Le 13/07/2018 à 14:34, Shivaprasad G Bhat a écrit : > 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> > --- > v3 - https://lists.gnu.org/archive/html/qemu-devel/2018-07/msg02923.html > Changes from v3: > - Fixed the tabs for case statements > - Addressed the comments on v3 wrt to the variable initialisation > and break from default case. > v2 - https://lists.gnu.org/archive/html/qemu-devel/2018-07/msg02920.html > Changes from v2: > - Fixed the braces, and indentation for comments. > v1 - https://lists.gnu.org/archive/html/qemu-devel/2018-07/msg02567.html > Changes from v1: > - Changed the overwrite of F*LK64* with 5, 6 and 7 in using #define > instead using the adjustment code similar to glibc as suggested. > - Dropped __linux__ check for the adjustment code as suggested. > - Moved the adjustment code inside target_to_host_fcntl_cmd to address > all possible|future cases. > > linux-user/syscall.c | 126 > ++++++++++++++++++++++++++++++++------------------ > 1 file changed, 80 insertions(+), 46 deletions(-) >
Reviewed-by: Laurent Vivier <laur...@vivier.eu>
