Messages in this thread | | | From | Roland McGrath <> | Subject | Re: [patch v2 4/4] ptrace: Add support for generic PTRACE_GETREGSET/PTRACE_SETREGSET | Date | Wed, 10 Feb 2010 11:12:40 -0800 (PST) |
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> +static int ptrace_regset(struct task_struct *task, int req, unsigned int type, > + struct iovec *uiov) ^__user > +{ > + const struct user_regset_view *view = task_user_regset_view(task); > + const struct user_regset *regset = find_regset(view, type); > + struct iovec kiov; > + > + if (!regset) > + return -EIO; > + > + if (copy_from_user(&kiov, uiov, sizeof kiov)) > + return -EFAULT;
Since it's just two words, most places handling struct iovec seem to just use two get_user() calls, which is probably more efficient.
Also, here is where this function would need to be split in half for compat_ptrace_request() calls where it has to use struct compat_iovec.
> + // I am not sure. Afaics it is OK to pass the > + // size which is less than n * size. If iov_len > + // is bigger, we can silently truncate it, or > + // even write the correct value back.
Modifying iov_len to report how much we accessed seems good to me. If we do that, we should certainly allow a larger size for get, so userland can just use a generic large buffer before even knowing the real size. I'm not sure whether we should allow a smaller size, especially for set. I could go either way.
Thanks, Roland
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