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From: Martijn Coenen <maco@android.com>
To: Jessica Yu <jeyu@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Michal Marek <michal.lkml@markovi.net>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	"the arch/x86 maintainers" <x86@kernel.org>,
	Alan Stern <stern@rowland.harvard.edu>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Oliver Neukum <oneukum@suse.com>, Arnd Bergmann <arnd@arndb.de>,
	Stephen Boyd <sboyd@codeaurora.org>,
	Philippe Ombredanne <pombredanne@nexb.com>,
	Kate Stewart <kstewart@linuxfoundation.org>,
	Sam Ravnborg <sam@ravnborg.org>,
	linux-kbuild@vger.kernel.org,
	linux-m68k <linux-m68k@lists.linux-m68k.org>,
	USB list <linux-usb@vger.kernel.org>,
	USB Storage list <usb-storage@lists.one-eyed-alien.net>,
	linux-scsi@vger.kernel.org,
	Linux-Arch <linux-arch@vger.kernel.org>,
	Martijn Coenen <maco@google.com>,
	Sandeep Patil <sspatil@google.com>,
	Iliyan Malchev <malchev@google.com>,
	Joel Fernandes <joelaf@google.com>
Subject: Re: [PATCH 2/6] module: add support for symbol namespaces.
Date: Fri, 20 Jul 2018 09:54:16 +0200
Message-ID: <CAB0TPYFVSWtJ6RPRUZ1bpS-rBaV7YyPR-4B2Ogxs+FNAbiScNw@mail.gmail.com> (raw)
In-Reply-To: <20180719163208.5xvrafugpcbhh7kj@linux-8ccs>

Hi Jessica,

On Thu, Jul 19, 2018 at 6:32 PM, Jessica Yu <jeyu@kernel.org> wrote:
> First, thanks a lot for the patchset. This is definitely something that
> will help distros as well to declutter the exported symbol space and
> provide a more cleanly defined kernel interface.

Thanks, that's good to hear!


> Hm, I'm wondering if we could avoid all this extra module-ns-dependency
> checking work if we just put the import stuff as a modinfo tag, like
> have MODULE_IMPORT_NS() insert an "import:" tag like we already do for
> module parameters, author, license, aliases, etc. Then we'd have that
> information pretty much from the start of load_module() and we don't
> need to wait for relocations to be applied to __knsimport. Then you
> could do the namespace checking right at resolve_symbol() instead of
> going through the extra step of building a dependency list to be
> verified later.

I believe I did consider modinfo when I started with this a while
back, but don't recall right now why I didn't decide to use it;
perhaps it was the lack of support for multiple identical tags. Since
both modpost and the module loader have access to them, I don't see
why it wouldn't work, and indeed I suspect it would make the module
loader a bit simpler. I'll rework this and see what it looks like.

Thanks,
Martijn

>
> Also, this would get rid of the extra __knsimport section, the extra
> ns_dependencies field in struct module, and all those helper functions that
> manage it. In addition, having the modinfo tag may potentially help with
> debugging as we have the namespace imports clearly listed if we don't have
> the source code for a module. We'd probably need to modify get_modinfo() to
> handle multiple import: tags though. Luis [1] had written some code a while
> ago to handle multiple (of the same) modinfo tags.
>
> Thoughts on this?
>
> Thanks,
>
> Jessica
>
> [1] https://lkml.kernel.org/r/20171130023605.29568-3-mcgrof@kernel.org
>
>
>> getname:
>>         /* We must make copy under the lock if we failed to get ref. */
>>         strncpy(ownername, module_name(owner), MODULE_NAME_LEN);
>> @@ -3061,6 +3118,11 @@ static int find_module_sections(struct module *mod,
>> struct load_info *info)
>>                                      sizeof(*mod->gpl_syms),
>>                                      &mod->num_gpl_syms);
>>         mod->gpl_crcs = section_addr(info, "__kcrctab_gpl");
>> +
>> +       mod->ns_imports = section_objs(info, "__knsimport",
>> +                                      sizeof(*mod->ns_imports),
>> +                                      &mod->num_ns_imports);
>> +
>>         mod->gpl_future_syms = section_objs(info,
>>                                             "__ksymtab_gpl_future",
>>                                             sizeof(*mod->gpl_future_syms),
>> @@ -3381,6 +3443,19 @@ static int post_relocation(struct module *mod,
>> const struct load_info *info)
>>         return module_finalize(info->hdr, info->sechdrs, mod);
>> }
>>
>> +static void verify_namespace_dependencies(struct module *mod)
>> +{
>> +       struct module_ns_dep *ns_dep;
>> +
>> +       list_for_each_entry(ns_dep, &mod->ns_dependencies, ns_dep) {
>> +               if (!module_imports_ns(mod, ns_dep->namespace)) {
>> +                       pr_warn("%s: module uses symbols from namespace
>> %s,"
>> +                               " but does not import it.\n",
>> +                               mod->name, ns_dep->namespace);
>> +               }
>> +       }
>> +}
>> +
>> /* Is this module of this name done loading?  No locks held. */
>> static bool finished_loading(const char *name)
>> {
>> @@ -3682,6 +3757,8 @@ static int load_module(struct load_info *info, const
>> char __user *uargs,
>>         if (err)
>>                 goto free_module;
>>
>> +       INIT_LIST_HEAD(&mod->ns_dependencies);
>> +
>> #ifdef CONFIG_MODULE_SIG
>>         mod->sig_ok = info->sig_ok;
>>         if (!mod->sig_ok) {
>> @@ -3730,6 +3807,8 @@ static int load_module(struct load_info *info, const
>> char __user *uargs,
>>         if (err < 0)
>>                 goto free_modinfo;
>>
>> +       verify_namespace_dependencies(mod);
>> +
>>         flush_module_icache(mod);
>>
>>         /* Now copy in args */
>> --
>> 2.18.0.203.gfac676dfb9-goog
>>
>

  reply index

Thread overview: 134+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-16 12:21 [PATCH 0/6] Symbol namespaces Martijn Coenen
2018-07-16 12:21 ` [PATCH 1/6] export: explicitly align struct kernel_symbol Martijn Coenen
2018-07-16 12:21 ` [PATCH 2/6] module: add support for symbol namespaces Martijn Coenen
2018-07-19 16:32   ` Jessica Yu
2018-07-20  7:54     ` Martijn Coenen [this message]
2018-07-20 14:49       ` Jessica Yu
2018-07-20 15:42         ` Martijn Coenen
2018-07-23 11:12           ` Jessica Yu
2018-07-24  7:44             ` Martijn Coenen
2018-07-24  7:56   ` Martijn Coenen
2018-07-25 15:55     ` Jessica Yu
2018-07-25 16:48       ` Lucas De Marchi
2018-07-26  7:44         ` Martijn Coenen
2018-07-16 12:21 ` [PATCH 3/6] modpost: add support for checking " Martijn Coenen
2018-07-16 12:21 ` [PATCH 4/6] modpost: add support for generating namespace dependencies Martijn Coenen
2018-07-23  6:49   ` Jessica Yu
2018-07-16 12:21 ` [PATCH 5/6] scripts: Coccinelle script for " Martijn Coenen
2018-07-16 12:21 ` [PATCH 6/6] RFC: USB: storage: move symbols into USB_STORAGE namespace Martijn Coenen
2018-07-17 15:04   ` Alan Stern
2018-07-18 13:28     ` Martijn Coenen
2018-07-16 15:33 ` [PATCH 0/6] Symbol namespaces Greg Kroah-Hartman
2018-07-23 14:28 ` Arnd Bergmann
2018-07-24  8:09   ` Martijn Coenen
2018-07-24  9:08     ` Arnd Bergmann
2019-08-13 12:16 ` [PATCH v2 0/10] Symbol namespaces - RFC Matthias Maennich
2019-08-13 12:16   ` [PATCH v2 01/10] module: support reading multiple values per modinfo tag Matthias Maennich
2019-08-13 12:40     ` Greg KH
2019-08-13 12:16   ` [PATCH v2 02/10] export: explicitly align struct kernel_symbol Matthias Maennich
2019-08-13 12:41     ` Greg KH
2019-08-13 12:17   ` [PATCH v2 03/10] module: add support for symbol namespaces Matthias Maennich
2019-08-13 15:26     ` Greg KH
2019-08-13 12:17   ` [PATCH v2 04/10] modpost: " Matthias Maennich
2019-08-13 15:27     ` Greg KH
2019-08-13 12:17   ` [PATCH v2 05/10] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-08-13 18:17     ` Greg KH
2019-08-13 20:15     ` Saravana Kannan
2019-08-14 12:54       ` Matthias Maennich
2019-08-14 17:34         ` Saravana Kannan
2019-08-13 12:17   ` [PATCH v2 06/10] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-08-13 18:16     ` Greg KH
2019-08-13 18:16     ` Greg KH
2019-08-13 12:17   ` [PATCH v2 07/10] modpost: add support for generating namespace dependencies Matthias Maennich
2019-08-13 18:21     ` Greg KH
2019-08-13 12:17   ` [PATCH v2 08/10] scripts: Coccinelle script for " Matthias Maennich
2019-08-13 12:31     ` Julia Lawall
2019-08-13 12:44     ` Greg KH
2019-08-14  6:36     ` [Cocci] " Himanshu Jha
2019-08-14  8:03       ` Matthias Maennich
2019-08-15 13:50     ` [v2 " Markus Elfring
2019-08-22  9:18       ` Matthias Maennich
2019-08-22 11:00         ` Markus Elfring
2019-08-13 12:17   ` [PATCH v2 09/10] usb-storage: remove single-use define for debugging Matthias Maennich
2019-08-13 12:42     ` Greg KH
2019-08-13 13:12       ` Greg KH
2019-08-13 12:17   ` [PATCH v2 10/10] RFC: usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-08-13 12:45     ` Greg KH
2019-08-13 12:47     ` Greg KH
2019-08-13 15:02       ` Matthias Maennich
     [not found]   ` <20190821114955.12788-1-maennich@google.com>
2019-08-21 11:49     ` [PATCH v3 01/11] module: support reading multiple values per modinfo tag Matthias Maennich
2019-08-21 11:49     ` [PATCH v3 02/11] export: explicitly align struct kernel_symbol Matthias Maennich
2019-08-21 11:49     ` [PATCH v3 03/11] module: add support for symbol namespaces Matthias Maennich
2019-08-27 15:37       ` Jessica Yu
2019-08-27 16:04         ` Matthias Maennich
2019-08-21 11:49     ` [PATCH v3 04/11] modpost: " Matthias Maennich
2019-08-26 16:21       ` Jessica Yu
2019-08-27 14:41         ` Matthias Maennich
2019-08-28  9:43           ` Jessica Yu
2019-08-28  9:55             ` Matthias Maennich
2019-08-28 10:16               ` Jessica Yu
2019-08-21 11:49     ` [PATCH v3 05/11] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-08-21 11:49     ` [PATCH v3 06/11] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-08-28 10:49       ` Jessica Yu
2019-08-28 10:56         ` Matthias Maennich
2019-08-21 11:49     ` [PATCH v3 07/11] modpost: add support for generating namespace dependencies Matthias Maennich
2019-08-21 11:49     ` [PATCH v3 08/11] scripts: Coccinelle script for " Matthias Maennich
2019-08-22  6:09       ` [v3 " Markus Elfring
2019-08-29 12:13       ` [PATCH v3 " Jessica Yu
2019-08-21 11:49     ` [PATCH v3 09/11] usb-storage: remove single-use define for debugging Matthias Maennich
2019-08-21 12:37       ` Greg KH
2019-08-21 13:21       ` Thomas Gleixner
2019-08-21 13:32         ` Greg KH
2019-08-21 11:49     ` [PATCH v3 10/11] RFC: usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-08-21 12:38       ` Greg KH
2019-08-21 14:36         ` Jessica Yu
2019-08-21 23:13       ` Christoph Hellwig
2019-08-22  8:32         ` Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 00/12] Symbol Namespaces Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 01/12] module: support reading multiple values per modinfo tag Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 02/12] export: explicitly align struct kernel_symbol Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 03/12] module: add support for symbol namespaces Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 04/12] modpost: " Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 05/12] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 06/12] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 07/12] modpost: add support for generating namespace dependencies Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 08/12] scripts: Coccinelle script for " Matthias Maennich
2019-09-04  9:53     ` Masahiro Yamada
2019-09-05 14:46       ` Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 09/12] docs: Add documentation for Symbol Namespaces Matthias Maennich
2019-09-04  7:16     ` Greg KH
2019-09-03 15:06   ` [PATCH v4 10/12] usb-storage: remove single-use define for debugging Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 11/12] RFC: usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 12/12] RFC: watchdog: export core symbols in WATCHDOG_CORE namespace Matthias Maennich
2019-09-03 16:10     ` Guenter Roeck
2019-09-04  8:45       ` Masahiro Yamada
2019-09-04 12:12         ` Guenter Roeck
2019-09-04 16:16           ` [usb-storage] " Matthew Dharm
2019-09-05 10:41             ` Jessica Yu
2019-09-05 10:52               ` Arnd Bergmann
2019-09-05 11:16                 ` Jessica Yu
2019-09-05 11:25                   ` Masahiro Yamada
2019-09-05 12:00                     ` Greg Kroah-Hartman
2019-09-05 11:25               ` Matthias Maennich
2019-09-04  9:37   ` [PATCH v4 00/12] Symbol Namespaces Masahiro Yamada
2019-09-06 10:32 ` [PATCH v5 00/11] " Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 01/11] module: support reading multiple values per modinfo tag Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 02/11] export: explicitly align struct kernel_symbol Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 03/11] module: add support for symbol namespaces Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 04/11] modpost: " Matthias Maennich
2019-09-26 22:24     ` [PATCH] modpost: Copy namespace string into 'struct symbol' Shaun Ruffell
2019-09-27  5:31       ` Greg Kroah-Hartman
2019-09-27  8:03       ` Matthias Maennich
2019-09-30 21:20         ` Shaun Ruffell
2019-10-01 16:19           ` Matthias Maennich
2019-10-01 19:37             ` Shaun Ruffell
2019-09-06 10:32   ` [PATCH v5 05/11] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 06/11] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 07/11] modpost: add support for generating namespace dependencies Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 08/11] scripts: Coccinelle script for " Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 09/11] docs: Add documentation for Symbol Namespaces Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 10/11] usb-storage: remove single-use define for debugging Matthias Maennich
2019-09-06 12:59     ` Jessica Yu
2019-09-06 13:22       ` Greg KH
2019-09-06 10:32   ` [PATCH v5 11/11] usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-09-09  8:35   ` [PATCH v5 00/11] Symbol Namespaces Jessica Yu

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