[CRIU] [PATCH 1/4] Restore registers not present in the sigreturn signal frame

[Andrei Vagin]

On Thu, Sep 28, 2017 at 01:50:09PM +0200, Alice Frosi wrote:
> Add new function arch_set_task_regs_nosigrt(). It allows to restore
> architecture-specific registers not present in sigreturn signal frame.
> 
> Each architecture can overwrite this function.
> 
> The arch_set_task_regs_nosigrt function restores the registers between the
> final sigreturn and PTRACE_DETACH. We do this at this point because
> we are sure that all threads have already been created.
> 
> Add arch_set_thread_regs in pre-dump because some registers may have
> been changed by the parasite infection and they are not present in
> sigreturn signal frame.
> 
> Signed-off-by: Alice Frosi <alice at linux.vnet.ibm.com>
> Reviewed-by: Michael Holzheu <holzheu at linux.vnet.ibm.com>
> ---
>  criu/cr-dump.c         | 14 ++++++++++++--
>  criu/cr-restore.c      | 10 ++++++++++
>  criu/include/dump.h    |  3 +++
>  criu/include/restore.h |  3 +++
>  4 files changed, 28 insertions(+), 2 deletions(-)
> 
> diff --git a/criu/cr-dump.c b/criu/cr-dump.c
> index c83f5ee..67284ae 100644
> --- a/criu/cr-dump.c
> +++ b/criu/cr-dump.c
> @@ -87,8 +87,13 @@
>  /*
>   * Architectures can overwrite this function to restore register sets that
>   * are not covered by ptrace_set/get_regs().
> + *
> + * with_threads = false: Only the register sets of the tasks are restored
> + * with_threads = true : The register sets of the tasks with all their threads
> + *			 are restored
>   */
> -int __attribute__((weak)) arch_set_thread_regs(struct pstree_item *item)
> +int __attribute__((weak)) arch_set_thread_regs(struct pstree_item *item,
> +					       bool with_threads)
>  {
>  	return 0;
>  }
> @@ -1560,6 +1565,11 @@ static int cr_pre_dump_finish(int ret)
>  {
>  	struct pstree_item *item;
>  
> +	/*
> +	 * Restore registers for tasks only. The threads have not been
> +	 * infected. Therefore, the thread register sets have not been changed.
> +	 */
> +	arch_set_thread_regs(root_item, false);

arch_set_thread_regs may return an error, why don't we handle it?

>  	pstree_switch_state(root_item, TASK_ALIVE);
>  
>  	timing_stop(TIME_FROZEN);
> @@ -1785,7 +1795,7 @@ static int cr_dump_finish(int ret)
>  	if (!ret && opts.lazy_pages)
>  		ret = cr_lazy_mem_dump();
>  
> -	arch_set_thread_regs(root_item);
> +	arch_set_thread_regs(root_item, true);

the same question

>  	pstree_switch_state(root_item,
>  			    (ret || post_dump_ret) ?
>  			    TASK_ALIVE : opts.final_state);
> diff --git a/criu/cr-restore.c b/criu/cr-restore.c
> index 4d6f6e4..a691b4f 100644
> --- a/criu/cr-restore.c
> +++ b/criu/cr-restore.c
> @@ -122,6 +122,15 @@ static int prepare_rlimits(int pid, struct task_restore_args *, CoreEntry *core)
>  static int prepare_posix_timers(int pid, struct task_restore_args *ta, CoreEntry *core);
>  static int prepare_signals(int pid, struct task_restore_args *, CoreEntry *core);
>  
> +/*
> + * Architectures can overwrite this function to restore registers that are not
> + * present in the sigreturn signal frame.
> + */
> +int __attribute__((weak)) arch_set_thread_regs_nosigrt(struct pid *pid)
> +{
> +	return 0;
> +}
> +
>  static inline int stage_participants(int next_stage)
>  {
>  	switch (next_stage) {
> @@ -2081,6 +2090,7 @@ static void finalize_restore_detach(int status)
>  				break;
>  			}
>  
> +			arch_set_thread_regs_nosigrt(item->threads[i]);
>  			if (ptrace(PTRACE_DETACH, pid, NULL, 0))
>  				pr_perror("Unable to execute %d", pid);
>  		}
> diff --git a/criu/include/dump.h b/criu/include/dump.h
> index d9a4b61..1c14468 100644
> --- a/criu/include/dump.h
> +++ b/criu/include/dump.h
> @@ -1,4 +1,7 @@
>  #ifndef __CR_INC_DUMP_H__
>  #define __CR_INC_DUMP_H__
>  #include "asm/dump.h"
> +
> +extern int arch_set_thread_regs(struct pstree_item *item, bool with_threads);
> +
>  #endif
> diff --git a/criu/include/restore.h b/criu/include/restore.h
> index 07e8fd8..511f253 100644
> --- a/criu/include/restore.h
> +++ b/criu/include/restore.h
> @@ -1,8 +1,11 @@
>  #ifndef __CR_INC_RESTORE_H__
>  #define __CR_INC_RESTORE_H__
> +
> +#include "pid.h"
>  #include "types.h"
>  #include "asm/restore.h"
>  
>  extern int criu_signals_setup(void (*handler)(int, siginfo_t *, void *));
> +extern int arch_set_thread_regs_nosigrt(struct pid *pid);
>  
>  #endif
> -- 
> 2.9.3
> 
> _______________________________________________
> CRIU mailing list
> CRIU at openvz.org
> https://lists.openvz.org/mailman/listinfo/criu