Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH 20/30] microblaze_mmu_v1: uaccess MMU update | Date | Wed, 29 Apr 2009 17:55:37 +0200 |
| |
On Wednesday 29 April 2009, Michal Simek wrote: > For powerpc I found these tree references. Where is the __get_user_bad definition?
> arch/powerpc/include/asm/uaccess.h:216:extern long __get_user_bad(void); > arch/powerpc/include/asm/uaccess.h:263: (x) = __get_user_bad(); \ > arch/powerpc/include/asm/uaccess.h:269: default: (x) = __get_user_bad(); \ >
As I tried to explain, the whole point is that there is no definition at all, just a declaration. Normally, the compiler will discard the 'default:' case of get_user, so the function is not called. However, if you pass a variable of a length other than 1, 2, or 4, the compiler will generate a function call to __get_user_bad in the object file. When you try to link the kernel afterwards, you will get an error message like
Unknown symbol __get_user_bad" for drivers/foo/bar.o
which tells you that some function in drivers/foo/bar.c calls get_user with an invalid argument.
Arnd <>< -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |