| Message ID | 1402671812-9078-1-git-send-email-pawel.moll@arm.com |
|---|---|
| State | Accepted |
| Commit | b3f207855f57b9c8f43a547a801340bb5cbc59e5 |
| Headers | show |
On Fri, Jun 13, 2014 at 04:03:32PM +0100, Pawel Moll wrote: > When running a 32-bit userspace on a 64-bit kernel (eg. i386 > application on x86_64 kernel or 32-bit arm userspace on arm64 > kernel) some of the perf ioctls must be treated with special > care, as they have a pointer size encoded in the command. > > For example, PERF_EVENT_IOC_ID in 32-bit world will be encoded > as 0x80042407, but 64-bit kernel will expect 0x80082407. In > result the ioctl will fail returning -ENOTTY. > > This patch solves the problem by adding code fixing up the > size as compat_ioctl file operation. > > Reported-by: Drew Richardson <drew.richardson@arm.com> > Signed-off-by: Pawel Moll <pawel.moll@arm.com> > --- This gets me (on my favourite x86_64 .config): kernel/events/core.c: In function ‘perf_compat_ioctl’: kernel/events/core.c:3726:32: error: ‘compat_uptr_t’ undeclared (first use in this function) kernel/events/core.c:3726:32: note: each undeclared identifier is reported only once for each function it appears in
On Tue, 2014-06-17 at 13:13 +0100, Peter Zijlstra wrote: > On Fri, Jun 13, 2014 at 04:03:32PM +0100, Pawel Moll wrote: > > When running a 32-bit userspace on a 64-bit kernel (eg. i386 > > application on x86_64 kernel or 32-bit arm userspace on arm64 > > kernel) some of the perf ioctls must be treated with special > > care, as they have a pointer size encoded in the command. > > > > For example, PERF_EVENT_IOC_ID in 32-bit world will be encoded > > as 0x80042407, but 64-bit kernel will expect 0x80082407. In > > result the ioctl will fail returning -ENOTTY. > > > > This patch solves the problem by adding code fixing up the > > size as compat_ioctl file operation. > > > > Reported-by: Drew Richardson <drew.richardson@arm.com> > > Signed-off-by: Pawel Moll <pawel.moll@arm.com> > > --- > > This gets me (on my favourite x86_64 .config): > > kernel/events/core.c: In function ‘perf_compat_ioctl’: > kernel/events/core.c:3726:32: error: ‘compat_uptr_t’ undeclared (first use in this function) > kernel/events/core.c:3726:32: note: each undeclared identifier is reported only once for each function it appears in Right, sorry. I've added the size check last minute and haven't re-tested it with x86_64. #include for compat.h was missing (wonder where was it included for arm64 ;-) Already posted v2. Pawel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
diff --git a/kernel/events/core.c b/kernel/events/core.c index 24d35cc..967af2c 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3700,6 +3700,26 @@ static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg) return 0; } +#ifdef CONFIG_COMPAT +static long perf_compat_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + switch (_IOC_NR(cmd)) { + case _IOC_NR(PERF_EVENT_IOC_SET_FILTER): + case _IOC_NR(PERF_EVENT_IOC_ID): + /* Fix up pointer size (usually 4 -> 8 in 32-on-64-bit case */ + if (_IOC_SIZE(cmd) == sizeof(compat_uptr_t)) { + cmd &= ~IOCSIZE_MASK; + cmd |= sizeof(void *) << IOCSIZE_SHIFT; + } + break; + } + return perf_ioctl(file, cmd, arg); +} +#else +#define perf_compat_ioctl NULL +#endif + int perf_event_task_enable(void) { struct perf_event *event; @@ -4205,7 +4225,7 @@ static const struct file_operations perf_fops = { .read = perf_read, .poll = perf_poll, .unlocked_ioctl = perf_ioctl, - .compat_ioctl = perf_ioctl, + .compat_ioctl = perf_compat_ioctl, .mmap = perf_mmap, .fasync = perf_fasync, };
When running a 32-bit userspace on a 64-bit kernel (eg. i386 application on x86_64 kernel or 32-bit arm userspace on arm64 kernel) some of the perf ioctls must be treated with special care, as they have a pointer size encoded in the command. For example, PERF_EVENT_IOC_ID in 32-bit world will be encoded as 0x80042407, but 64-bit kernel will expect 0x80082407. In result the ioctl will fail returning -ENOTTY. This patch solves the problem by adding code fixing up the size as compat_ioctl file operation. Reported-by: Drew Richardson <drew.richardson@arm.com> Signed-off-by: Pawel Moll <pawel.moll@arm.com> --- kernel/events/core.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-)