linux-toradex.git/arch, branch v3.2.34

xen/mmu: Use Xen specific TLB flush instead of the generic one.

2012-11-16T16:47:03+00:00

commit 95a7d76897c1e7243d4137037c66d15cbf2cce76 upstream.

As Mukesh explained it, the MMUEXT_TLB_FLUSH_ALL allows the
hypervisor to do a TLB flush on all active vCPUs. If instead
we were using the generic one (which ends up being xen_flush_tlb)
we end up making the MMUEXT_TLB_FLUSH_LOCAL hypercall. But
before we make that hypercall the kernel will IPI all of the
vCPUs (even those that were asleep from the hypervisor
perspective). The end result is that we needlessly wake them
up and do a TLB flush when we can just let the hypervisor
do it correctly.

This patch gives around 50% speed improvement when migrating
idle guest's from one host to another.

Oracle-bug: 14630170

Tested-by:  Jingjie Jiang 
Suggested-by:  Mukesh Rathor 
Signed-off-by: Konrad Rzeszutek Wilk 
Signed-off-by: Ben Hutchings

ARM: at91/i2c: change id to let i2c-gpio work

2012-11-16T16:46:55+00:00

commit 7840487cd6298f9f931103b558290d8d98d41c49 upstream.

The i2c core driver will turn the platform device ID to busnum
When using platfrom device ID as -1, it means dynamically assigned
the busnum. When writing code, we need to make sure the busnum,
and call i2c_register_board_info(int busnum, ...) to register device
if using -1, we do not know the value of busnum

In order to solve this issue, set the platform device ID as a fix number
Here using 0 to match the busnum used in i2c_regsiter_board_info()

Signed-off-by: Bo Shen 
Acked-by: Jean Delvare 
Signed-off-by: Nicolas Ferre 
Acked-by: Jean-Christophe PLAGNIOL-VILLARD 
Acked-by: Ludovic Desroches 
Signed-off-by: Ben Hutchings

ARM: at91: at91sam9g10: fix SOC type detection

2012-11-16T16:46:55+00:00

commit 3d9a0183dd3423353e9e363bcc261c1220d05f9f upstream.

Newer at91sam9g10 SoC revision can't be detected, so the kernel can't boot with
this kind of kernel panic:
"AT91: Impossible to detect the SOC type"

CPU: ARM926EJ-S [41069265] revision 5 (ARMv5TEJ), cr=00053177
CPU: VIVT data cache, VIVT instruction cache
Machine: Atmel AT91SAM9G10-EK
Ignoring tag cmdline (using the default kernel command line)
bootconsole [earlycon0] enabled
Memory policy: ECC disabled, Data cache writeback
Kernel panic - not syncing: AT91: Impossible to detect the SOC type
[] (unwind_backtrace+0x0/0xe0) from [] (panic+0x78/0x1cc)
[] (panic+0x78/0x1cc) from [] (at91_map_io+0x90/0xc8)
[] (at91_map_io+0x90/0xc8) from [] (paging_init+0x564/0x6d0)
[] (paging_init+0x564/0x6d0) from [] (setup_arch+0x464/0x704)
[] (setup_arch+0x464/0x704) from [] (start_kernel+0x6c/0x2d4)
[] (start_kernel+0x6c/0x2d4) from [<20008040>] (0x20008040)

The reason for this is that the Debug Unit Chip ID Register has changed between
Engineering Sample and definitive revision of the SoC. Changing the check of
cidr to socid will address the problem. We do not integrate this check to the
list just above because we also have to make sure that the extended id is
disregarded.

Signed-off-by: Ivan Shugov 
[nicolas.ferre@atmel.com: change commit message]
Signed-off-by: Nicolas Ferre 
Acked-by: Jean-Christophe PLAGNIOL-VILLARD 
Signed-off-by: Ben Hutchings

x86: Remove the ancient and deprecated disable_hlt() and enable_hlt() facility

2012-11-16T16:46:46+00:00

commit f6365201d8a21fb347260f89d6e9b3e718d63c70 upstream.

The X86_32-only disable_hlt/enable_hlt mechanism was used by the
32-bit floppy driver. Its effect was to replace the use of the
HLT instruction inside default_idle() with cpu_relax() - essentially
it turned off the use of HLT.

This workaround was commented in the code as:

 "disable hlt during certain critical i/o operations"

 "This halt magic was a workaround for ancient floppy DMA
  wreckage. It should be safe to remove."

H. Peter Anvin additionally adds:

 "To the best of my knowledge, no-hlt only existed because of
  flaky power distributions on 386/486 systems which were sold to
  run DOS.  Since DOS did no power management of any kind,
  including HLT, the power draw was fairly uniform; when exposed
  to the much hhigher noise levels you got when Linux used HLT
  caused some of these systems to fail.

  They were by far in the minority even back then."

Alan Cox further says:

 "Also for the Cyrix 5510 which tended to go castors up if a HLT
  occurred during a DMA cycle and on a few other boxes HLT during
  DMA tended to go astray.

  Do we care ? I doubt it. The 5510 was pretty obscure, the 5520
  fixed it, the 5530 is probably the oldest still in any kind of
  use."

So, let's finally drop this.

Signed-off-by: Len Brown 
Signed-off-by: Josh Boyer 
Signed-off-by: Andrew Morton 
Acked-by: "H. Peter Anvin" 
Acked-by: Alan Cox 
Cc: Stephen Hemminger 
Link: http://lkml.kernel.org/n/tip-3rhk9bzf0x9rljkv488tloib@git.kernel.org
[ If anyone cares then alternative instruction patching could be
  used to replace HLT with a one-byte NOP instruction. Much simpler. ]
Signed-off-by: Ingo Molnar 
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings

arch/tile: avoid generating .eh_frame information in modules

2012-10-30T23:26:55+00:00

commit 627072b06c362bbe7dc256f618aaa63351f0cfe6 upstream.

The tile tool chain uses the .eh_frame information for backtracing.
The vmlinux build drops any .eh_frame sections at link time, but when
present in kernel modules, it causes a module load failure due to the
presence of unsupported pc-relative relocations.  When compiling to
use compiler feedback support, the compiler by default omits .eh_frame
information, so we don't see this problem.  But when not using feedback,
we need to explicitly suppress the .eh_frame.

Signed-off-by: Chris Metcalf 
Signed-off-by: Ben Hutchings

ARM: 7559/1: smp: switch away from the idmap before updating init_mm.mm_count

2012-10-30T23:26:54+00:00

commit 5f40b909728ad784eb43aa309d3c4e9bdf050781 upstream.

When booting a secondary CPU, the primary CPU hands two sets of page
tables via the secondary_data struct:

	(1) swapper_pg_dir: a normal, cacheable, shared (if SMP) mapping
	    of the kernel image (i.e. the tables used by init_mm).

	(2) idmap_pgd: an uncached mapping of the .idmap.text ELF
	    section.

The idmap is generally used when enabling and disabling the MMU, which
includes early CPU boot. In this case, the secondary CPU switches to
swapper as soon as it enters C code:

	struct mm_struct *mm = &init_mm;
	unsigned int cpu = smp_processor_id();

	/*
	 * All kernel threads share the same mm context; grab a
	 * reference and switch to it.
	 */
	atomic_inc(&mm->mm_count);
	current->active_mm = mm;
	cpumask_set_cpu(cpu, mm_cpumask(mm));
	cpu_switch_mm(mm->pgd, mm);

This causes a problem on ARMv7, where the identity mapping is treated as
strongly-ordered leading to architecturally UNPREDICTABLE behaviour of
exclusive accesses, such as those used by atomic_inc.

This patch re-orders the secondary_start_kernel function so that we
switch to swapper before performing any exclusive accesses.

Cc: David McKay 
Reported-by: Gilles Chanteperdrix 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King 
Signed-off-by: Ben Hutchings

xen/x86: don't corrupt %eip when returning from a signal handler

2012-10-30T23:26:52+00:00

commit a349e23d1cf746f8bdc603dcc61fae9ee4a695f6 upstream.

In 32 bit guests, if a userspace process has %eax == -ERESTARTSYS
(-512) or -ERESTARTNOINTR (-513) when it is interrupted by an event
/and/ the process has a pending signal then %eip (and %eax) are
corrupted when returning to the main process after handling the
signal.  The application may then crash with SIGSEGV or a SIGILL or it
may have subtly incorrect behaviour (depending on what instruction it
returned to).

The occurs because handle_signal() is incorrectly thinking that there
is a system call that needs to restarted so it adjusts %eip and %eax
to re-execute the system call instruction (even though user space had
not done a system call).

If %eax == -514 (-ERESTARTNOHAND (-514) or -ERESTART_RESTARTBLOCK
(-516) then handle_signal() only corrupted %eax (by setting it to
-EINTR).  This may cause the application to crash or have incorrect
behaviour.

handle_signal() assumes that regs->orig_ax >= 0 means a system call so
any kernel entry point that is not for a system call must push a
negative value for orig_ax.  For example, for physical interrupts on
bare metal the inverse of the vector is pushed and page_fault() sets
regs->orig_ax to -1, overwriting the hardware provided error code.

xen_hypervisor_callback() was incorrectly pushing 0 for orig_ax
instead of -1.

Classic Xen kernels pushed %eax which works as %eax cannot be both
non-negative and -RESTARTSYS (etc.), but using -1 is consistent with
other non-system call entry points and avoids some of the tests in
handle_signal().

There were similar bugs in xen_failsafe_callback() of both 32 and
64-bit guests. If the fault was corrected and the normal return path
was used then 0 was incorrectly pushed as the value for orig_ax.

Signed-off-by: David Vrabel 
Acked-by: Jan Beulich 
Acked-by: Ian Campbell 
Signed-off-by: Konrad Rzeszutek Wilk 
Signed-off-by: Ben Hutchings

s390: fix linker script for 31 bit builds

2012-10-30T23:26:52+00:00

commit c985cb37f1b39c2c8035af741a2a0b79f1fbaca7 upstream.

Because of a change in the s390 arch backend of binutils (commit 23ecd77
"Pick the default arch depending on the target size" in binutils repo)
31 bit builds will fail since the linker would now try to create 64 bit
binary output.
Fix this by setting OUTPUT_ARCH to s390:31-bit instead of s390.
Thanks to Andreas Krebbel for figuring out the issue.

Fixes this build error:

  LD      init/built-in.o
s390x-4.7.2-ld: s390:31-bit architecture of input file
 `arch/s390/kernel/head.o' is incompatible with s390:64-bit output

Cc: Andreas Krebbel 
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings

oprofile, x86: Fix wrapping bug in op_x86_get_ctrl()

2012-10-30T23:26:45+00:00

commit 44009105081b51417f311f4c3be0061870b6b8ed upstream.

The "event" variable is a u16 so the shift will always wrap to zero
making the line a no-op.

Signed-off-by: Dan Carpenter 
Signed-off-by: Robert Richter 
Signed-off-by: Ben Hutchings

xen/bootup: allow {read|write}_cr8 pvops call.

2012-10-30T23:26:45+00:00

commit 1a7bbda5b1ab0e02622761305a32dc38735b90b2 upstream.

We actually do not do anything about it. Just return a default
value of zero and if the kernel tries to write anything but 0
we BUG_ON.

This fixes the case when an user tries to suspend the machine
and it blows up in save_processor_state b/c 'read_cr8' is set
to NULL and we get:

kernel BUG at /home/konrad/ssd/linux/arch/x86/include/asm/paravirt.h:100!
invalid opcode: 0000 [#1] SMP
Pid: 2687, comm: init.late Tainted: G           O 3.6.0upstream-00002-gac264ac-dirty #4 Bochs Bochs
RIP: e030:[]  [] save_processor_state+0x212/0x270

.. snip..
Call Trace:
 [] do_suspend_lowlevel+0xf/0xac
 [] ? x86_acpi_suspend_lowlevel+0x10c/0x150
 [] acpi_suspend_enter+0x57/0xd5

Signed-off-by: Konrad Rzeszutek Wilk 
Signed-off-by: Ben Hutchings