Declares a data linker table entry.
+ */
+#define DECLARE_LINKTABLE_DATA(type, name) \
+ extern type name[], name##__end[];
+
+/**
+ * DECLARE_LINKTABLE_RO - Declares a read-only linker table entry
+ *
+ * @type: data type
+ * @name: table name
+ *
+ * Declares a read-only linker table entry.
+ */
+#define DECLARE_LINKTABLE_RO(type, name) \
+ extern const type name[], name##__end[];
+
+/**
+ * DECLARE_LINKTABLE_INIT - Declares a linker table entry to be used on init
+ *
+ * @type: data type
+ * @name: table name
+ *
+ * Declares a linker table entry to be used on init for execution.
+ */
+#define DECLARE_LINKTABLE_INIT(type, name) \
+ extern type name[], name##__end[];
+
+/**
+ * DECLARE_LINKTABLE_INIT_DATA - Declares a data init linker table entry
+ *
+ * @type: data type
+ * @name: table name
+ *
+ * Declares a linker table entry to be used on init for data
+ */
+#define DECLARE_LINKTABLE_INIT_DATA(type, name) \
+ extern type name[], name##__end[];
+
+
+/**
+ * DOC: Defining Linker tables
+ *
+ * Linker tables are defined in the code that takes ownership over
+ * the linker table. This is typically done in the same code that is in
+ * charge of iterating over the linker table as well.
+ */
+
+/**
+ * DEFINE_LINKTABLE_TEXT - Defines a linker table for execution
+ *
+ * @type: data type
+ * @name: table name
+ *
+ * Defines a linker table which used for execution.
+ */
+#define DEFINE_LINKTABLE_TEXT(type, name) \
+ DECLARE_LINKTABLE_TEXT(type, name); \
+ LINKTABLE_TEXT_WEAK(name, ) VMLINUX_SYMBOL(name)[0] = {}; \
+ LTO_REFERENCE_INITCALL(name); \
+ LINKTABLE_TEXT(name, ~) VMLINUX_SYMBOL(name##__end)[0] = {};\
+ LTO_REFERENCE_INITCALL(name##__end);
+
+/**
+ * DEFINE_LINKTABLE_DATA - Defines a linker table for data
+ *
+ * @type: data type
+ * @name: table name
+ *
+ * Defines a linker table which used for data.
+ */
+#define DEFINE_LINKTABLE_DATA(type, name) \
+ DECLARE_LINKTABLE_DATA(type, name); \
+ LINKTABLE_DATA_WEAK(name, ) VMLINUX_SYMBOL(name)[0] = {}; \
+ LTO_REFERENCE_INITCALL(name); \
+ LINKTABLE_DATA(name, ~) VMLINUX_SYMBOL(name##__end)[0] = {};\
+ LTO_REFERENCE_INITCALL(name##__end);
+
+/**
+ * DEFINE_LINKTABLE_RO - Defines a read-only linker table
+ *
+ * @type: data type
+ * @name: table name
+ *
+ * Defines a linker table which we know only requires read-only access.
+ */
+#define DEFINE_LINKTABLE_RO(type, name) \
+ DECLARE_LINKTABLE_RO(type, name); \
+ LINKTABLE_RO_WEAK(name, ) VMLINUX_SYMBOL(name)[0] = {}; \
+ LTO_REFERENCE_INITCALL(name); \
+ LINKTABLE_RO(name, ~) VMLINUX_SYMBOL(name##__end)[0] = {}; \
+ LTO_REFERENCE_INITCALL(name##__end);
+
+/**
+ * DEFINE_LINKTABLE_INIT - Defines an init time linker table for execution
+ *
+ * @type: data type
+ * @name: table name
+ *
+ * Defines a linker table. If you are adding a new type you should
+ * enable CONFIG_DEBUG_SECTION_MISMATCH and ensure routines that make
+ * use of the linker tables get a respective __ref tag.
+ */
+#define DEFINE_LINKTABLE_INIT(type, name) \
+ DECLARE_LINKTABLE_INIT(type, name); \
+ LINKTABLE_INIT_WEAK(name, ) VMLINUX_SYMBOL(name)[0] = {}; \
+ LTO_REFERENCE_INITCALL(name); \
+ LINKTABLE_INIT(name, ~) VMLINUX_SYMBOL(name##__end)[0] = {}; \
+ LTO_REFERENCE_INITCALL(name##__end);
+
+/**
+ * DEFINE_LINKTABLE_INIT_DATA - Defines an init time linker table for data
+ *
+ * @type: data type
+ * @name: table name
+ *
+ * Defines a linker table for init data. If you are adding a new type you
+ * should enable CONFIG_DEBUG_SECTION_MISMATCH and ensure routines that make
+ * use of the linker tables get a respective __ref tag.
+ */
+#define DEFINE_LINKTABLE_INIT_DATA(type, name) \
+ DECLARE_LINKTABLE_INIT_DATA(type, name); \
+ LINKTABLE_INIT_DATA_WEAK(name, ) VMLINUX_SYMBOL(name)[0] = {}; \
+ LTO_REFERENCE_INITCALL(name); \
+ LINKTABLE_INIT_DATA(name, ~) VMLINUX_SYMBOL(name##__end)[0] = {}; \
+ LTO_REFERENCE_INITCALL(name##__end);
+
+/**
+ * DOC: Iterating over Linker tables
+ *
+ * To make use of the linker tables you want to be able to iterate over
+ * them. This section documents the different iterators available.
+ */
+
+/**
+ * LINKTABLE_FOR_EACH - iterate through all entries within a linker table
+ *
+ * @pointer: entry pointer
+ * @tbl: linker table
+ *
+ * Example usage:
+ *
+ * struct frobnicator *frob;
+ *
+ * LINKTABLE_FOR_EACH(frob, frobnicator_fns) {
+ * ...
+ * }
+ */
+#define LINKTABLE_FOR_EACH(pointer, tbl) \
+ for (pointer = LINKTABLE_START(tbl); \
+ pointer < LINKTABLE_END(tbl); \
+ pointer++)
+
+/**
+ * LINKTABLE_RUN_ALL - iterate and run through all entries on a linker table
+ *
+ * @tbl: linker table
+ * @func: structure name for the function name we want to call.
+ * @args...: arguments to pass to func
+ *
+ * Example usage:
+ *
+ * LINKTABLE_RUN_ALL(frobnicator_fns, some_run,);
+ */
+#define LINKTABLE_RUN_ALL(tbl, func, args...) \
+do { \
+ size_t i; \
+ for (i = 0; i < LINKTABLE_SIZE(tbl); i++) \
+ (tbl[i]).func (args); \
+} while (0);
+
+/**
+ * LINKTABLE_RUN_ERR - run each linker table entry func and return error if any
+ *
+ * @tbl: linker table
+ * @func: structure name for the function name we want to call.
+ * @args...: arguments to pass to func
+ *
+ * Example usage:
+ *
+ * unsigned int err = LINKTABLE_RUN_ERR(frobnicator_fns, some_run,);
+ */
+#define LINKTABLE_RUN_ERR(tbl, func, args...) \
+({ \
+ size_t i; \
+ int err = 0; \
+ for (i = 0; !err && i < LINKTABLE_SIZE(tbl); i++) \
+ err = (tbl[i]).func (args); \
+ err; \
+})
+
+#endif /* _LINUX_LINKER_TABLES_H */
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 2c47f9c305aa..33720528edaf 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -91,7 +91,7 @@ modorder-target := $(obj)/modules.order
# We keep a list of all modules in $(MODVERDIR)
-__build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
+__build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y) $(table-y)) \
$(if $(KBUILD_MODULES),$(obj-m) $(modorder-target)) \
$(subdir-ym) $(always)
@:
@@ -294,7 +294,7 @@ $(obj)/%.o: $(src)/%.S FORCE
$(call if_changed_dep,as_o_S)
targets += $(real-objs-y) $(real-objs-m) $(lib-y)
-targets += $(extra-y) $(MAKECMDGOALS) $(always)
+targets += $(extra-y) $(table-y) $(MAKECMDGOALS) $(always)
# Linker scripts preprocessor (.lds.S -> .lds)
# ---------------------------------------------------------------------------
diff --git a/scripts/Makefile.clean b/scripts/Makefile.clean
index 55c96cb8070f..0af1e12c9749 100644
--- a/scripts/Makefile.clean
+++ b/scripts/Makefile.clean
@@ -36,6 +36,7 @@ subdir-ymn := $(addprefix $(obj)/,$(subdir-ymn))
# directory
__clean-files := $(extra-y) $(extra-m) $(extra-) \
+ $(table-y) $(table-m) $(table-) \
$(always) $(targets) $(clean-files) \
$(host-progs) \
$(hostprogs-y) $(hostprogs-m) $(hostprogs-)
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 2edbcadb3d7f..5c71d1b0631a 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -12,6 +12,16 @@ export KBUILD_SUBDIR_CCFLAGS := $(KBUILD_SUBDIR_CCFLAGS) $(subdir-ccflags-y)
# Figure out what we need to build from the various variables
# ===========================================================================
+# Linker tables objects always wish to be built to avoid bit-rot in
+# code, but only linked in *iff* they were enabled. We accomplish this
+# using pegging linker table objects into extra-y, which forces
+# compilation and then using the respective table-y and table-m as
+# as hints for things we do want enabled. Objects which we want to
+# avoid linking in will be in table-, not table-y and table-m.
+extra-y += $(table-)
+obj-m += $(table-m)
+obj-y += $(table-y)
+
# When an object is listed to be built compiled-in and modular,
# only build the compiled-in version
@@ -72,6 +82,8 @@ real-objs-m := $(foreach m, $(obj-m), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y)
# Add subdir path
extra-y := $(addprefix $(obj)/,$(extra-y))
+table-y := $(addprefix $(obj)/,$(table-y))
+table-m := $(addprefix $(obj)/,$(table-m))
always := $(addprefix $(obj)/,$(always))
targets := $(addprefix $(obj)/,$(targets))
modorder := $(addprefix $(obj)/,$(modorder))
diff --git a/tools/include/linux/sections.h b/tools/include/linux/sections.h
new file mode 100644
index 000000000000..cc6f07f11583
--- /dev/null
+++ b/tools/include/linux/sections.h
@@ -0,0 +1,13 @@
+#ifndef _TOOLS_LINUX_SECTIONS_H_
+
+/* Mostly a copy of what we need only */
+
+#define SECTION_INIT .init.text
+#define SECTION_RODATA .rodata
+
+#define ___SECTION_TBL_STR(section, name) \
+ #section ".tbl." #name
+#define SECTION_TBL_ALL_STR(section) \
+ ___SECTION_TBL_STR(section, *)
+
+#endif /* _TOOLS_LINUX_SECTIONS_H_ */
--
2.7.0
^ permalink raw reply related [flat|nested] 46+ messages in thread* Re: [RFC v2 2/7] tables.h: add linker table support
2016-02-19 13:45 ` [RFC v2 2/7] tables.h: add linker table support Luis R. Rodriguez
@ 2016-02-19 20:25 ` H. Peter Anvin
2016-02-19 21:48 ` Luis R. Rodriguez
2016-02-19 20:33 ` H. Peter Anvin
1 sibling, 1 reply; 46+ messages in thread
From: H. Peter Anvin @ 2016-02-19 20:25 UTC (permalink / raw)
To: Luis R. Rodriguez, tglx, mingo, bp
Cc: benh, ming.lei, masami.hiramatsu.pt, linux-arch, xen-devel,
linux, x86, anil.s.keshavamurthy, arnd, rusty, jbaron,
boris.ostrovsky, andriy.shevchenko, mcb30, jgross, ananth,
gregkh, linux-kernel, luto, david.vrabel, dwmw2, davem
On 02/19/2016 05:45 AM, Luis R. Rodriguez wrote:
> +
> +/**
> + * DOC: Regular linker linker table constructors
> + *
> + * Regular constructors are expected to be used for valid linker table entries.
> + * Valid uses of weak entries other than the beginning and is currently
> + * untested but should in theory work.
> + */
> +
> +/**
> + * LINKTABLE_TEXT - Declares a linker table entry for execution
> + *
> + * @name: linker table name
> + * @level: order level
> + *
> + * Declares a linker table to be used for execution.
> + */
> +#define LINKTABLE_TEXT(name, level) \
> + __typeof__(name[0]) \
> + __attribute__((used, \
> + __aligned__(LINKTABLE_ALIGNMENT(name)), \
> + section(SECTION_TBL(SECTION_TEXT, name, level))))
I'm really confused by this. Text should obviously be readonly, but I'm
not at all clear how this works here.
The issue with linktables for text is kind of confusing if nothing else;
Russel is right about that. It doesn't prevent us from doing something
similar, but perhaps it ought to have a different name.
For one thing, priority level is meaningless for text, since it is not a
table that can be indexed into.
-hpa
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 2/7] tables.h: add linker table support
2016-02-19 20:25 ` H. Peter Anvin
@ 2016-02-19 21:48 ` Luis R. Rodriguez
2016-02-23 23:08 ` Luis R. Rodriguez
0 siblings, 1 reply; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-19 21:48 UTC (permalink / raw)
To: H. Peter Anvin
Cc: Luis R. Rodriguez, tglx, mingo, bp, x86, linux-kernel, luto,
boris.ostrovsky, rusty, david.vrabel, konrad.wilk, mcb30, jgross,
ming.lei, gregkh, arnd, linux-arch, linux, benh, jbaron, ananth,
anil.s.keshavamurthy, davem, masami.hiramatsu.pt,
andriy.shevchenko, dwmw2, xen-devel
On Fri, Feb 19, 2016 at 12:25:55PM -0800, H. Peter Anvin wrote:
> On 02/19/2016 05:45 AM, Luis R. Rodriguez wrote:
> > +
> > +/**
> > + * DOC: Regular linker linker table constructors
> > + *
> > + * Regular constructors are expected to be used for valid linker table entries.
> > + * Valid uses of weak entries other than the beginning and is currently
> > + * untested but should in theory work.
> > + */
> > +
> > +/**
> > + * LINKTABLE_TEXT - Declares a linker table entry for execution
> > + *
> > + * @name: linker table name
> > + * @level: order level
> > + *
> > + * Declares a linker table to be used for execution.
> > + */
> > +#define LINKTABLE_TEXT(name, level) \
> > + __typeof__(name[0]) \
> > + __attribute__((used, \
> > + __aligned__(LINKTABLE_ALIGNMENT(name)), \
> > + section(SECTION_TBL(SECTION_TEXT, name, level))))
>
> I'm really confused by this. Text should obviously be readonly,
So this uses SECTION_TEXT, so we just pegged the linker table entry right below
the standard SECTION_TEXT:
@@ -422,7 +426,8 @@
* during second ld run in second ld pass when generating System.map */
#define TEXT_TEXT \
ALIGN_FUNCTION(); \
- *(.text.hot .text .text.fixup .text.unlikely) \
+ *(.text.hot SECTION_TEXT .text.fixup .text.unlikely) \
+ *(SORT(SECTION_TBL_ALL(SECTION_TEXT))) \
*(.ref.text) \
MEM_KEEP(init.text) \
MEM_KEEP(exit.text)
So this gets folded under TEXT_TEXT and we don't see to force all
architectures for this to be read-only specifically. I can't be sure
if it is always read-only for all architectures based on a cursory
review.
> but I'm not at all clear how this works here.
Its simply trying to piggy back on top of where the standard section
it is using so in this case SECTION_TEXT (.text). What attributes are
part of that follow.
> The issue with linktables for text is kind of confusing if nothing else;
> Russel is right about that. It doesn't prevent us from doing something
> similar, but perhaps it ought to have a different name.
Any recommendations?
> For one thing, priority level is meaningless for text, since it is not a
> table that can be indexed into.
Ah right, there is no structure so we can't foo->in, let alone, know what
arguments to pass... the order level certainly would still kick in but
I agree that it would seem kind of pointless as something else would
have to know how to use it. I could simply remove the iterator and
order-level for SECTION_TEXT linker tables if we are sure we can't use it.
The only gain then here would be that of saving custom linker script
changes and having a unified way to represent the attributes.
If order is desired a structured data would would make more sense and
I could document / recommend that, however I don't yet have a ported
use case in mind yet, any ideas? The use case I have that follows
similar logic is for the x86 init stuff which I am sending separately
and that's a new use case though. It uses SECTION_INIT (.init.text)
and that allows for both use of structuralized data + callbacks we
can execute. It was not clear to me what section to use for this sort
of stuff for non init stuff, and I can envision people highly wanting
to use this to help clean up init paths on code, what sectoin
should be used in those cases?
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread* Re: [RFC v2 2/7] tables.h: add linker table support
2016-02-19 21:48 ` Luis R. Rodriguez
@ 2016-02-23 23:08 ` Luis R. Rodriguez
2016-02-23 23:22 ` H. Peter Anvin
0 siblings, 1 reply; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-23 23:08 UTC (permalink / raw)
To: H. Peter Anvin
Cc: Luis R. Rodriguez, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
X86 ML, linux-kernel, Andy Lutomirski, Boris Ostrovsky,
Rusty Russell, David Vrabel, Konrad Rzeszutek Wilk,
Michael Brown, Juergen Gross, Ming Lei, Greg Kroah-Hartman,
Arnd Bergmann, linux-arch, Russell King, Benjamin Herrenschmidt,
jbaron, ananth, anil.s.keshavamurthy, David Miller,
Masami Hiramatsu
On Fri, Feb 19, 2016 at 1:48 PM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> On Fri, Feb 19, 2016 at 12:25:55PM -0800, H. Peter Anvin wrote:
>> On 02/19/2016 05:45 AM, Luis R. Rodriguez wrote:
>> > +
>> > +/**
>> > + * DOC: Regular linker linker table constructors
>> > + *
>> > + * Regular constructors are expected to be used for valid linker table entries.
>> > + * Valid uses of weak entries other than the beginning and is currently
>> > + * untested but should in theory work.
>> > + */
>> > +
>> > +/**
>> > + * LINKTABLE_TEXT - Declares a linker table entry for execution
>> > + *
>> > + * @name: linker table name
>> > + * @level: order level
>> > + *
>> > + * Declares a linker table to be used for execution.
>> > + */
>> > +#define LINKTABLE_TEXT(name, level) \
>> > + __typeof__(name[0]) \
>> > + __attribute__((used, \
>> > + __aligned__(LINKTABLE_ALIGNMENT(name)), \
>> > + section(SECTION_TBL(SECTION_TEXT, name, level))))
>>
>> I'm really confused by this. Text should obviously be readonly,
>
> So this uses SECTION_TEXT, so we just pegged the linker table entry right below
> the standard SECTION_TEXT:
OK yes I see the issue now. I've modified this to use const, and
retested the kprobe patch and it works well still. kprobe would not
use LINKTABLE_TEXT, instead it uses its own macro, however users of
LINKTABLE_TEXT would then have const declared. The implications are
that you *can* declare structs so long as everything is const.
Folks may at times need to modify the structural definitions -- for
that LINKTABLE_DATA() is more appropriate, and as per my testing it
still allows execution of callbacks. I can document this.
Do we want .init.text to match this? I'd port my "struct x86_init_fn"
to use LINKTABLE_INIT_DATA() then. FWIW below is a paste of a simple
test program that demos what I mean.
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/workqueue.h>
#include <linux/tables.h>
static void stuff_todo(struct work_struct *work);
static DECLARE_WORK(stuff_work, stuff_todo);
struct stuff {
int a;
int b;
void (*print_a)(struct stuff *);
void (*print_b)(struct stuff *);
void (*print_a_ro)(const struct stuff *);
void (*print_b_ro)(const struct stuff *);
};
void print_a(struct stuff *s)
{
pr_info("print_a a: %d\n", s->a);
}
void print_a_ro(const struct stuff *s)
{
pr_info("print_a a: %d\n", s->a);
}
void print_b(struct stuff *s)
{
pr_info("print_b b: %d\n", s->b);
}
void print_b_ro(const struct stuff *s)
{
pr_info("print_b b: %d\n", s->b);
}
DEFINE_LINKTABLE_TEXT(struct stuff, my_stuff_fns_ro);
DEFINE_LINKTABLE_DATA(struct stuff, my_stuff_fns);
static LINKTABLE_TEXT(my_stuff_fns_ro, 0000) stuff_a_ro = {
.a = 1,
.b = 1,
.print_a_ro = print_a_ro,
.print_b_ro = print_b_ro,
};
static LINKTABLE_TEXT(my_stuff_fns_ro, 0000) stuff_b_ro = {
.a = 2,
.b = 2,
.print_a_ro = print_a_ro,
.print_b_ro = print_b_ro,
};
static LINKTABLE_TEXT(my_stuff_fns_ro, 0000) stuff_c_ro = {
.a = 3,
.b = 3,
.print_a_ro = print_a_ro,
.print_b_ro = print_b_ro,
};
static LINKTABLE_DATA(my_stuff_fns, 0000) stuff_a = {
.a = 1,
.b = 1,
.print_a = print_a,
.print_b = print_b,
};
static LINKTABLE_DATA(my_stuff_fns, 0000) stuff_b = {
.a = 2,
.b = 2,
.print_a = print_a,
.print_b = print_b,
};
static void stuff_todo(struct work_struct *work)
{
struct stuff *s;
const struct stuff *s_ro;
unsigned int i = 0;
pr_info("Looping over my_stuff_fns_ro\n");
LINKTABLE_FOR_EACH(s_ro, my_stuff_fns_ro) {
pr_info("Looping on s ro %d\n", i++);
s_ro->print_a_ro(s_ro);
s_ro->print_b_ro(s_ro);
}
i=0;
pr_info("Looping over my_stuff_fns\n");
LINKTABLE_FOR_EACH(s, my_stuff_fns) {
pr_info("Looping on s %d\n", i++);
s->print_a(s);
s->print_b(s);
}
i=0;
pr_info("Looping over my_stuff_fns and creating modifications\n");
LINKTABLE_FOR_EACH(s, my_stuff_fns) {
s->a = 10;
s->b = 10;
s->print_a(s);
s->print_b(s);
}
}
static int __init stuff_init(void)
{
/* get out of __init context */
schedule_work(&stuff_work);
return 0;
}
static void __exit stuff_exit(void)
{
cancel_work_sync(&stuff_work);
}
module_init(stuff_init)
module_exit(stuff_exit)
MODULE_LICENSE("GPL");
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread* Re: [RFC v2 2/7] tables.h: add linker table support
2016-02-23 23:08 ` Luis R. Rodriguez
@ 2016-02-23 23:22 ` H. Peter Anvin
2016-02-23 23:36 ` Luis R. Rodriguez
0 siblings, 1 reply; 46+ messages in thread
From: H. Peter Anvin @ 2016-02-23 23:22 UTC (permalink / raw)
To: Luis R. Rodriguez
Cc: Thomas Gleixner, Ingo Molnar, Borislav Petkov, X86 ML,
linux-kernel, Andy Lutomirski, Boris Ostrovsky, Rusty Russell,
David Vrabel, Konrad Rzeszutek Wilk, Michael Brown,
Juergen Gross, Ming Lei, Greg Kroah-Hartman, Arnd Bergmann,
linux-arch, Russell King, Benjamin Herrenschmidt, jbaron, ananth,
anil.s.keshavamurthy, David Miller, Masami Hiramatsu,
andriy.shevchenko
On 02/23/2016 03:08 PM, Luis R. Rodriguez wrote:
>
> OK yes I see the issue now. I've modified this to use const, and
> retested the kprobe patch and it works well still. kprobe would not
> use LINKTABLE_TEXT, instead it uses its own macro, however users of
> LINKTABLE_TEXT would then have const declared. The implications are
> that you *can* declare structs so long as everything is const.
>
No, such structures belong in .rodata not in .text.
I have been thinking about it somewhat, and for text we really have text
"ranges" rather than tables. The big difference between the two are:
1. priority ordering doesn't make any sense for ranges.
2. ranges can be hierarchial, that is, range "bar" can be entirely
inside range "foo".
3. ranges aren't typed (although in C, that pretty much means they are
"char" or "unsigned char" as there really isn't any way to define an
"array of void".)
4. the only useful operator on a range is "is address X inside this
range"; this operator is likely *not* useful for a table, since
if you have to ever invoke it you are probably doing something very
wrong.
For this to work, we need strings such that they will always sort in the
appropriate order with the bracket symbols around subranges. I need to
think about this a few minutes before I actually say anything about it...
-hpa
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 2/7] tables.h: add linker table support
2016-02-23 23:22 ` H. Peter Anvin
@ 2016-02-23 23:36 ` Luis R. Rodriguez
2016-02-24 0:06 ` H. Peter Anvin
0 siblings, 1 reply; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-23 23:36 UTC (permalink / raw)
To: H. Peter Anvin
Cc: Thomas Gleixner, Ingo Molnar, Borislav Petkov, X86 ML,
linux-kernel, Andy Lutomirski, Boris Ostrovsky, Rusty Russell,
David Vrabel, Konrad Rzeszutek Wilk, Michael Brown,
Juergen Gross, Ming Lei, Greg Kroah-Hartman, Arnd Bergmann,
linux-arch, Russell King, Benjamin Herrenschmidt, jbaron, ananth,
anil.s.keshavamurthy, David Miller, Masami Hiramatsu,
andriy.shevchenko
On Tue, Feb 23, 2016 at 3:22 PM, H. Peter Anvin <hpa@zytor.com> wrote:
> On 02/23/2016 03:08 PM, Luis R. Rodriguez wrote:
>>
>> OK yes I see the issue now. I've modified this to use const, and
>> retested the kprobe patch and it works well still. kprobe would not
>> use LINKTABLE_TEXT, instead it uses its own macro, however users of
>> LINKTABLE_TEXT would then have const declared. The implications are
>> that you *can* declare structs so long as everything is const.
>>
>
> No, such structures belong in .rodata not in .text.
>
> I have been thinking about it somewhat, and for text we really have text
> "ranges" rather than tables. The big difference between the two are:
>
> 1. priority ordering doesn't make any sense for ranges.
I considered the possibility perhaps we want to just split out a
series of initial basic macros that enables *only* such basic
functionality and declarations, and linker tables would then build on
top of these. I think that ma help here.
> 2. ranges can be hierarchial, that is, range "bar" can be entirely
> inside range "foo".
We'd want to enable this without having to modify the linker script
further -- I thought about how such things might be possible but not
for this case but rather, for the case where in linker tables a
developer may wish to get range addresses for a specific order level.
Although separate, the problem seems similar. At least in theory I was
convinced I had a solution to the order level problem, perhaps it may
suffice for this too:
When and if you need an intermediary set of range addresses you then
also declare another set of extern pointers, similar in nature with
the empty string and ~ ending delimiter, we just move one notch in.
SORT() will take care of ordering things for us, but the issue here is
the empty string doesn't allow hierarchies so perhaps to enable that
we may need another beginning delimiter that would enable recursive
hierarchies. If this seems to at least in theory make sense I can give
it a shot through a simple proof of concept and see if it works.
> 3. ranges aren't typed (although in C, that pretty much means they are
> "char" or "unsigned char" as there really isn't any way to define an
> "array of void".)
Sure. kprobe is a good example.
> 4. the only useful operator on a range is "is address X inside this
> range"; this operator is likely *not* useful for a table, since
> if you have to ever invoke it you are probably doing something very
> wrong.
kprobe uses it :P
> For this to work, we need strings such that they will always sort in the
> appropriate order with the bracket symbols around subranges. I need to
> think about this a few minutes before I actually say anything about it...
Ah seems we're in the same line of thought ?
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 2/7] tables.h: add linker table support
2016-02-23 23:36 ` Luis R. Rodriguez
@ 2016-02-24 0:06 ` H. Peter Anvin
2016-02-24 0:54 ` Luis R. Rodriguez
0 siblings, 1 reply; 46+ messages in thread
From: H. Peter Anvin @ 2016-02-24 0:06 UTC (permalink / raw)
To: Luis R. Rodriguez
Cc: Thomas Gleixner, Ingo Molnar, Borislav Petkov, X86 ML,
linux-kernel, Andy Lutomirski, Boris Ostrovsky, Rusty Russell,
David Vrabel, Konrad Rzeszutek Wilk, Michael Brown,
Juergen Gross, Ming Lei, Greg Kroah-Hartman, Arnd Bergmann,
linux-arch, Russell King, Benjamin Herrenschmidt, jbaron, ananth,
anil.s.keshavamurthy, David Miller, Masami Hiramatsu,
andriy.shevchenko
On 02/23/2016 03:36 PM, Luis R. Rodriguez wrote:
>
>> 4. the only useful operator on a range is "is address X inside this
>> range"; this operator is likely *not* useful for a table, since
>> if you have to ever invoke it you are probably doing something very
>> wrong.
>
> kprobe uses it :P
>
Could you explain how?
-hpa
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 2/7] tables.h: add linker table support
2016-02-24 0:06 ` H. Peter Anvin
@ 2016-02-24 0:54 ` Luis R. Rodriguez
0 siblings, 0 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-24 0:54 UTC (permalink / raw)
To: H. Peter Anvin
Cc: Luis R. Rodriguez, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
X86 ML, linux-kernel, Andy Lutomirski, Boris Ostrovsky,
Rusty Russell, David Vrabel, Konrad Rzeszutek Wilk,
Michael Brown, Juergen Gross, Ming Lei, Greg Kroah-Hartman,
Arnd Bergmann, linux-arch, Russell King, Benjamin Herrenschmidt,
jbaron, ananth, anil.s.keshavamurthy, David Miller,
Masami Hiramatsu
On Tue, Feb 23, 2016 at 04:06:55PM -0800, H. Peter Anvin wrote:
> On 02/23/2016 03:36 PM, Luis R. Rodriguez wrote:
> >
> >> 4. the only useful operator on a range is "is address X inside this
> >> range"; this operator is likely *not* useful for a table, since
^^^^^^^^^^^^
> >> if you have to ever invoke it you are probably doing something very
> >> wrong.
> >
> > kprobe uses it :P
> >
>
> Could you explain how?
Sorry I misread this as "unless you are a table", kprobes has two
ranges, one is a table (blacklist) and the other just a range
(for kprobes); only kprobes uses "address inside this range",
as reflected below. So I agree with you.
index d10ab6b9b5e0..d816c659f358 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1328,8 +1328,7 @@ out:
bool __weak arch_within_kprobe_blacklist(unsigned long addr)
{
/* The __kprobes marked functions and entry code must not be probed */
- return addr >= (unsigned long)__kprobes_text_start &&
- addr < (unsigned long)__kprobes_text_end;
+ return LINKTABLE_ADDR_WITHIN(kprobes, addr);
}
bool within_kprobe_blacklist(unsigned long addr)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index d10ab6b9b5e0..d816c659f358 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1328,8 +1328,7 @@ out:
bool __weak arch_within_kprobe_blacklist(unsigned long addr)
{
/* The __kprobes marked functions and entry code must not be probed */
- return addr >= (unsigned long)__kprobes_text_start &&
- addr < (unsigned long)__kprobes_text_end;
+ return LINKTABLE_ADDR_WITHIN(kprobes, addr);
}
What about rebranding general section primitives under section.h
#define DECLARE_SECTION_TEXT_TYPE(type, name) \
extern const type name[], name##__end[];
#define DECLARE_SECTION_TEXT(name) \
DECLARE_SECTION_TEXT_TYPE(char, name)
Then tables.h would use the TYPE version:
#define DECLARE_LINKTABLE_TEXT(type, name) \
DECLARE_SECTION_TEXT_TYPE(type, name)
Since I've been making _TEXT the implicit type for section names(SECTION_INIT
is .init.text) the above could just be DECLARE_SECTION_TYPE() and DECLARE_SECTION()
for text if we prefer.
Luis
^ permalink raw reply related [flat|nested] 46+ messages in thread
* Re: [RFC v2 2/7] tables.h: add linker table support
2016-02-19 13:45 ` [RFC v2 2/7] tables.h: add linker table support Luis R. Rodriguez
2016-02-19 20:25 ` H. Peter Anvin
@ 2016-02-19 20:33 ` H. Peter Anvin
2016-02-19 21:12 ` Luis R. Rodriguez
1 sibling, 1 reply; 46+ messages in thread
From: H. Peter Anvin @ 2016-02-19 20:33 UTC (permalink / raw)
To: Luis R. Rodriguez, tglx, mingo, bp
Cc: x86, linux-kernel, luto, boris.ostrovsky, rusty, david.vrabel,
konrad.wilk, mcb30, jgross, ming.lei, gregkh, arnd, linux-arch,
linux, benh, jbaron, ananth, anil.s.keshavamurthy, davem,
masami.hiramatsu.pt, andriy.shevchenko, dwmw2, xen-devel
On 02/19/2016 05:45 AM, Luis R. Rodriguez wrote:
> +/**
> + * LINKTABLE_RUN_ERR - run each linker table entry func and return error if any
> + *
> + * @tbl: linker table
> + * @func: structure name for the function name we want to call.
> + * @args...: arguments to pass to func
> + *
> + * Example usage:
> + *
> + * unsigned int err = LINKTABLE_RUN_ERR(frobnicator_fns, some_run,);
> + */
> +#define LINKTABLE_RUN_ERR(tbl, func, args...) \
> +({ \
> + size_t i; \
> + int err = 0; \
> + for (i = 0; !err && i < LINKTABLE_SIZE(tbl); i++) \
> + err = (tbl[i]).func (args); \
> + err; \
> +})
This is wrong and pointless. As written it returns the error code of
the last instance.
What I suggested for this macro was that we ought to exit the loop on error.
Furthermore:
1. Using an advancing pointer would make more sense than a counter.
2. .func doesn't make any sense -- it ought to be "func"; otherwise you
can't call into either a table containing pure function pointers,
nor into a field of table *pointed to* by the table; which is
likely to be quite common.
So the idea is to use something like:
/* Array of function pointers */
LINKTABLE_RUN_ALL(frobnicator_fns, , arg1, arg2);
/* Array of structures */
LINKTABLE_RUN_ALL(frobnicator_fns, .some_run, arg1, arg2);
/* Array of structure pointers */
LINKTABLE_RUN_ALL(frobnicator_fns, ->some_run, arg1, arg2);
^ permalink raw reply [flat|nested] 46+ messages in thread* Re: [RFC v2 2/7] tables.h: add linker table support
2016-02-19 20:33 ` H. Peter Anvin
@ 2016-02-19 21:12 ` Luis R. Rodriguez
0 siblings, 0 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-19 21:12 UTC (permalink / raw)
To: H. Peter Anvin
Cc: Luis R. Rodriguez, tglx, mingo, bp, x86, linux-kernel, luto,
boris.ostrovsky, rusty, david.vrabel, konrad.wilk, mcb30, jgross,
ming.lei, gregkh, arnd, linux-arch, linux, benh, jbaron, ananth,
anil.s.keshavamurthy, davem, masami.hiramatsu.pt,
andriy.shevchenko, dwmw2, xen-devel
On Fri, Feb 19, 2016 at 12:33:27PM -0800, H. Peter Anvin wrote:
> On 02/19/2016 05:45 AM, Luis R. Rodriguez wrote:
> > +/**
> > + * LINKTABLE_RUN_ERR - run each linker table entry func and return error if any
> > + *
> > + * @tbl: linker table
> > + * @func: structure name for the function name we want to call.
> > + * @args...: arguments to pass to func
> > + *
> > + * Example usage:
> > + *
> > + * unsigned int err = LINKTABLE_RUN_ERR(frobnicator_fns, some_run,);
> > + */
> > +#define LINKTABLE_RUN_ERR(tbl, func, args...) \
> > +({ \
> > + size_t i; \
> > + int err = 0; \
> > + for (i = 0; !err && i < LINKTABLE_SIZE(tbl); i++) \
> > + err = (tbl[i]).func (args); \
> > + err; \
> > +})
>
> This is wrong and pointless. As written it returns the error code of
> the last instance.
>
> What I suggested for this macro was that we ought to exit the loop on error.
>
> Furthermore:
>
> 1. Using an advancing pointer would make more sense than a counter.
OK I'll modify to use LINKTABLE_FOR_EACH and much cleaner and obvious
code to bail on error.
> 2. .func doesn't make any sense -- it ought to be "func"; otherwise you
> can't call into either a table containing pure function pointers,
> nor into a field of table *pointed to* by the table; which is
> likely to be quite common.
>
> So the idea is to use something like:
>
> /* Array of function pointers */
> LINKTABLE_RUN_ALL(frobnicator_fns, , arg1, arg2);
>
> /* Array of structures */
> LINKTABLE_RUN_ALL(frobnicator_fns, .some_run, arg1, arg2);
>
> /* Array of structure pointers */
> LINKTABLE_RUN_ALL(frobnicator_fns, ->some_run, arg1, arg2);
Ah that's sexy, thanks. Will amend.
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread
* [RFC v2 3/7] firmware: port built-in section to linker table
2016-02-19 13:45 [RFC v2 0/7] linux: add linker tables Luis R. Rodriguez
2016-02-19 13:45 ` [RFC v2 1/7] sections.h: add sections header to collect all section info Luis R. Rodriguez
2016-02-19 13:45 ` [RFC v2 2/7] tables.h: add linker table support Luis R. Rodriguez
@ 2016-02-19 13:45 ` Luis R. Rodriguez
2016-02-29 10:12 ` David Woodhouse
2016-02-19 13:45 ` [RFC v2 4/7] asm/sections: add a generic push_section_tbl() Luis R. Rodriguez
` (4 subsequent siblings)
7 siblings, 1 reply; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-19 13:45 UTC (permalink / raw)
To: hpa, tglx, mingo, bp
Cc: x86, linux-kernel, luto, boris.ostrovsky, rusty, david.vrabel,
konrad.wilk, mcb30, jgross, ming.lei, gregkh, arnd, linux-arch,
linux, benh, jbaron, ananth, anil.s.keshavamurthy, davem,
masami.hiramatsu.pt, andriy.shevchenko, dwmw2, xen-devel,
Luis R. Rodriguez
This ports built-in firmware to use linker tables,
this replaces the custom section solution with a
generic solution.
This also demos the use of the .rodata (SECTION_RO)
linker tables.
Tested with 0 built-in firmware, 1 and 2 built-in
firmwares successfully.
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
arch/x86/kernel/cpu/microcode/core.c | 7 +++----
drivers/base/firmware_class.c | 11 +++++------
firmware/Makefile | 2 +-
include/asm-generic/vmlinux.lds.h | 7 -------
4 files changed, 9 insertions(+), 18 deletions(-)
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index faec7120c508..7ee73cd64c95 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -99,15 +99,14 @@ static bool __init check_loader_disabled_bsp(void)
return *res;
}
-extern struct builtin_fw __start_builtin_fw[];
-extern struct builtin_fw __end_builtin_fw[];
+DECLARE_LINKTABLE_RO(struct builtin_fw, builtin_fw);
bool get_builtin_firmware(struct cpio_data *cd, const char *name)
{
#ifdef CONFIG_FW_LOADER
- struct builtin_fw *b_fw;
+ const struct builtin_fw *b_fw;
- for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++) {
+ LINKTABLE_FOR_EACH(b_fw, builtin_fw) {
if (!strcmp(name, b_fw->name)) {
cd->size = b_fw->size;
cd->data = b_fw->data;
diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index b9250e564ebf..50b9cf3d0294 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -42,14 +42,13 @@ MODULE_LICENSE("GPL");
#ifdef CONFIG_FW_LOADER
-extern struct builtin_fw __start_builtin_fw[];
-extern struct builtin_fw __end_builtin_fw[];
+DEFINE_LINKTABLE_RO(struct builtin_fw, builtin_fw);
static bool fw_get_builtin_firmware(struct firmware *fw, const char *name)
{
- struct builtin_fw *b_fw;
+ const struct builtin_fw *b_fw;
- for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++) {
+ LINKTABLE_FOR_EACH(b_fw, builtin_fw) {
if (strcmp(name, b_fw->name) == 0) {
fw->size = b_fw->size;
fw->data = b_fw->data;
@@ -62,9 +61,9 @@ static bool fw_get_builtin_firmware(struct firmware *fw, const char *name)
static bool fw_is_builtin_firmware(const struct firmware *fw)
{
- struct builtin_fw *b_fw;
+ const struct builtin_fw *b_fw;
- for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++)
+ LINKTABLE_FOR_EACH(b_fw, builtin_fw)
if (fw->data == b_fw->data)
return true;
diff --git a/firmware/Makefile b/firmware/Makefile
index e297e1b52636..e13549362577 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -164,7 +164,7 @@ quiet_cmd_fwbin = MK_FW $@
echo " .p2align $${ASM_ALIGN}" >>$@;\
echo "_fw_$${FWSTR}_name:" >>$@;\
echo " .string \"$$FWNAME\"" >>$@;\
- echo " .section .builtin_fw,\"a\",$${PROGBITS}" >>$@;\
+ echo " .section .rodata.tbl.builtin_fw.all,\"a\",$${PROGBITS}" >>$@;\
echo " .p2align $${ASM_ALIGN}" >>$@;\
echo " $${ASM_WORD} _fw_$${FWSTR}_name" >>$@;\
echo " $${ASM_WORD} _fw_$${FWSTR}_bin" >>$@;\
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index eb23738ef4bd..91815fb1f2fa 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -302,13 +302,6 @@
VMLINUX_SYMBOL(__end_pci_fixups_suspend_late) = .; \
} \
\
- /* Built-in firmware blobs */ \
- .builtin_fw : AT(ADDR(.builtin_fw) - LOAD_OFFSET) { \
- VMLINUX_SYMBOL(__start_builtin_fw) = .; \
- *(.builtin_fw) \
- VMLINUX_SYMBOL(__end_builtin_fw) = .; \
- } \
- \
TRACEDATA \
\
/* Kernel symbol table: Normal symbols */ \
--
2.7.0
^ permalink raw reply related [flat|nested] 46+ messages in thread* Re: [RFC v2 3/7] firmware: port built-in section to linker table
2016-02-19 13:45 ` [RFC v2 3/7] firmware: port built-in section to linker table Luis R. Rodriguez
@ 2016-02-29 10:12 ` David Woodhouse
2016-02-29 18:56 ` Luis R. Rodriguez
2016-03-01 16:10 ` James Bottomley
0 siblings, 2 replies; 46+ messages in thread
From: David Woodhouse @ 2016-02-29 10:12 UTC (permalink / raw)
To: Luis R. Rodriguez, hpa, tglx, mingo, bp
Cc: x86, linux-kernel, luto, boris.ostrovsky, rusty, david.vrabel,
konrad.wilk, mcb30, jgross, ming.lei, gregkh, arnd, linux-arch,
linux, benh, jbaron, ananth, anil.s.keshavamurthy, davem,
masami.hiramatsu.pt, andriy.shevchenko, xen-devel
[-- Attachment #1: Type: text/plain, Size: 584 bytes --]
On Fri, 2016-02-19 at 05:45 -0800, Luis R. Rodriguez wrote:
> This ports built-in firmware to use linker tables,
> this replaces the custom section solution with a
> generic solution.
>
> This also demos the use of the .rodata (SECTION_RO)
> linker tables.
>
> Tested with 0 built-in firmware, 1 and 2 built-in
> firmwares successfully.
I think we'd do better to rip this support out entirely. It just isn't
needed; firmware can live in an initramfs and don't even need *any*
actual running userspace support to load it from there these days, do
we?
--
dwmw2
[-- Attachment #2: smime.p7s --]
[-- Type: application/x-pkcs7-signature, Size: 5691 bytes --]
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 3/7] firmware: port built-in section to linker table
2016-02-29 10:12 ` David Woodhouse
@ 2016-02-29 18:56 ` Luis R. Rodriguez
2016-05-02 18:34 ` Kees Cook
2016-03-01 16:10 ` James Bottomley
1 sibling, 1 reply; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-29 18:56 UTC (permalink / raw)
To: David Woodhouse
Cc: Luis R. Rodriguez, hpa, tglx, mingo, bp, x86, linux-kernel, luto,
boris.ostrovsky, rusty, david.vrabel, konrad.wilk, mcb30, jgross,
ming.lei, gregkh, arnd, linux-arch, linux, benh, jbaron, ananth,
anil.s.keshavamurthy, davem, masami.hiramatsu.pt,
andriy.shevchenko, xen-devel
On Mon, Feb 29, 2016 at 10:12:50AM +0000, David Woodhouse wrote:
> On Fri, 2016-02-19 at 05:45 -0800, Luis R. Rodriguez wrote:
> > This ports built-in firmware to use linker tables,
> > this replaces the custom section solution with a
> > generic solution.
> >
> > This also demos the use of the .rodata (SECTION_RO)
> > linker tables.
> >
> > Tested with 0 built-in firmware, 1 and 2 built-in
> > firmwares successfully.
>
> I think we'd do better to rip this support out entirely. It just isn't
> needed; firmware can live in an initramfs and don't even need *any*
> actual running userspace support to load it from there these days, do
> we?
I think this is reasonable if and only if we really don't know of anyone
out there not able to use initramfs. I'm happy to rip it out.
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 3/7] firmware: port built-in section to linker table
2016-02-29 18:56 ` Luis R. Rodriguez
@ 2016-05-02 18:34 ` Kees Cook
2016-05-02 18:41 ` Greg KH
2016-05-03 17:07 ` Luis R. Rodriguez
0 siblings, 2 replies; 46+ messages in thread
From: Kees Cook @ 2016-05-02 18:34 UTC (permalink / raw)
To: Luis R. Rodriguez
Cc: David Woodhouse, Luis R. Rodriguez, H. Peter Anvin,
Thomas Gleixner, Ingo Molnar, Borislav Petkov, x86, LKML,
Andy Lutomirski, Boris Ostrovsky, Rusty Russell, David Vrabel,
Konrad Rzeszutek Wilk, mcb30, jgross, Ming Lei, Greg KH,
Arnd Bergmann, linux-arch, Russell King - ARM Linux, benh,
jbaron, ananth, anil.s.keshavamurthy
On Mon, Feb 29, 2016 at 10:56 AM, Luis R. Rodriguez <mcgrof@suse.com> wrote:
> On Mon, Feb 29, 2016 at 10:12:50AM +0000, David Woodhouse wrote:
>> On Fri, 2016-02-19 at 05:45 -0800, Luis R. Rodriguez wrote:
>> > This ports built-in firmware to use linker tables,
>> > this replaces the custom section solution with a
>> > generic solution.
>> >
>> > This also demos the use of the .rodata (SECTION_RO)
>> > linker tables.
>> >
>> > Tested with 0 built-in firmware, 1 and 2 built-in
>> > firmwares successfully.
>>
>> I think we'd do better to rip this support out entirely. It just isn't
>> needed; firmware can live in an initramfs and don't even need *any*
>> actual running userspace support to load it from there these days, do
>> we?
>
> I think this is reasonable if and only if we really don't know of anyone
> out there not able to use initramfs. I'm happy to rip it out.
The changelog for this doesn't say anything about _why_ the change is
being made? (and what about other architectures.) Also, Chrome OS
doesn't use an initramfs (and plenty of other things don't too). Being
able to build monolithic kernels (e.g. Android and Brillo) with
builtin firmware is very handy. Please don't remove built-in firmware
support.
-Kees
--
Kees Cook
Chrome OS & Brillo Security
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 3/7] firmware: port built-in section to linker table
2016-05-02 18:34 ` Kees Cook
@ 2016-05-02 18:41 ` Greg KH
2016-05-03 17:08 ` Luis R. Rodriguez
2016-05-03 17:07 ` Luis R. Rodriguez
1 sibling, 1 reply; 46+ messages in thread
From: Greg KH @ 2016-05-02 18:41 UTC (permalink / raw)
To: Kees Cook
Cc: Luis R. Rodriguez, David Woodhouse, Luis R. Rodriguez,
H. Peter Anvin, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
x86, LKML, Andy Lutomirski, Boris Ostrovsky, Rusty Russell,
David Vrabel, Konrad Rzeszutek Wilk, mcb30, jgross, Ming Lei,
Arnd Bergmann, linux-arch, Russell King - ARM Linux, benh,
jbaron, ananth, anil.s.keshavamurthy
On Mon, May 02, 2016 at 11:34:33AM -0700, Kees Cook wrote:
> On Mon, Feb 29, 2016 at 10:56 AM, Luis R. Rodriguez <mcgrof@suse.com> wrote:
> > On Mon, Feb 29, 2016 at 10:12:50AM +0000, David Woodhouse wrote:
> >> On Fri, 2016-02-19 at 05:45 -0800, Luis R. Rodriguez wrote:
> >> > This ports built-in firmware to use linker tables,
> >> > this replaces the custom section solution with a
> >> > generic solution.
> >> >
> >> > This also demos the use of the .rodata (SECTION_RO)
> >> > linker tables.
> >> >
> >> > Tested with 0 built-in firmware, 1 and 2 built-in
> >> > firmwares successfully.
> >>
> >> I think we'd do better to rip this support out entirely. It just isn't
> >> needed; firmware can live in an initramfs and don't even need *any*
> >> actual running userspace support to load it from there these days, do
> >> we?
> >
> > I think this is reasonable if and only if we really don't know of anyone
> > out there not able to use initramfs. I'm happy to rip it out.
>
> The changelog for this doesn't say anything about _why_ the change is
> being made? (and what about other architectures.) Also, Chrome OS
> doesn't use an initramfs (and plenty of other things don't too). Being
> able to build monolithic kernels (e.g. Android and Brillo) with
> builtin firmware is very handy. Please don't remove built-in firmware
> support.
I second this, we can't break existing systems at all. I thought we
were going to keep built-in firmware, right Luis?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 3/7] firmware: port built-in section to linker table
2016-05-02 18:41 ` Greg KH
@ 2016-05-03 17:08 ` Luis R. Rodriguez
0 siblings, 0 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-05-03 17:08 UTC (permalink / raw)
To: Greg KH
Cc: Kees Cook, David Woodhouse, H. Peter Anvin, Thomas Gleixner,
Ingo Molnar, Borislav Petkov, x86, LKML, Andy Lutomirski,
Boris Ostrovsky, Rusty Russell, David Vrabel,
Konrad Rzeszutek Wilk, Michael Brown, Juergen Gross, Ming Lei,
Arnd Bergmann, linux-arch, Russell King - ARM Linux, benh,
jbaron, ananth, anil.s.keshavamurthy, David
On Mon, May 2, 2016 at 11:41 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
> On Mon, May 02, 2016 at 11:34:33AM -0700, Kees Cook wrote:
>> On Mon, Feb 29, 2016 at 10:56 AM, Luis R. Rodriguez <mcgrof@suse.com> wrote:
>> > On Mon, Feb 29, 2016 at 10:12:50AM +0000, David Woodhouse wrote:
>> >> On Fri, 2016-02-19 at 05:45 -0800, Luis R. Rodriguez wrote:
>> >> > This ports built-in firmware to use linker tables,
>> >> > this replaces the custom section solution with a
>> >> > generic solution.
>> >> >
>> >> > This also demos the use of the .rodata (SECTION_RO)
>> >> > linker tables.
>> >> >
>> >> > Tested with 0 built-in firmware, 1 and 2 built-in
>> >> > firmwares successfully.
>> >>
>> >> I think we'd do better to rip this support out entirely. It just isn't
>> >> needed; firmware can live in an initramfs and don't even need *any*
>> >> actual running userspace support to load it from there these days, do
>> >> we?
>> >
>> > I think this is reasonable if and only if we really don't know of anyone
>> > out there not able to use initramfs. I'm happy to rip it out.
>>
>> The changelog for this doesn't say anything about _why_ the change is
>> being made? (and what about other architectures.) Also, Chrome OS
>> doesn't use an initramfs (and plenty of other things don't too). Being
>> able to build monolithic kernels (e.g. Android and Brillo) with
>> builtin firmware is very handy. Please don't remove built-in firmware
>> support.
>
> I second this, we can't break existing systems at all. I thought we
> were going to keep built-in firmware, right Luis?
Removing built-in firmware was simply a suggestion by David which we
were evaluating here -- patches were not even yet produced, although I
have them now if we wanted to rip it out. Since Kees noted it has
users, we'll keep it.
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 3/7] firmware: port built-in section to linker table
2016-05-02 18:34 ` Kees Cook
2016-05-02 18:41 ` Greg KH
@ 2016-05-03 17:07 ` Luis R. Rodriguez
2016-05-03 17:10 ` Luis R. Rodriguez
1 sibling, 1 reply; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-05-03 17:07 UTC (permalink / raw)
To: Kees Cook
Cc: David Woodhouse, H. Peter Anvin, Thomas Gleixner, Ingo Molnar,
Borislav Petkov, x86, LKML, Andy Lutomirski, Boris Ostrovsky,
Rusty Russell, David Vrabel, Konrad Rzeszutek Wilk,
Michael Brown, Juergen Gross, Ming Lei, Greg KH, Arnd Bergmann,
linux-arch, Russell King - ARM Linux, benh, jbaron, ananth,
anil.s.keshavamurthy, David
On Mon, May 2, 2016 at 11:34 AM, Kees Cook <keescook@chromium.org> wrote:
> On Mon, Feb 29, 2016 at 10:56 AM, Luis R. Rodriguez <mcgrof@suse.com> wrote:
>> On Mon, Feb 29, 2016 at 10:12:50AM +0000, David Woodhouse wrote:
>>> On Fri, 2016-02-19 at 05:45 -0800, Luis R. Rodriguez wrote:
>>> > This ports built-in firmware to use linker tables,
>>> > this replaces the custom section solution with a
>>> > generic solution.
>>> >
>>> > This also demos the use of the .rodata (SECTION_RO)
>>> > linker tables.
>>> >
>>> > Tested with 0 built-in firmware, 1 and 2 built-in
>>> > firmwares successfully.
>>>
>>> I think we'd do better to rip this support out entirely. It just isn't
>>> needed; firmware can live in an initramfs and don't even need *any*
>>> actual running userspace support to load it from there these days, do
>>> we?
>>
>> I think this is reasonable if and only if we really don't know of anyone
>> out there not able to use initramfs. I'm happy to rip it out.
>
> The changelog for this doesn't say anything about _why_ the change is
> being made? (and what about other architectures.)
To be clear the RFC patch here is about linker table use and porting
custom table uses for a generic linker table solution. The topic of
conversation later changed to suggest that instead of porting built-in
firmware to linker tables we should just consider removing built-in
firmware all together. As for the reason _why_ we'd port built-in
firmware to linker tables, I'll be sure to add that in the next
iteration. The reason is that Linux has scattered strategies to both
extend and use custom linker sections, often requiring modifying the
custom linker script. The effort behind the linker script provides a
unified mechanism to do this, and also enables us to avoid having to
extend the custom linker script for this type of use.
> Also, Chrome OS
> doesn't use an initramfs (and plenty of other things don't too). Being
> able to build monolithic kernels (e.g. Android and Brillo) with
> builtin firmware is very handy. Please don't remove built-in firmware
> support.
Thanks! Can you confirm if any Android or Brillo builds are already using it?
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 3/7] firmware: port built-in section to linker table
2016-05-03 17:07 ` Luis R. Rodriguez
@ 2016-05-03 17:10 ` Luis R. Rodriguez
2016-05-03 17:11 ` Luis R. Rodriguez
` (2 more replies)
0 siblings, 3 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-05-03 17:10 UTC (permalink / raw)
To: Kees Cook
Cc: David Woodhouse, H. Peter Anvin, Thomas Gleixner, Ingo Molnar,
Borislav Petkov, x86, LKML, Andy Lutomirski, Boris Ostrovsky,
Rusty Russell, David Vrabel, Konrad Rzeszutek Wilk,
Michael Brown, Juergen Gross, Ming Lei, Greg KH, Arnd Bergmann,
linux-arch, Russell King - ARM Linux, benh, jbaron, ananth,
anil.s.keshavamurthy, David
On Tue, May 3, 2016 at 10:07 AM, Luis R. Rodriguez <mcgrof@suse.com> wrote:
> Thanks! Can you confirm if any Android or Brillo builds are already using it?
Also more importantly, any chance you can provide any technical
reasons why initramfs cannot be used, or it was decided to not use it
on these systems? It should help others in the future as well.
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread* Re: [RFC v2 3/7] firmware: port built-in section to linker table
2016-05-03 17:10 ` Luis R. Rodriguez
@ 2016-05-03 17:11 ` Luis R. Rodriguez
2016-05-03 17:21 ` Kees Cook
2016-05-03 18:12 ` Greg KH
2 siblings, 0 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-05-03 17:11 UTC (permalink / raw)
To: Kees Cook
Cc: David Woodhouse, H. Peter Anvin, Thomas Gleixner, Ingo Molnar,
Borislav Petkov, x86, LKML, Andy Lutomirski, Boris Ostrovsky,
Rusty Russell, David Vrabel, Konrad Rzeszutek Wilk,
Michael Brown, Juergen Gross, Ming Lei, Greg KH, Arnd Bergmann,
linux-arch, Russell King - ARM Linux, benh, jbaron, ananth,
anil.s.keshavamurthy, David
On Tue, May 3, 2016 at 10:10 AM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> or it was decided
Sorry I meant to say: 'or _why_ it was decided to not use initramfs on
these systems?'
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 3/7] firmware: port built-in section to linker table
2016-05-03 17:10 ` Luis R. Rodriguez
2016-05-03 17:11 ` Luis R. Rodriguez
@ 2016-05-03 17:21 ` Kees Cook
2016-05-03 18:12 ` Greg KH
2 siblings, 0 replies; 46+ messages in thread
From: Kees Cook @ 2016-05-03 17:21 UTC (permalink / raw)
To: Luis R. Rodriguez
Cc: David Woodhouse, H. Peter Anvin, Thomas Gleixner, Ingo Molnar,
Borislav Petkov, x86, LKML, Andy Lutomirski, Boris Ostrovsky,
Rusty Russell, David Vrabel, Konrad Rzeszutek Wilk,
Michael Brown, Juergen Gross, Ming Lei, Greg KH, Arnd Bergmann,
linux-arch, Russell King - ARM Linux, benh, jbaron, ananth,
anil.s.keshavamurthy, David
On Tue, May 3, 2016 at 10:10 AM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> On Tue, May 3, 2016 at 10:07 AM, Luis R. Rodriguez <mcgrof@suse.com> wrote:
>> Thanks! Can you confirm if any Android or Brillo builds are already using it?
>
> Also more importantly, any chance you can provide any technical
> reasons why initramfs cannot be used, or it was decided to not use it
> on these systems? It should help others in the future as well.
In Chrome OS, the kernels are built specifically for the hardware
they're going to be on, so an initramfs was seen as a needless
additional boot step. Since Chrome OS was heavily optimized for boot
speed, it was designed to not need the initramfs at all. This is
actually enforced by the read-only boot firmware, so there's no
trivial way to _start_ using an initramfs on (existing) Chrome OS
devices either.
-Kees
--
Kees Cook
Chrome OS & Brillo Security
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 3/7] firmware: port built-in section to linker table
2016-05-03 17:10 ` Luis R. Rodriguez
2016-05-03 17:11 ` Luis R. Rodriguez
2016-05-03 17:21 ` Kees Cook
@ 2016-05-03 18:12 ` Greg KH
2 siblings, 0 replies; 46+ messages in thread
From: Greg KH @ 2016-05-03 18:12 UTC (permalink / raw)
To: Luis R. Rodriguez
Cc: Kees Cook, David Woodhouse, H. Peter Anvin, Thomas Gleixner,
Ingo Molnar, Borislav Petkov, x86, LKML, Andy Lutomirski,
Boris Ostrovsky, Rusty Russell, David Vrabel,
Konrad Rzeszutek Wilk, Michael Brown, Juergen Gross, Ming Lei,
Arnd Bergmann, linux-arch, Russell King - ARM Linux, benh,
jbaron, ananth, anil.s.keshavamurthy, David
On Tue, May 03, 2016 at 10:10:24AM -0700, Luis R. Rodriguez wrote:
> On Tue, May 3, 2016 at 10:07 AM, Luis R. Rodriguez <mcgrof@suse.com> wrote:
> > Thanks! Can you confirm if any Android or Brillo builds are already using it?
>
> Also more importantly, any chance you can provide any technical
> reasons why initramfs cannot be used, or it was decided to not use it
> on these systems? It should help others in the future as well.
Some systems just don't need it, nor want it. We can't break working
systems, so this is not something we can remove, sorry.
thanks,
greg k-h
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 3/7] firmware: port built-in section to linker table
2016-02-29 10:12 ` David Woodhouse
2016-02-29 18:56 ` Luis R. Rodriguez
@ 2016-03-01 16:10 ` James Bottomley
2016-03-01 17:54 ` Luis R. Rodriguez
1 sibling, 1 reply; 46+ messages in thread
From: James Bottomley @ 2016-03-01 16:10 UTC (permalink / raw)
To: David Woodhouse, Luis R. Rodriguez, hpa, tglx, mingo, bp
Cc: x86, linux-kernel, luto, boris.ostrovsky, rusty, david.vrabel,
konrad.wilk, mcb30, jgross, ming.lei, gregkh, arnd, linux-arch,
linux, benh, jbaron, ananth, anil.s.keshavamurthy, davem,
masami.hiramatsu.pt, andriy.shevchenko, xen-devel
[-- Attachment #1: Type: text/plain, Size: 1243 bytes --]
On Mon, 2016-02-29 at 10:12 +0000, David Woodhouse wrote:
> On Fri, 2016-02-19 at 05:45 -0800, Luis R. Rodriguez wrote:
> > This ports built-in firmware to use linker tables,
> > this replaces the custom section solution with a
> > generic solution.
> >
> > This also demos the use of the .rodata (SECTION_RO)
> > linker tables.
> >
> > Tested with 0 built-in firmware, 1 and 2 built-in
> > firmwares successfully.
>
> I think we'd do better to rip this support out entirely. It just
> isn't needed; firmware can live in an initramfs and don't even need
> *any* actual running userspace support to load it from there these
> days, do we?
We have lots of SCSI drivers with built in firmware. The obvious
examples are 53c700, aic7xxx and aic79xx. For them, we actually have
the firmware compilers in tree. The firmware model they use just isn't
amenable to the firmware loader: they're not monolithic blobs, it's a
set of firmware scripts we use to handle particular operations before
giving control back to the host, so the firmware and the driver are
very much symbiotic.
On the other hand, I don't think any of them uses firmware sections, so
it's not an argument for not ripping out this type.
James
[-- Attachment #2: smime.p7s --]
[-- Type: application/x-pkcs7-signature, Size: 5819 bytes --]
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 3/7] firmware: port built-in section to linker table
2016-03-01 16:10 ` James Bottomley
@ 2016-03-01 17:54 ` Luis R. Rodriguez
2016-04-29 19:24 ` Luis R. Rodriguez
0 siblings, 1 reply; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-03-01 17:54 UTC (permalink / raw)
To: James Bottomley
Cc: David Woodhouse, Luis R. Rodriguez, hpa, tglx, mingo, bp, x86,
linux-kernel, luto, boris.ostrovsky, rusty, david.vrabel,
konrad.wilk, mcb30, jgross, ming.lei, gregkh, arnd, linux-arch,
linux, benh, jbaron, ananth, anil.s.keshavamurthy, davem,
masami.hiramatsu.pt, andriy.shevchenko, xen-devel
On Tue, Mar 01, 2016 at 08:10:24AM -0800, James Bottomley wrote:
> On Mon, 2016-02-29 at 10:12 +0000, David Woodhouse wrote:
> > On Fri, 2016-02-19 at 05:45 -0800, Luis R. Rodriguez wrote:
> > > This ports built-in firmware to use linker tables,
> > > this replaces the custom section solution with a
> > > generic solution.
> > >
> > > This also demos the use of the .rodata (SECTION_RO)
> > > linker tables.
> > >
> > > Tested with 0 built-in firmware, 1 and 2 built-in
> > > firmwares successfully.
> >
> > I think we'd do better to rip this support out entirely. It just
> > isn't needed; firmware can live in an initramfs and don't even need
> > *any* actual running userspace support to load it from there these
> > days, do we?
>
> We have lots of SCSI drivers with built in firmware. The obvious
> examples are 53c700, aic7xxx and aic79xx. For them, we actually have
> the firmware compilers in tree. The firmware model they use just isn't
> amenable to the firmware loader: they're not monolithic blobs, it's a
> set of firmware scripts we use to handle particular operations before
> giving control back to the host, so the firmware and the driver are
> very much symbiotic.
I'm in the process of doing some other cleanups with the firmware_class
stuff so that odd requirements get supported but clean interfaces are
also not hampered by these odd requirements, so I'll take a look at
this later. If you have other oddball firmware requirements please
let me know so I can also keep in mind.
> On the other hand, I don't think any of them uses firmware sections, so
> it's not an argument for not ripping out this type.
Thanks for confirming. I'll rip this out.
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 3/7] firmware: port built-in section to linker table
2016-03-01 17:54 ` Luis R. Rodriguez
@ 2016-04-29 19:24 ` Luis R. Rodriguez
0 siblings, 0 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-04-29 19:24 UTC (permalink / raw)
To: James Bottomley, Kees Cook
Cc: David Woodhouse, Luis R. Rodriguez, H. Peter Anvin,
Thomas Gleixner, Ingo Molnar, Borislav Petkov, X86 ML,
linux-kernel, Andy Lutomirski, Boris Ostrovsky, Rusty Russell,
David Vrabel, Konrad Rzeszutek Wilk, Michael Brown,
Juergen Gross, Ming Lei, Greg Kroah-Hartman, Arnd Bergmann,
linux-arch, Russell King, Benjamin Herrenschmidt, jbaron, ananth,
anil.s.keshavamurthy
On Tue, Mar 1, 2016 at 9:54 AM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> On Tue, Mar 01, 2016 at 08:10:24AM -0800, James Bottomley wrote:
>> On Mon, 2016-02-29 at 10:12 +0000, David Woodhouse wrote:
>> > On Fri, 2016-02-19 at 05:45 -0800, Luis R. Rodriguez wrote:
>> > > This ports built-in firmware to use linker tables,
>> > > this replaces the custom section solution with a
>> > > generic solution.
>> > >
>> > > This also demos the use of the .rodata (SECTION_RO)
>> > > linker tables.
>> > >
>> > > Tested with 0 built-in firmware, 1 and 2 built-in
>> > > firmwares successfully.
>> >
>> > I think we'd do better to rip this support out entirely. It just
>> > isn't needed; firmware can live in an initramfs and don't even need
>> > *any* actual running userspace support to load it from there these
>> > days, do we?
>>
>> We have lots of SCSI drivers with built in firmware. The obvious
>> examples are 53c700, aic7xxx and aic79xx. For them, we actually have
>> the firmware compilers in tree. The firmware model they use just isn't
>> amenable to the firmware loader: they're not monolithic blobs, it's a
>> set of firmware scripts we use to handle particular operations before
>> giving control back to the host, so the firmware and the driver are
>> very much symbiotic.
>
> I'm in the process of doing some other cleanups with the firmware_class
> stuff so that odd requirements get supported but clean interfaces are
> also not hampered by these odd requirements, so I'll take a look at
> this later. If you have other oddball firmware requirements please
> let me know so I can also keep in mind.
>
>> On the other hand, I don't think any of them uses firmware sections, so
>> it's not an argument for not ripping out this type.
>
> Thanks for confirming. I'll rip this out.
Just a heads up, I've put the removal through 0-day without issues,
I'll be folding the removal into another series of changes for the
firmware API which should help compartmentalize the user mode helper
stuff as well.
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread
* [RFC v2 4/7] asm/sections: add a generic push_section_tbl()
2016-02-19 13:45 [RFC v2 0/7] linux: add linker tables Luis R. Rodriguez
` (2 preceding siblings ...)
2016-02-19 13:45 ` [RFC v2 3/7] firmware: port built-in section to linker table Luis R. Rodriguez
@ 2016-02-19 13:45 ` Luis R. Rodriguez
2016-02-19 20:26 ` H. Peter Anvin
2016-02-19 13:45 ` [RFC v2 5/7] jump_label: port __jump_table to linker tables Luis R. Rodriguez
` (3 subsequent siblings)
7 siblings, 1 reply; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-19 13:45 UTC (permalink / raw)
To: hpa, tglx, mingo, bp
Cc: benh, ming.lei, masami.hiramatsu.pt, linux-arch, xen-devel,
linux, x86, anil.s.keshavamurthy, arnd, rusty, jbaron,
boris.ostrovsky, andriy.shevchenko, mcb30, jgross, ananth,
gregkh, linux-kernel, luto, Luis R. Rodriguez, david.vrabel,
dwmw2, davem
With a generic linker tables solution in place we
need a general asm solution for declaring entries
with asm. The first easy target is to cover the C
asm declarations, guard the header file for now
and define a first generic entry push_section_tbl()
to be used later for custom linker table annotations.
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
include/asm-generic/sections.h | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index af0254c09424..f5ea98bd85d2 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -3,8 +3,10 @@
/* References to section boundaries */
+#ifndef __ASSEMBLY__
#include <linux/compiler.h>
#include <linux/types.h>
+#include <linux/sections.h>
/*
* Usage guidelines:
@@ -128,4 +130,12 @@ static inline bool init_section_intersects(void *virt, size_t size)
return memory_intersects(__init_begin, __init_end, virt, size);
}
+/*
+ * Some architectures do not like the "\t" at the end (s39), we should be
+ * able to generalize this further, but so far this covers most architectures.
+ */
+#define push_section_tbl(section, name, level, flags) \
+ ".pushsection " SECTION_TBL(section,name,level) ", \"" #flags "\"\n\t"
+#endif
+
#endif /* _ASM_GENERIC_SECTIONS_H_ */
--
2.7.0
^ permalink raw reply related [flat|nested] 46+ messages in thread* Re: [RFC v2 4/7] asm/sections: add a generic push_section_tbl()
2016-02-19 13:45 ` [RFC v2 4/7] asm/sections: add a generic push_section_tbl() Luis R. Rodriguez
@ 2016-02-19 20:26 ` H. Peter Anvin
2016-02-19 21:06 ` Luis R. Rodriguez
0 siblings, 1 reply; 46+ messages in thread
From: H. Peter Anvin @ 2016-02-19 20:26 UTC (permalink / raw)
To: Luis R. Rodriguez, tglx, mingo, bp
Cc: x86, linux-kernel, luto, boris.ostrovsky, rusty, david.vrabel,
konrad.wilk, mcb30, jgross, ming.lei, gregkh, arnd, linux-arch,
linux, benh, jbaron, ananth, anil.s.keshavamurthy, davem,
masami.hiramatsu.pt, andriy.shevchenko, dwmw2, xen-devel
On 02/19/2016 05:45 AM, Luis R. Rodriguez wrote:
> With a generic linker tables solution in place we
> need a general asm solution for declaring entries
> with asm. The first easy target is to cover the C
> asm declarations, guard the header file for now
> and define a first generic entry push_section_tbl()
> to be used later for custom linker table annotations.
>
> Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> ---
> include/asm-generic/sections.h | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
> index af0254c09424..f5ea98bd85d2 100644
> --- a/include/asm-generic/sections.h
> +++ b/include/asm-generic/sections.h
> @@ -3,8 +3,10 @@
>
> /* References to section boundaries */
>
> +#ifndef __ASSEMBLY__
> #include <linux/compiler.h>
> #include <linux/types.h>
> +#include <linux/sections.h>
>
> /*
> * Usage guidelines:
> @@ -128,4 +130,12 @@ static inline bool init_section_intersects(void *virt, size_t size)
> return memory_intersects(__init_begin, __init_end, virt, size);
> }
>
> +/*
> + * Some architectures do not like the "\t" at the end (s39), we should be
> + * able to generalize this further, but so far this covers most architectures.
> + */
> +#define push_section_tbl(section, name, level, flags) \
> + ".pushsection " SECTION_TBL(section,name,level) ", \"" #flags "\"\n\t"
> +#endif
> +
I think the \n\t is unnecessary.
-hpa
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 4/7] asm/sections: add a generic push_section_tbl()
2016-02-19 20:26 ` H. Peter Anvin
@ 2016-02-19 21:06 ` Luis R. Rodriguez
2016-02-22 2:55 ` H. Peter Anvin
0 siblings, 1 reply; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-19 21:06 UTC (permalink / raw)
To: H. Peter Anvin, schwidefsky, heiko.carstens, linux-s390
Cc: Luis R. Rodriguez, tglx, mingo, bp, x86, linux-kernel, luto,
boris.ostrovsky, rusty, david.vrabel, konrad.wilk, mcb30, jgross,
ming.lei, gregkh, arnd, linux-arch, linux, benh, jbaron, ananth,
anil.s.keshavamurthy, davem, masami.hiramatsu.pt,
andriy.shevchenko, dwmw2, xen-devel
On Fri, Feb 19, 2016 at 12:26:51PM -0800, H. Peter Anvin wrote:
> On 02/19/2016 05:45 AM, Luis R. Rodriguez wrote:
> > With a generic linker tables solution in place we
> > need a general asm solution for declaring entries
> > with asm. The first easy target is to cover the C
> > asm declarations, guard the header file for now
> > and define a first generic entry push_section_tbl()
> > to be used later for custom linker table annotations.
> >
> > Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> > ---
> > include/asm-generic/sections.h | 10 ++++++++++
> > 1 file changed, 10 insertions(+)
> >
> > diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
> > index af0254c09424..f5ea98bd85d2 100644
> > --- a/include/asm-generic/sections.h
> > +++ b/include/asm-generic/sections.h
> > @@ -3,8 +3,10 @@
> >
> > /* References to section boundaries */
> >
> > +#ifndef __ASSEMBLY__
> > #include <linux/compiler.h>
> > #include <linux/types.h>
> > +#include <linux/sections.h>
> >
> > /*
> > * Usage guidelines:
> > @@ -128,4 +130,12 @@ static inline bool init_section_intersects(void *virt, size_t size)
> > return memory_intersects(__init_begin, __init_end, virt, size);
> > }
> >
> > +/*
> > + * Some architectures do not like the "\t" at the end (s39), we should be
> > + * able to generalize this further, but so far this covers most architectures.
> > + */
> > +#define push_section_tbl(section, name, level, flags) \
> > + ".pushsection " SECTION_TBL(section,name,level) ", \"" #flags "\"\n\t"
> > +#endif
> > +
>
> I think the \n\t is unnecessary.
Super! I wonder if we we can just use this on s390 as well without it pooping?
I ask as this would set a precedent.
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 4/7] asm/sections: add a generic push_section_tbl()
2016-02-19 21:06 ` Luis R. Rodriguez
@ 2016-02-22 2:55 ` H. Peter Anvin
2016-02-26 14:56 ` Heiko Carstens
0 siblings, 1 reply; 46+ messages in thread
From: H. Peter Anvin @ 2016-02-22 2:55 UTC (permalink / raw)
To: Luis R. Rodriguez, schwidefsky, heiko.carstens, linux-s390
Cc: tglx, mingo, bp, x86, linux-kernel, luto, boris.ostrovsky, rusty,
david.vrabel, konrad.wilk, mcb30, jgross, ming.lei, gregkh, arnd,
linux-arch, linux, benh, jbaron, ananth, anil.s.keshavamurthy,
davem, masami.hiramatsu.pt, andriy.shevchenko, dwmw2, xen-devel
On 02/19/16 13:06, Luis R. Rodriguez wrote:
>>
>> I think the \n\t is unnecessary.
>
> Super! I wonder if we we can just use this on s390 as well without it pooping?
> I ask as this would set a precedent.
>
Ask Heike, but I think just ; or \n ought be be fine. I do not know of
*any* case where \t at the end of a string would ever be necessary, and
it would *always* be possible to replace it with a space in a pinch.
-hpa
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 4/7] asm/sections: add a generic push_section_tbl()
2016-02-22 2:55 ` H. Peter Anvin
@ 2016-02-26 14:56 ` Heiko Carstens
2016-05-20 19:53 ` Luis R. Rodriguez
0 siblings, 1 reply; 46+ messages in thread
From: Heiko Carstens @ 2016-02-26 14:56 UTC (permalink / raw)
To: H. Peter Anvin
Cc: Luis R. Rodriguez, schwidefsky, linux-s390, tglx, mingo, bp, x86,
linux-kernel, luto, boris.ostrovsky, rusty, david.vrabel,
konrad.wilk, mcb30, jgross, ming.lei, gregkh, arnd, linux-arch,
linux, benh, jbaron, ananth, anil.s.keshavamurthy, davem,
masami.hiramatsu.pt, andriy.shevchenko, dwmw2, xen-devel
On Sun, Feb 21, 2016 at 06:55:05PM -0800, H. Peter Anvin wrote:
> On 02/19/16 13:06, Luis R. Rodriguez wrote:
> >>
> >> I think the \n\t is unnecessary.
> >
> > Super! I wonder if we we can just use this on s390 as well without it pooping?
> > I ask as this would set a precedent.
> >
>
> Ask Heike, but I think just ; or \n ought be be fine. I do not know of
> *any* case where \t at the end of a string would ever be necessary, and
> it would *always* be possible to replace it with a space in a pinch.
\n should be fine on s390.
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 4/7] asm/sections: add a generic push_section_tbl()
2016-02-26 14:56 ` Heiko Carstens
@ 2016-05-20 19:53 ` Luis R. Rodriguez
0 siblings, 0 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-05-20 19:53 UTC (permalink / raw)
To: Heiko Carstens
Cc: H. Peter Anvin, Luis R. Rodriguez, schwidefsky, linux-s390, tglx,
mingo, bp, x86, linux-kernel, luto, boris.ostrovsky, rusty,
david.vrabel, konrad.wilk, mcb30, jgross, ming.lei, gregkh, arnd,
linux-arch, linux, benh, jbaron, ananth, anil.s.keshavamurthy,
davem, masami.hiramatsu.pt, andriy.shevchenko, dwmw2, xen-devel,
torvalds
On Fri, Feb 26, 2016 at 03:56:04PM +0100, Heiko Carstens wrote:
> On Sun, Feb 21, 2016 at 06:55:05PM -0800, H. Peter Anvin wrote:
> > On 02/19/16 13:06, Luis R. Rodriguez wrote:
> > >>
> > >> I think the \n\t is unnecessary.
> > >
> > > Super! I wonder if we we can just use this on s390 as well without it pooping?
> > > I ask as this would set a precedent.
> > >
> >
> > Ask Heike, but I think just ; or \n ought be be fine. I do not know of
> > *any* case where \t at the end of a string would ever be necessary, and
> > it would *always* be possible to replace it with a space in a pinch.
>
> \n should be fine on s390.
Great, thanks, I'll move forward with just \n in v3.
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread
* [RFC v2 5/7] jump_label: port __jump_table to linker tables
2016-02-19 13:45 [RFC v2 0/7] linux: add linker tables Luis R. Rodriguez
` (3 preceding siblings ...)
2016-02-19 13:45 ` [RFC v2 4/7] asm/sections: add a generic push_section_tbl() Luis R. Rodriguez
@ 2016-02-19 13:45 ` Luis R. Rodriguez
2016-02-19 13:45 ` [RFC v2 6/7] dynamic_debug: port to use " Luis R. Rodriguez
` (2 subsequent siblings)
7 siblings, 0 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-19 13:45 UTC (permalink / raw)
To: hpa, tglx, mingo, bp
Cc: benh, ming.lei, masami.hiramatsu.pt, linux-arch, xen-devel,
linux, x86, anil.s.keshavamurthy, arnd, rusty, jbaron,
boris.ostrovsky, andriy.shevchenko, mcb30, jgross, ananth,
gregkh, linux-kernel, luto, Luis R. Rodriguez, david.vrabel,
dwmw2, davem
Move the __jump_table from the a custom section solution
to a generic solution, this avoiding extra vmlinux.lds.h
customizations.
This also demos the use of the .data (SECTION_DATA)
linker tables and of push_section_tbl().
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
arch/arm/include/asm/jump_label.h | 4 ++--
arch/arm64/include/asm/jump_label.h | 4 ++--
arch/mips/include/asm/jump_label.h | 4 ++--
arch/powerpc/include/asm/jump_label.h | 6 +++---
arch/s390/include/asm/jump_label.h | 4 ++--
arch/sparc/include/asm/jump_label.h | 4 ++--
arch/x86/include/asm/jump_label.h | 9 +++++----
include/asm-generic/vmlinux.lds.h | 4 ----
include/linux/jump_label.h | 5 +++--
kernel/jump_label.c | 16 +++++++++-------
kernel/module.c | 4 +++-
11 files changed, 33 insertions(+), 31 deletions(-)
diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h
index 34f7b6980d21..c1df4f105df3 100644
--- a/arch/arm/include/asm/jump_label.h
+++ b/arch/arm/include/asm/jump_label.h
@@ -12,7 +12,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
{
asm_volatile_goto("1:\n\t"
WASM(nop) "\n\t"
- ".pushsection __jump_table, \"aw\"\n\t"
+ push_section_tbl(SECTION_DATA, __jump_table, all, aw)
".word 1b, %l[l_yes], %c0\n\t"
".popsection\n\t"
: : "i" (&((char *)key)[branch]) : : l_yes);
@@ -26,7 +26,7 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
{
asm_volatile_goto("1:\n\t"
WASM(b) " %l[l_yes]\n\t"
- ".pushsection __jump_table, \"aw\"\n\t"
+ push_section_tbl(SECTION_DATA, __jump_table, all, aw)
".word 1b, %l[l_yes], %c0\n\t"
".popsection\n\t"
: : "i" (&((char *)key)[branch]) : : l_yes);
diff --git a/arch/arm64/include/asm/jump_label.h b/arch/arm64/include/asm/jump_label.h
index 1b5e0e843c3a..18f5ca294eaa 100644
--- a/arch/arm64/include/asm/jump_label.h
+++ b/arch/arm64/include/asm/jump_label.h
@@ -29,7 +29,7 @@
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
asm goto("1: nop\n\t"
- ".pushsection __jump_table, \"aw\"\n\t"
+ push_section_tbl(SECTION_DATA, __jump_table, all, aw)
".align 3\n\t"
".quad 1b, %l[l_yes], %c0\n\t"
".popsection\n\t"
@@ -43,7 +43,7 @@ l_yes:
static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
{
asm goto("1: b %l[l_yes]\n\t"
- ".pushsection __jump_table, \"aw\"\n\t"
+ push_section_tbl(SECTION_DATA, __jump_table, all, aw)
".align 3\n\t"
".quad 1b, %l[l_yes], %c0\n\t"
".popsection\n\t"
diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h
index e77672539e8e..13e70e290830 100644
--- a/arch/mips/include/asm/jump_label.h
+++ b/arch/mips/include/asm/jump_label.h
@@ -30,7 +30,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
{
asm_volatile_goto("1:\t" NOP_INSN "\n\t"
"nop\n\t"
- ".pushsection __jump_table, \"aw\"\n\t"
+ push_section_tbl(SECTION_DATA, __jump_table, all, aw)
WORD_INSN " 1b, %l[l_yes], %0\n\t"
".popsection\n\t"
: : "i" (&((char *)key)[branch]) : : l_yes);
@@ -44,7 +44,7 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
{
asm_volatile_goto("1:\tj %l[l_yes]\n\t"
"nop\n\t"
- ".pushsection __jump_table, \"aw\"\n\t"
+ push_section_tbl(SECTION_DATA, __jump_table, all, aw)
WORD_INSN " 1b, %l[l_yes], %0\n\t"
".popsection\n\t"
: : "i" (&((char *)key)[branch]) : : l_yes);
diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h
index 47e155f15433..5fffc7b12361 100644
--- a/arch/powerpc/include/asm/jump_label.h
+++ b/arch/powerpc/include/asm/jump_label.h
@@ -22,7 +22,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
{
asm_volatile_goto("1:\n\t"
"nop\n\t"
- ".pushsection __jump_table, \"aw\"\n\t"
+ push_section_tbl(SECTION_DATA, __jump_table, all, aw)
JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t"
".popsection \n\t"
: : "i" (&((char *)key)[branch]) : : l_yes);
@@ -36,7 +36,7 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
{
asm_volatile_goto("1:\n\t"
"b %l[l_yes]\n\t"
- ".pushsection __jump_table, \"aw\"\n\t"
+ push_section_tbl(SECTION_DATA, __jump_table, all, aw)
JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t"
".popsection \n\t"
: : "i" (&((char *)key)[branch]) : : l_yes);
@@ -61,7 +61,7 @@ struct jump_entry {
#else
#define ARCH_STATIC_BRANCH(LABEL, KEY) \
1098: nop; \
- .pushsection __jump_table, "aw"; \
+ .pushsection .data.tbl.__jump_table.all, "aw"; \
FTR_ENTRY_LONG 1098b, LABEL, KEY; \
.popsection
#endif
diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h
index 7f9fd5e3f1bf..1ebfb7ddcb11 100644
--- a/arch/s390/include/asm/jump_label.h
+++ b/arch/s390/include/asm/jump_label.h
@@ -15,7 +15,7 @@
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
asm_volatile_goto("0: brcl 0,"__stringify(JUMP_LABEL_NOP_OFFSET)"\n"
- ".pushsection __jump_table, \"aw\"\n"
+ ".pushsection .data.tbl.__jump_table.all, \"aw\"\n"
".balign 8\n"
".quad 0b, %l[label], %0\n"
".popsection\n"
@@ -29,7 +29,7 @@ label:
static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
{
asm_volatile_goto("0: brcl 15, %l[label]\n"
- ".pushsection __jump_table, \"aw\"\n"
+ ".pushsection .data.tbl.__jump_table.all, \"aw\"\n"
".balign 8\n"
".quad 0b, %l[label], %0\n"
".popsection\n"
diff --git a/arch/sparc/include/asm/jump_label.h b/arch/sparc/include/asm/jump_label.h
index 62d0354d1727..848bece455bb 100644
--- a/arch/sparc/include/asm/jump_label.h
+++ b/arch/sparc/include/asm/jump_label.h
@@ -12,7 +12,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
asm_volatile_goto("1:\n\t"
"nop\n\t"
"nop\n\t"
- ".pushsection __jump_table, \"aw\"\n\t"
+ push_section_tbl(SECTION_DATA, __jump_table, all, aw)
".align 4\n\t"
".word 1b, %l[l_yes], %c0\n\t"
".popsection \n\t"
@@ -28,7 +28,7 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
asm_volatile_goto("1:\n\t"
"b %l[l_yes]\n\t"
"nop\n\t"
- ".pushsection __jump_table, \"aw\"\n\t"
+ push_section_tbl(SECTION_DATA, __jump_table, all, aw)
".align 4\n\t"
".word 1b, %l[l_yes], %c0\n\t"
".popsection \n\t"
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index adc54c12cbd1..5b80a0e755df 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -29,12 +29,13 @@
#include <linux/stringify.h>
#include <linux/types.h>
+#include <asm-generic/sections.h>
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
asm_volatile_goto("1:"
".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t"
- ".pushsection __jump_table, \"aw\" \n\t"
+ push_section_tbl(SECTION_DATA, __jump_table, all, aw)
_ASM_ALIGN "\n\t"
_ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t"
".popsection \n\t"
@@ -50,7 +51,7 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
asm_volatile_goto("1:"
".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t"
"2:\n\t"
- ".pushsection __jump_table, \"aw\" \n\t"
+ push_section_tbl(SECTION_DATA, __jump_table, all, aw)
_ASM_ALIGN "\n\t"
_ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t"
".popsection \n\t"
@@ -85,7 +86,7 @@ struct jump_entry {
.else
.byte STATIC_KEY_INIT_NOP
.endif
- .pushsection __jump_table, "aw"
+ .pushsection .data.tbl.__jump_table.all, "aw"
_ASM_ALIGN
_ASM_PTR .Lstatic_jump_\@, \target, \key
.popsection
@@ -101,7 +102,7 @@ struct jump_entry {
.long \target - .Lstatic_jump_after_\@
.Lstatic_jump_after_\@:
.endif
- .pushsection __jump_table, "aw"
+ .pushsection .data.tbl.__jump_table.all, "aw"
_ASM_ALIGN
_ASM_PTR .Lstatic_jump_\@, \target, \key + 1
.popsection
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 91815fb1f2fa..11e1adcbcb24 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -210,10 +210,6 @@
STRUCT_ALIGN(); \
*(__tracepoints) \
/* implement dynamic printk debug */ \
- . = ALIGN(8); \
- VMLINUX_SYMBOL(__start___jump_table) = .; \
- *(__jump_table) \
- VMLINUX_SYMBOL(__stop___jump_table) = .; \
. = ALIGN(8); \
VMLINUX_SYMBOL(__start___verbose) = .; \
*(__verbose) \
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 0536524bb9eb..42b68b1e4a39 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -1,6 +1,8 @@
#ifndef _LINUX_JUMP_LABEL_H
#define _LINUX_JUMP_LABEL_H
+#include <linux/tables.h>
+
/*
* Jump label support
*
@@ -138,8 +140,7 @@ static __always_inline bool static_key_true(struct static_key *key)
return !arch_static_branch(key, true);
}
-extern struct jump_entry __start___jump_table[];
-extern struct jump_entry __stop___jump_table[];
+DECLARE_LINKTABLE_DATA(struct jump_entry, __jump_table);
extern void jump_label_init(void);
extern void jump_label_lock(void);
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 05254eeb4b4e..66d6e24148be 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -17,6 +17,8 @@
#ifdef HAVE_JUMP_LABEL
+DEFINE_LINKTABLE_DATA(struct jump_entry, __jump_table);
+
/* mutex to protect coming/going of the the jump_label table */
static DEFINE_MUTEX(jump_label_mutex);
@@ -200,15 +202,14 @@ static void __jump_label_update(struct static_key *key,
void __init jump_label_init(void)
{
- struct jump_entry *iter_start = __start___jump_table;
- struct jump_entry *iter_stop = __stop___jump_table;
struct static_key *key = NULL;
struct jump_entry *iter;
jump_label_lock();
- jump_label_sort_entries(iter_start, iter_stop);
+ jump_label_sort_entries(LINKTABLE_START(__jump_table),
+ LINKTABLE_END(__jump_table));
- for (iter = iter_start; iter < iter_stop; iter++) {
+ LINKTABLE_FOR_EACH(iter, __jump_table) {
struct static_key *iterk;
/* rewrite NOPs */
@@ -450,8 +451,9 @@ early_initcall(jump_label_init_module);
*/
int jump_label_text_reserved(void *start, void *end)
{
- int ret = __jump_label_text_reserved(__start___jump_table,
- __stop___jump_table, start, end);
+ int ret = __jump_label_text_reserved(LINKTABLE_START(__jump_table),
+ LINKTABLE_END(__jump_table),
+ start, end);
if (ret)
return ret;
@@ -464,7 +466,7 @@ int jump_label_text_reserved(void *start, void *end)
static void jump_label_update(struct static_key *key)
{
- struct jump_entry *stop = __stop___jump_table;
+ struct jump_entry *stop = LINKTABLE_END(__jump_table);
struct jump_entry *entry = static_key_entries(key);
#ifdef CONFIG_MODULES
struct module *mod;
diff --git a/kernel/module.c b/kernel/module.c
index 9537da37ce87..42249ee8e462 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2930,7 +2930,9 @@ static int find_module_sections(struct module *mod, struct load_info *info)
&mod->num_tracepoints);
#endif
#ifdef HAVE_JUMP_LABEL
- mod->jump_entries = section_objs(info, "__jump_table",
+ mod->jump_entries = section_objs(info,
+ SECTION_TBL(SECTION_DATA,
+ __jump_table,),
sizeof(*mod->jump_entries),
&mod->num_jump_entries);
#endif
--
2.7.0
^ permalink raw reply related [flat|nested] 46+ messages in thread* [RFC v2 6/7] dynamic_debug: port to use linker tables
2016-02-19 13:45 [RFC v2 0/7] linux: add linker tables Luis R. Rodriguez
` (4 preceding siblings ...)
2016-02-19 13:45 ` [RFC v2 5/7] jump_label: port __jump_table to linker tables Luis R. Rodriguez
@ 2016-02-19 13:45 ` Luis R. Rodriguez
2016-02-19 13:45 ` [RFC v2 7/7] kprobes: port to linker table Luis R. Rodriguez
2016-02-19 20:16 ` [RFC v2 0/7] linux: add linker tables H. Peter Anvin
7 siblings, 0 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-19 13:45 UTC (permalink / raw)
To: hpa, tglx, mingo, bp
Cc: benh, ming.lei, masami.hiramatsu.pt, linux-arch, xen-devel,
linux, x86, anil.s.keshavamurthy, arnd, rusty, jbaron,
boris.ostrovsky, andriy.shevchenko, mcb30, jgross, ananth,
gregkh, linux-kernel, luto, Luis R. Rodriguez, david.vrabel,
dwmw2, davem
This removes the custom vmlinux.lds.h hacks and uses
the generalized solution for .data (SECTION_DATA)
entries.
This is much more potential for further fine tuning here
though in the future. For instance, linker tables enable
an extra postfix for order level annotations, this could
easily be used as the KBUILD_MODNAME and with a bit of
linker table changes we may be able to get a direct O(1)
count of the entries for that KBUILD_MODNAME: it would
just be a count on the number of entries for the given
order level. This should help make dynamic_debug_init()
cleaner and also reduce the amount of time it takes at
boot time. Instead of iterating over each print until we
have all for a KBUILD_MODNAME, we'd instead directly
operate on each KBUILD_MODNAME directly.
Tested dynamic debug with dyndbg query ana debugfs control
and it works as expected.
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
include/asm-generic/vmlinux.lds.h | 5 -----
include/linux/dynamic_debug.h | 6 ++++--
kernel/module.c | 2 +-
lib/dynamic_debug.c | 13 ++++++-------
4 files changed, 11 insertions(+), 15 deletions(-)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 11e1adcbcb24..c5fcac902cbe 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -209,11 +209,6 @@
*(.data.unlikely) \
STRUCT_ALIGN(); \
*(__tracepoints) \
- /* implement dynamic printk debug */ \
- . = ALIGN(8); \
- VMLINUX_SYMBOL(__start___verbose) = .; \
- *(__verbose) \
- VMLINUX_SYMBOL(__stop___verbose) = .; \
LIKELY_PROFILE() \
BRANCH_PROFILE() \
TRACE_PRINTKS() \
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 4f1bbc68cd1b..6cd14a22b795 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -1,6 +1,8 @@
#ifndef _DYNAMIC_DEBUG_H
#define _DYNAMIC_DEBUG_H
+#include <linux/tables.h>
+
/*
* An instance of this structure is created in a special
* ELF section at every dynamic debug callsite. At runtime,
@@ -40,6 +42,7 @@ int ddebug_add_module(struct _ddebug *tab, unsigned int n,
const char *modname);
#if defined(CONFIG_DYNAMIC_DEBUG)
+DECLARE_LINKTABLE_DATA(struct _ddebug, __verbose);
extern int ddebug_remove_module(const char *mod_name);
extern __printf(2, 3)
void __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...);
@@ -61,8 +64,7 @@ void __dynamic_netdev_dbg(struct _ddebug *descriptor,
const char *fmt, ...);
#define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt) \
- static struct _ddebug __aligned(8) \
- __attribute__((section("__verbose"))) name = { \
+ static LINKTABLE_DATA(__verbose, all) name = { \
.modname = KBUILD_MODNAME, \
.function = __func__, \
.filename = __FILE__, \
diff --git a/kernel/module.c b/kernel/module.c
index 42249ee8e462..22d768abb1ec 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2962,7 +2962,7 @@ static int find_module_sections(struct module *mod, struct load_info *info)
if (section_addr(info, "__obsparm"))
pr_warn("%s: Ignoring obsolete parameters\n", mod->name);
- info->debug = section_objs(info, "__verbose",
+ info->debug = section_objs(info, SECTION_TBL(SECTION_DATA, __verbose,),
sizeof(*info->debug), &info->num_debug);
return 0;
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index fe42b6ec3f0c..ae7b9b4ac022 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -37,8 +37,7 @@
#include <linux/device.h>
#include <linux/netdevice.h>
-extern struct _ddebug __start___verbose[];
-extern struct _ddebug __stop___verbose[];
+DEFINE_LINKTABLE_DATA(struct _ddebug, __verbose);
struct ddebug_table {
struct list_head link;
@@ -971,14 +970,14 @@ static int __init dynamic_debug_init(void)
int n = 0, entries = 0, modct = 0;
int verbose_bytes = 0;
- if (__start___verbose == __stop___verbose) {
- pr_warn("_ddebug table is empty in a CONFIG_DYNAMIC_DEBUG build\n");
+ if (LINKTABLE_EMPTY(__verbose)) {
+ pr_warn("dynamic debug linker table empty on CONFIG_DYNAMIC_DEBUG build\n");
return 1;
}
- iter = __start___verbose;
+ iter = LINKTABLE_START(__verbose);
modname = iter->modname;
iter_start = iter;
- for (; iter < __stop___verbose; iter++) {
+ LINKTABLE_FOR_EACH(iter, __verbose) {
entries++;
verbose_bytes += strlen(iter->modname) + strlen(iter->function)
+ strlen(iter->filename) + strlen(iter->format);
@@ -1001,7 +1000,7 @@ static int __init dynamic_debug_init(void)
ddebug_init_success = 1;
vpr_info("%d modules, %d entries and %d bytes in ddebug tables, %d bytes in (readonly) verbose section\n",
modct, entries, (int)(modct * sizeof(struct ddebug_table)),
- verbose_bytes + (int)(__stop___verbose - __start___verbose));
+ verbose_bytes + (int)(LINKTABLE_SIZE(__verbose)));
/* apply ddebug_query boot param, dont unload tables on err */
if (ddebug_setup_string[0] != '\0') {
--
2.7.0
^ permalink raw reply related [flat|nested] 46+ messages in thread* [RFC v2 7/7] kprobes: port to linker table
2016-02-19 13:45 [RFC v2 0/7] linux: add linker tables Luis R. Rodriguez
` (5 preceding siblings ...)
2016-02-19 13:45 ` [RFC v2 6/7] dynamic_debug: port to use " Luis R. Rodriguez
@ 2016-02-19 13:45 ` Luis R. Rodriguez
2016-02-19 14:15 ` Russell King - ARM Linux
2016-02-22 1:34 ` 平松雅巳 / HIRAMATU，MASAMI
2016-02-19 20:16 ` [RFC v2 0/7] linux: add linker tables H. Peter Anvin
7 siblings, 2 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-19 13:45 UTC (permalink / raw)
To: hpa, tglx, mingo, bp
Cc: x86, linux-kernel, luto, boris.ostrovsky, rusty, david.vrabel,
konrad.wilk, mcb30, jgross, ming.lei, gregkh, arnd, linux-arch,
linux, benh, jbaron, ananth, anil.s.keshavamurthy, davem,
masami.hiramatsu.pt, andriy.shevchenko, dwmw2, xen-devel,
Luis R. Rodriguez
kprobe makes use of two custom sections:
type name begin end
init.data _kprobe_blacklist __start_kprobe_blacklist __stop_kprobe_blacklist
text .kprobes.text __kprobes_text_start __kprobes_text_end
Port these to the linker table generic solution. This lets
us remove all the custom kprobe section declarations on the
linker script.
Tested with CONFIG_KPROBES_SANITY_TEST, it passes with:
Kprobe smoke test: started
Kprobe smoke test: passed successfully
Then tested CONFIG_SAMPLE_KPROBES on do_fork, and the
kprobe bites and kicks as expected. Lastly tried registering
a kprobe on a kprobe blacklisted symbol (NOKPROBE_SYMBOL()),
and confirms that fails to work.
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
arch/arc/kernel/vmlinux.lds.S | 1 -
arch/arm/kernel/entry-armv.S | 2 +-
arch/arm/kernel/vmlinux.lds.S | 1 -
arch/avr32/kernel/entry-avr32b.S | 4 ++--
arch/avr32/kernel/vmlinux.lds.S | 1 -
arch/blackfin/kernel/vmlinux.lds.S | 1 -
arch/c6x/kernel/vmlinux.lds.S | 1 -
arch/hexagon/kernel/vmlinux.lds.S | 1 -
arch/ia64/kernel/jprobes.S | 2 +-
arch/ia64/kernel/vmlinux.lds.S | 1 -
arch/ia64/lib/flush.S | 4 ++--
arch/metag/kernel/vmlinux.lds.S | 1 -
arch/microblaze/kernel/vmlinux.lds.S | 1 -
arch/mips/kernel/vmlinux.lds.S | 1 -
arch/mn10300/kernel/vmlinux.lds.S | 1 -
arch/nios2/kernel/vmlinux.lds.S | 1 -
arch/openrisc/kernel/vmlinux.lds.S | 1 -
arch/parisc/kernel/vmlinux.lds.S | 1 -
arch/powerpc/include/asm/ppc_asm.h | 6 +++---
arch/powerpc/kernel/vmlinux.lds.S | 1 -
arch/s390/kernel/entry.S | 4 ++--
arch/s390/kernel/kprobes.c | 2 +-
arch/s390/kernel/mcount.S | 2 +-
arch/s390/kernel/vmlinux.lds.S | 1 -
arch/score/kernel/vmlinux.lds.S | 1 -
arch/sh/kernel/vmlinux.lds.S | 1 -
arch/sparc/kernel/vmlinux.lds.S | 1 -
arch/sparc/mm/ultra.S | 2 +-
arch/tile/kernel/vmlinux.lds.S | 1 -
arch/x86/kernel/kprobes/core.c | 10 ++++++----
arch/x86/kernel/vmlinux.lds.S | 1 -
include/asm-generic/sections.h | 4 ++--
include/asm-generic/vmlinux.lds.h | 16 ----------------
include/linux/compiler.h | 3 ++-
include/linux/kprobes.h | 7 +++++--
kernel/kprobes.c | 16 +++++++---------
scripts/mod/modpost.c | 3 ++-
scripts/recordmcount.c | 3 ++-
scripts/recordmcount.pl | 2 +-
39 files changed, 41 insertions(+), 72 deletions(-)
diff --git a/arch/arc/kernel/vmlinux.lds.S b/arch/arc/kernel/vmlinux.lds.S
index 894e696bddaa..52f23df2b9b6 100644
--- a/arch/arc/kernel/vmlinux.lds.S
+++ b/arch/arc/kernel/vmlinux.lds.S
@@ -98,7 +98,6 @@ SECTIONS
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
*(.fixup)
*(.gnu.warning)
}
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 3ce377f7251f..4959a83833fd 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -83,7 +83,7 @@
.endm
#ifdef CONFIG_KPROBES
- .section .kprobes.text,"ax",%progbits
+ .section .text.tbl.kprobes.all,"ax",%progbits
#else
.text
#endif
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 8b60fde5ce48..8de7921ac331 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -108,7 +108,6 @@ SECTIONS
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
*(.gnu.warning)
*(.glue_7)
*(.glue_7t)
diff --git a/arch/avr32/kernel/entry-avr32b.S b/arch/avr32/kernel/entry-avr32b.S
index 7301f4806bbe..c0fe699d0a21 100644
--- a/arch/avr32/kernel/entry-avr32b.S
+++ b/arch/avr32/kernel/entry-avr32b.S
@@ -605,7 +605,7 @@ fault_exit_work:
brcc fault_resume_user
rjmp enter_monitor_mode
- .section .kprobes.text, "ax", @progbits
+ .section .text.tbl.kprobes.all, "ax", @progbits
.type handle_debug, @function
handle_debug:
sub sp, 4 /* r12_orig */
@@ -826,7 +826,7 @@ irq_level\level:
IRQ_LEVEL 2
IRQ_LEVEL 3
- .section .kprobes.text, "ax", @progbits
+ .section .text.tbl.kprobes.all, "ax", @progbits
.type enter_monitor_mode, @function
enter_monitor_mode:
/*
diff --git a/arch/avr32/kernel/vmlinux.lds.S b/arch/avr32/kernel/vmlinux.lds.S
index a4589176bed5..bf4f3f1f9dbb 100644
--- a/arch/avr32/kernel/vmlinux.lds.S
+++ b/arch/avr32/kernel/vmlinux.lds.S
@@ -49,7 +49,6 @@ SECTIONS
_stext = .;
*(.ex.text)
*(.irq.text)
- KPROBES_TEXT
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
diff --git a/arch/blackfin/kernel/vmlinux.lds.S b/arch/blackfin/kernel/vmlinux.lds.S
index c9eec84aa258..8a193fad4c5d 100644
--- a/arch/blackfin/kernel/vmlinux.lds.S
+++ b/arch/blackfin/kernel/vmlinux.lds.S
@@ -35,7 +35,6 @@ SECTIONS
#endif
LOCK_TEXT
IRQENTRY_TEXT
- KPROBES_TEXT
#ifdef CONFIG_ROMKERNEL
__sinittext = .;
INIT_TEXT
diff --git a/arch/c6x/kernel/vmlinux.lds.S b/arch/c6x/kernel/vmlinux.lds.S
index 5a6e141d1641..a23bed62cec3 100644
--- a/arch/c6x/kernel/vmlinux.lds.S
+++ b/arch/c6x/kernel/vmlinux.lds.S
@@ -72,7 +72,6 @@ SECTIONS
SCHED_TEXT
LOCK_TEXT
IRQENTRY_TEXT
- KPROBES_TEXT
*(.fixup)
*(.gnu.warning)
}
diff --git a/arch/hexagon/kernel/vmlinux.lds.S b/arch/hexagon/kernel/vmlinux.lds.S
index 5f268c1071b3..a358b699ec64 100644
--- a/arch/hexagon/kernel/vmlinux.lds.S
+++ b/arch/hexagon/kernel/vmlinux.lds.S
@@ -51,7 +51,6 @@ SECTIONS
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
*(.fixup)
}
_etext = .;
diff --git a/arch/ia64/kernel/jprobes.S b/arch/ia64/kernel/jprobes.S
index f69389c7be1d..c6c23a3e92fb 100644
--- a/arch/ia64/kernel/jprobes.S
+++ b/arch/ia64/kernel/jprobes.S
@@ -50,7 +50,7 @@
/*
* void jprobe_break(void)
*/
- .section .kprobes.text, "ax"
+ .section .text.tbl.kprobes.all, "ax"
ENTRY(jprobe_break)
break.m __IA64_BREAK_JPROBE
END(jprobe_break)
diff --git a/arch/ia64/kernel/vmlinux.lds.S b/arch/ia64/kernel/vmlinux.lds.S
index dc506b05ffbd..884f36d38989 100644
--- a/arch/ia64/kernel/vmlinux.lds.S
+++ b/arch/ia64/kernel/vmlinux.lds.S
@@ -47,7 +47,6 @@ SECTIONS {
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
*(.gnu.linkonce.t*)
}
diff --git a/arch/ia64/lib/flush.S b/arch/ia64/lib/flush.S
index 1d8c88860063..7f257810e858 100644
--- a/arch/ia64/lib/flush.S
+++ b/arch/ia64/lib/flush.S
@@ -20,7 +20,7 @@
*
* Note: "in0" and "in1" are preserved for debugging purposes.
*/
- .section .kprobes.text,"ax"
+ .section .text.tbl.kprobes.all,"ax"
GLOBAL_ENTRY(flush_icache_range)
.prologue
@@ -72,7 +72,7 @@ END(flush_icache_range)
*
* Note: "in0" and "in1" are preserved for debugging purposes.
*/
- .section .kprobes.text,"ax"
+ .section .text.tbl.kprobes.all,"ax"
GLOBAL_ENTRY(clflush_cache_range)
.prologue
diff --git a/arch/metag/kernel/vmlinux.lds.S b/arch/metag/kernel/vmlinux.lds.S
index e12055e88bfe..da1689c85bc8 100644
--- a/arch/metag/kernel/vmlinux.lds.S
+++ b/arch/metag/kernel/vmlinux.lds.S
@@ -22,7 +22,6 @@ SECTIONS
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
IRQENTRY_TEXT
*(.text.*)
*(.gnu.warning)
diff --git a/arch/microblaze/kernel/vmlinux.lds.S b/arch/microblaze/kernel/vmlinux.lds.S
index be9488d69734..94c1c5574a77 100644
--- a/arch/microblaze/kernel/vmlinux.lds.S
+++ b/arch/microblaze/kernel/vmlinux.lds.S
@@ -34,7 +34,6 @@ SECTIONS {
EXIT_CALL
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
IRQENTRY_TEXT
. = ALIGN (4) ;
_etext = . ;
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index 0a93e83cd014..9183e9235651 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -56,7 +56,6 @@ SECTIONS
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
IRQENTRY_TEXT
*(.text.*)
*(.fixup)
diff --git a/arch/mn10300/kernel/vmlinux.lds.S b/arch/mn10300/kernel/vmlinux.lds.S
index 13c4814c29f8..ead5efc01802 100644
--- a/arch/mn10300/kernel/vmlinux.lds.S
+++ b/arch/mn10300/kernel/vmlinux.lds.S
@@ -31,7 +31,6 @@ SECTIONS
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
*(.fixup)
*(.gnu.warning)
} = 0xcb
diff --git a/arch/nios2/kernel/vmlinux.lds.S b/arch/nios2/kernel/vmlinux.lds.S
index 326fab40a9de..dc8a84183700 100644
--- a/arch/nios2/kernel/vmlinux.lds.S
+++ b/arch/nios2/kernel/vmlinux.lds.S
@@ -39,7 +39,6 @@ SECTIONS
SCHED_TEXT
LOCK_TEXT
IRQENTRY_TEXT
- KPROBES_TEXT
} =0
_etext = .;
diff --git a/arch/openrisc/kernel/vmlinux.lds.S b/arch/openrisc/kernel/vmlinux.lds.S
index 2d69a853b742..b010cb75edc4 100644
--- a/arch/openrisc/kernel/vmlinux.lds.S
+++ b/arch/openrisc/kernel/vmlinux.lds.S
@@ -48,7 +48,6 @@ SECTIONS
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
IRQENTRY_TEXT
*(.fixup)
*(.text.__*)
diff --git a/arch/parisc/kernel/vmlinux.lds.S b/arch/parisc/kernel/vmlinux.lds.S
index 308f29081d46..9d9dc4984465 100644
--- a/arch/parisc/kernel/vmlinux.lds.S
+++ b/arch/parisc/kernel/vmlinux.lds.S
@@ -70,7 +70,6 @@ SECTIONS
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
IRQENTRY_TEXT
*(.text.do_softirq)
*(.text.sys_exit)
diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index 499d9f89435a..4e36e86338f3 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -218,7 +218,7 @@ name: \
.localentry name,.-name
#define _KPROBE(name) \
- .section ".kprobes.text","a"; \
+ .section ".text.tbl.kprobes.all","a"; \
.align 2 ; \
.type name,@function; \
.globl name; \
@@ -248,7 +248,7 @@ GLUE(.,name):
#define _GLOBAL_TOC(name) _GLOBAL(name)
#define _KPROBE(name) \
- .section ".kprobes.text","a"; \
+ .section ".text.tbl.kprobes.all","a"; \
.align 2 ; \
.globl name; \
.globl GLUE(.,name); \
@@ -280,7 +280,7 @@ n:
#define _GLOBAL_TOC(name) _GLOBAL(name)
#define _KPROBE(n) \
- .section ".kprobes.text","a"; \
+ .section ".text.tbl.kprobes.all","a"; \
.globl n; \
n:
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index d41fd0af8980..8779ae180783 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -53,7 +53,6 @@ SECTIONS
*(.text .fixup __ftr_alt_* .ref.text)
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
IRQENTRY_TEXT
#ifdef CONFIG_PPC32
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index cd5a191381b9..b09aa9ab5a1f 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -162,7 +162,7 @@ _PIF_WORK = (_PIF_PER_TRAP)
tm off+\addr, \mask
.endm
- .section .kprobes.text, "ax"
+ .section .text.tbl.kprobes.all, "ax"
/*
* Scheduler resume function, called by switch_to
@@ -965,7 +965,7 @@ ENTRY(restart_int_handler)
brc 2,2b
3: j 3b
- .section .kprobes.text, "ax"
+ .section .text.tbl.kprobes.all, "ax"
#ifdef CONFIG_CHECK_STACK
/*
diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index 250f5972536a..376d4bd487c5 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -288,7 +288,7 @@ static void kprobe_reenter_check(struct kprobe_ctlblk *kcb, struct kprobe *p)
default:
/*
* A kprobe on the code path to single step an instruction
- * is a BUG. The code path resides in the .kprobes.text
+ * is a BUG. The code path resides in the .text.tbl.kprobes.all
* section and is executed with interrupts disabled.
*/
printk(KERN_EMERG "Invalid kprobe detected at %p.\n", p->addr);
diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S
index e499370fbccb..4572045b968e 100644
--- a/arch/s390/kernel/mcount.S
+++ b/arch/s390/kernel/mcount.S
@@ -10,7 +10,7 @@
#include <asm/ftrace.h>
#include <asm/ptrace.h>
- .section .kprobes.text, "ax"
+ .section .text.tbl.kprobes.all, "ax"
ENTRY(ftrace_stub)
br %r14
diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index 445657fe658c..4614b5bcab5e 100644
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -26,7 +26,6 @@ SECTIONS
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
IRQENTRY_TEXT
*(.fixup)
*(.gnu.warning)
diff --git a/arch/score/kernel/vmlinux.lds.S b/arch/score/kernel/vmlinux.lds.S
index 7274b5c4287e..36ebcb3b1215 100644
--- a/arch/score/kernel/vmlinux.lds.S
+++ b/arch/score/kernel/vmlinux.lds.S
@@ -41,7 +41,6 @@ SECTIONS
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
*(.text.*)
*(.fixup)
. = ALIGN (4) ;
diff --git a/arch/sh/kernel/vmlinux.lds.S b/arch/sh/kernel/vmlinux.lds.S
index db88cbf9eafd..af4f37375345 100644
--- a/arch/sh/kernel/vmlinux.lds.S
+++ b/arch/sh/kernel/vmlinux.lds.S
@@ -37,7 +37,6 @@ SECTIONS
EXTRA_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
IRQENTRY_TEXT
*(.fixup)
*(.gnu.warning)
diff --git a/arch/sparc/kernel/vmlinux.lds.S b/arch/sparc/kernel/vmlinux.lds.S
index f1a2f688b28a..a1c8e3a3ebb6 100644
--- a/arch/sparc/kernel/vmlinux.lds.S
+++ b/arch/sparc/kernel/vmlinux.lds.S
@@ -46,7 +46,6 @@ SECTIONS
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
IRQENTRY_TEXT
*(.gnu.warning)
} = 0
diff --git a/arch/sparc/mm/ultra.S b/arch/sparc/mm/ultra.S
index b4f4733abc6e..a08fb40656ac 100644
--- a/arch/sparc/mm/ultra.S
+++ b/arch/sparc/mm/ultra.S
@@ -148,7 +148,7 @@ __spitfire_flush_tlb_mm_slow:
/*
* The following code flushes one page_size worth.
*/
- .section .kprobes.text, "ax"
+ .section .text.tbl.kprobes.all, "ax"
.align 32
.globl __flush_icache_page
__flush_icache_page: /* %o0 = phys_page */
diff --git a/arch/tile/kernel/vmlinux.lds.S b/arch/tile/kernel/vmlinux.lds.S
index 0e059a0101ea..0f04268fc394 100644
--- a/arch/tile/kernel/vmlinux.lds.S
+++ b/arch/tile/kernel/vmlinux.lds.S
@@ -43,7 +43,6 @@ SECTIONS
HEAD_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
IRQENTRY_TEXT
__fix_text_end = .; /* tile-cpack won't rearrange before this */
ALIGN_FUNCTION();
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 1deffe6cc873..dde4ec0e0185 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -577,7 +577,10 @@ static int reenter_kprobe(struct kprobe *p, struct pt_regs *regs,
case KPROBE_REENTER:
/* A probe has been hit in the codepath leading up to, or just
* after, single-stepping of a probed instruction. This entire
- * codepath should strictly reside in .kprobes.text section.
+ * codepath should strictly reside in the kprobes section:
+ *
+ * SECTION_TBL(SECTION_TEXT, kprobes, all)
+ *
* Raise a BUG or we'll continue in an endless reentering loop
* and eventually a stack overflow.
*/
@@ -1114,10 +1117,9 @@ NOKPROBE_SYMBOL(longjmp_break_handler);
bool arch_within_kprobe_blacklist(unsigned long addr)
{
- return (addr >= (unsigned long)__kprobes_text_start &&
- addr < (unsigned long)__kprobes_text_end) ||
+ return (LINKTABLE_ADDR_WITHIN(kprobes, addr) ||
(addr >= (unsigned long)__entry_text_start &&
- addr < (unsigned long)__entry_text_end);
+ addr < (unsigned long)__entry_text_end));
}
int __init arch_init_kprobes(void)
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 74e4bf11f562..80a9f9106d2a 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -99,7 +99,6 @@ SECTIONS
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
- KPROBES_TEXT
ENTRY_TEXT
IRQENTRY_TEXT
*(.fixup)
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index f5ea98bd85d2..0438aab5cb58 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -24,7 +24,7 @@
* Following global variables are optional and may be unavailable on some
* architectures and/or kernel configurations.
* _text, _data
- * __kprobes_text_start, __kprobes_text_end
+ * LINKTABLE_START(kprobes), LINKTABLE_END(kprobes)
* __entry_text_start, __entry_text_end
* __ctors_start, __ctors_end
*/
@@ -35,7 +35,7 @@ extern char __init_begin[], __init_end[];
extern char _sinittext[], _einittext[];
extern char _end[];
extern char __per_cpu_load[], __per_cpu_start[], __per_cpu_end[];
-extern char __kprobes_text_start[], __kprobes_text_end[];
+DECLARE_LINKTABLE_TEXT(char, kprobes);
extern char __entry_text_start[], __entry_text_end[];
extern char __start_rodata[], __end_rodata[];
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index c5fcac902cbe..f1420714a549 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -112,15 +112,6 @@
#define BRANCH_PROFILE()
#endif
-#ifdef CONFIG_KPROBES
-#define KPROBE_BLACKLIST() . = ALIGN(8); \
- VMLINUX_SYMBOL(__start_kprobe_blacklist) = .; \
- *(_kprobe_blacklist) \
- VMLINUX_SYMBOL(__stop_kprobe_blacklist) = .;
-#else
-#define KPROBE_BLACKLIST()
-#endif
-
#ifdef CONFIG_EVENT_TRACING
#define FTRACE_EVENTS() . = ALIGN(8); \
VMLINUX_SYMBOL(__start_ftrace_events) = .; \
@@ -433,12 +424,6 @@
*(.spinlock.text) \
VMLINUX_SYMBOL(__lock_text_end) = .;
-#define KPROBES_TEXT \
- ALIGN_FUNCTION(); \
- VMLINUX_SYMBOL(__kprobes_text_start) = .; \
- *(.kprobes.text) \
- VMLINUX_SYMBOL(__kprobes_text_end) = .;
-
#define ENTRY_TEXT \
ALIGN_FUNCTION(); \
VMLINUX_SYMBOL(__entry_text_start) = .; \
@@ -504,7 +489,6 @@
*(.init.rodata) \
FTRACE_EVENTS() \
TRACE_SYSCALLS() \
- KPROBE_BLACKLIST() \
MEM_DISCARD(init.rodata) \
CLK_OF_TABLES() \
RESERVEDMEM_OF_TABLES() \
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 00b042c49ccd..8e33fc1ffd3c 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -546,7 +546,8 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
/* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
#ifdef CONFIG_KPROBES
-# define __kprobes __attribute__((__section__(".kprobes.text")))
+#include <linux/sections.h>
+# define __kprobes __attribute__((__section__(SECTION_TBL(SECTION_TEXT, kprobes, all))))
# define nokprobe_inline __always_inline
#else
# define __kprobes
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 8f6849084248..544eb59cdbb9 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -42,8 +42,12 @@
#include <linux/ftrace.h>
#ifdef CONFIG_KPROBES
+#include <linux/tables.h>
#include <asm/kprobes.h>
+DECLARE_LINKTABLE_TEXT(char, kprobes);
+DECLARE_LINKTABLE_INIT_DATA(unsigned long, _kprobe_blacklist);
+
/* kprobe_status settings */
#define KPROBE_HIT_ACTIVE 0x00000001
#define KPROBE_HIT_SS 0x00000002
@@ -487,8 +491,7 @@ static inline int enable_jprobe(struct jprobe *jp)
* by using this macro.
*/
#define __NOKPROBE_SYMBOL(fname) \
-static unsigned long __used \
- __attribute__((section("_kprobe_blacklist"))) \
+static LINKTABLE_INIT_DATA(_kprobe_blacklist, all) \
_kbl_addr_##fname = (unsigned long)fname;
#define NOKPROBE_SYMBOL(fname) __NOKPROBE_SYMBOL(fname)
#else
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index d10ab6b9b5e0..d816c659f358 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1328,8 +1328,7 @@ out:
bool __weak arch_within_kprobe_blacklist(unsigned long addr)
{
/* The __kprobes marked functions and entry code must not be probed */
- return addr >= (unsigned long)__kprobes_text_start &&
- addr < (unsigned long)__kprobes_text_end;
+ return LINKTABLE_ADDR_WITHIN(kprobes, addr);
}
bool within_kprobe_blacklist(unsigned long addr)
@@ -2054,14 +2053,13 @@ NOKPROBE_SYMBOL(dump_kprobe);
* since a kprobe need not necessarily be at the beginning
* of a function.
*/
-static int __init populate_kprobe_blacklist(unsigned long *start,
- unsigned long *end)
+static int __init populate_kprobe_blacklist(void)
{
unsigned long *iter;
struct kprobe_blacklist_entry *ent;
unsigned long entry, offset = 0, size = 0;
- for (iter = start; iter < end; iter++) {
+ LINKTABLE_FOR_EACH(iter, _kprobe_blacklist) {
entry = arch_deref_entry_point((void *)*iter);
if (!kernel_text_address(entry) ||
@@ -2126,8 +2124,9 @@ static struct notifier_block kprobe_module_nb = {
};
/* Markers of _kprobe_blacklist section */
-extern unsigned long __start_kprobe_blacklist[];
-extern unsigned long __stop_kprobe_blacklist[];
+DEFINE_LINKTABLE_INIT_DATA(unsigned long, _kprobe_blacklist);
+/* Actual kprobes linker table */
+DEFINE_LINKTABLE_TEXT(char, kprobes);
static int __init init_kprobes(void)
{
@@ -2141,8 +2140,7 @@ static int __init init_kprobes(void)
raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
}
- err = populate_kprobe_blacklist(__start_kprobe_blacklist,
- __stop_kprobe_blacklist);
+ err = populate_kprobe_blacklist();
if (err) {
pr_err("kprobes: failed to populate blacklist: %d\n", err);
pr_err("Please take care of using kprobes.\n");
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 48958d3cec9e..b0a8f519efb8 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -22,6 +22,7 @@
#include "../../include/generated/autoconf.h"
#include "../../include/linux/license.h"
#include "../../include/linux/export.h"
+#include "../../include/linux/sections.h"
/* Are we using CONFIG_MODVERSIONS? */
static int modversions = 0;
@@ -888,7 +889,7 @@ static void check_section(const char *modname, struct elf_info *elf,
#define DATA_SECTIONS ".data", ".data.rel"
#define TEXT_SECTIONS ".text", ".text.unlikely", ".sched.text", \
- ".kprobes.text"
+ SECTION_TBL(SECTION_TEXT, kprobes, all)
#define OTHER_TEXT_SECTIONS ".ref.text", ".head.text", ".spinlock.text", \
".fixup", ".entry.text", ".exception.text", ".text.*", \
".coldtext"
diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index e167592793a7..f37dac17f033 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -32,6 +32,7 @@
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
+#include "../../include/linux/sections.h"
#ifndef EM_METAG
/* Remove this when these make it to the standard system elf.h. */
@@ -356,7 +357,7 @@ is_mcounted_section_name(char const *const txtname)
strcmp(".sched.text", txtname) == 0 ||
strcmp(".spinlock.text", txtname) == 0 ||
strcmp(".irqentry.text", txtname) == 0 ||
- strcmp(".kprobes.text", txtname) == 0 ||
+ strcmp(SECTION_TBL(SECTION_TEXT, kprobe, all), txtname) == 0 ||
strcmp(".text.unlikely", txtname) == 0;
}
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 96e2486a6fc4..63e13009dda9 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -134,7 +134,7 @@ my %text_sections = (
".sched.text" => 1,
".spinlock.text" => 1,
".irqentry.text" => 1,
- ".kprobes.text" => 1,
+ ".text.tbl.kprobes.all" => 1,
".text.unlikely" => 1,
);
--
2.7.0
^ permalink raw reply related [flat|nested] 46+ messages in thread* Re: [RFC v2 7/7] kprobes: port to linker table
2016-02-19 13:45 ` [RFC v2 7/7] kprobes: port to linker table Luis R. Rodriguez
@ 2016-02-19 14:15 ` Russell King - ARM Linux
2016-02-19 14:55 ` Luis R. Rodriguez
2016-02-22 1:34 ` 平松雅巳 / HIRAMATU，MASAMI
1 sibling, 1 reply; 46+ messages in thread
From: Russell King - ARM Linux @ 2016-02-19 14:15 UTC (permalink / raw)
To: Luis R. Rodriguez
Cc: hpa, tglx, mingo, bp, x86, linux-kernel, luto, boris.ostrovsky,
rusty, david.vrabel, konrad.wilk, mcb30, jgross, ming.lei,
gregkh, arnd, linux-arch, benh, jbaron, ananth,
anil.s.keshavamurthy, davem, masami.hiramatsu.pt,
andriy.shevchenko, dwmw2, xen-devel
On Fri, Feb 19, 2016 at 05:45:59AM -0800, Luis R. Rodriguez wrote:
> kprobe makes use of two custom sections:
>
> type name begin end
> init.data _kprobe_blacklist __start_kprobe_blacklist __stop_kprobe_blacklist
> text .kprobes.text __kprobes_text_start __kprobes_text_end
>
> Port these to the linker table generic solution. This lets
> us remove all the custom kprobe section declarations on the
> linker script.
I don't like this. You create this "table" thing, which you use for
tables, and then you go and use it for something else - for kprobes
text which is not a table. The kprobes text section is a section for
text which is not kprobe-able.
So, it seems to be a complete mis-nomer to me. Maybe you can explain
the rationale here?
--
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 7/7] kprobes: port to linker table
2016-02-19 14:15 ` Russell King - ARM Linux
@ 2016-02-19 14:55 ` Luis R. Rodriguez
0 siblings, 0 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-19 14:55 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: Luis R. Rodriguez, hpa, tglx, mingo, bp, x86, linux-kernel, luto,
boris.ostrovsky, rusty, david.vrabel, konrad.wilk, mcb30, jgross,
ming.lei, gregkh, arnd, linux-arch, benh, jbaron, ananth,
anil.s.keshavamurthy, davem, masami.hiramatsu.pt,
andriy.shevchenko, dwmw2, xen-devel
On Fri, Feb 19, 2016 at 02:15:11PM +0000, Russell King - ARM Linux wrote:
> On Fri, Feb 19, 2016 at 05:45:59AM -0800, Luis R. Rodriguez wrote:
> > kprobe makes use of two custom sections:
> >
> > type name begin end
> > init.data _kprobe_blacklist __start_kprobe_blacklist __stop_kprobe_blacklist
> > text .kprobes.text __kprobes_text_start __kprobes_text_end
> >
> > Port these to the linker table generic solution. This lets
> > us remove all the custom kprobe section declarations on the
> > linker script.
>
> I don't like this. You create this "table" thing, which you use for
> tables, and then you go and use it for something else - for kprobes
> text which is not a table. The kprobes text section is a section for
> text which is not kprobe-able.
No the thing about linker tables is its generalizing custom section solutions
we have scattered all over the place.
> So, it seems to be a complete mis-nomer to me. Maybe you can explain
> the rationale here?
Sure, so each custom section solution requires modifying the linker script.
With linker tables we end up only with a few basic types of tables, a
read-only, text, data, init init_data, etc. A linker table belongs to one of
these. The linker table provides a means by which to describe explicitly
what type of section you are using for your solution but also allows us
to enable such custom solutions without furthering the custom linker
script.
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread
* RE: [RFC v2 7/7] kprobes: port to linker table
2016-02-19 13:45 ` [RFC v2 7/7] kprobes: port to linker table Luis R. Rodriguez
2016-02-19 14:15 ` Russell King - ARM Linux
@ 2016-02-22 1:34 ` 平松雅巳 / HIRAMATU，MASAMI
2016-02-23 0:52 ` [Xen-devel] " Luis R. Rodriguez
1 sibling, 1 reply; 46+ messages in thread
From: 平松雅巳 / HIRAMATU，MASAMI @ 2016-02-22 1:34 UTC (permalink / raw)
To: 'Luis R. Rodriguez', hpa, tglx, mingo, bp
Cc: x86, linux-kernel, luto, boris.ostrovsky, rusty, david.vrabel,
konrad.wilk, mcb30, jgross, ming.lei, gregkh, arnd, linux-arch,
linux, benh, jbaron, ananth, anil.s.keshavamurthy@intel.com
>From: Luis R. Rodriguez [mailto:mcgrof@kernel.org]
>
>kprobe makes use of two custom sections:
>
>type name begin end
>init.data _kprobe_blacklist __start_kprobe_blacklist __stop_kprobe_blacklist
>text .kprobes.text __kprobes_text_start __kprobes_text_end
>
>Port these to the linker table generic solution. This lets
>us remove all the custom kprobe section declarations on the
>linker script.
>
>Tested with CONFIG_KPROBES_SANITY_TEST, it passes with:
>
>Kprobe smoke test: started
>Kprobe smoke test: passed successfully
>
>Then tested CONFIG_SAMPLE_KPROBES on do_fork, and the
>kprobe bites and kicks as expected. Lastly tried registering
>a kprobe on a kprobe blacklisted symbol (NOKPROBE_SYMBOL()),
>and confirms that fails to work.
Could you also check to run the testcases by using ftracetest as below?
$ cd tools/testing/selftests/ftrace/
$ sudo ./ftracetest
And I'm not sure about linker table. Is that possible to support
__kprobes prefix, which moves the functions into kprobes.text?
Actually, I'm on the way to replacing __kprobes to NOKPROBE_SYMBOL
macro, since NOKPROBE_SYMBOL() doesn't effect the kernel text itself.
On x86, it is already replaced (see commit 820aede0209a), and same
work should be done on other archs. So, could you hold this after
that? I think we should remove .kprobes.text first and move to
linker table.
Thank you,
>
>Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
>---
> arch/arc/kernel/vmlinux.lds.S | 1 -
> arch/arm/kernel/entry-armv.S | 2 +-
> arch/arm/kernel/vmlinux.lds.S | 1 -
> arch/avr32/kernel/entry-avr32b.S | 4 ++--
> arch/avr32/kernel/vmlinux.lds.S | 1 -
> arch/blackfin/kernel/vmlinux.lds.S | 1 -
> arch/c6x/kernel/vmlinux.lds.S | 1 -
> arch/hexagon/kernel/vmlinux.lds.S | 1 -
> arch/ia64/kernel/jprobes.S | 2 +-
> arch/ia64/kernel/vmlinux.lds.S | 1 -
> arch/ia64/lib/flush.S | 4 ++--
> arch/metag/kernel/vmlinux.lds.S | 1 -
> arch/microblaze/kernel/vmlinux.lds.S | 1 -
> arch/mips/kernel/vmlinux.lds.S | 1 -
> arch/mn10300/kernel/vmlinux.lds.S | 1 -
> arch/nios2/kernel/vmlinux.lds.S | 1 -
> arch/openrisc/kernel/vmlinux.lds.S | 1 -
> arch/parisc/kernel/vmlinux.lds.S | 1 -
> arch/powerpc/include/asm/ppc_asm.h | 6 +++---
> arch/powerpc/kernel/vmlinux.lds.S | 1 -
> arch/s390/kernel/entry.S | 4 ++--
> arch/s390/kernel/kprobes.c | 2 +-
> arch/s390/kernel/mcount.S | 2 +-
> arch/s390/kernel/vmlinux.lds.S | 1 -
> arch/score/kernel/vmlinux.lds.S | 1 -
> arch/sh/kernel/vmlinux.lds.S | 1 -
> arch/sparc/kernel/vmlinux.lds.S | 1 -
> arch/sparc/mm/ultra.S | 2 +-
> arch/tile/kernel/vmlinux.lds.S | 1 -
> arch/x86/kernel/kprobes/core.c | 10 ++++++----
> arch/x86/kernel/vmlinux.lds.S | 1 -
> include/asm-generic/sections.h | 4 ++--
> include/asm-generic/vmlinux.lds.h | 16 ----------------
> include/linux/compiler.h | 3 ++-
> include/linux/kprobes.h | 7 +++++--
> kernel/kprobes.c | 16 +++++++---------
> scripts/mod/modpost.c | 3 ++-
> scripts/recordmcount.c | 3 ++-
> scripts/recordmcount.pl | 2 +-
> 39 files changed, 41 insertions(+), 72 deletions(-)
>
>diff --git a/arch/arc/kernel/vmlinux.lds.S b/arch/arc/kernel/vmlinux.lds.S
>index 894e696bddaa..52f23df2b9b6 100644
>--- a/arch/arc/kernel/vmlinux.lds.S
>+++ b/arch/arc/kernel/vmlinux.lds.S
>@@ -98,7 +98,6 @@ SECTIONS
> TEXT_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> *(.fixup)
> *(.gnu.warning)
> }
>diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
>index 3ce377f7251f..4959a83833fd 100644
>--- a/arch/arm/kernel/entry-armv.S
>+++ b/arch/arm/kernel/entry-armv.S
>@@ -83,7 +83,7 @@
> .endm
>
> #ifdef CONFIG_KPROBES
>- .section .kprobes.text,"ax",%progbits
>+ .section .text.tbl.kprobes.all,"ax",%progbits
> #else
> .text
> #endif
>diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
>index 8b60fde5ce48..8de7921ac331 100644
>--- a/arch/arm/kernel/vmlinux.lds.S
>+++ b/arch/arm/kernel/vmlinux.lds.S
>@@ -108,7 +108,6 @@ SECTIONS
> TEXT_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> *(.gnu.warning)
> *(.glue_7)
> *(.glue_7t)
>diff --git a/arch/avr32/kernel/entry-avr32b.S b/arch/avr32/kernel/entry-avr32b.S
>index 7301f4806bbe..c0fe699d0a21 100644
>--- a/arch/avr32/kernel/entry-avr32b.S
>+++ b/arch/avr32/kernel/entry-avr32b.S
>@@ -605,7 +605,7 @@ fault_exit_work:
> brcc fault_resume_user
> rjmp enter_monitor_mode
>
>- .section .kprobes.text, "ax", @progbits
>+ .section .text.tbl.kprobes.all, "ax", @progbits
> .type handle_debug, @function
> handle_debug:
> sub sp, 4 /* r12_orig */
>@@ -826,7 +826,7 @@ irq_level\level:
> IRQ_LEVEL 2
> IRQ_LEVEL 3
>
>- .section .kprobes.text, "ax", @progbits
>+ .section .text.tbl.kprobes.all, "ax", @progbits
> .type enter_monitor_mode, @function
> enter_monitor_mode:
> /*
>diff --git a/arch/avr32/kernel/vmlinux.lds.S b/arch/avr32/kernel/vmlinux.lds.S
>index a4589176bed5..bf4f3f1f9dbb 100644
>--- a/arch/avr32/kernel/vmlinux.lds.S
>+++ b/arch/avr32/kernel/vmlinux.lds.S
>@@ -49,7 +49,6 @@ SECTIONS
> _stext = .;
> *(.ex.text)
> *(.irq.text)
>- KPROBES_TEXT
> TEXT_TEXT
> SCHED_TEXT
> LOCK_TEXT
>diff --git a/arch/blackfin/kernel/vmlinux.lds.S b/arch/blackfin/kernel/vmlinux.lds.S
>index c9eec84aa258..8a193fad4c5d 100644
>--- a/arch/blackfin/kernel/vmlinux.lds.S
>+++ b/arch/blackfin/kernel/vmlinux.lds.S
>@@ -35,7 +35,6 @@ SECTIONS
> #endif
> LOCK_TEXT
> IRQENTRY_TEXT
>- KPROBES_TEXT
> #ifdef CONFIG_ROMKERNEL
> __sinittext = .;
> INIT_TEXT
>diff --git a/arch/c6x/kernel/vmlinux.lds.S b/arch/c6x/kernel/vmlinux.lds.S
>index 5a6e141d1641..a23bed62cec3 100644
>--- a/arch/c6x/kernel/vmlinux.lds.S
>+++ b/arch/c6x/kernel/vmlinux.lds.S
>@@ -72,7 +72,6 @@ SECTIONS
> SCHED_TEXT
> LOCK_TEXT
> IRQENTRY_TEXT
>- KPROBES_TEXT
> *(.fixup)
> *(.gnu.warning)
> }
>diff --git a/arch/hexagon/kernel/vmlinux.lds.S b/arch/hexagon/kernel/vmlinux.lds.S
>index 5f268c1071b3..a358b699ec64 100644
>--- a/arch/hexagon/kernel/vmlinux.lds.S
>+++ b/arch/hexagon/kernel/vmlinux.lds.S
>@@ -51,7 +51,6 @@ SECTIONS
> TEXT_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> *(.fixup)
> }
> _etext = .;
>diff --git a/arch/ia64/kernel/jprobes.S b/arch/ia64/kernel/jprobes.S
>index f69389c7be1d..c6c23a3e92fb 100644
>--- a/arch/ia64/kernel/jprobes.S
>+++ b/arch/ia64/kernel/jprobes.S
>@@ -50,7 +50,7 @@
> /*
> * void jprobe_break(void)
> */
>- .section .kprobes.text, "ax"
>+ .section .text.tbl.kprobes.all, "ax"
> ENTRY(jprobe_break)
> break.m __IA64_BREAK_JPROBE
> END(jprobe_break)
>diff --git a/arch/ia64/kernel/vmlinux.lds.S b/arch/ia64/kernel/vmlinux.lds.S
>index dc506b05ffbd..884f36d38989 100644
>--- a/arch/ia64/kernel/vmlinux.lds.S
>+++ b/arch/ia64/kernel/vmlinux.lds.S
>@@ -47,7 +47,6 @@ SECTIONS {
> TEXT_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> *(.gnu.linkonce.t*)
> }
>
>diff --git a/arch/ia64/lib/flush.S b/arch/ia64/lib/flush.S
>index 1d8c88860063..7f257810e858 100644
>--- a/arch/ia64/lib/flush.S
>+++ b/arch/ia64/lib/flush.S
>@@ -20,7 +20,7 @@
> *
> * Note: "in0" and "in1" are preserved for debugging purposes.
> */
>- .section .kprobes.text,"ax"
>+ .section .text.tbl.kprobes.all,"ax"
> GLOBAL_ENTRY(flush_icache_range)
>
> .prologue
>@@ -72,7 +72,7 @@ END(flush_icache_range)
> *
> * Note: "in0" and "in1" are preserved for debugging purposes.
> */
>- .section .kprobes.text,"ax"
>+ .section .text.tbl.kprobes.all,"ax"
> GLOBAL_ENTRY(clflush_cache_range)
>
> .prologue
>diff --git a/arch/metag/kernel/vmlinux.lds.S b/arch/metag/kernel/vmlinux.lds.S
>index e12055e88bfe..da1689c85bc8 100644
>--- a/arch/metag/kernel/vmlinux.lds.S
>+++ b/arch/metag/kernel/vmlinux.lds.S
>@@ -22,7 +22,6 @@ SECTIONS
> TEXT_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> IRQENTRY_TEXT
> *(.text.*)
> *(.gnu.warning)
>diff --git a/arch/microblaze/kernel/vmlinux.lds.S b/arch/microblaze/kernel/vmlinux.lds.S
>index be9488d69734..94c1c5574a77 100644
>--- a/arch/microblaze/kernel/vmlinux.lds.S
>+++ b/arch/microblaze/kernel/vmlinux.lds.S
>@@ -34,7 +34,6 @@ SECTIONS {
> EXIT_CALL
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> IRQENTRY_TEXT
> . = ALIGN (4) ;
> _etext = . ;
>diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
>index 0a93e83cd014..9183e9235651 100644
>--- a/arch/mips/kernel/vmlinux.lds.S
>+++ b/arch/mips/kernel/vmlinux.lds.S
>@@ -56,7 +56,6 @@ SECTIONS
> TEXT_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> IRQENTRY_TEXT
> *(.text.*)
> *(.fixup)
>diff --git a/arch/mn10300/kernel/vmlinux.lds.S b/arch/mn10300/kernel/vmlinux.lds.S
>index 13c4814c29f8..ead5efc01802 100644
>--- a/arch/mn10300/kernel/vmlinux.lds.S
>+++ b/arch/mn10300/kernel/vmlinux.lds.S
>@@ -31,7 +31,6 @@ SECTIONS
> TEXT_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> *(.fixup)
> *(.gnu.warning)
> } = 0xcb
>diff --git a/arch/nios2/kernel/vmlinux.lds.S b/arch/nios2/kernel/vmlinux.lds.S
>index 326fab40a9de..dc8a84183700 100644
>--- a/arch/nios2/kernel/vmlinux.lds.S
>+++ b/arch/nios2/kernel/vmlinux.lds.S
>@@ -39,7 +39,6 @@ SECTIONS
> SCHED_TEXT
> LOCK_TEXT
> IRQENTRY_TEXT
>- KPROBES_TEXT
> } =0
> _etext = .;
>
>diff --git a/arch/openrisc/kernel/vmlinux.lds.S b/arch/openrisc/kernel/vmlinux.lds.S
>index 2d69a853b742..b010cb75edc4 100644
>--- a/arch/openrisc/kernel/vmlinux.lds.S
>+++ b/arch/openrisc/kernel/vmlinux.lds.S
>@@ -48,7 +48,6 @@ SECTIONS
> TEXT_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> IRQENTRY_TEXT
> *(.fixup)
> *(.text.__*)
>diff --git a/arch/parisc/kernel/vmlinux.lds.S b/arch/parisc/kernel/vmlinux.lds.S
>index 308f29081d46..9d9dc4984465 100644
>--- a/arch/parisc/kernel/vmlinux.lds.S
>+++ b/arch/parisc/kernel/vmlinux.lds.S
>@@ -70,7 +70,6 @@ SECTIONS
> TEXT_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> IRQENTRY_TEXT
> *(.text.do_softirq)
> *(.text.sys_exit)
>diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
>index 499d9f89435a..4e36e86338f3 100644
>--- a/arch/powerpc/include/asm/ppc_asm.h
>+++ b/arch/powerpc/include/asm/ppc_asm.h
>@@ -218,7 +218,7 @@ name: \
> .localentry name,.-name
>
> #define _KPROBE(name) \
>- .section ".kprobes.text","a"; \
>+ .section ".text.tbl.kprobes.all","a"; \
> .align 2 ; \
> .type name,@function; \
> .globl name; \
>@@ -248,7 +248,7 @@ GLUE(.,name):
> #define _GLOBAL_TOC(name) _GLOBAL(name)
>
> #define _KPROBE(name) \
>- .section ".kprobes.text","a"; \
>+ .section ".text.tbl.kprobes.all","a"; \
> .align 2 ; \
> .globl name; \
> .globl GLUE(.,name); \
>@@ -280,7 +280,7 @@ n:
> #define _GLOBAL_TOC(name) _GLOBAL(name)
>
> #define _KPROBE(n) \
>- .section ".kprobes.text","a"; \
>+ .section ".text.tbl.kprobes.all","a"; \
> .globl n; \
> n:
>
>diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
>index d41fd0af8980..8779ae180783 100644
>--- a/arch/powerpc/kernel/vmlinux.lds.S
>+++ b/arch/powerpc/kernel/vmlinux.lds.S
>@@ -53,7 +53,6 @@ SECTIONS
> *(.text .fixup __ftr_alt_* .ref.text)
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> IRQENTRY_TEXT
>
> #ifdef CONFIG_PPC32
>diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
>index cd5a191381b9..b09aa9ab5a1f 100644
>--- a/arch/s390/kernel/entry.S
>+++ b/arch/s390/kernel/entry.S
>@@ -162,7 +162,7 @@ _PIF_WORK = (_PIF_PER_TRAP)
> tm off+\addr, \mask
> .endm
>
>- .section .kprobes.text, "ax"
>+ .section .text.tbl.kprobes.all, "ax"
>
> /*
> * Scheduler resume function, called by switch_to
>@@ -965,7 +965,7 @@ ENTRY(restart_int_handler)
> brc 2,2b
> 3: j 3b
>
>- .section .kprobes.text, "ax"
>+ .section .text.tbl.kprobes.all, "ax"
>
> #ifdef CONFIG_CHECK_STACK
> /*
>diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
>index 250f5972536a..376d4bd487c5 100644
>--- a/arch/s390/kernel/kprobes.c
>+++ b/arch/s390/kernel/kprobes.c
>@@ -288,7 +288,7 @@ static void kprobe_reenter_check(struct kprobe_ctlblk *kcb, struct kprobe *p)
> default:
> /*
> * A kprobe on the code path to single step an instruction
>- * is a BUG. The code path resides in the .kprobes.text
>+ * is a BUG. The code path resides in the .text.tbl.kprobes.all
> * section and is executed with interrupts disabled.
> */
> printk(KERN_EMERG "Invalid kprobe detected at %p.\n", p->addr);
>diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S
>index e499370fbccb..4572045b968e 100644
>--- a/arch/s390/kernel/mcount.S
>+++ b/arch/s390/kernel/mcount.S
>@@ -10,7 +10,7 @@
> #include <asm/ftrace.h>
> #include <asm/ptrace.h>
>
>- .section .kprobes.text, "ax"
>+ .section .text.tbl.kprobes.all, "ax"
>
> ENTRY(ftrace_stub)
> br %r14
>diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
>index 445657fe658c..4614b5bcab5e 100644
>--- a/arch/s390/kernel/vmlinux.lds.S
>+++ b/arch/s390/kernel/vmlinux.lds.S
>@@ -26,7 +26,6 @@ SECTIONS
> TEXT_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> IRQENTRY_TEXT
> *(.fixup)
> *(.gnu.warning)
>diff --git a/arch/score/kernel/vmlinux.lds.S b/arch/score/kernel/vmlinux.lds.S
>index 7274b5c4287e..36ebcb3b1215 100644
>--- a/arch/score/kernel/vmlinux.lds.S
>+++ b/arch/score/kernel/vmlinux.lds.S
>@@ -41,7 +41,6 @@ SECTIONS
> TEXT_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> *(.text.*)
> *(.fixup)
> . = ALIGN (4) ;
>diff --git a/arch/sh/kernel/vmlinux.lds.S b/arch/sh/kernel/vmlinux.lds.S
>index db88cbf9eafd..af4f37375345 100644
>--- a/arch/sh/kernel/vmlinux.lds.S
>+++ b/arch/sh/kernel/vmlinux.lds.S
>@@ -37,7 +37,6 @@ SECTIONS
> EXTRA_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> IRQENTRY_TEXT
> *(.fixup)
> *(.gnu.warning)
>diff --git a/arch/sparc/kernel/vmlinux.lds.S b/arch/sparc/kernel/vmlinux.lds.S
>index f1a2f688b28a..a1c8e3a3ebb6 100644
>--- a/arch/sparc/kernel/vmlinux.lds.S
>+++ b/arch/sparc/kernel/vmlinux.lds.S
>@@ -46,7 +46,6 @@ SECTIONS
> TEXT_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> IRQENTRY_TEXT
> *(.gnu.warning)
> } = 0
>diff --git a/arch/sparc/mm/ultra.S b/arch/sparc/mm/ultra.S
>index b4f4733abc6e..a08fb40656ac 100644
>--- a/arch/sparc/mm/ultra.S
>+++ b/arch/sparc/mm/ultra.S
>@@ -148,7 +148,7 @@ __spitfire_flush_tlb_mm_slow:
> /*
> * The following code flushes one page_size worth.
> */
>- .section .kprobes.text, "ax"
>+ .section .text.tbl.kprobes.all, "ax"
> .align 32
> .globl __flush_icache_page
> __flush_icache_page: /* %o0 = phys_page */
>diff --git a/arch/tile/kernel/vmlinux.lds.S b/arch/tile/kernel/vmlinux.lds.S
>index 0e059a0101ea..0f04268fc394 100644
>--- a/arch/tile/kernel/vmlinux.lds.S
>+++ b/arch/tile/kernel/vmlinux.lds.S
>@@ -43,7 +43,6 @@ SECTIONS
> HEAD_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> IRQENTRY_TEXT
> __fix_text_end = .; /* tile-cpack won't rearrange before this */
> ALIGN_FUNCTION();
>diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
>index 1deffe6cc873..dde4ec0e0185 100644
>--- a/arch/x86/kernel/kprobes/core.c
>+++ b/arch/x86/kernel/kprobes/core.c
>@@ -577,7 +577,10 @@ static int reenter_kprobe(struct kprobe *p, struct pt_regs *regs,
> case KPROBE_REENTER:
> /* A probe has been hit in the codepath leading up to, or just
> * after, single-stepping of a probed instruction. This entire
>- * codepath should strictly reside in .kprobes.text section.
>+ * codepath should strictly reside in the kprobes section:
>+ *
>+ * SECTION_TBL(SECTION_TEXT, kprobes, all)
>+ *
> * Raise a BUG or we'll continue in an endless reentering loop
> * and eventually a stack overflow.
> */
>@@ -1114,10 +1117,9 @@ NOKPROBE_SYMBOL(longjmp_break_handler);
>
> bool arch_within_kprobe_blacklist(unsigned long addr)
> {
>- return (addr >= (unsigned long)__kprobes_text_start &&
>- addr < (unsigned long)__kprobes_text_end) ||
>+ return (LINKTABLE_ADDR_WITHIN(kprobes, addr) ||
> (addr >= (unsigned long)__entry_text_start &&
>- addr < (unsigned long)__entry_text_end);
>+ addr < (unsigned long)__entry_text_end));
> }
>
> int __init arch_init_kprobes(void)
>diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
>index 74e4bf11f562..80a9f9106d2a 100644
>--- a/arch/x86/kernel/vmlinux.lds.S
>+++ b/arch/x86/kernel/vmlinux.lds.S
>@@ -99,7 +99,6 @@ SECTIONS
> TEXT_TEXT
> SCHED_TEXT
> LOCK_TEXT
>- KPROBES_TEXT
> ENTRY_TEXT
> IRQENTRY_TEXT
> *(.fixup)
>diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
>index f5ea98bd85d2..0438aab5cb58 100644
>--- a/include/asm-generic/sections.h
>+++ b/include/asm-generic/sections.h
>@@ -24,7 +24,7 @@
> * Following global variables are optional and may be unavailable on some
> * architectures and/or kernel configurations.
> * _text, _data
>- * __kprobes_text_start, __kprobes_text_end
>+ * LINKTABLE_START(kprobes), LINKTABLE_END(kprobes)
> * __entry_text_start, __entry_text_end
> * __ctors_start, __ctors_end
> */
>@@ -35,7 +35,7 @@ extern char __init_begin[], __init_end[];
> extern char _sinittext[], _einittext[];
> extern char _end[];
> extern char __per_cpu_load[], __per_cpu_start[], __per_cpu_end[];
>-extern char __kprobes_text_start[], __kprobes_text_end[];
>+DECLARE_LINKTABLE_TEXT(char, kprobes);
> extern char __entry_text_start[], __entry_text_end[];
> extern char __start_rodata[], __end_rodata[];
>
>diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
>index c5fcac902cbe..f1420714a549 100644
>--- a/include/asm-generic/vmlinux.lds.h
>+++ b/include/asm-generic/vmlinux.lds.h
>@@ -112,15 +112,6 @@
> #define BRANCH_PROFILE()
> #endif
>
>-#ifdef CONFIG_KPROBES
>-#define KPROBE_BLACKLIST() . = ALIGN(8); \
>- VMLINUX_SYMBOL(__start_kprobe_blacklist) = .; \
>- *(_kprobe_blacklist) \
>- VMLINUX_SYMBOL(__stop_kprobe_blacklist) = .;
>-#else
>-#define KPROBE_BLACKLIST()
>-#endif
>-
> #ifdef CONFIG_EVENT_TRACING
> #define FTRACE_EVENTS() . = ALIGN(8); \
> VMLINUX_SYMBOL(__start_ftrace_events) = .; \
>@@ -433,12 +424,6 @@
> *(.spinlock.text) \
> VMLINUX_SYMBOL(__lock_text_end) = .;
>
>-#define KPROBES_TEXT \
>- ALIGN_FUNCTION(); \
>- VMLINUX_SYMBOL(__kprobes_text_start) = .; \
>- *(.kprobes.text) \
>- VMLINUX_SYMBOL(__kprobes_text_end) = .;
>-
> #define ENTRY_TEXT \
> ALIGN_FUNCTION(); \
> VMLINUX_SYMBOL(__entry_text_start) = .; \
>@@ -504,7 +489,6 @@
> *(.init.rodata) \
> FTRACE_EVENTS() \
> TRACE_SYSCALLS() \
>- KPROBE_BLACKLIST() \
> MEM_DISCARD(init.rodata) \
> CLK_OF_TABLES() \
> RESERVEDMEM_OF_TABLES() \
>diff --git a/include/linux/compiler.h b/include/linux/compiler.h
>index 00b042c49ccd..8e33fc1ffd3c 100644
>--- a/include/linux/compiler.h
>+++ b/include/linux/compiler.h
>@@ -546,7 +546,8 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
>
> /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
> #ifdef CONFIG_KPROBES
>-# define __kprobes __attribute__((__section__(".kprobes.text")))
>+#include <linux/sections.h>
>+# define __kprobes __attribute__((__section__(SECTION_TBL(SECTION_TEXT, kprobes, all))))
> # define nokprobe_inline __always_inline
> #else
> # define __kprobes
>diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
>index 8f6849084248..544eb59cdbb9 100644
>--- a/include/linux/kprobes.h
>+++ b/include/linux/kprobes.h
>@@ -42,8 +42,12 @@
> #include <linux/ftrace.h>
>
> #ifdef CONFIG_KPROBES
>+#include <linux/tables.h>
> #include <asm/kprobes.h>
>
>+DECLARE_LINKTABLE_TEXT(char, kprobes);
>+DECLARE_LINKTABLE_INIT_DATA(unsigned long, _kprobe_blacklist);
>+
> /* kprobe_status settings */
> #define KPROBE_HIT_ACTIVE 0x00000001
> #define KPROBE_HIT_SS 0x00000002
>@@ -487,8 +491,7 @@ static inline int enable_jprobe(struct jprobe *jp)
> * by using this macro.
> */
> #define __NOKPROBE_SYMBOL(fname) \
>-static unsigned long __used \
>- __attribute__((section("_kprobe_blacklist"))) \
>+static LINKTABLE_INIT_DATA(_kprobe_blacklist, all) \
> _kbl_addr_##fname = (unsigned long)fname;
> #define NOKPROBE_SYMBOL(fname) __NOKPROBE_SYMBOL(fname)
> #else
>diff --git a/kernel/kprobes.c b/kernel/kprobes.c
>index d10ab6b9b5e0..d816c659f358 100644
>--- a/kernel/kprobes.c
>+++ b/kernel/kprobes.c
>@@ -1328,8 +1328,7 @@ out:
> bool __weak arch_within_kprobe_blacklist(unsigned long addr)
> {
> /* The __kprobes marked functions and entry code must not be probed */
>- return addr >= (unsigned long)__kprobes_text_start &&
>- addr < (unsigned long)__kprobes_text_end;
>+ return LINKTABLE_ADDR_WITHIN(kprobes, addr);
> }
>
> bool within_kprobe_blacklist(unsigned long addr)
>@@ -2054,14 +2053,13 @@ NOKPROBE_SYMBOL(dump_kprobe);
> * since a kprobe need not necessarily be at the beginning
> * of a function.
> */
>-static int __init populate_kprobe_blacklist(unsigned long *start,
>- unsigned long *end)
>+static int __init populate_kprobe_blacklist(void)
> {
> unsigned long *iter;
> struct kprobe_blacklist_entry *ent;
> unsigned long entry, offset = 0, size = 0;
>
>- for (iter = start; iter < end; iter++) {
>+ LINKTABLE_FOR_EACH(iter, _kprobe_blacklist) {
> entry = arch_deref_entry_point((void *)*iter);
>
> if (!kernel_text_address(entry) ||
>@@ -2126,8 +2124,9 @@ static struct notifier_block kprobe_module_nb = {
> };
>
> /* Markers of _kprobe_blacklist section */
>-extern unsigned long __start_kprobe_blacklist[];
>-extern unsigned long __stop_kprobe_blacklist[];
>+DEFINE_LINKTABLE_INIT_DATA(unsigned long, _kprobe_blacklist);
>+/* Actual kprobes linker table */
>+DEFINE_LINKTABLE_TEXT(char, kprobes);
>
> static int __init init_kprobes(void)
> {
>@@ -2141,8 +2140,7 @@ static int __init init_kprobes(void)
> raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
> }
>
>- err = populate_kprobe_blacklist(__start_kprobe_blacklist,
>- __stop_kprobe_blacklist);
>+ err = populate_kprobe_blacklist();
> if (err) {
> pr_err("kprobes: failed to populate blacklist: %d\n", err);
> pr_err("Please take care of using kprobes.\n");
>diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
>index 48958d3cec9e..b0a8f519efb8 100644
>--- a/scripts/mod/modpost.c
>+++ b/scripts/mod/modpost.c
>@@ -22,6 +22,7 @@
> #include "../../include/generated/autoconf.h"
> #include "../../include/linux/license.h"
> #include "../../include/linux/export.h"
>+#include "../../include/linux/sections.h"
>
> /* Are we using CONFIG_MODVERSIONS? */
> static int modversions = 0;
>@@ -888,7 +889,7 @@ static void check_section(const char *modname, struct elf_info *elf,
>
> #define DATA_SECTIONS ".data", ".data.rel"
> #define TEXT_SECTIONS ".text", ".text.unlikely", ".sched.text", \
>- ".kprobes.text"
>+ SECTION_TBL(SECTION_TEXT, kprobes, all)
> #define OTHER_TEXT_SECTIONS ".ref.text", ".head.text", ".spinlock.text", \
> ".fixup", ".entry.text", ".exception.text", ".text.*", \
> ".coldtext"
>diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
>index e167592793a7..f37dac17f033 100644
>--- a/scripts/recordmcount.c
>+++ b/scripts/recordmcount.c
>@@ -32,6 +32,7 @@
> #include <stdlib.h>
> #include <string.h>
> #include <unistd.h>
>+#include "../../include/linux/sections.h"
>
> #ifndef EM_METAG
> /* Remove this when these make it to the standard system elf.h. */
>@@ -356,7 +357,7 @@ is_mcounted_section_name(char const *const txtname)
> strcmp(".sched.text", txtname) == 0 ||
> strcmp(".spinlock.text", txtname) == 0 ||
> strcmp(".irqentry.text", txtname) == 0 ||
>- strcmp(".kprobes.text", txtname) == 0 ||
>+ strcmp(SECTION_TBL(SECTION_TEXT, kprobe, all), txtname) == 0 ||
> strcmp(".text.unlikely", txtname) == 0;
> }
>
>diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
>index 96e2486a6fc4..63e13009dda9 100755
>--- a/scripts/recordmcount.pl
>+++ b/scripts/recordmcount.pl
>@@ -134,7 +134,7 @@ my %text_sections = (
> ".sched.text" => 1,
> ".spinlock.text" => 1,
> ".irqentry.text" => 1,
>- ".kprobes.text" => 1,
>+ ".text.tbl.kprobes.all" => 1,
> ".text.unlikely" => 1,
> );
>
>--
>2.7.0
^ permalink raw reply [flat|nested] 46+ messages in thread* Re: [Xen-devel] [RFC v2 7/7] kprobes: port to linker table
2016-02-22 1:34 ` 平松雅巳 / HIRAMATU，MASAMI
@ 2016-02-23 0:52 ` Luis R. Rodriguez
2016-07-21 23:53 ` Luis R. Rodriguez
0 siblings, 1 reply; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-23 0:52 UTC (permalink / raw)
To: 平松雅巳 / HIRAMATU，MASAMI
Cc: 'Luis R. Rodriguez',
hpa, tglx, mingo, bp, benh, ming.lei, linux-arch, xen-devel,
linux, x86, anil.s.keshavamurthy, arnd, rusty, jbaron,
boris.ostrovsky, andriy.shevchenko, mcb30, jgross
On Mon, Feb 22, 2016 at 01:34:05AM +0000, 平松雅巳 / HIRAMATU，MASAMI wrote:
> >From: Luis R. Rodriguez [mailto:mcgrof@kernel.org]
> >
> >kprobe makes use of two custom sections:
> >
> >type name begin end
> >init.data _kprobe_blacklist __start_kprobe_blacklist __stop_kprobe_blacklist
> >text .kprobes.text __kprobes_text_start __kprobes_text_end
> >
> >Port these to the linker table generic solution. This lets
> >us remove all the custom kprobe section declarations on the
> >linker script.
> >
> >Tested with CONFIG_KPROBES_SANITY_TEST, it passes with:
> >
> >Kprobe smoke test: started
> >Kprobe smoke test: passed successfully
> >
> >Then tested CONFIG_SAMPLE_KPROBES on do_fork, and the
> >kprobe bites and kicks as expected. Lastly tried registering
> >a kprobe on a kprobe blacklisted symbol (NOKPROBE_SYMBOL()),
> >and confirms that fails to work.
>
> Could you also check to run the testcases by using ftracetest as below?
>
> $ cd tools/testing/selftests/ftrace/
> $ sudo ./ftracetest
Sure, it all passed:
$ sudo ./ftracetest
=== Ftrace unit tests ===
[1] Basic trace file check [PASS]
[2] Basic test for tracers [PASS]
[3] Basic trace clock test [PASS]
[4] Basic event tracing check [PASS]
[5] event tracing - enable/disable with event level files [PASS]
[6] event tracing - enable/disable with subsystem level files [PASS]
[7] event tracing - enable/disable with top level files [PASS]
[8] ftrace - function graph filters with stack tracer [PASS]
[9] ftrace - function graph filters [PASS]
[10] ftrace - function profiler with function tracing [PASS]
[11] Test creation and deletion of trace instances [PASS]
[12] Kprobe dynamic event - adding and removing [PASS]
[13] Kprobe dynamic event - busy event check [PASS]
[14] Kprobe dynamic event with arguments [PASS]
[15] Kprobe dynamic event with function tracer [PASS]
[16] Kretprobe dynamic event with arguments [PASS]
# of passed: 16
# of failed: 0
# of unresolved: 0
# of untested: 0
# of unsupported: 0
# of xfailed: 0
# of undefined(test bug): 0
> And I'm not sure about linker table.
So there's really a few parts to the linker table work, out of
the ones that relate to kprobes:
* linker tables try to generalize our section use, and provide some
helpers for common section use
* provides helpers to make it easier to make custom section,
but by re-using standard sections
* when a custom section uses standard sections and helpers
we also get a few gains:
- developers reviewing code can more easily get a quicker
understanding and have expectations set of how the code
feature using the custom section could be used
- people grep'ing on the kernel can more easily find
specific types of custom section use by looking for
the type of interest
- developers adding features do not need to modify
any linker scripts (vmlinux.lds.S) to make use of
custom sections
In kprobe's case, since it uses two custom sections, we have
only a small use for the first case: .kprobe.text is just used
as a place holder for future developer annotated special cased
executable code. It also makes use of the generic helpers:
LINKTABLE_ADDR_WITHIN(), LINKTABLE_START(), LINKTABLE_END().
The second use case, for the _kprobe_blacklist, makes much more
use of the more advanced linker table helpers, for instance the
iterator LINKTABLE_FOR_EACH().
For both though we now have each custom section's actual section
clearly highlighted:
* kprobes: .text (SECTION_TEXT)
* kprobe blacklist: init.data (SECTION_INIT_DATA)
A reader / developer can more easily gain an understanding
of how the above custom sections could be used just by its
type.
Another feature of linker tables, but outside of the scope of how kprobe
would use linker tables, is the ability to enable folks to avoid code
bit rot by using table-$(CONFIG_FOO) instead of oby-$(CONFIG_FOO) on
init paths of code but since this is outside of the scope of how kprobe would
use I leave that just as a reference as another part of linker table.
Unless of course you want to make people force compile all kprobe
support code but only have it linked in when actually enabled. That
would be outside of the scope and purpose of this patch though.
> Is that possible to support
> __kprobes prefix, which moves the functions into kprobes.text?
Absolutely, the respective change was just to annotate and make
it clear the section kprobes were using:
-# define __kprobes __attribute__((__section__(".kprobes.text")))
+#include <linux/sections.h>
+# define __kprobes __attribute__((__section__(SECTION_TBL(SECTION_TEXT, kprobes, all))))
> Actually, I'm on the way to replacing __kprobes to NOKPROBE_SYMBOL
> macro, since NOKPROBE_SYMBOL() doesn't effect the kernel text itself.
> On x86, it is already replaced (see commit 820aede0209a), and same
> work should be done on other archs. So, could you hold this after
> that?
Sure.
> I think we should remove .kprobes.text first
You mean just remove the incorrect users of .kprobes.text because as I read
what you described above we have abuse of __kprobes use to protect against
kprobes being introduced on those routines, and we should be using
NOKPROBE_SYMBOL() instead. So from what I gather its not that you will
remove .kprobes.text but rather clean our current abuse of __kprobes
for protection to use NOKPROBE_SYMBOL() instead. Is that right?
> and move to linker table.
Sure, can you Cc me on your patches? I can follow up later.
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread* Re: [Xen-devel] [RFC v2 7/7] kprobes: port to linker table
2016-02-23 0:52 ` [Xen-devel] " Luis R. Rodriguez
@ 2016-07-21 23:53 ` Luis R. Rodriguez
0 siblings, 0 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-07-21 23:53 UTC (permalink / raw)
To: Luis R. Rodriguez
Cc: 平松雅巳 / HIRAMATU，MASAMI, hpa,
tglx, mingo, bp, benh, ming.lei, linux-arch, xen-devel, linux,
x86, anil.s.keshavamurthy, arnd, rusty, jbaron, boris.ostrovsky,
andriy.shevchenko
On Tue, Feb 23, 2016 at 01:52:44AM +0100, Luis R. Rodriguez wrote:
> On Mon, Feb 22, 2016 at 01:34:05AM +0000, 平松雅巳 / HIRAMATU，MASAMI wrote:
> > >From: Luis R. Rodriguez [mailto:mcgrof@kernel.org]
> > >
> > >kprobe makes use of two custom sections:
> > >
> > >type name begin end
> > >init.data _kprobe_blacklist __start_kprobe_blacklist __stop_kprobe_blacklist
> > >text .kprobes.text __kprobes_text_start __kprobes_text_end
> > >
> > >Port these to the linker table generic solution. This lets
> > >us remove all the custom kprobe section declarations on the
> > >linker script.
> > >
> > >Tested with CONFIG_KPROBES_SANITY_TEST, it passes with:
> > >
> > >Kprobe smoke test: started
> > >Kprobe smoke test: passed successfully
> > >
> > >Then tested CONFIG_SAMPLE_KPROBES on do_fork, and the
> > >kprobe bites and kicks as expected. Lastly tried registering
> > >a kprobe on a kprobe blacklisted symbol (NOKPROBE_SYMBOL()),
> > >and confirms that fails to work.
> >
> > Could you also check to run the testcases by using ftracetest as below?
> >
> > $ cd tools/testing/selftests/ftrace/
> > $ sudo ./ftracetest
>
> Sure, it all passed:
>
> $ sudo ./ftracetest
> === Ftrace unit tests ===
> [1] Basic trace file check [PASS]
> [2] Basic test for tracers [PASS]
> [3] Basic trace clock test [PASS]
> [4] Basic event tracing check [PASS]
> [5] event tracing - enable/disable with event level files [PASS]
> [6] event tracing - enable/disable with subsystem level files [PASS]
> [7] event tracing - enable/disable with top level files [PASS]
> [8] ftrace - function graph filters with stack tracer [PASS]
> [9] ftrace - function graph filters [PASS]
> [10] ftrace - function profiler with function tracing [PASS]
> [11] Test creation and deletion of trace instances [PASS]
> [12] Kprobe dynamic event - adding and removing [PASS]
> [13] Kprobe dynamic event - busy event check [PASS]
> [14] Kprobe dynamic event with arguments [PASS]
> [15] Kprobe dynamic event with function tracer [PASS]
> [16] Kretprobe dynamic event with arguments [PASS]
>
> # of passed: 16
> # of failed: 0
> # of unresolved: 0
> # of untested: 0
> # of unsupported: 0
> # of xfailed: 0
> # of undefined(test bug): 0
The number of tests have grown, this still passes in the new rebase.
> > And I'm not sure about linker table.
>
> So there's really a few parts to the linker table work, out of
> the ones that relate to kprobes:
>
> * linker tables try to generalize our section use, and provide some
> helpers for common section use
> * provides helpers to make it easier to make custom section,
> but by re-using standard sections
> * when a custom section uses standard sections and helpers
> we also get a few gains:
> - developers reviewing code can more easily get a quicker
> understanding and have expectations set of how the code
> feature using the custom section could be used
> - people grep'ing on the kernel can more easily find
> specific types of custom section use by looking for
> the type of interest
> - developers adding features do not need to modify
> any linker scripts (vmlinux.lds.S) to make use of
> custom sections
>
> In kprobe's case, since it uses two custom sections, we have
> only a small use for the first case: .kprobe.text is just used
> as a place holder for future developer annotated special cased
> executable code. It also makes use of the generic helpers:
> LINKTABLE_ADDR_WITHIN(), LINKTABLE_START(), LINKTABLE_END().
>
> The second use case, for the _kprobe_blacklist, makes much more
> use of the more advanced linker table helpers, for instance the
> iterator LINKTABLE_FOR_EACH().
>
> For both though we now have each custom section's actual section
> clearly highlighted:
>
> * kprobes: .text (SECTION_TEXT)
> * kprobe blacklist: init.data (SECTION_INIT_DATA)
I ended up splitting this in two patches, in the new v3 series
kprobes will go under a simple section range, while the blacklist
stuff gets its linker table.
> A reader / developer can more easily gain an understanding
> of how the above custom sections could be used just by its
> type.
>
> Another feature of linker tables, but outside of the scope of how kprobe
> would use linker tables, is the ability to enable folks to avoid code
> bit rot by using table-$(CONFIG_FOO) instead of oby-$(CONFIG_FOO) on
> init paths of code but since this is outside of the scope of how kprobe would
> use I leave that just as a reference as another part of linker table.
> Unless of course you want to make people force compile all kprobe
> support code but only have it linked in when actually enabled. That
> would be outside of the scope and purpose of this patch though.
>
> > Is that possible to support
> > __kprobes prefix, which moves the functions into kprobes.text?
>
> Absolutely, the respective change was just to annotate and make
> it clear the section kprobes were using:
>
> -# define __kprobes __attribute__((__section__(".kprobes.text")))
> +#include <linux/sections.h>
> +# define __kprobes __attribute__((__section__(SECTION_TBL(SECTION_TEXT, kprobes, all))))
>
> > Actually, I'm on the way to replacing __kprobes to NOKPROBE_SYMBOL
> > macro, since NOKPROBE_SYMBOL() doesn't effect the kernel text itself.
> > On x86, it is already replaced (see commit 820aede0209a), and same
> > work should be done on other archs. So, could you hold this after
> > that?
>
> Sure.
>
> > I think we should remove .kprobes.text first
>
> You mean just remove the incorrect users of .kprobes.text because as I read
> what you described above we have abuse of __kprobes use to protect against
> kprobes being introduced on those routines, and we should be using
> NOKPROBE_SYMBOL() instead. So from what I gather its not that you will
> remove .kprobes.text but rather clean our current abuse of __kprobes
> for protection to use NOKPROBE_SYMBOL() instead. Is that right?
I never heard back :(
> > and move to linker table.
>
> Sure, can you Cc me on your patches? I can follow up later.
And I was never Cc'd on these patches so its unclear if this work
is done. I'll be posting a v3 series now.
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [RFC v2 0/7] linux: add linker tables
2016-02-19 13:45 [RFC v2 0/7] linux: add linker tables Luis R. Rodriguez
` (6 preceding siblings ...)
2016-02-19 13:45 ` [RFC v2 7/7] kprobes: port to linker table Luis R. Rodriguez
@ 2016-02-19 20:16 ` H. Peter Anvin
2016-02-19 21:19 ` Luis R. Rodriguez
7 siblings, 1 reply; 46+ messages in thread
From: H. Peter Anvin @ 2016-02-19 20:16 UTC (permalink / raw)
To: Luis R. Rodriguez, tglx, mingo, bp
Cc: x86, linux-kernel, luto, boris.ostrovsky, rusty, david.vrabel,
konrad.wilk, mcb30, jgross, ming.lei, gregkh, arnd, linux-arch,
linux, benh, jbaron, ananth, anil.s.keshavamurthy, davem,
masami.hiramatsu.pt, andriy.shevchenko, dwmw2, xen-devel
On 02/19/2016 05:45 AM, Luis R. Rodriguez wrote:
> This is my v2 of the original linker table work [0], now with
> six proof of concepts ports of existing code using custom section
> with custom linker script modifications:
>
> * DEFINE_LINKTABLE_TEXT(char, kprobes);
> * DEFINE_LINKTABLE_DATA(struct jump_entry, __jump_table);
> * DEFINE_LINKTABLE_DATA(struct _ddebug, __verbose);
> * DEFINE_LINKTABLE_RO(struct builtin_fw, builtin_fw);
> * DEFINE_LINKTABLE_INIT(struct x86_init_fn, x86_init_fns);
> * DEFINE_LINKTABLE_INIT_DATA(unsigned long, _kprobe_blacklist);
>
> I've tested all except jump tables, I'd appreaciate some help with that.
>
We should add support for read-mostly, probably. In fact, some of these
probably *are* read-mostly.
-hpa
^ permalink raw reply [flat|nested] 46+ messages in thread* Re: [RFC v2 0/7] linux: add linker tables
2016-02-19 20:16 ` [RFC v2 0/7] linux: add linker tables H. Peter Anvin
@ 2016-02-19 21:19 ` Luis R. Rodriguez
0 siblings, 0 replies; 46+ messages in thread
From: Luis R. Rodriguez @ 2016-02-19 21:19 UTC (permalink / raw)
To: H. Peter Anvin
Cc: Luis R. Rodriguez, tglx, mingo, bp, x86, linux-kernel, luto,
boris.ostrovsky, rusty, david.vrabel, konrad.wilk, mcb30, jgross,
ming.lei, gregkh, arnd, linux-arch, linux, benh, jbaron, ananth,
anil.s.keshavamurthy, davem, masami.hiramatsu.pt,
andriy.shevchenko, dwmw2, xen-devel
On Fri, Feb 19, 2016 at 12:16:29PM -0800, H. Peter Anvin wrote:
> On 02/19/2016 05:45 AM, Luis R. Rodriguez wrote:
> > This is my v2 of the original linker table work [0], now with
> > six proof of concepts ports of existing code using custom section
> > with custom linker script modifications:
> >
> > * DEFINE_LINKTABLE_TEXT(char, kprobes);
> > * DEFINE_LINKTABLE_DATA(struct jump_entry, __jump_table);
> > * DEFINE_LINKTABLE_DATA(struct _ddebug, __verbose);
> > * DEFINE_LINKTABLE_RO(struct builtin_fw, builtin_fw);
> > * DEFINE_LINKTABLE_INIT(struct x86_init_fn, x86_init_fns);
> > * DEFINE_LINKTABLE_INIT_DATA(unsigned long, _kprobe_blacklist);
> >
> > I've tested all except jump tables, I'd appreaciate some help with that.
> >
>
> We should add support for read-mostly, probably.
Sure, any candidate in mind? I actually don't see any hacks built
on top of READ_MOSTLY_DATA include/asm-generic/vmlinux.lds.h so
pointers appreciated for a case I could try.
> In fact, some of these probably *are* read-mostly.
To avoid regressions I made sure to use the same exact section that
these original solutions came from, do we want to move some? If so
I think perhaps that's best done as a separate atomic patch and
it may be easier to read and review once ported on linker tables?
Luis
^ permalink raw reply [flat|nested] 46+ messages in thread