Commit breaks strace: ARM: entry: allow ARM-private syscalls to be restarted

[Will Deacon]

On Tue, Sep 17, 2013 at 10:57:49PM +0100, Jason Gunthorpe wrote:
> Hi Will,

Hi Jason,

> I was just testing v3.12-rc1 (on kirkwood) and noticed that strace is
> not working:

Thanks for the report!

> $ strace /bin/ls
> mmap2(0xb6f79000, 9552, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb6f79000
> close(3)                                = 0
> mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb6fad000
> set_tls(0xb6fad4c0, 0xb6fadb98, 0xb6fb1050, 0xb6fad4c0, 0xb6fb1050) = -1 ENOSYS (Function not implemented)
> writev(2, [{"cannot set up thread-local stora"..., 36}, {"unknown error", 13}, {"\n", 1}], 3cannot set up thread-local storage: unknown error
> ) = 50
> exit_group(127)                         = ?
> +++ exited with 127 +++
> 
> I determined that reverting your commit below makes strace work again.
> I've tested 3.10.12 and it is OK.

Hmm, so if you don't run with strace, does `/bin/ls' work as expected? From
the trace above, it seems that set_tls is failing rather than anything in
strace (unless of course, the trace is just plain wrong).

> This happens with the latest git head for strace, as well as the 4.7
> release.
> 
> Hopefully you can cook up a fix :)

I'll take a look today, thanks.

Will