@@ -275,6 +275,7 @@ The payload contains at least three sections:
* `.livepatch.funcs` - which is an array of livepatch_func structures.
and/or any of:
* `.livepatch.hooks.{preapply,postapply,prerevert,postrevert}'
+ * `.livepatch.hooks.{apply,revert}`
- which are a pointer to a hook function pointer.
* `.livepatch.xen_depends` - which is an ELF Note that describes what Xen
@@ -356,6 +357,14 @@ met.
* `.livepatch.hooks.{prerevert,postrevert}`
- which are a pointer to a single hook function pointer.
+Finally, it optionally may also contain the address of apply or revert action
+hooks to be called instead of the default apply and revert payload actions
+(while all CPUs are kept in quiescing zone). These hooks do have access to
+payload structure.
+
+ * `.livepatch.hooks.{apply,revert}`
+ - which are a pointer to a single hook function pointer.
+
### Example of .livepatch.funcs
A simple example of what a payload file can be:
@@ -469,6 +478,20 @@ The type definition of the function are as follow:
typedef void livepatch_postcall_t(livepatch_payload_t *arg);
+#### .livepatch.hooks.apply and .livepatch.hooks.revert
+
+This section contains a pointer to a single function pointer to be executed
+instead of a default apply (or revert) action function. This is useful to
+replace or augment default behavior of the apply (or revert) action that
+requires all CPUs to be in the quiescing zone.
+This type of hooks do have access to payload structure.
+
+Each entry in this array is eight bytes.
+
+The type definition of the function are as follow:
+
+ typedef int livepatch_actioncall_t(livepatch_payload_t *arg);
+
### .livepatch.xen_depends, .livepatch.depends and .note.gnu.build-id
To support dependencies checking and safe loading (to load the
@@ -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;
@@ -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;
@@ -22,6 +22,7 @@ LIVEPATCH_NOP := xen_nop.livepatch
LIVEPATCH_NO_XEN_BUILDID := xen_no_xen_buildid.livepatch
LIVEPATCH_PREPOST_HOOKS := xen_prepost_hooks.livepatch
LIVEPATCH_PREPOST_HOOKS_FAIL := xen_prepost_hooks_fail.livepatch
+LIVEPATCH_ACTION_HOOKS := xen_action_hooks.livepatch
LIVEPATCHES += $(LIVEPATCH)
LIVEPATCHES += $(LIVEPATCH_BYE)
@@ -30,6 +31,7 @@ LIVEPATCHES += $(LIVEPATCH_NOP)
LIVEPATCHES += $(LIVEPATCH_NO_XEN_BUILDID)
LIVEPATCHES += $(LIVEPATCH_PREPOST_HOOKS)
LIVEPATCHES += $(LIVEPATCH_PREPOST_HOOKS_FAIL)
+LIVEPATCHES += $(LIVEPATCH_ACTION_HOOKS)
LIVEPATCH_DEBUG_DIR ?= $(DEBUG_DIR)/xen-livepatch
@@ -144,6 +146,12 @@ xen_prepost_hooks_fail.o: config.h
$(LIVEPATCH_PREPOST_HOOKS_FAIL): xen_prepost_hooks_fail.o xen_hello_world_func.o note.o xen_note.o
$(LD) $(LDFLAGS) $(build_id_linker) -r -o $(LIVEPATCH_PREPOST_HOOKS_FAIL) $^
+xen_actions_hooks.o: config.h
+
+.PHONY: $(LIVEPATCH_ACTION_HOOKS)
+$(LIVEPATCH_ACTION_HOOKS): xen_action_hooks.o xen_hello_world_func.o note.o xen_note.o
+ $(LD) $(LDFLAGS) $(build_id_linker) -r -o $(LIVEPATCH_ACTION_HOOKS) $^
+
.PHONY: livepatch
livepatch: $(LIVEPATCH) $(LIVEPATCH_BYE) $(LIVEPATCH_REPLACE) $(LIVEPATCH_NOP) $(LIVEPATCH_NO_XEN_BUILDID) \
- $(LIVEPATCH_PREPOST_HOOKS) $(LIVEPATCH_PREPOST_HOOKS_FAIL)
+ $(LIVEPATCH_PREPOST_HOOKS) $(LIVEPATCH_PREPOST_HOOKS_FAIL) $(LIVEPATCH_ACTION_HOOKS)
new file mode 100644
@@ -0,0 +1,100 @@
+/*
+ * Copyright (c) 2019 Amazon.com, Inc. or its affiliates. All rights reserved.
+ *
+ */
+
+#include "config.h"
+#include <xen/lib.h>
+#include <xen/types.h>
+#include <xen/version.h>
+#include <xen/livepatch.h>
+#include <xen/livepatch_payload.h>
+
+#include <public/sysctl.h>
+
+static const char hello_world_patch_this_fnc[] = "xen_extra_version";
+extern const char *xen_hello_world(void);
+
+static unsigned int apply_cnt;
+static unsigned int revert_cnt;
+
+static int apply_hook(livepatch_payload_t *payload)
+{
+ int i;
+
+ printk(KERN_DEBUG "%s: Hook starting.\n", __func__);
+
+ for (i = 0; i < payload->nfuncs; i++)
+ {
+ struct livepatch_func *func = &payload->funcs[i];
+
+ apply_cnt++;
+
+ printk(KERN_DEBUG "%s: applying: %s\n", __func__, func->name);
+ }
+
+ printk(KERN_DEBUG "%s: Hook done.\n", __func__);
+
+ return 0;
+}
+
+static int revert_hook(livepatch_payload_t *payload)
+{
+ int i;
+
+ printk(KERN_DEBUG "%s: Hook starting.\n", __func__);
+
+ for (i = 0; i < payload->nfuncs; i++)
+ {
+ struct livepatch_func *func = &payload->funcs[i];
+
+ revert_cnt++;
+
+ printk(KERN_DEBUG "%s: reverting: %s\n", __func__, func->name);
+ }
+
+ printk(KERN_DEBUG "%s: Hook done.\n", __func__);
+
+ return 0;
+}
+
+static void post_revert_hook(livepatch_payload_t *payload)
+{
+ int i;
+
+ printk(KERN_DEBUG "%s: Hook starting.\n", __func__);
+
+ for (i = 0; i < payload->nfuncs; i++)
+ {
+ struct livepatch_func *func = &payload->funcs[i];
+
+ printk(KERN_DEBUG "%s: reverted: %s\n", __func__, func->name);
+ }
+
+ BUG_ON(apply_cnt != 1 || revert_cnt != 1);
+ printk(KERN_DEBUG "%s: Hook done.\n", __func__);
+}
+
+LIVEPATCH_APPLY_HOOK(apply_hook);
+LIVEPATCH_REVERT_HOOK(revert_hook);
+
+LIVEPATCH_POSTREVERT_HOOK(post_revert_hook);
+
+struct livepatch_func __section(".livepatch.funcs") livepatch_xen_hello_world = {
+ .version = LIVEPATCH_PAYLOAD_VERSION,
+ .name = hello_world_patch_this_fnc,
+ .new_addr = xen_hello_world,
+ .old_addr = xen_extra_version,
+ .new_size = NEW_CODE_SZ,
+ .old_size = OLD_CODE_SZ,
+};
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */