[CRIU] [PATCH 1/8] signals: dump alternate stack as misc parameters

[Andrey Wagin]

2013/7/11 Pavel Emelyanov <xemul at parallels.com>:
> On 07/11/2013 01:46 PM, Andrey Vagin wrote:
>> The initilization stage is not good for that, because it can fail.
>
> IMO it should be done as early as possible, as the sas info is to
> be used by sigreturn rescue from parasite.

Yes, you are rigth. I forgot about this. Thanks.

>
>> Signed-off-by: Andrey Vagin <avagin at openvz.org>
>> ---
>>  cr-dump.c          |  3 +++
>>  include/parasite.h | 10 +++++++++-
>>  parasite-syscall.c | 10 ----------
>>  pie/parasite.c     |  8 ++++----
>>  4 files changed, 16 insertions(+), 15 deletions(-)
>>
>> diff --git a/cr-dump.c b/cr-dump.c
>> index ceee96f..9a7d756 100644
>> --- a/cr-dump.c
>> +++ b/cr-dump.c
>> @@ -668,6 +668,9 @@ static int dump_task_core_all(struct parasite_ctl *ctl,
>>       core_put_tls(core, misc->tls);
>>       CORE_THREAD_ARCH_INFO(core)->clear_tid_addr = encode_pointer(misc->tid_addr);
>>
>> +     BUG_ON(!core->thread_core->sas);
>> +     copy_sas(core->thread_core->sas, &misc->sas);
>> +
>>       ret = pb_write_one(fd_core, core, PB_CORE);
>>       if (ret < 0)
>>               goto err;
>> diff --git a/include/parasite.h b/include/parasite.h
>> index 0fbdd2c..334e31d 100644
>> --- a/include/parasite.h
>> +++ b/include/parasite.h
>> @@ -71,7 +71,6 @@ struct parasite_init_args {
>>       k_rtsigset_t            sig_blocked;
>>
>>       struct rt_sigframe      *sigframe;
>> -     stack_t                 sas;
>>  };
>>
>>  struct parasite_log_args {
>> @@ -150,6 +149,8 @@ struct parasite_dump_misc {
>>       u32 pgid;
>>       u32 tls;
>>       u32 umask;
>> +
>> +     stack_t                 sas;
>>  };
>>
>>  #define PARASITE_MAX_GROUPS  (PAGE_SIZE / sizeof(unsigned int) - 2 * sizeof(unsigned))
>> @@ -168,6 +169,13 @@ struct parasite_dump_thread {
>>       stack_t                 sas;
>>  };
>>
>> +static inline void copy_sas(ThreadSasEntry *dst, const stack_t *src)
>> +{
>> +     dst->ss_sp = encode_pointer(src->ss_sp);
>> +     dst->ss_size = (u64)src->ss_size;
>> +     dst->ss_flags = src->ss_flags;
>> +}
>> +
>>  #define PARASITE_MAX_FDS     (PAGE_SIZE / sizeof(int))
>>
>>  struct parasite_drain_fd {
>> diff --git a/parasite-syscall.c b/parasite-syscall.c
>> index 2ca90f6..79dc7cd 100644
>> --- a/parasite-syscall.c
>> +++ b/parasite-syscall.c
>> @@ -370,13 +370,6 @@ static int parasite_set_logfd(struct parasite_ctl *ctl, pid_t pid)
>>       return 0;
>>  }
>>
>> -static void copy_sas(ThreadSasEntry *dst, stack_t *src)
>> -{
>> -     dst->ss_sp = encode_pointer(src->ss_sp);
>> -     dst->ss_size = (u64)src->ss_size;
>> -     dst->ss_flags = src->ss_flags;
>> -}
>> -
>>  static int parasite_init(struct parasite_ctl *ctl, pid_t pid, struct pstree_item *item)
>>  {
>>       static int ssock = -1;
>> @@ -428,9 +421,6 @@ static int parasite_init(struct parasite_ctl *ctl, pid_t pid, struct pstree_item
>>       ctl->sig_blocked = args->sig_blocked;
>>       ctl->use_sig_blocked = true;
>>
>> -     BUG_ON(!item->core[0]->thread_core->sas);
>> -     copy_sas(item->core[0]->thread_core->sas, &args->sas);
>> -
>>       sock = accept(ssock, NULL, 0);
>>       if (sock < 0) {
>>               pr_perror("Can't accept connection to the transport socket");
>> diff --git a/pie/parasite.c b/pie/parasite.c
>> index 125305e..eb5186d 100644
>> --- a/pie/parasite.c
>> +++ b/pie/parasite.c
>> @@ -149,6 +149,10 @@ static int dump_misc(struct parasite_dump_misc *args)
>>       args->umask = sys_umask(0);
>>       sys_umask(args->umask); /* never fails */
>>
>> +     ret = sys_sigaltstack(NULL, &args->sas);
>> +     if (ret)
>> +             return ret;
>> +
>>       ret = sys_prctl(PR_GET_TID_ADDRESS, (unsigned long) &args->tid_addr, 0, 0, 0);
>>
>>       return ret;
>> @@ -250,10 +254,6 @@ static int init(struct parasite_init_args *args)
>>       if (ret)
>>               return -1;
>>
>> -     ret = sys_sigaltstack(NULL, &args->sas);
>> -     if (ret)
>> -             goto err;
>> -
>>       tsock = sys_socket(PF_UNIX, SOCK_STREAM, 0);
>>       if (tsock < 0) {
>>               ret = tsock;
>>
>
>