Re: [PATCH 3/3] linux-user: Add strace support for printing arguments of some clock and time functions

[Laurent Vivier]

Le 26/06/2020 à 23:39, Filip Bozuta a écrit :
> This patch implements strace argument printing functionality for following 
> syscalls:
> 
>     * clock_getres, clock_gettime, clock_settime - clock and time functions
> 
>         int clock_getres(clockid_t clockid, struct timespec *res)
>         int clock_gettime(clockid_t clockid, struct timespec *tp)
>         int clock_settime(clockid_t clockid, const struct timespec *tp)
>         man page: https://man7.org/linux/man-pages/man2/clock_getres.2.html
> 
>     * gettimeofday - get time
> 
>         int gettimeofday(struct timeval *tv, struct timezone *tz)
>         man page: https://man7.org/linux/man-pages/man2/gettimeofday.2.html
> 
>     * getitimer, setitimer - get or set value of an interval timer
> 
>         int getitimer(int which, struct itimerval *curr_value)
>         int setitimer(int which, const struct itimerval *new_value,
>                       struct itimerval *old_value)
>         man page: https://man7.org/linux/man-pages/man2/getitimer.2.html
> 
> Implementation notes:
> 
>     All of the syscalls have some structue types as argument types and thus
>     a separate printing function was stated in file "strace.list" for each
>     of them. All of these functions use existing functions for their
>     appropriate structure types ("print_timeval()" and "print_timezone()").
>     Functions "print_timespec()" and "print_itimerval()" were added in this
>     patch so that they can be used to print types "struct timespec" and
>     "struct itimerval" used by some of the syscalls. Function 
> "print_itimerval()"
>     uses the existing function "print_timeval()" to print fields of the
>     structure "struct itimerval" that are of type "struct timeval".
>     Also, the existing function "print_timeval()" was changed a little so
>     that it prints the field names beside the values. Syscalls 
> "clock_getres()"
>     and "clocK_gettime()" have the same number and types of arguments and
>     thus their print functions "print_clock_getres" and "print_clock_gettime"
>     shate a common definition in file "strace.c".
> 
> Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
> ---
>  linux-user/strace.c    | 186 ++++++++++++++++++++++++++++++++++++++++-
>  linux-user/strace.list |  16 ++--
>  2 files changed, 194 insertions(+), 8 deletions(-)
> 
> diff --git a/linux-user/strace.c b/linux-user/strace.c
> index 1fc4404310..414748d0fa 100644
> --- a/linux-user/strace.c
> +++ b/linux-user/strace.c
> @@ -64,7 +64,9 @@ UNUSED static void print_string(abi_long, int);
>  UNUSED static void print_buf(abi_long addr, abi_long len, int last);
>  UNUSED static void print_raw_param(const char *, abi_long, int);
>  UNUSED static void print_timeval(abi_ulong, int);
> +UNUSED static void print_timespec(abi_ulong, int);
>  UNUSED static void print_timezone(abi_ulong, int);
> +UNUSED static void print_itimerval(abi_ulong, int);
>  UNUSED static void print_number(abi_long, int);
>  UNUSED static void print_signal(abi_ulong, int);
>  UNUSED static void print_sockaddr(abi_ulong, abi_long, int);
> @@ -833,6 +835,65 @@ print_syscall_ret_adjtimex(const struct syscallname 
> *name, abi_long ret,
>  }
>  #endif
>  
> +#if defined(TARGET_NR_clock_gettime) || defined(TARGET_NR_clock_getres)
> +static void
> +print_syscall_ret_clock_gettime(const struct syscallname *name, abi_long ret,
> +                                abi_long arg0, abi_long arg1, abi_long arg2,
> +                                abi_long arg3, abi_long arg4, abi_long arg5)
> +{
> +    print_syscall_err(ret);
> +
> +    if (ret >= 0) {
> +        qemu_log(TARGET_ABI_FMT_ld, ret);
> +        qemu_log(" (");
> +        print_timespec(arg1, 1);
> +        qemu_log(")");
> +    }
> +
> +    qemu_log("\n");
> +}
> +#define print_syscall_ret_clock_getres     print_syscall_ret_clock_gettime
> +#endif
> +
> +#ifdef TARGET_NR_gettimeofday
> +static void
> +print_syscall_ret_gettimeofday(const struct syscallname *name, abi_long ret,
> +                               abi_long arg0, abi_long arg1, abi_long arg2,
> +                               abi_long arg3, abi_long arg4, abi_long arg5)
> +{
> +    print_syscall_err(ret);
> +
> +    if (ret >= 0) {
> +        qemu_log(TARGET_ABI_FMT_ld, ret);
> +        qemu_log(" (");
> +        print_timeval(arg0, 0);
> +        print_timezone(arg1, 1);
> +        qemu_log(")");
> +    }
> +
> +    qemu_log("\n");
> +}
> +#endif
> +
> +#ifdef TARGET_NR_getitimer
> +static void
> +print_syscall_ret_getitimer(const struct syscallname *name, abi_long ret,
> +                            abi_long arg0, abi_long arg1, abi_long arg2,
> +                            abi_long arg3, abi_long arg4, abi_long arg5)
> +{
> +    print_syscall_err(ret);
> +
> +    if (ret >= 0) {
> +        qemu_log(TARGET_ABI_FMT_ld, ret);
> +        qemu_log(" (");
> +        print_itimerval(arg1, 1);
> +        qemu_log(")");
> +    }
> +
> +    qemu_log("\n");
> +}
> +#endif
> +
>  #if defined(TARGET_NR_listxattr) || defined(TARGET_NR_llistxattr) \
>   || defined(TARGGET_NR_flistxattr)
>  static void
> @@ -1371,13 +1432,34 @@ print_timeval(abi_ulong tv_addr, int last)
>              print_pointer(tv_addr, last);
>              return;
>          }
> -        qemu_log("{" TARGET_ABI_FMT_ld "," TARGET_ABI_FMT_ld "}%s",
> -            tswapal(tv->tv_sec), tswapal(tv->tv_usec), get_comma(last));
> +        qemu_log("{tv_sec = " TARGET_ABI_FMT_ld
> +                 ",tv_usec = " TARGET_ABI_FMT_ld "}%s",
> +                 tswapal(tv->tv_sec), tswapal(tv->tv_usec), get_comma(last));
>          unlock_user(tv, tv_addr, 0);
>      } else
>          qemu_log("NULL%s", get_comma(last));
>  }
>  
> +static void
> +print_timespec(abi_ulong ts_addr, int last)
> +{
> +    if (ts_addr) {
> +        struct target_timespec *ts;
> +
> +        ts = lock_user(VERIFY_READ, ts_addr, sizeof(*ts), 1);
> +        if (!ts) {
> +            print_pointer(ts_addr, last);
> +            return;
> +        }
> +        qemu_log("{tv_sec = " TARGET_ABI_FMT_ld
> +                 ",tv_nsec = " TARGET_ABI_FMT_ld "}%s",
> +                 tswapal(ts->tv_sec), tswapal(ts->tv_nsec), get_comma(last));
> +        unlock_user(ts, ts_addr, 0);
> +    } else {
> +        qemu_log("NULL%s", get_comma(last));
> +    }
> +}
> +
>  static void
>  print_timezone(abi_ulong tz_addr, int last)
>  {
> @@ -1397,6 +1479,21 @@ print_timezone(abi_ulong tz_addr, int last)
>      }
>  }
>  
> +static void
> +print_itimerval(abi_ulong it_addr, int last)
> +{
> +    if (it_addr) {
> +        qemu_log("{it_interval=");
> +        print_timeval(it_addr, 0);
> +        qemu_log("it_value=");
> +        print_timeval(it_addr +
> +                      offsetof(struct target_itimerval, it_value), 1);
> +        qemu_log("}%s", get_comma(last));

It would be cleaner to define a target_itimerval, but as it is already
decoded like that in syscall.c I think we can take this also in strace.c

> +    } else {
> +        qemu_log("NULL%s", get_comma(last));
> +    }
> +}
> +
>  #undef UNUSED
>  
>  #ifdef TARGET_NR_accept
> @@ -1839,6 +1936,19 @@ print_futimesat(const struct syscallname *name,
>  }
>  #endif
>  
> +#ifdef TARGET_NR_gettimeofday
> +static void
> +print_gettimeofday(const struct syscallname *name,
> +    abi_long arg0, abi_long arg1, abi_long arg2,
> +    abi_long arg3, abi_long arg4, abi_long arg5)
> +{
> +    print_syscall_prologue(name);
> +    print_pointer(arg0, 0);
> +    print_pointer(arg1, 1);
> +    print_syscall_epilogue(name);
> +}
> +#endif
> +
>  #ifdef TARGET_NR_settimeofday
>  static void
>  print_settimeofday(const struct syscallname *name,
> @@ -1852,6 +1962,78 @@ print_settimeofday(const struct syscallname *name,
>  }
>  #endif
>  
> +#if defined(TARGET_NR_clock_gettime) || defined(TARGET_NR_clock_getres)
> +static void
> +print_clock_gettime(const struct syscallname *name,
> +    abi_long arg0, abi_long arg1, abi_long arg2,
> +    abi_long arg3, abi_long arg4, abi_long arg5)
> +{
> +    print_syscall_prologue(name);
> +    print_clockid(arg0, 0);
> +    print_pointer(arg1, 1);
> +    print_syscall_epilogue(name);
> +}
> +#define print_clock_getres     print_clock_gettime
> +#endif
> +
> +#ifdef TARGET_NR_clock_settime
> +static void
> +print_clock_settime(const struct syscallname *name,
> +    abi_long arg0, abi_long arg1, abi_long arg2,
> +    abi_long arg3, abi_long arg4, abi_long arg5)
> +{
> +    print_syscall_prologue(name);
> +    print_clockid(arg0, 0);
> +    print_timespec(arg1, 1);
> +    print_syscall_epilogue(name);
> +}
> +#endif
> +
> +#ifdef TARGET_NR_getitimer
> +static void
> +print_getitimer(const struct syscallname *name,
> +    abi_long arg0, abi_long arg1, abi_long arg2,
> +    abi_long arg3, abi_long arg4, abi_long arg5)
> +{
> +    print_syscall_prologue(name);
> +    switch (arg0) {
> +    case ITIMER_REAL:
> +        qemu_log("ITIMER_REAL,"); break;
> +    case ITIMER_VIRTUAL:
> +        qemu_log("ITIMER_VIRTUAL,"); break;
> +    case ITIMER_PROF:
> +        qemu_log("ITIMER_PROF,"); break;
> +    default:
> +        print_raw_param("%#x", arg1, 0);
> +    }

Perhaps you can move the switch to a function and use it in
print_getitimer() and in print_setitimer().

> +    print_pointer(arg1, 1);
> +    print_syscall_epilogue(name);
> +}
> +#endif
> +
> +#ifdef TARGET_NR_setitimer
> +static void
> +print_setitimer(const struct syscallname *name,
> +    abi_long arg0, abi_long arg1, abi_long arg2,
> +    abi_long arg3, abi_long arg4, abi_long arg5)
> +{
> +    print_syscall_prologue(name);
> +    switch (arg0) {
> +    case ITIMER_REAL:
> +        qemu_log("ITIMER_REAL,"); break;
> +    case ITIMER_VIRTUAL:
> +        qemu_log("ITIMER_VIRTUAL,"); break;
> +    case ITIMER_PROF:
> +        qemu_log("ITIMER_PROF,"); break;
> +    default:
> +        print_raw_param("%#x", arg1, 0);
> +    }
> +    print_itimerval(arg1, 0);
> +    print_itimerval(arg2, 1);

arg2 is old value and should be displaye in a ret function.

> +    print_syscall_epilogue(name);
> +}
> +#endif
> +
>  #ifdef TARGET_NR_link
>  static void
>  print_link(const struct syscallname *name,
> diff --git a/linux-user/strace.list b/linux-user/strace.list
> index 822b6be49c..6b5cef149f 100644
> --- a/linux-user/strace.list
> +++ b/linux-user/strace.list
> @@ -83,16 +83,18 @@
>  { TARGET_NR_clock_adjtime, "clock_adjtime" , NULL, print_clock_adjtime, NULL 
> },
>  #endif
>  #ifdef TARGET_NR_clock_getres
> -{ TARGET_NR_clock_getres, "clock_getres" , NULL, NULL, NULL },
> +{ TARGET_NR_clock_getres, "clock_getres" , NULL, print_clock_getres,
> +                          print_syscall_ret_clock_getres },
>  #endif
>  #ifdef TARGET_NR_clock_gettime
> -{ TARGET_NR_clock_gettime, "clock_gettime" , NULL, NULL, NULL },
> +{ TARGET_NR_clock_gettime, "clock_gettime" , NULL, print_clock_gettime,
> +                           print_syscall_ret_clock_gettime },
>  #endif
>  #ifdef TARGET_NR_clock_nanosleep
>  { TARGET_NR_clock_nanosleep, "clock_nanosleep" , NULL, NULL, NULL },
>  #endif
>  #ifdef TARGET_NR_clock_settime
> -{ TARGET_NR_clock_settime, "clock_settime" , NULL, NULL, NULL },
> +{ TARGET_NR_clock_settime, "clock_settime" , NULL, print_clock_settime, NULL 
> },
>  #endif
>  #ifdef TARGET_NR_clone
>  { TARGET_NR_clone, "clone" , NULL, print_clone, NULL },
> @@ -315,7 +317,8 @@
>  { TARGET_NR_gethostname, "gethostname" , NULL, NULL, NULL },
>  #endif
>  #ifdef TARGET_NR_getitimer
> -{ TARGET_NR_getitimer, "getitimer" , NULL, NULL, NULL },
> +{ TARGET_NR_getitimer, "getitimer" , NULL, print_getitimer,
> +                       print_syscall_ret_getitimer },
>  #endif
>  #ifdef TARGET_NR_get_kernel_syms
>  { TARGET_NR_get_kernel_syms, "get_kernel_syms" , NULL, NULL, NULL },
> @@ -388,7 +391,8 @@
>  { TARGET_NR_gettid, "gettid" , "%s()", NULL, NULL },
>  #endif
>  #ifdef TARGET_NR_gettimeofday
> -{ TARGET_NR_gettimeofday, "gettimeofday" , NULL, NULL, NULL },
> +{ TARGET_NR_gettimeofday, "gettimeofday" , NULL, print_gettimeofday,
> +                          print_syscall_ret_gettimeofday },
>  #endif
>  #ifdef TARGET_NR_getuid
>  { TARGET_NR_getuid, "getuid" , "%s()", NULL, NULL },
> @@ -1290,7 +1294,7 @@
>  { TARGET_NR_sethostname, "sethostname" , NULL, NULL, NULL },
>  #endif
>  #ifdef TARGET_NR_setitimer
> -{ TARGET_NR_setitimer, "setitimer" , NULL, NULL, NULL },
> +{ TARGET_NR_setitimer, "setitimer" , NULL, print_setitimer, NULL },
>  #endif
>  #ifdef TARGET_NR_set_mempolicy
>  { TARGET_NR_set_mempolicy, "set_mempolicy" , NULL, NULL, NULL },
> 

Thanks,
Laurent