On Sat, Jul 14, 2018 at 07:37:43AM +0200, Laurent Vivier wrote: > Le 14/07/2018 à 03:07, David Gibson a écrit : > > On Fri, Jul 13, 2018 at 07:34:46AM -0500, Shivaprasad G Bhat wrote: > >> Qemu includes the glibc headers for the host defines and target headers are > >> part of the qemu source themselves. The glibc has the F_GETLK64, F_SETLK64 > >> and F_SETLKW64 defined to 12, 13 and 14 for all archs in > >> sysdeps/unix/sysv/linux/bits/fcntl-linux.h. The linux kernel generic > >> definition for F_*LK is 5, 6 & 7 and F_*LK64* is 12,13, and 14 as seen in > >> include/uapi/asm-generic/fcntl.h. On 64bit machine, by default the kernel > >> assumes all F_*LK to 64bit calls and doesnt support use of F_*LK64* as > >> can be seen in include/linux/fcntl.h in linux source. > >> > >> On x86_64 host, the values for F_*LK64* are set to 5, 6 and 7 > >> explicitly in /usr/include/x86_64-linux-gnu/bits/fcntl.h by the glibc. > >> Whereas, a PPC64 host doesn't have such a definition in > >> /usr/include/powerpc64le-linux-gnu/bits/fcntl.h by the glibc. So, > >> the sources on PPC64 host sees the default value of F_*LK64* > >> as 12, 13 & 14(fcntl-linux.h). > >> > >> Since the 64bit kernel doesnt support 12, 13 & 14; the glibc fcntl syscall > >> implementation(__libc_fcntl*(), __fcntl64_nocancel) does the F_*LK64* value > >> convertion back to F_*LK* values on PPC64 as seen in > >> sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h with FCNTL_ADJUST_CMD() > >> macro. Whereas on x86_64 host the values for F_*LK64* are set to 5, 6 and 7 > >> and no adjustments are needed. > >> > >> Since qemu doesnt use the glibc fcntl, but makes the safe_syscall* on its > >> own, the PPC64 qemu is calling the syscall with 12, 13, and 14(without > >> adjustment) and they all fail. The fcntl calls to F_GETLK/F_SETLK|W all > >> fail by all pplications run on PPC64 host user emulation. > >> > >> The fix here could be to see why on PPC64 the glibc is still keeping > >> F_*LK64* different from F_*LK and why adjusting them to 5, 6 and 7 before > >> the syscall for PPC only. See if we can make the > >> /usr/include/powerpc64le-linux-gnu/bits/fcntl.h to have the values > >> 5, 6 & 7 just like x86_64 and remove the adjustment code in glibc. That > >> way, qemu sources see the kernel supported values in glibc headers. > >> > >> OR > >> > >> On PPC64 host, qemu sources see both F_*LK & F_*LK64* as same and set to > >> 12, 13 and 14 because __USE_FILE_OFFSET64 is defined in qemu > >> sources(also refer sysdeps/unix/sysv/linux/bits/fcntl-linux.h). > >> Do the value adjustment just like it is done by glibc source by using > >> F_GETLK value of 5. That way, we make the syscalls with the actual > >> supported values in Qemu. The patch is taking this approach. > >> > >> Signed-off-by: Shivaprasad G Bhat <sb...@linux.vnet.ibm.com> > > > > Reviewed-by: David Gibson <da...@gibson.dropbear.id.au> > > > > I'm not sure if this should go in through my tree or not. > > I will take it through my linux-user tree, I have some fixes to send for > the next -rc.
Great, thanks.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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