Am 09.03.2012 15:33, schrieb Peter Maydell: > Cast the argument of the g2h() macro to a target_ulong so that > it isn't accidentally sign-extended if it is a signed 32 bit > type and long is a 64 bit type. In particular, this fixes a > bug where it would return the wrong value for 32 bit guests > on 64 bit hosts when passed in one of the arg* values from > do_syscall() [which are all abi_long and thus signed types]. > This could result in spurious failure of mlock(), among others. > > Signed-off-by: Peter Maydell <peter.mayd...@linaro.org> > --- > This should be committed before Alex's patch to make mmap allocate > downwards (http://patchwork.ozlabs.org/patch/144476/) because that > hugely increases the chances that g2h will get passed a pointer > that has the high bit set. > > cpu-all.h | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/cpu-all.h b/cpu-all.h > index 80e6d42..a174532 100644 > --- a/cpu-all.h > +++ b/cpu-all.h > @@ -197,7 +197,7 @@ extern unsigned long reserved_va; > #endif > > /* All direct uses of g2h and h2g need to go away for usermode softmmu. */ > -#define g2h(x) ((void *)((unsigned long)(x) + GUEST_BASE)) > +#define g2h(x) ((void *)((unsigned long)(target_ulong)(x) + GUEST_BASE))
So *only* for a 32-bit guest does this cast from signed int to unsigned int and then to unsigned long, avoiding the sign extension on 64-bit host. For 64-bit guests it remains as broken as before. Commit message could be clearer. Reviewed-by: Andreas Färber <afaer...@suse.de> Note that unsigned long would be wrong for Win64 (where we don't currently have any user emulation using this macro). uintptr_t would be cleaner. Andreas > > #if HOST_LONG_BITS <= TARGET_VIRT_ADDR_SPACE_BITS > #define h2g_valid(x) 1 -- SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg
