Messages in this thread | | | Date | Sat, 27 Oct 2007 17:54:53 -0700 | From | "H. Peter Anvin" <> | Subject | struct user . u_ar0 |
| |
I recently noticed that all architectures appear to have an entry n struct user called u_ar0:
struct user_pt_regs * u_ar0; /* Used by gdb to help find the values for */ /* the registers. */
In all cases, u_ar0 is a pointer type, although the type of pointer varies with the architecture.
However, under no conditions does this field ever contain a pointer value! It is set by the a.out code and its derivatives as an offset, not a pointer value (there are a total of four references in the kernel, in arch/{m68k,blackfin}/kernel/process.c, arch/x86/ia32/ia32_aout.c and fs/binfmt_aout.c -- they are all functionally identical and write-only):
dump.u_ar0 = (void *)(((unsigned long)(&dump.regs)) - ((unsigned long)(&dump)));
Any reason to *NOT* change this field to "unsigned long"? <asm/user.h>, where struct user is defined, is not exported to userspace in any architecture as far as I can tell, although <linux/user.h>, which just contains #include <asm/user.h>, *is* exported (clearly a bug.)
-hpa
- 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/
| |