On 04/20/2011 11:34 AM, Lennart Poettering wrote:
On Wed, 20.04.11 11:19, David Daney (dda...@caviumnetworks.com) wrote:
On 04/20/2011 11:09 AM, Lennart Poettering wrote:
On Wed, 20.04.11 10:36, David Daney (dda...@caviumnetworks.com) wrote:
You would have to do something like this (untested):
int foo_fanotify_mark(int fanotify_fd, unsigned int flags, u64 mask,
int dfd, const char __user * pathname)
{
u32 mask_low = (u32)mask;
u32 mask_high = (u32)(mask>> 32);
return syscall(4337, fanotify_fd, flags, mask_low, mask_high, dfd,
pathname);
}
The order of mask_low, mask_high in the syscall argument list
depends on the endianness. Figuring out the correct order is left
as an exercise for the reader.
That's basically the same patch as this one, right?
http://lists.freedesktop.org/archives/systemd-devel/attachments/20110420/be2d393b/attachment.obj
It looks like it might do the same thing. Someone should try it on
an o32 MIPS userland running on a mips64 kernel.
I think the behavior of the union thing is undefined, but should
work on GCC.
Hmm, but unions is the official C99 way to do these things, isn't it?
Instead of doing casts here and there which create aliasing probs?
Any comment whether this will break non-MIPS 32bit archs, like x86?
It would break the MIPS n32 ABI userspace.
On MIPS n32 we are still __LP64__, but 64-bit values are passed in a
single register.
I expect that the experimental x86_64 x32 ABI would suffer the same way.
So the change would have to be gated by ABI rather than __LP64__
David Daney
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