On 05/14/2014 04:24 PM, Pedro Alves wrote: > On 05/14/14 08:10, Anshuman Khandual wrote: >> On 05/13/2014 11:39 PM, Pedro Alves wrote: >>> On 05/05/14 05:10, Anshuman Khandual wrote: >>>> On 05/01/2014 07:43 PM, Pedro Alves wrote: >>> OK, then this is what I suggest instead: > ... >>>> Shall I resend the patch with the your proposed changes and your >>>> "Signed-off-by" and >>>> moving myself as "Reported-by" ? >>> >>> No idea of the actual policy to follow. Feel free to do that if that's the >>> standard procedure. >> >> Even I am not sure about this, so to preserve the correct authorship, would >> you >> mind sending this patch ? > > Here you go. This is against current Linus'. Please take it from > here if necessary. > > 8<------------------------------------------ > From 1237f5ac5896f3910f66df83a5093bb548006188 Mon Sep 17 00:00:00 2001 > From: Pedro Alves <pal...@redhat.com> > Date: Wed, 14 May 2014 11:05:07 +0100 > Subject: [PATCH] ptrace: Clarify PTRACE_GETREGSET/PTRACE_SETREGSET > documentation in uapi header > > The current comments don't explicitly state in plain words that > iov.len must be set to the buffer's length prior to the ptrace call. > A user might get confused and leave that uninitialized. > > In the ptrace_regset function (snippet below) we see that the buffer > length has to be a multiple of the slot/register size for the given > NT_XXX_TYPE: > > if (!regset || (kiov->iov_len % regset->size) != 0) > return -EINVAL; > > Note regset->size is the size of each slot/register in the set, not > the size of the whole set. > > And then, we see here: > > kiov->iov_len = min(kiov->iov_len, > (__kernel_size_t) (regset->n * regset->size)); > > that the kernel takes care of capping the requested length to the size > of the whole regset. > > Signed-off-by: Pedro Alves <pal...@redhat.com> > Reported-by: Anshuman Khandual <khand...@linux.vnet.ibm.com> > --- > include/uapi/linux/ptrace.h | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h > index cf1019e..30836b9 100644 > --- a/include/uapi/linux/ptrace.h > +++ b/include/uapi/linux/ptrace.h > @@ -39,12 +39,17 @@ > * payload are exactly the same layout. > * > * This interface usage is as follows: > - * struct iovec iov = { buf, len}; > + * struct iovec iov = { buf, len }; > * > * ret = ptrace(PTRACE_GETREGSET/PTRACE_SETREGSET, pid, NT_XXX_TYPE, &iov); > * > - * On the successful completion, iov.len will be updated by the kernel, > - * specifying how much the kernel has written/read to/from the user's > iov.buf. > + * On entry, iov describes the buffer's address and length. The buffer's > length > + * must be a multiple of the size of a single register in the register set. > The > + * kernel never reads or writes more than iov.len, and caps the buffer > length to > + * the register set's size. In other words, the kernel reads or writes > + * min(iov.len, regset size). On successful completion, iov.len is updated > by > + * the kernel, specifying how much the kernel has read from / written to the > + * user's iov.buf. > */ > #define PTRACE_GETREGSET 0x4204 > #define PTRACE_SETREGSET 0x4205
Hey Peter/Oleg, The above patch is a documentation fix which we discussed sometime back. Could you please kindly review and consider merging. Thank you. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/