From: "Jan Beulich" <JBeulich@suse.com>
To: ross.lagerwall@citrix.com,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Keir Fraser <keir@xen.org>,
andrew.cooper3@citrix.com,
Ian Jackson <ian.jackson@eu.citrix.com>, Tim Deegan <tim@xen.org>,
mpohlack@amazon.de, sasha.levin@oracle.com,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH v5 27/28] xsplice: Add support for shadow variables.
Date: Mon, 04 Apr 2016 09:18:34 -0600 [thread overview]
Message-ID: <5702A1EA02000078000E2C97@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1458849640-22588-28-git-send-email-konrad.wilk@oracle.com>
>>> On 24.03.16 at 21:00, <konrad.wilk@oracle.com> wrote:
> Shadow variables are a piece of infrastructure to be used by xsplice
> modules. They are used to attach a new piece of data to an existing
> structure in memory.
An already known question again: Out of recent XSAs, how many
needed such? I.e. can#t we put this off for now?
> Martin Pohlack also mentions that using the SHADOW_SLOTS of small
> prime numbers has the advantage of having a simple hash function.
This reads kind of backwards.
> +void xsplice_shadow_free(const void *obj, const char *var)
> +{
> + struct shadow_var *entry, *shadow = NULL;
> + unsigned int slot;
> + struct hlist_node *next;
> +
> + slot = (unsigned long)obj % SHADOW_SLOTS;
> +
> + spin_lock(&shadow_lock);
> + hlist_for_each_entry(entry, next, &shadow_tbl[slot], list)
> + {
> + if ( entry->obj == obj &&
> + !strcmp(entry->var, var) )
> + {
> + shadow = entry;
> + break;
> + }
> + }
> + if (shadow)
Coding style.
> + {
> + hlist_del(&shadow->list);
> + xfree(shadow->data);
> + xfree(shadow);
> + }
> + spin_unlock(&shadow_lock);
> +}
Uniqueness not being guaranteed by the allocation function, how
can you free the first hit here ...
> +void *xsplice_shadow_get(const void *obj, const char *var)
> +{
> + struct shadow_var *entry;
> + unsigned int slot;
> + struct hlist_node *next;
> + void *ret = NULL;
> +
> + slot = (unsigned long)obj % SHADOW_SLOTS;
> +
> + spin_lock(&shadow_lock);
> + hlist_for_each_entry(entry, next, &shadow_tbl[slot], list)
> + {
> + if ( entry->obj == obj &&
> + !strcmp(entry->var, var) )
> + {
> + ret = entry->data;
> + break;
> + }
> + }
> +
> + spin_unlock(&shadow_lock);
> + return ret;
> +}
.. or return the first match here?
> +static int __init xsplice_shadow_init(void)
> +{
> + int i;
unsigned int
> --- a/xen/include/xen/xsplice_patch.h
> +++ b/xen/include/xen/xsplice_patch.h
> @@ -56,4 +56,40 @@ typedef void (*xsplice_unloadcall_t)(void);
> #define XSPLICE_UNLOAD_HOOK(_fn) \
> xsplice_unloadcall_t __attribute__((weak)) xsplice_unload_data
> __section(".xsplice.hooks.unload") = _fn;
>
> +
> +/*
> + * The following definitions are to be used in patches. They are taken
> + * from kpatch.
> + */
> +
> +/*
> + * xsplice shadow variables
> + *
> + * These functions can be used to add new "shadow" fields to existing data
> + * structures. For example, to allocate a "newpid" variable associated with an
> + * instance of task_struct, and assign it a value of 1000:
> + *
> + * struct task_struct *tsk = current;
> + * int *newpid;
> + * newpid = xsplice_shadow_alloc(tsk, "newpid", sizeof(int));
> + * if (newpid)
> + * *newpid = 1000;
> + *
> + * To retrieve a pointer to the variable:
> + *
> + * struct task_struct *tsk = current;
> + * int *newpid;
> + * newpid = xsplice_shadow_get(tsk, "newpid");
> + * if (newpid)
> + * printk("task newpid = %d\n", *newpid); // prints "task newpid = 1000"
> + *
> + * To free it:
> + *
> + * xsplice_shadow_free(tsk, "newpid");
> + */
While this indeed provides some basic understanding, I think this
should be using a more Xen-affine example, and I fail to see how
with particularly the example given this is going to be useful: How
would the patch module sanely and within reasonable time get
hold of all instances of a particular type?
Jan
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
next prev parent reply other threads:[~2016-04-04 15:18 UTC|newest]
Thread overview: 190+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-24 20:00 [PATCH v5] xSplice v1 design and implementation Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 01/28] HYPERCALL_version_op. New hypercall mirroring XENVER_ but sane Konrad Rzeszutek Wilk
2016-03-24 20:22 ` Andrew Cooper
2016-03-24 21:07 ` Konrad Rzeszutek Wilk
2016-03-24 21:30 ` Konrad Rzeszutek Wilk
2016-03-30 15:43 ` Jan Beulich
2016-03-31 6:30 ` Jan Beulich
2016-03-31 11:43 ` Konrad Rzeszutek Wilk
2016-03-31 12:07 ` Jan Beulich
2016-03-31 13:28 ` REST MAINTAINERS feedback requested Was:Re: " Konrad Rzeszutek Wilk
2016-03-31 13:50 ` Jan Beulich
2016-04-08 16:33 ` Jan Beulich
2016-04-08 17:09 ` Konrad Rzeszutek Wilk
2016-04-08 17:13 ` Jan Beulich
2016-04-08 17:21 ` Wei Liu
2016-04-08 17:23 ` Konrad Rzeszutek Wilk
2016-04-08 17:27 ` Wei Liu
2016-04-08 17:21 ` Ian Jackson
2016-04-08 17:41 ` Andrew Cooper
2016-04-08 17:54 ` Jan Beulich
2016-04-11 10:50 ` Ian Jackson
2016-04-11 13:56 ` Konrad Rzeszutek Wilk
2016-04-11 14:22 ` Ian Jackson
2016-04-11 15:48 ` Jan Beulich
2016-04-11 16:25 ` Ian Jackson
2016-04-11 16:53 ` Konrad Rzeszutek Wilk
2016-04-11 17:06 ` Jan Beulich
2016-04-11 17:00 ` Jan Beulich
2016-04-11 17:13 ` Ian Jackson
2016-04-11 17:34 ` Jan Beulich
2016-04-11 17:46 ` Jan Beulich
2016-04-12 9:58 ` George Dunlap
2016-04-12 13:56 ` Konrad Rzeszutek Wilk
2016-04-12 14:38 ` George Dunlap
2016-04-12 15:00 ` Konrad Rzeszutek Wilk
2016-04-12 15:26 ` Ian Jackson
2016-04-13 4:21 ` Jan Beulich
2016-04-13 16:07 ` Ian Jackson
2016-04-14 15:13 ` George Dunlap
2016-04-14 15:59 ` Jan Beulich
2016-04-14 16:19 ` George Dunlap
2016-04-14 17:01 ` Jan Beulich
2016-04-14 18:11 ` REST MAINTAINERS feedback requested Was:Re: [PATCH v5 01/28] HYPERCALL_version_op. New hypercall mirroring XENVER_ but sane. [and 1 more messages] Ian Jackson
2016-04-14 19:22 ` Konrad Rzeszutek Wilk
2016-04-17 7:23 ` Jan Beulich
2016-04-15 11:23 ` REST MAINTAINERS feedback requested Was:Re: [PATCH v5 01/28] HYPERCALL_version_op. New hypercall mirroring XENVER_ but sane George Dunlap
2016-04-17 7:52 ` Jan Beulich
2016-04-12 15:31 ` Jan Beulich
2016-04-12 15:17 ` Jan Beulich
2016-04-12 15:28 ` Konrad Rzeszutek Wilk
2016-04-08 17:24 ` George Dunlap
2016-04-08 17:34 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 02/28] libxc/libxl/python/xenstat/ocaml: Use new XEN_VERSION hypercall Konrad Rzeszutek Wilk
2016-03-24 21:24 ` Wei Liu
2016-03-25 13:21 ` Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 03/28] arm/x86: Use struct virtual_region to do bug, symbol, and (x86) exception tables lookup Konrad Rzeszutek Wilk
2016-03-30 16:09 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 04/28] vmap: Add vmalloc_cb and vfree_cb Konrad Rzeszutek Wilk
2016-03-30 16:24 ` Jan Beulich
2016-03-30 16:44 ` Konrad Rzeszutek Wilk
2016-03-31 6:46 ` Jan Beulich
2016-03-31 11:49 ` Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 05/28] xsplice: Design document Konrad Rzeszutek Wilk
2016-03-29 9:36 ` Jan Beulich
2016-03-29 20:46 ` Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 06/28] xen/xsplice: Hypervisor implementation of XEN_XSPLICE_op Konrad Rzeszutek Wilk
2016-03-31 9:45 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 07/28] libxc: Implementation of XEN_XSPLICE_op in libxc Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 08/28] xen-xsplice: Tool to manipulate xsplice payloads Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 09/28] xsplice: Add helper elf routines Konrad Rzeszutek Wilk
2016-03-31 12:03 ` Jan Beulich
2016-04-06 1:38 ` Konrad Rzeszutek Wilk
2016-04-07 0:38 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 10/28] xsplice: Implement payload loading Konrad Rzeszutek Wilk
2016-03-31 13:45 ` Jan Beulich
2016-03-31 21:26 ` Konrad Rzeszutek Wilk
2016-04-01 9:18 ` Jan Beulich
2016-04-04 19:44 ` Konrad Rzeszutek Wilk
2016-04-05 1:57 ` Konrad Rzeszutek Wilk
2016-04-05 7:34 ` Jan Beulich
2016-04-05 15:50 ` Konrad Rzeszutek Wilk
2016-04-05 16:15 ` Jan Beulich
2016-04-05 16:45 ` Konrad Rzeszutek Wilk
2016-04-05 17:48 ` Konrad Rzeszutek Wilk
2016-04-07 0:49 ` Jan Beulich
2016-04-07 0:46 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 11/28] xsplice: Implement support for applying/reverting/replacing patches Konrad Rzeszutek Wilk
2016-04-01 13:28 ` Jan Beulich
2016-04-01 21:04 ` Konrad Rzeszutek Wilk
2016-04-04 7:07 ` Jan Beulich
2016-04-07 3:05 ` Konrad Rzeszutek Wilk
2016-04-07 15:38 ` Jan Beulich
2016-04-09 14:42 ` Konrad Rzeszutek Wilk
2016-04-11 15:38 ` Jan Beulich
2016-04-07 3:09 ` Konrad Rzeszutek Wilk
2016-04-07 15:43 ` Jan Beulich
2016-04-10 2:36 ` Konrad Rzeszutek Wilk
2016-04-10 2:45 ` Konrad Rzeszutek Wilk
2016-04-11 15:41 ` Jan Beulich
2016-04-11 23:29 ` Konrad Rzeszutek Wilk
2016-04-10 19:47 ` Is: ARM maintainers advice ..Was:Re: " Konrad Rzeszutek Wilk
2016-04-10 20:58 ` Stefano Stabellini
2016-04-11 15:44 ` Jan Beulich
2016-04-11 15:50 ` Konrad Rzeszutek Wilk
2016-04-11 16:05 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 12/28] x86/xen_hello_world.xsplice: Test payload for patching 'xen_extra_version' Konrad Rzeszutek Wilk
2016-04-01 13:33 ` Jan Beulich
2016-04-06 2:03 ` Konrad Rzeszutek Wilk
2016-04-07 1:03 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 13/28] xsplice, symbols: Implement symbol name resolution on address Konrad Rzeszutek Wilk
2016-04-01 15:11 ` Jan Beulich
2016-04-07 3:14 ` Konrad Rzeszutek Wilk
2016-04-07 15:46 ` Jan Beulich
2016-04-08 1:32 ` Konrad Rzeszutek Wilk
2016-04-08 15:21 ` Jan Beulich
2016-04-08 15:27 ` Konrad Rzeszutek Wilk
2016-04-08 15:29 ` Jan Beulich
[not found] ` <5707D68A.8090006@citrix.com>
[not found] ` <5707FA8B02000078000E6178@prv-mh.provo.novell.com>
2016-04-11 8:07 ` Ross Lagerwall
2016-03-24 20:00 ` [PATCH v5 14/28] x86, xsplice: Print payload's symbol name and payload name in backtraces Konrad Rzeszutek Wilk
2016-04-01 15:23 ` Jan Beulich
2016-04-06 2:39 ` Konrad Rzeszutek Wilk
2016-04-07 1:07 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 15/28] xsplice: Add .xsplice.hooks functions and test-case Konrad Rzeszutek Wilk
2016-04-01 15:50 ` Jan Beulich
2016-04-06 2:42 ` Konrad Rzeszutek Wilk
2016-04-06 6:39 ` Martin Pohlack
2016-04-07 1:15 ` Jan Beulich
2016-04-08 15:57 ` Ross Lagerwall
2016-04-08 17:39 ` Jan Beulich
2016-04-11 8:23 ` Ross Lagerwall
2016-04-22 13:33 ` Jan Beulich
2016-04-22 13:58 ` Jan Beulich
2016-04-22 17:32 ` Konrad Rzeszutek Wilk
2016-04-07 1:11 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 16/28] xsplice: Add support for bug frames Konrad Rzeszutek Wilk
2016-04-01 16:00 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 17/28] xsplice: Add support for exception tables Konrad Rzeszutek Wilk
2016-04-01 16:06 ` Jan Beulich
2016-04-06 14:41 ` Konrad Rzeszutek Wilk
2016-04-06 15:32 ` Andrew Cooper
2016-04-07 1:21 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 18/28] xsplice: Add support for alternatives Konrad Rzeszutek Wilk
2016-04-01 16:20 ` Jan Beulich
2016-04-07 3:11 ` Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 19/28] build_id: Provide ld-embedded build-ids Konrad Rzeszutek Wilk
2016-04-04 12:46 ` Jan Beulich
2016-04-07 2:58 ` Konrad Rzeszutek Wilk
2016-04-08 15:49 ` Ross Lagerwall
2016-04-08 18:47 ` Konrad Rzeszutek Wilk
2016-04-08 18:54 ` Andrew Cooper
2016-04-08 19:54 ` Jan Beulich
2016-04-08 0:18 ` Konrad Rzeszutek Wilk
2016-04-08 1:52 ` Konrad Rzeszutek Wilk
2016-04-08 15:27 ` Jan Beulich
2016-04-08 17:06 ` Konrad Rzeszutek Wilk
2016-04-08 17:44 ` Jan Beulich
2016-04-08 19:23 ` Konrad Rzeszutek Wilk
2016-04-08 19:39 ` Konrad Rzeszutek Wilk
2016-04-08 20:14 ` Jan Beulich
2016-04-08 20:50 ` Konrad Rzeszutek Wilk
2016-04-08 21:11 ` Jan Beulich
2016-04-08 21:15 ` Konrad Rzeszutek Wilk
2016-04-08 15:25 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 20/28] HYPERCALL_version_op: Add VERSION_build_id to retrieve build-id Konrad Rzeszutek Wilk
2016-03-25 16:26 ` Daniel De Graaf
2016-04-04 13:35 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 21/28] libxl: info: Display build_id of the hypervisor using XEN_VERSION_build_id Konrad Rzeszutek Wilk
2016-03-25 13:25 ` Konrad Rzeszutek Wilk
2016-03-25 15:27 ` Wei Liu
2016-03-24 20:00 ` [PATCH v5 22/28] xsplice: Print build_id in keyhandler and on bootup Konrad Rzeszutek Wilk
2016-04-04 13:38 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 23/28] xsplice: Stacking build-id dependency checking Konrad Rzeszutek Wilk
2016-04-04 15:00 ` Jan Beulich
2016-04-04 20:01 ` Konrad Rzeszutek Wilk
2016-04-05 7:43 ` Jan Beulich
2016-04-08 16:15 ` Ross Lagerwall
2016-04-08 17:47 ` Jan Beulich
2016-04-06 20:05 ` Konrad Rzeszutek Wilk
2016-04-07 1:24 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 24/28] xsplice/xen_replace_world: Test-case for XSPLICE_ACTION_REPLACE Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 25/28] xsplice: Print dependency and payloads build_id in the keyhandler Konrad Rzeszutek Wilk
2016-04-04 15:03 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 26/28] xsplice: Prevent duplicate payloads from being loaded Konrad Rzeszutek Wilk
2016-04-04 15:06 ` Jan Beulich
2016-04-04 19:52 ` Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 27/28] xsplice: Add support for shadow variables Konrad Rzeszutek Wilk
2016-04-04 15:18 ` Jan Beulich [this message]
2016-04-06 2:26 ` Konrad Rzeszutek Wilk
2016-04-08 15:58 ` Ross Lagerwall
2016-03-24 20:00 ` [PATCH v5 28/28] MAINTAINERS/xsplice: Add myself and Ross as the maintainers Konrad Rzeszutek Wilk
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5702A1EA02000078000E2C97@prv-mh.provo.novell.com \
--to=jbeulich@suse.com \
--cc=andrew.cooper3@citrix.com \
--cc=ian.jackson@eu.citrix.com \
--cc=keir@xen.org \
--cc=konrad.wilk@oracle.com \
--cc=mpohlack@amazon.de \
--cc=ross.lagerwall@citrix.com \
--cc=sasha.levin@oracle.com \
--cc=tim@xen.org \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).