Re: [Qemu-devel] [PATCH v3 11/23] linux-user: Initialize pseudo-random seeds for all guest cpus

[Philippe Mathieu-Daudé]

On 3/15/19 4:26 AM, Richard Henderson wrote:
> When the -seed option is given, call qemu_guest_random_seed_main,
> putting the subsystem into deterministic mode.  Pass derived seeds
> to each cpu created during clone; which is a no-op unless the
> subsystem is in deterministic mode.
> 
> Cc: Laurent Vivier <address@hidden>
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  linux-user/main.c    | 21 ++++++++++-----------
>  linux-user/syscall.c |  3 +++
>  2 files changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/linux-user/main.c b/linux-user/main.c
> index a0aba9cb1e..cf7095bdaf 100644
> --- a/linux-user/main.c
> +++ b/linux-user/main.c
> @@ -33,6 +33,7 @@
>  #include "tcg.h"
>  #include "qemu/timer.h"
>  #include "qemu/envlist.h"
> +#include "qemu/guest-random.h"
>  #include "elf.h"
>  #include "trace/control.h"
>  #include "target_elf.h"
> @@ -47,6 +48,7 @@ static int gdbstub_port;
>  static envlist_t *envlist;
>  static const char *cpu_model;
>  static const char *cpu_type;
> +static const char *seed_optarg;
>  unsigned long mmap_min_addr;
>  unsigned long guest_base;
>  int have_guest_base;
> @@ -289,15 +291,9 @@ static void handle_arg_pagesize(const char *arg)
>      }
>  }
>  
> -static void handle_arg_randseed(const char *arg)
> +static void handle_arg_seed(const char *arg)
>  {
> -    unsigned long long seed;
> -
> -    if (parse_uint_full(arg, &seed, 0) != 0 || seed > UINT_MAX) {
> -        fprintf(stderr, "Invalid seed number: %s\n", arg);
> -        exit(EXIT_FAILURE);
> -    }
> -    srand(seed);
> +    seed_optarg = arg;
>  }
>  
>  static void handle_arg_gdb(const char *arg)
> @@ -432,7 +428,7 @@ static const struct qemu_argument arg_table[] = {
>       "",           "run in singlestep mode"},
>      {"strace",     "QEMU_STRACE",      false, handle_arg_strace,
>       "",           "log system calls"},
> -    {"seed",       "QEMU_RAND_SEED",   true,  handle_arg_randseed,
> +    {"seed",       "QEMU_RAND_SEED",   true,  handle_arg_seed,
>       "",           "Seed for pseudo-random number generator"},
>      {"trace",      "QEMU_TRACE",       true,  handle_arg_trace,
>       "",           "[[enable=]<pattern>][,events=<file>][,file=<file>]"},
> @@ -687,8 +683,11 @@ int main(int argc, char **argv, char **envp)
>          do_strace = 1;
>      }
>  
> -    if (getenv("QEMU_RAND_SEED")) {
> -        handle_arg_randseed(getenv("QEMU_RAND_SEED"));
> +    if (seed_optarg == NULL) {
> +        seed_optarg = getenv("QEMU_RAND_SEED");
> +    }
> +    if (seed_optarg != NULL) {
> +        qemu_guest_random_seed_main(seed_optarg, &error_fatal);
>      }
>  
>      target_environ = envlist_to_environ(envlist, NULL);
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 208fd1813d..8f7125cd67 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -110,6 +110,7 @@
>  #include "uname.h"
>  
>  #include "qemu.h"
> +#include "qemu/guest-random.h"
>  #include "fd-trans.h"
>  
>  #ifndef CLONE_IO
> @@ -5448,6 +5449,7 @@ static void *clone_func(void *arg)
>          put_user_u32(info->tid, info->child_tidptr);
>      if (info->parent_tidptr)
>          put_user_u32(info->tid, info->parent_tidptr);
> +    qemu_guest_random_seed_thread_part2(cpu->random_seed);
>      /* Enable signals.  */
>      sigprocmask(SIG_SETMASK, &info->sigmask, NULL);
>      /* Signal to the parent that we're ready.  */
> @@ -5534,6 +5536,7 @@ static int do_fork(CPUArchState *env, unsigned int 
> flags, abi_ulong newsp,
>             initializing, so temporarily block all signals.  */
>          sigfillset(&sigmask);
>          sigprocmask(SIG_BLOCK, &sigmask, &info.sigmask);
> +        cpu->random_seed = qemu_guest_random_seed_thread_part1();
>  
>          /* If this is our first additional thread, we need to ensure we
>           * generate code for parallel execution and flush old translations.
> 

Reviewed-by: Philippe Mathieu-Daudé <address@hidden>