Re: [Qemu-devel] [PATCH] linux-user: use libc wrapper instead of direct mremap syscall

[Riku Voipio]

On Fri, Sep 30, 2016 at 07:39:27PM -0400, Felix Janda wrote:
> This commit essentially reverts commit
> 3af72a4d98dca033492102603734cbc63cd2694a, which has replaced
> five-argument calls to mremap() by direct mremap syscalls for
> compatibility with glibc older than version 2.4.
> 
> The direct syscall was buggy for 64bit targets on 32bit hosts
> because of the default integer type promotions. Since glibc-2.4
> is now a decade old, we can remove this workaround.

Applied this and the <poll.h> patch to linux-user

Thanks,
Riku
 
> Signed-off-by: Felix Janda <address@hidden>
> ---
>  linux-user/mmap.c | 14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)
> 
> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
> index c4371d9..ffd099d 100644
> --- a/linux-user/mmap.c
> +++ b/linux-user/mmap.c
> @@ -17,8 +17,6 @@
>   *  along with this program; if not, see <http://www.gnu.org/licenses/>.
>   */
>  #include "qemu/osdep.h"
> -#include <linux/mman.h>
> -#include <linux/unistd.h>
>  
>  #include "qemu.h"
>  #include "qemu-common.h"
> @@ -681,10 +679,8 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong 
> old_size,
>      mmap_lock();
>  
>      if (flags & MREMAP_FIXED) {
> -        host_addr = (void *) syscall(__NR_mremap, g2h(old_addr),
> -                                     old_size, new_size,
> -                                     flags,
> -                                     g2h(new_addr));
> +        host_addr = mremap(g2h(old_addr), old_size, new_size,
> +                           flags, g2h(new_addr));
>  
>          if (reserved_va && host_addr != MAP_FAILED) {
>              /* If new and old addresses overlap then the above mremap will
> @@ -700,10 +696,8 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong 
> old_size,
>              errno = ENOMEM;
>              host_addr = MAP_FAILED;
>          } else {
> -            host_addr = (void *) syscall(__NR_mremap, g2h(old_addr),
> -                                         old_size, new_size,
> -                                         flags | MREMAP_FIXED,
> -                                         g2h(mmap_start));
> +            host_addr = mremap(g2h(old_addr), old_size, new_size,
> +                               flags | MREMAP_FIXED, g2h(mmap_start));
>              if (reserved_va) {
>                  mmap_reserve(old_addr, old_size);
>              }
> -- 
> 2.7.3
> 
>