Messages in this thread Patch in this message | | | From | Milton Miller <> | Date | Wed, 01 Dec 2010 11:37:58 -0600 | Subject | (No subject header) |
| |
On Tue, 30 Nov 2010 about 20:01:29 -0000, Oleg Nesterov wrote: > Teach get_arg_ptr() to handle compat = T case correctly.
> #include <asm/uaccess.h> > #include <asm/mmu_context.h> > @@ -395,6 +396,18 @@ get_arg_ptr(const char __user * const __ > { > const char __user *ptr; > > +#ifdef CONFIG_COMPAT > + if (unlikely(compat)) {
This should not be marked unlikely. Unlikely tells gcc the path with over 99% confidence and disables branch predictors on some architectures. If called from a compat processes this will result in a mispredicted branch every iteration. Just use if (compat) and let the hardware branch predictors do their job.
> + compat_uptr_t __user *a = (void __user*)argv; > + compat_uptr_t p; > + > + if (get_user(p, a + argc)) > + return ERR_PTR(-EFAULT); > + > + return compat_ptr(p); > + } > +#endif > + > if (get_user(ptr, argv + argc)) > return ERR_PTR(-EFAULT); > > @@ -1501,6 +1514,18 @@ int do_execve(const char *filename, > return do_execve_common(filename, argv, envp, regs, false); > } > > +#ifdef CONFIG_COMPAT > +int compat_do_execve(char * filename, > + compat_uptr_t __user *argv, > + compat_uptr_t __user *envp, > + struct pt_regs * regs) > +{ > + return do_execve_common(filename, > + (void __user*)argv, (void __user*)envp,
Shouldn't these be compat_ptr(argv)? (makes a difference on s390)
> + regs, true); > +} > +#endif > + > void set_binfmt(struct linux_binfmt *new) > { > struct mm_struct *mm = current->mm;
Thanks, milton
| |