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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [livepatch-hooks-2 PATCH 3/4] livepatch: Add support for apply|revert action replacement hooks
By default, in the quiescing zone, a hotpatch payload is applied with
apply_payload() and reverted with revert_payload() functions. Both of
the functions receive the payload struct pointer as a parameter. The
functions are also a place where standard 'load' and 'unload' module
hooks are executed.
To increase hotpatching system's agility and provide more flexiable
long-term hotpatch solution, allow to overwrite the default apply
and revert action functions with hook-like supplied alternatives.
The alternative functions are optional and the default functions are
used by default.
Since the alternative functions have direct access to the hotpatch
payload structure, they can better control context of the 'load' and
'unload' hooks execution as well as exact instructions replacement
workflows. They can be also easily extended to support extra features
in the future.
To simplify the alternative function generation move code responsible
for payload and hotpatch region registration outside of the function.
That way it is guaranteed that the registration step occurs even for
newly supplied functions.
Signed-off-by: Pawel Wieczorkiewicz <wipawel@xxxxxxxxx>
Reviewed-by: Petre Eftime <epetre@xxxxxxxxxx>
Reviewed-by: Martin Pohlack <mpohlack@xxxxxxxxxx>
Reviewed-by: Norbert Manthey <nmanthey@xxxxxxxxxx>
Reviewed-by: Andra-Irina Paraschiv <andraprs@xxxxxxxxxx>
Reviewed-by: Bjoern Doebel <doebel@xxxxxxxxxx>
---
xen/common/livepatch.c | 66 +++++++++++++++++++++++++++++++------
xen/include/xen/livepatch_payload.h | 10 ++++++
2 files changed, 66 insertions(+), 10 deletions(-)
diff --git a/xen/common/livepatch.c b/xen/common/livepatch.c
index 464c07ad28..38fab8b240 100644
--- a/xen/common/livepatch.c
+++ b/xen/common/livepatch.c
@@ -587,8 +587,11 @@ static int prepare_payload(struct payload *payload,
LIVEPATCH_ASSIGN_MULTI_HOOK(elf, payload->unload_funcs,
payload->n_unload_funcs, ".livepatch.hooks.unload");
LIVEPATCH_ASSIGN_SINGLE_HOOK(elf, payload->hooks.apply.pre,
".livepatch.hooks.preapply");
+ LIVEPATCH_ASSIGN_SINGLE_HOOK(elf, payload->hooks.apply.action,
".livepatch.hooks.apply");
LIVEPATCH_ASSIGN_SINGLE_HOOK(elf, payload->hooks.apply.post,
".livepatch.hooks.postapply");
+
LIVEPATCH_ASSIGN_SINGLE_HOOK(elf, payload->hooks.revert.pre,
".livepatch.hooks.prerevert");
+ LIVEPATCH_ASSIGN_SINGLE_HOOK(elf, payload->hooks.revert.action,
".livepatch.hooks.revert");
LIVEPATCH_ASSIGN_SINGLE_HOOK(elf, payload->hooks.revert.post,
".livepatch.hooks.postrevert");
sec = livepatch_elf_sec_by_name(elf, ELF_BUILD_ID_NOTE);
@@ -1114,6 +1117,11 @@ static int apply_payload(struct payload *data)
arch_livepatch_revive();
+ return 0;
+}
+
+static inline void apply_payload_tail(struct payload *data)
+{
/*
* We need RCU variant (which has barriers) in case we crash here.
* The applied_list is iterated by the trap code.
@@ -1121,7 +1129,7 @@ static int apply_payload(struct payload *data)
list_add_tail_rcu(&data->applied_list, &applied_list);
register_virtual_region(&data->region);
- return 0;
+ data->state = LIVEPATCH_STATE_APPLIED;
}
static int revert_payload(struct payload *data)
@@ -1154,6 +1162,11 @@ static int revert_payload(struct payload *data)
ASSERT(!local_irq_is_enabled());
arch_livepatch_revive();
+ return 0;
+}
+
+static inline void revert_payload_tail(struct payload *data)
+{
/*
* We need RCU variant (which has barriers) in case we crash here.
@@ -1163,7 +1176,7 @@ static int revert_payload(struct payload *data)
unregister_virtual_region(&data->region);
data->reverted = true;
- return 0;
+ data->state = LIVEPATCH_STATE_CHECKED;
}
/*
@@ -1183,15 +1196,31 @@ static void livepatch_do_action(void)
switch ( livepatch_work.cmd )
{
case LIVEPATCH_ACTION_APPLY:
- rc = apply_payload(data);
+ if ( is_hook_enabled(data->hooks.apply.action) )
+ {
+ printk(XENLOG_INFO LIVEPATCH "%s: Calling apply action hook
function\n", data->name);
+
+ rc = (*data->hooks.apply.action)(data);
+ }
+ else
+ rc = apply_payload(data);
+
if ( rc == 0 )
- data->state = LIVEPATCH_STATE_APPLIED;
+ apply_payload_tail(data);
break;
case LIVEPATCH_ACTION_REVERT:
- rc = revert_payload(data);
+ if ( is_hook_enabled(data->hooks.revert.action) )
+ {
+ printk(XENLOG_INFO LIVEPATCH "%s: Calling revert action hook
function\n", data->name);
+
+ rc = (*data->hooks.revert.action)(data);
+ }
+ else
+ rc = revert_payload(data);
+
if ( rc == 0 )
- data->state = LIVEPATCH_STATE_CHECKED;
+ revert_payload_tail(data);
break;
case LIVEPATCH_ACTION_REPLACE:
@@ -1202,9 +1231,18 @@ static void livepatch_do_action(void)
*/
list_for_each_entry_safe_reverse ( other, tmp, &applied_list,
applied_list )
{
- other->rc = revert_payload(other);
+ if ( is_hook_enabled(other->hooks.revert.action) )
+ {
+ printk(XENLOG_INFO LIVEPATCH "%s: Calling revert action hook
function\n", other->name);
+
+ other->rc = (*other->hooks.revert.action)(other);
+ }
+ else
+ other->rc = revert_payload(other);
+
+
if ( other->rc == 0 )
- other->state = LIVEPATCH_STATE_CHECKED;
+ revert_payload_tail(other);
else
{
rc = -EINVAL;
@@ -1214,9 +1252,17 @@ static void livepatch_do_action(void)
if ( rc == 0 )
{
- rc = apply_payload(data);
+ if ( is_hook_enabled(data->hooks.apply.action) )
+ {
+ printk(XENLOG_INFO LIVEPATCH "%s: Calling apply action hook
function\n", data->name);
+
+ rc = (*data->hooks.apply.action)(data);
+ }
+ else
+ rc = apply_payload(data);
+
if ( rc == 0 )
- data->state = LIVEPATCH_STATE_APPLIED;
+ apply_payload_tail(data);
}
break;
diff --git a/xen/include/xen/livepatch_payload.h
b/xen/include/xen/livepatch_payload.h
index cd20944cc4..ff16af0dd6 100644
--- a/xen/include/xen/livepatch_payload.h
+++ b/xen/include/xen/livepatch_payload.h
@@ -22,11 +22,13 @@ typedef void livepatch_loadcall_t(void);
typedef void livepatch_unloadcall_t(void);
typedef int livepatch_precall_t(livepatch_payload_t *arg);
+typedef int livepatch_actioncall_t(livepatch_payload_t *arg);
typedef void livepatch_postcall_t(livepatch_payload_t *arg);
struct livepatch_hooks {
struct {
livepatch_precall_t *const *pre;
+ livepatch_actioncall_t *const *action;
livepatch_postcall_t *const *post;
} apply, revert;
};
@@ -91,6 +93,10 @@ struct payload {
livepatch_precall_t *__attribute__((weak, used)) \
const livepatch_preapply_data_##_fn
__section(".livepatch.hooks.preapply") = _fn;
+#define LIVEPATCH_APPLY_HOOK(_fn) \
+ livepatch_actioncall_t *__attribute__((weak, used)) \
+ const livepatch_apply_data_##_fn __section(".livepatch.hooks.apply") =
_fn;
+
#define LIVEPATCH_POSTAPPLY_HOOK(_fn) \
livepatch_postcall_t *__attribute__((weak, used)) \
const livepatch_postapply_data_##_fn
__section(".livepatch.hooks.postapply") = _fn;
@@ -99,6 +105,10 @@ struct payload {
livepatch_precall_t *__attribute__((weak, used)) \
const livepatch_prerevert_data_##_fn
__section(".livepatch.hooks.prerevert") = _fn;
+#define LIVEPATCH_REVERT_HOOK(_fn) \
+ livepatch_actioncall_t *__attribute__((weak, used)) \
+ const livepatch_revert_data_##_fn __section(".livepatch.hooks.revert")
= _fn;
+
#define LIVEPATCH_POSTREVERT_HOOK(_fn) \
livepatch_postcall_t *__attribute__((weak, used)) \
const livepatch_postrevert_data_##_fn
__section(".livepatch.hooks.postrevert") = _fn;
--
2.16.5
Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879
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