... no need to read current_thread_info()->task only to
feed it to task_thread_page() immediately afterwards.
Moreover, not using current_thread_info() at all ends
up with better assembler - we need a location very close
to the top of kernel stack page and it's actually better
to do or with 0x1fff, followed be subtracting a small
constant than and with ~0x1fff, followed by adding a large
one. Both & and | would be a couple of insns (mvn lsr/mvn lsl
for |, a pair of bic for &), but the following addition
would cost a pair of add while the subtraction ends up
as a single sub.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Selected by __ARCH_WANT_SYS_EXECVE in unistd.h. Requires
* working current_pt_regs()
* *NOT* doing a syscall-in-kernel kind of kernel_execve()
implementation. Using generic kernel_execve() is fine.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
based mostly on arm and alpha versions. Architectures can define
__ARCH_WANT_KERNEL_EXECVE and use it, provided that
* they have working current_pt_regs(), even for kernel threads.
* kernel_thread-spawned threads do have space for pt_regs
in the normal location. Normally that's as simple as switching to
generic kernel_thread() and making sure that kernel threads do *not*
go through return from syscall path; call the payload from equivalent
of ret_from_fork if we are in a kernel thread (or just have separate
ret_from_kernel_thread and make copy_thread() use it instead of
ret_from_fork in kernel thread case).
* they have ret_from_kernel_execve(); it is called after
successful do_execve() done by kernel_execve() and gets normal
pt_regs location passed to it as argument. It's essentially
a longjmp() analog - it should set sp, etc. to the situation
expected at the return for syscall and go there. Eventually
the need for that sucker will disappear, but that'll take some
surgery on kernel_thread() payloads.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Normally (and that's the default) it's just task_pt_regs(current).
However, if an architecture can optimize that, it can do so by
making a macro of its own available from asm/ptrace.h. More
importantly, some architectures have task_pt_regs() working only
for traced tasks blocked on signal delivery. current_pt_regs()
needs to work for *all* processes, so before those architectures
start using stuff relying on current_pt_regs() they'll need a
properly working variant.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Let architectures select GENERIC_KERNEL_THREAD and have their copy_thread()
treat NULL regs as "it came from kernel_thread(), sp argument contains
the function new thread will be calling and stack_size - the argument for
that function". Switching the architectures begins shortly...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
we only use that to tell copy_thread() done by syscall from that
done by kernel_thread(). However, it's easier to do simply by
checking PF_KTHREAD in thread flags.
Merge sys_clone() guts for 32bit and 64bit, while we are at it...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
TIF_NOTIFY_RESUME will work in precisely the same way; all that
is achieved by TIF_IRET is appearing that there's some work to be
done, so we end up on the iret exit path. Just use NOTIFY_RESUME.
And for execve() do that in 32bit start_thread(), not sys_execve()
itself.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull block fixes from Jens Axboe:
"A small collection of driver fixes/updates and a core fix for 3.6. It
contains:
- Bug fixes for mtip32xx, and support for new hardware (just addition
of IDs). They have been queued up for 3.7 for a few weeks as well.
- rate-limit a failing command error message in block core.
- A fix for an old cciss bug from Stephen.
- Prevent overflow of partition count from Alan."
* 'for-linus' of git://git.kernel.dk/linux-block:
cciss: fix handling of protocol error
blk: add an upper sanity check on partition adding
mtip32xx: fix user_buffer check in exec_drive_command
mtip32xx: Remove dead code
mtip32xx: Change printk to pr_xxxx
mtip32xx: Proper reporting of write protect status on big-endian
mtip32xx: Increase timeout for standby command
mtip32xx: Handle NCQ commands during the security locked state
mtip32xx: Add support for new devices
block: rate-limit the error message from failing commands
Pull SuperH fixes from Paul Mundt.
* tag 'sh-for-linus' of git://github.com/pmundt/linux-sh:
sh: Fix up TIF_NOTIFY_RESUME sans TIF_SIGPENDING handling.
sh: pfc: Release spinlock in sh_pfc_gpio_request_enable() error path
sh: intc: Fix up multi-evt irq association.
Pull rpmsg fix from Ohad Ben-Cohen:
"A quick rpmsg fix from Fernando, fixing two buggy invocations of
dma_free_coherent"
* tag 'rpmsg-3.6-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/ohad/rpmsg:
rpmsg: fix dma_free_coherent dev parameter
Pull md fixes from NeilBrown:
"3 fixes for md in 3.6.
One reverts a recent patch which turns out to not be such a good idea.
Other two fix minor bugs with the new (since 3.3) 'replacement' code
and have been tagged for -stable."
* tag 'md-3.6-fixes' of git://neil.brown.name/md:
md: make sure metadata is updated when spares are activated or removed.
md/raid5: fix calculate of 'degraded' when a replacement becomes active.
Revert "md/raid5: For odirect-write performance, do not set STRIPE_PREREAD_ACTIVE."
Pull workqueue / powernow-k8 fix from Tejun Heo:
"This is the fix for the bug where cpufreq/powernow-k8 was tripping
BUG_ON() in try_to_wake_up_local() by migrating workqueue worker to a
different CPU.
https://bugzilla.kernel.org/show_bug.cgi?id=47301
As discussed, the fix is now two parts - one to reimplement
work_on_cpu() so that it doesn't create a new kthread each time and
the actual fix which makes powernow-k8 use work_on_cpu() instead of
performing manual migration.
While pretty late in the merge cycle, both changes are on the safer
side. Jiri and I verified two existing users of work_on_cpu() and
Duncan confirmed that the powernow-k8 fix survived about 18 hours of
testing."
* 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
cpufreq/powernow-k8: workqueue user shouldn't migrate the kworker to another CPU
workqueue: reimplement work_on_cpu() using system_wq
Al Viro
Linus Torvalds