From 5564323f643715f9d364df88e0eb9c7d6fd2c22b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= Date: Tue, 5 Mar 2024 11:59:43 +0100 Subject: [PATCH 32/67] xen/livepatch: fix norevert test attempt to open-code revert MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The purpose of the norevert test is to install a dummy handler that replaces the internal Xen revert code, and then perform the revert in the post-revert hook. For that purpose the usage of the previous common_livepatch_revert() is not enough, as that just reverts specific functions, but not the whole state of the payload. Remove both common_livepatch_{apply,revert}() and instead expose revert_payload{,_tail}() in order to perform the patch revert from the post-revert hook. Fixes: 6047104c3ccc ('livepatch: Add per-function applied/reverted state tracking marker') Signed-off-by: Roger Pau Monné Reviewed-by: Ross Lagerwall master commit: cdae267ce10d04d71d1687b5701ff2911a96b6dc master date: 2024-02-28 16:57:25 +0000 --- xen/common/livepatch.c | 41 +++++++++++++++++-- xen/include/xen/livepatch.h | 32 ++------------- .../livepatch/xen_action_hooks_norevert.c | 22 +++------- 3 files changed, 46 insertions(+), 49 deletions(-) diff --git a/xen/common/livepatch.c b/xen/common/livepatch.c index a129ab9973..a5068a2217 100644 --- a/xen/common/livepatch.c +++ b/xen/common/livepatch.c @@ -1310,7 +1310,22 @@ static int apply_payload(struct payload *data) ASSERT(!local_irq_is_enabled()); for ( i = 0; i < data->nfuncs; i++ ) - common_livepatch_apply(&data->funcs[i], &data->fstate[i]); + { + const struct livepatch_func *func = &data->funcs[i]; + struct livepatch_fstate *state = &data->fstate[i]; + + /* If the action has been already executed on this function, do nothing. */ + if ( state->applied == LIVEPATCH_FUNC_APPLIED ) + { + printk(XENLOG_WARNING LIVEPATCH + "%s: %s has been already applied before\n", + __func__, func->name); + continue; + } + + arch_livepatch_apply(func, state); + state->applied = LIVEPATCH_FUNC_APPLIED; + } arch_livepatch_revive(); @@ -1326,7 +1341,7 @@ static inline void apply_payload_tail(struct payload *data) data->state = LIVEPATCH_STATE_APPLIED; } -static int revert_payload(struct payload *data) +int revert_payload(struct payload *data) { unsigned int i; int rc; @@ -1341,7 +1356,25 @@ static int revert_payload(struct payload *data) } for ( i = 0; i < data->nfuncs; i++ ) - common_livepatch_revert(&data->funcs[i], &data->fstate[i]); + { + const struct livepatch_func *func = &data->funcs[i]; + struct livepatch_fstate *state = &data->fstate[i]; + + /* + * If the apply action hasn't been executed on this function, do + * nothing. + */ + if ( !func->old_addr || state->applied == LIVEPATCH_FUNC_NOT_APPLIED ) + { + printk(XENLOG_WARNING LIVEPATCH + "%s: %s has not been applied before\n", + __func__, func->name); + continue; + } + + arch_livepatch_revert(func, state); + state->applied = LIVEPATCH_FUNC_NOT_APPLIED; + } /* * Since we are running with IRQs disabled and the hooks may call common @@ -1359,7 +1392,7 @@ static int revert_payload(struct payload *data) return 0; } -static inline void revert_payload_tail(struct payload *data) +void revert_payload_tail(struct payload *data) { list_del(&data->applied_list); diff --git a/xen/include/xen/livepatch.h b/xen/include/xen/livepatch.h index 537d3d58b6..c9ee58fd37 100644 --- a/xen/include/xen/livepatch.h +++ b/xen/include/xen/livepatch.h @@ -136,35 +136,11 @@ void arch_livepatch_post_action(void); void arch_livepatch_mask(void); void arch_livepatch_unmask(void); -static inline void common_livepatch_apply(const struct livepatch_func *func, - struct livepatch_fstate *state) -{ - /* If the action has been already executed on this function, do nothing. */ - if ( state->applied == LIVEPATCH_FUNC_APPLIED ) - { - printk(XENLOG_WARNING LIVEPATCH "%s: %s has been already applied before\n", - __func__, func->name); - return; - } - - arch_livepatch_apply(func, state); - state->applied = LIVEPATCH_FUNC_APPLIED; -} +/* Only for testing purposes. */ +struct payload; +int revert_payload(struct payload *data); +void revert_payload_tail(struct payload *data); -static inline void common_livepatch_revert(const struct livepatch_func *func, - struct livepatch_fstate *state) -{ - /* If the apply action hasn't been executed on this function, do nothing. */ - if ( !func->old_addr || state->applied == LIVEPATCH_FUNC_NOT_APPLIED ) - { - printk(XENLOG_WARNING LIVEPATCH "%s: %s has not been applied before\n", - __func__, func->name); - return; - } - - arch_livepatch_revert(func, state); - state->applied = LIVEPATCH_FUNC_NOT_APPLIED; -} #else /* diff --git a/xen/test/livepatch/xen_action_hooks_norevert.c b/xen/test/livepatch/xen_action_hooks_norevert.c index c173855192..c5fbab1746 100644 --- a/xen/test/livepatch/xen_action_hooks_norevert.c +++ b/xen/test/livepatch/xen_action_hooks_norevert.c @@ -96,26 +96,14 @@ static int revert_hook(livepatch_payload_t *payload) static void post_revert_hook(livepatch_payload_t *payload) { - int i; + unsigned long flags; printk(KERN_DEBUG "%s: Hook starting.\n", __func__); - for (i = 0; i < payload->nfuncs; i++) - { - const struct livepatch_func *func = &payload->funcs[i]; - struct livepatch_fstate *fstate = &payload->fstate[i]; - - BUG_ON(revert_cnt != 1); - BUG_ON(fstate->applied != LIVEPATCH_FUNC_APPLIED); - - /* Outside of quiesce zone: MAY TRIGGER HOST CRASH/UNDEFINED BEHAVIOR */ - arch_livepatch_quiesce(); - common_livepatch_revert(payload); - arch_livepatch_revive(); - BUG_ON(fstate->applied == LIVEPATCH_FUNC_APPLIED); - - printk(KERN_DEBUG "%s: post reverted: %s\n", __func__, func->name); - } + local_irq_save(flags); + BUG_ON(revert_payload(payload)); + revert_payload_tail(payload); + local_irq_restore(flags); printk(KERN_DEBUG "%s: Hook done.\n", __func__); } -- 2.44.0