Re: [Qemu-devel] [PATCH] linux-user/syscall.c: Notice about lock bitmask translation for fcntl

[Chen Gang <chengang@emindsoft.com.cn>]

I found this issue during my working time, it is about sw_64 (almost the
same as alpha) host running i386 wine programs.

I also found another issue, but I am not quite sure whether it is worth
enough for our upstream: The related fix patch is below, which will let
the initialization slower, but for most archs, they have no this issue.

    linux-user/mmap.c: Always zero MAP_ANONYMOUS memory in target_mmap()
    
    In some architectures, they have no policy to zero MAP_ANONYMOUS memory,
    which will cause issue for qemu target_mmap.
    
    Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>

diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index 7b459d5..9c9152d 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -567,6 +567,10 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
     printf("\n");
 #endif
     tb_invalidate_phys_range(start, start + len);
+    if ((prot & PROT_WRITE) && (flags & MAP_ANONYMOUS)
+        && ((flags & MAP_PRIVATE) || (fd == -1))) {
+        memset(g2h(start), 0, len);
+    }
     mmap_unlock();
     return start;
 fail:


Thanks.

On 2015年12月18日 14:26, Chen Gang wrote:
> 
> For fcntl, it always needs to notice about it, just like do_fcntl() has
> done, or it will cause issue (e.g. alpha host run i386 guest).
> 
> Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
> ---
>  linux-user/syscall.c |   18 ++++++++++++------
>  1 files changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 0f8adeb..1a60e6f 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -9007,7 +9007,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
>              if (((CPUARMState *)cpu_env)->eabi) {
>                  if (!lock_user_struct(VERIFY_READ, target_efl, arg3, 1)) 
>                      goto efault;
> -                fl.l_type = tswap16(target_efl->l_type);
> +                fl.l_type = target_to_host_bitmask(tswap16(target_fl->l_type),
> +                                                   flock_tbl);
>                  fl.l_whence = tswap16(target_efl->l_whence);
>                  fl.l_start = tswap64(target_efl->l_start);
>                  fl.l_len = tswap64(target_efl->l_len);
> @@ -9018,7 +9019,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
>              {
>                  if (!lock_user_struct(VERIFY_READ, target_fl, arg3, 1)) 
>                      goto efault;
> -                fl.l_type = tswap16(target_fl->l_type);
> +                fl.l_type = target_to_host_bitmask(tswap16(target_fl->l_type),
> +                                                   flock_tbl);
>                  fl.l_whence = tswap16(target_fl->l_whence);
>                  fl.l_start = tswap64(target_fl->l_start);
>                  fl.l_len = tswap64(target_fl->l_len);
> @@ -9031,7 +9033,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
>                  if (((CPUARMState *)cpu_env)->eabi) {
>                      if (!lock_user_struct(VERIFY_WRITE, target_efl, arg3, 0)) 
>                          goto efault;
> -                    target_efl->l_type = tswap16(fl.l_type);
> +                    target_efl->l_type = host_to_target_bitmask(
> +                                                 tswap16(fl.l_type), flock_tbl);
>                      target_efl->l_whence = tswap16(fl.l_whence);
>                      target_efl->l_start = tswap64(fl.l_start);
>                      target_efl->l_len = tswap64(fl.l_len);
> @@ -9042,7 +9045,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
>                  {
>                      if (!lock_user_struct(VERIFY_WRITE, target_fl, arg3, 0)) 
>                          goto efault;
> -                    target_fl->l_type = tswap16(fl.l_type);
> +                    target_fl->l_type = host_to_target_bitmask(
> +                                                 tswap16(fl.l_type), flock_tbl);
>                      target_fl->l_whence = tswap16(fl.l_whence);
>                      target_fl->l_start = tswap64(fl.l_start);
>                      target_fl->l_len = tswap64(fl.l_len);
> @@ -9058,7 +9062,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
>              if (((CPUARMState *)cpu_env)->eabi) {
>                  if (!lock_user_struct(VERIFY_READ, target_efl, arg3, 1)) 
>                      goto efault;
> -                fl.l_type = tswap16(target_efl->l_type);
> +                fl.l_type = target_to_host_bitmask(tswap16(target_fl->l_type),
> +                                                   flock_tbl);
>                  fl.l_whence = tswap16(target_efl->l_whence);
>                  fl.l_start = tswap64(target_efl->l_start);
>                  fl.l_len = tswap64(target_efl->l_len);
> @@ -9069,7 +9074,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
>              {
>                  if (!lock_user_struct(VERIFY_READ, target_fl, arg3, 1)) 
>                      goto efault;
> -                fl.l_type = tswap16(target_fl->l_type);
> +                fl.l_type = target_to_host_bitmask(tswap16(target_fl->l_type),
> +                                                   flock_tbl);
>                  fl.l_whence = tswap16(target_fl->l_whence);
>                  fl.l_start = tswap64(target_fl->l_start);
>                  fl.l_len = tswap64(target_fl->l_len);
> 

-- 
Chen Gang (陈刚)

Open, share, and attitude like air, water, and life which God blessed