Re: [Qemu-devel] [PATCH] bsd-user/mmap.c: Don't try to override g_malloc/g_free

[Sean Bruno]

On Wed, 2014-06-04 at 00:51 +0100, Peter Maydell wrote:
> Trying to override the implementations of g_malloc and g_free is
> a really bad idea -- it means statically linked builds fail to
> link (because of the multiple definitions provided by this file
> and by glib), and non-statically linked builds segfault as soon
> as they try to do anything more complicated than printing the
> usage message. Remove these overridden versions and just use
> the glib ones.
> 
> This is sufficient that bsd-user can run basic x86-64
> binaries on OpenBSD again; FreeBSD and NetBSD seem to have
> further issues.
> 
> Signed-off-by: Peter Maydell <address@hidden>

Reviewed by:  Sean Bruno address@hidden
> ---
> The FreeBSD QEMU bsd-user tree took this same approach.
> 
> Blue, I'm planning to put this together with a few other bsd-user
> patches (and further submissions from the FreeBSD folk as they
> get them into shape) into a 'bsd-user.next' queue. Let me
> know if you'd rather do that yourself (as the listed bsd-user
> maintainer). My current queue is at:
> https://git.linaro.org/people/peter.maydell/qemu-arm.git/shortlog/refs/heads/bsd-user.next
> (though not all of those have been through review yet).
> 
>  bsd-user/mmap.c | 60 
> ---------------------------------------------------------
>  1 file changed, 60 deletions(-)
> 
> diff --git a/bsd-user/mmap.c b/bsd-user/mmap.c
> index aae8ea1..092bf7f 100644
> --- a/bsd-user/mmap.c
> +++ b/bsd-user/mmap.c
> @@ -74,66 +74,6 @@ void mmap_unlock(void)
>  }
>  #endif
>  
> -static void *bsd_vmalloc(size_t size)
> -{
> -    void *p;
> -    mmap_lock();
> -    /* Use map and mark the pages as used.  */
> -    p = mmap(NULL, size, PROT_READ | PROT_WRITE,
> -             MAP_PRIVATE | MAP_ANON, -1, 0);
> -
> -    if (h2g_valid(p)) {
> -        /* Allocated region overlaps guest address space.
> -           This may recurse.  */
> -        abi_ulong addr = h2g(p);
> -        page_set_flags(addr & TARGET_PAGE_MASK, TARGET_PAGE_ALIGN(addr + 
> size),
> -                       PAGE_RESERVED);
> -    }
> -
> -    mmap_unlock();
> -    return p;
> -}
> -
> -void *g_malloc(size_t size)
> -{
> -    char * p;
> -    size += 16;
> -    p = bsd_vmalloc(size);
> -    *(size_t *)p = size;
> -    return p + 16;
> -}
> -
> -/* We use map, which is always zero initialized.  */
> -void * g_malloc0(size_t size)
> -{
> -    return g_malloc(size);
> -}
> -
> -void g_free(void *ptr)
> -{
> -    /* FIXME: We should unmark the reserved pages here.  However this gets
> -       complicated when one target page spans multiple host pages, so we
> -       don't bother.  */
> -    size_t *p;
> -    p = (size_t *)((char *)ptr - 16);
> -    munmap(p, *p);
> -}
> -
> -void *g_realloc(void *ptr, size_t size)
> -{
> -    size_t old_size, copy;
> -    void *new_ptr;
> -
> -    if (!ptr)
> -        return g_malloc(size);
> -    old_size = *(size_t *)((char *)ptr - 16);
> -    copy = old_size < size ? old_size : size;
> -    new_ptr = g_malloc(size);
> -    memcpy(new_ptr, ptr, copy);
> -    g_free(ptr);
> -    return new_ptr;
> -}
> -
>  /* NOTE: all the constants are the HOST ones, but addresses are target. */
>  int target_mprotect(abi_ulong start, abi_ulong len, int prot)
>  {