we *really* don't want to have restart logics hit when we are returning from
sigreturn() - random replacement of %r4 with -4 just because a signal had
been noticed from timer interrupt that came when %r4 happened to contain
-514 is not nice at all.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The tricky part here is that task_pt_regs() on m68k works *only* for
process inside do_signal(). However, we need something much simpler -
pt_regs of a process inside do_signal() may be at different offsets
from the stack bottom, depending on the way we'd entered the kernel,
but for a task inside sys_execve() it *is* at constant offset.
Moreover, for a kernel thread about to become a userland process the
same location is also fine - setting sp to that will leave the kernel
stack pointer at the very bottom of the kernel stack when we finally
switch to userland.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The stack frame "format" field needs to be explicitly set on thread creation
on ColdFire. For a normal long word aligned user stack pointer the frame
format is 0x4.
We were doing this for non-MMU ColdFire, but not for the case with MMU enabled.
So fix it so we always do it if targeting ColdFire.
The old code happend to rely on the stack frame format being inhereted from
the process calling exec. Furture changes means that may not always work,
so we really do want to set it explicitly.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
the only non-obvious part is that current_pt_regs() is really needed
here - task_pt_regs() is NULL for kernel threads; it's OK for ptrace
uses (the thing task_pt_regs() is intended for), but not for us.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
32bit wrapper is lost on that; 64bit one is *not*, since
we need to arrange for full pt_regs on stack when we call
sys_execve() and we need to load callee-saved ones from
there afterwards.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
... 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
