diff options
Diffstat (limited to 'results/classifier/111/review/1893003')
| -rw-r--r-- | results/classifier/111/review/1893003 | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/results/classifier/111/review/1893003 b/results/classifier/111/review/1893003 new file mode 100644 index 00000000..c86dd986 --- /dev/null +++ b/results/classifier/111/review/1893003 @@ -0,0 +1,108 @@ +other: 0.112 +semantic: 0.107 +debug: 0.088 +permissions: 0.086 +device: 0.082 +graphic: 0.075 +PID: 0.066 +performance: 0.065 +boot: 0.064 +files: 0.056 +vnc: 0.056 +socket: 0.056 +KVM: 0.046 +network: 0.042 +files: 0.196 +debug: 0.139 +semantic: 0.114 +PID: 0.101 +device: 0.080 +other: 0.080 +network: 0.073 +performance: 0.054 +boot: 0.043 +socket: 0.036 +permissions: 0.028 +graphic: 0.021 +vnc: 0.020 +KVM: 0.015 + +qemu linux-user doesn't translate host/target data for iovec I/O + +When using iovec I/O functions (like `readv`), no data translation happens. I'm hitting this issue with libevent upon constructing a bufferevent over an inotify descriptor, and then building for either ppc64 or s390x (both big-endian) on x86_64 (little-endian) and running resulting code with qemu-ppc64 or qemu-s390x on Gentoo using latest QEMU version available (5.0.0-r2). + +The code in question is in https://github.com/transmission/transmission/blob/master/libtransmission/watchdir-inotify.c (`tr_watchdir_inotify_new`, `tr_watchdir_inotify_on_event`). + +While `read` syscall is handled properly, `readv` (which libevent is using in my case) doesn't have any logic to call `host_to_target_data_inotify` or any other translation function, leaving inotify data unchanged (with values in little-endian), which then leads to unit test failures. Quoting `do_syscall1` implementation bits for the reference: + +---8<---begin--- + case TARGET_NR_read: + if (arg2 == 0 && arg3 == 0) { + return get_errno(safe_read(arg1, 0, 0)); + } else { + if (!(p = lock_user(VERIFY_WRITE, arg2, arg3, 0))) + return -TARGET_EFAULT; + ret = get_errno(safe_read(arg1, p, arg3)); + if (ret >= 0 && + fd_trans_host_to_target_data(arg1)) { + ret = fd_trans_host_to_target_data(arg1)(p, ret); + } + unlock_user(p, arg2, ret); + } + return ret; +... + case TARGET_NR_readv: + { + struct iovec *vec = lock_iovec(VERIFY_WRITE, arg2, arg3, 0); + if (vec != NULL) { + ret = get_errno(safe_readv(arg1, vec, arg3)); + unlock_iovec(vec, arg2, arg3, 1); + } else { + ret = -host_to_target_errno(errno); + } + } + return ret; +---8<---end--- + +To reiterate, the issue is not only with `readv` but with other iovec functions as well. + +The attached patch fixes the issue for me, but is incomplete (and not thoroughly tested) as I've only implemented inotify data translation for readv syscall. + +The QEMU project is currently moving its bug tracking to another system. +For this we need to know which bugs are still valid and which could be +closed already. Thus we are setting the bug state to "Incomplete" now. + +If the bug has already been fixed in the latest upstream version of QEMU, +then please close this ticket as "Fix released". + +If it is not fixed yet and you think that this bug report here is still +valid, then you have two options: + +1) If you already have an account on gitlab.com, please open a new ticket +for this problem in our new tracker here: + + https://gitlab.com/qemu-project/qemu/-/issues + +and then close this ticket here on Launchpad (or let it expire auto- +matically after 60 days). Please mention the URL of this bug ticket on +Launchpad in the new ticket on GitLab. + +2) If you don't have an account on gitlab.com and don't intend to get +one, but still would like to keep this ticket opened, then please switch +the state back to "New" or "Confirmed" within the next 60 days (other- +wise it will get closed as "Expired"). We will then eventually migrate +the ticket automatically to the new system (but you won't be the reporter +of the bug in the new system and thus you won't get notified on changes +anymore). + +Thank you and sorry for the inconvenience. + + + +This is an automated cleanup. This bug report has been moved to QEMU's +new bug tracker on gitlab.com and thus gets marked as 'expired' now. +Please continue with the discussion here: + + https://gitlab.com/qemu-project/qemu/-/issues/426 + + |