From: Petr Mladek <pmladek@suse.com>
To: Chris J Arges <chris.j.arges@canonical.com>
Cc: live-patching@vger.kernel.org, jeyu@redhat.com,
Josh Poimboeuf <jpoimboe@redhat.com>,
Seth Jennings <sjenning@redhat.com>,
Jiri Kosina <jikos@kernel.org>, Vojtech Pavlik <vojtech@suse.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4 v5] livepatch: add old_sympos as disambiguator field to klp_func
Date: Fri, 13 Nov 2015 17:27:05 +0100 [thread overview]
Message-ID: <20151113162705.GW2599@pathway.suse.cz> (raw)
In-Reply-To: <1447347595-30728-2-git-send-email-chris.j.arges@canonical.com>
On Thu 2015-11-12 10:59:50, Chris J Arges wrote:
> In cases of duplicate symbols, old_sympos will be used to disambiguate
> instead of old_addr. By default old_sympos will be 0, and patching will
> only succeed if the symbol is unique. Specifying a positive value will
> ensure that occurrence of the symbol in kallsyms for the patched object
> will be used for patching if it is valid.
>
> In addition, make old_addr an internal structure field not to be specified
> by the user. Finally, remove klp_find_verify_func_addr as it can be
> replaced by klp_find_object_symbol directly.
>
> Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
> ---
> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
> index 6e53441..479d75e 100644
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c
> @@ -159,36 +154,46 @@ static int klp_find_callback(void *data, const char *name,
> return 0;
>
> /*
> - * args->addr might be overwritten if another match is found
> - * but klp_find_object_symbol() handles this and only returns the
> - * addr if count == 1.
> + * Increment and assign the address. Return 1 when the desired symbol
> + * position is found or the search for a unique symbol fails.
> */
> args->addr = addr;
> args->count++;
I would avoid the obvious things and move the comment here:
/*
* Finish the search when the symbol is found on the desired
* position or the position is not defined for non-unique
* symbol.
*/
> + if (((args->pos > 0) && (args->count == args->pos)) ||
> + ((args->pos == 0) && (args->count > 1)))
> + return 1;
I wonder if this is better readable:
if ((args->pos && (args->count == args->pos)) ||
(!args->pos && (args->count > 1)))
return 1;
> return 0;
> }
>
[...]
> @@ -277,7 +261,7 @@ static int klp_find_external_symbol(struct module *pmod, const char *name,
> preempt_enable();
>
> /* otherwise check if it's in another .o within the patch module */
> - return klp_find_object_symbol(pmod->name, name, addr);
> + return klp_find_object_symbol(pmod->name, name, addr, 0);
Please, add a comment here that external symbols always have to be unique.
> }
>
> static int klp_write_object_relocations(struct module *pmod,
> @@ -307,7 +291,7 @@ static int klp_write_object_relocations(struct module *pmod,
> else
> ret = klp_find_object_symbol(obj->mod->name,
> reloc->name,
> - &reloc->val);
> + &reloc->val, 0);
Please, mention in the commit message that the support for sympos will
be added into relocations in a separate patch. Or add a FIXME comment
here. It will make easier the review and git history archaeology.
Thank you,
Petr
next prev parent reply other threads:[~2015-11-13 16:27 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-02 17:58 [PATCH] livepatch: old_name.number scheme in livepatch sysfs directory Chris J Arges
2015-11-02 19:15 ` Jessica Yu
2015-11-02 19:52 ` [PATCH] " Josh Poimboeuf
2015-11-02 20:16 ` Chris J Arges
2015-11-02 20:32 ` Josh Poimboeuf
2015-11-02 22:59 ` [PATCH v2] " Chris J Arges
2015-11-03 9:50 ` Miroslav Benes
2015-11-03 15:03 ` Josh Poimboeuf
2015-11-03 10:52 ` Miroslav Benes
2015-11-03 12:44 ` Petr Mladek
2015-11-03 15:03 ` Josh Poimboeuf
2015-11-03 19:57 ` Jiri Kosina
2015-11-03 20:06 ` Josh Poimboeuf
[not found] ` <1447259366-7055-1-git-send-email-chris.j.arges@canonical.com>
2015-11-11 16:28 ` [PATCH 1/3 v4] livepatch: add old_sympos as disambiguator field to klp_func Chris J Arges
2015-11-11 17:43 ` Josh Poimboeuf
2015-11-12 10:22 ` Miroslav Benes
2015-11-11 16:29 ` [PATCH 2/3 v4] livepatch: add old_sympos as disambiguator field to klp_reloc Chris J Arges
2015-11-11 16:39 ` Chris J Arges
2015-11-11 17:57 ` Josh Poimboeuf
2015-11-12 14:31 ` Petr Mladek
2015-11-12 19:19 ` Josh Poimboeuf
2015-11-13 13:54 ` Petr Mladek
2015-11-13 16:59 ` Josh Poimboeuf
2015-11-16 12:11 ` Petr Mladek
2015-11-12 10:23 ` Miroslav Benes
2015-11-11 16:29 ` [PATCH 3/3 v4] livepatch: old_name,number scheme in livepatch sysfs directory Chris J Arges
2015-11-11 18:01 ` Josh Poimboeuf
[not found] ` <1447347595-30728-1-git-send-email-chris.j.arges@canonical.com>
2015-11-12 16:59 ` [PATCH 1/4 v5] livepatch: add old_sympos as disambiguator field to klp_func Chris J Arges
2015-11-12 19:45 ` Josh Poimboeuf
2015-11-13 9:56 ` Jiri Kosina
2015-11-13 10:14 ` Miroslav Benes
2015-11-13 16:27 ` Petr Mladek [this message]
2015-11-12 16:59 ` [PATCH 2/4 v5] livepatch: Simplify code for relocated external symbols Chris J Arges
2015-11-13 10:24 ` Miroslav Benes
2015-11-13 13:55 ` Petr Mladek
2015-11-12 16:59 ` [PATCH 3/4 v5] livepatch: add sympos as disambiguator field to klp_reloc Chris J Arges
2015-11-12 19:50 ` Josh Poimboeuf
2015-11-13 16:42 ` Petr Mladek
2015-11-12 16:59 ` [PATCH 4/4 v5] livepatch: function,sympos scheme in livepatch sysfs directory Chris J Arges
[not found] ` <1447431804-18786-1-git-send-email-chris.j.arges@canonical.com>
2015-11-13 16:23 ` [PATCH 1/3 v6] livepatch: add old_sympos as disambiguator field to klp_func Chris J Arges
2015-11-13 16:23 ` [PATCH 2/3 v6] livepatch: add sympos as disambiguator field to klp_reloc Chris J Arges
2015-11-13 16:23 ` [PATCH 3/3 v6] livepatch: function,sympos scheme in livepatch sysfs directory Chris J Arges
[not found] ` <1447693391-10065-1-git-send-email-chris.j.arges@canonical.com>
2015-11-16 17:03 ` [PATCH 1/3 v7] livepatch: add old_sympos as disambiguator field to klp_func Chris J Arges
2015-11-16 21:59 ` Jiri Kosina
2015-11-17 14:29 ` Chris J Arges
2015-11-19 10:02 ` Jiri Kosina
2015-11-16 17:03 ` [PATCH 2/3 v7] livepatch: add sympos as disambiguator field to klp_reloc Chris J Arges
2015-11-18 9:56 ` Miroslav Benes
2015-11-18 14:01 ` Josh Poimboeuf
2015-11-18 16:47 ` Petr Mladek
2015-11-18 16:37 ` Petr Mladek
2015-11-18 16:39 ` Chris J Arges
2015-11-18 16:55 ` Petr Mladek
2015-11-18 20:34 ` Jiri Kosina
2015-11-16 17:03 ` [PATCH 3/3 v7] livepatch: function,sympos scheme in livepatch sysfs directory Chris J Arges
2015-11-20 17:25 ` [PATCH 0/3 v8] livepatch: disambiguate symbols with the same name Chris J Arges
2015-11-20 17:25 ` [PATCH 1/3 v8] livepatch: add old_sympos as disambiguator field to klp_func Chris J Arges
2015-11-23 9:47 ` Miroslav Benes
2015-11-20 17:25 ` [PATCH 2/3 v8] livepatch: add sympos as disambiguator field to klp_reloc Chris J Arges
2015-11-23 9:52 ` Miroslav Benes
2015-11-30 20:46 ` Chris J Arges
2015-12-01 1:17 ` Josh Poimboeuf
2015-11-20 17:25 ` [PATCH 3/3 v8] livepatch: function,sympos scheme in livepatch sysfs directory Chris J Arges
2015-11-23 9:47 ` Miroslav Benes
2015-12-02 2:40 ` [PATCH 0/3 v9] livepatch: disambiguate symbols with the same name Chris J Arges
2015-12-02 2:40 ` [PATCH 1/3 v9] livepatch: add old_sympos as disambiguator field to klp_func Chris J Arges
2015-12-02 2:40 ` [PATCH 2/3 v9] livepatch: add sympos as disambiguator field to klp_reloc Chris J Arges
2015-12-14 12:45 ` Miroslav Benes
2015-12-02 2:40 ` [PATCH 3/3 v9] livepatch: function,sympos scheme in livepatch sysfs directory Chris J Arges
2015-12-02 15:28 ` [PATCH 0/3 v9] livepatch: disambiguate symbols with the same name Petr Mladek
2015-12-03 17:59 ` Josh Poimboeuf
2015-12-03 22:04 ` Jiri Kosina
2015-11-03 14:58 ` [PATCH v2] livepatch: old_name.number scheme in livepatch sysfs directory Josh Poimboeuf
2015-11-03 16:09 ` Miroslav Benes
2015-11-03 16:50 ` Josh Poimboeuf
2015-11-03 20:42 ` Chris J Arges
2015-11-04 9:52 ` Miroslav Benes
2015-11-04 16:03 ` Josh Poimboeuf
2015-11-04 16:17 ` Chris J Arges
2015-11-05 15:18 ` Miroslav Benes
2015-11-05 15:56 ` Josh Poimboeuf
2015-11-05 16:07 ` Chris J Arges
2015-11-09 16:16 ` [PATCH v3] livepatch: old_name,number " Chris J Arges
2015-11-09 20:56 ` Josh Poimboeuf
2015-11-09 23:01 ` Chris J Arges
2015-11-10 4:54 ` Josh Poimboeuf
2015-11-10 8:49 ` Miroslav Benes
2015-11-10 13:40 ` Josh Poimboeuf
2015-11-10 9:02 ` Miroslav Benes
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