linux-toradex.git/arch/powerpc/kernel/paca.c, branch v4.2.7

powerpc/kernel: Avoid memory corruption at early stage

2015-01-23T03:02:52+00:00

When calling to early_setup(), we pick "boot_paca" up for the master CPU
and initialize that with initialise_paca(). At that point, the SLB
shadow buffer isn't populated yet. Updating the SLB shadow buffer should
corrupt what we had in physical address 0 where the trap instruction is
usually stored.

This hasn't been observed to cause any trouble in practice, but is
obviously fishy.

Fixes: 6f4441ef7009 ("powerpc: Dynamically allocate slb_shadow from memblock")
Signed-off-by: Gavin Shan 
Signed-off-by: Michael Ellerman

KVM: PPC: Book3S PR: Rework SLB switching code

2014-05-30T12:26:30+00:00

On LPAR guest systems Linux enables the shadow SLB to indicate to the
hypervisor a number of SLB entries that always have to be available.

Today we go through this shadow SLB and disable all ESID's valid bits.
However, pHyp doesn't like this approach very much and honors us with
fancy machine checks.

Fortunately the shadow SLB descriptor also has an entry that indicates
the number of valid entries following. During the lifetime of a guest
we can just swap that value to 0 and don't have to worry about the
SLB restoration magic.

While we're touching the code, let's also make it more readable (get
rid of rldicl), allow it to deal with a dynamic number of bolted
SLB entries and only do shadow SLB swizzling on LPAR systems.

Signed-off-by: Alexander Graf

powerpc/ppc64: Gracefully handle early interrupts

2014-04-07T00:33:15+00:00

If we take an interrupt such as a trap caused by a BUG_ON before the
MMU has been setup, the interrupt handlers try to enable virutal mode
and cause a recursive crash, making the original problem very hard
to debug.

This fixes it by adjusting the "kernel_msr" value in the PACA so that
it only has MSR_IR and MSR_DR (translation for instruction and data)
set after the MMU has been initialized for the processor.

We may still not have a console yet but at least we don't get into
a recursive fault (and early debug console or memory dump via JTAG
of the kernel buffer *will* give us the proper error).

Signed-off-by: Benjamin Herrenschmidt

powerpc/e6500: TLB miss handler with hardware tablewalk support

2014-01-09T23:52:19+00:00

There are a few things that make the existing hw tablewalk handlers
unsuitable for e6500:

 - Indirect entries go in TLB1 (though the resulting direct entries go in
   TLB0).

 - It has threads, but no "tlbsrx." -- so we need a spinlock and
   a normal "tlbsx".  Because we need this lock, hardware tablewalk
   is mandatory on e6500 unless we want to add spinlock+tlbsx to
   the normal bolted TLB miss handler.

 - TLB1 has no HES (nor next-victim hint) so we need software round robin
   (TODO: integrate this round robin data with hugetlb/KVM)

 - The existing tablewalk handlers map half of a page table at a time,
   because IBM hardware has a fixed 1MiB indirect page size.  e6500
   has variable size indirect entries, with a minimum of 2MiB.
   So we can't do the half-page indirect mapping, and even if we
   could it would be less efficient than mapping the full page.

 - Like on e5500, the linear mapping is bolted, so we don't need the
   overhead of supporting nested tlb misses.

Note that hardware tablewalk does not work in rev1 of e6500.
We do not expect to support e6500 rev1 in mainline Linux.

Signed-off-by: Scott Wood 
Cc: Mihai Caraman

powerpc: Dynamically allocate slb_shadow from memblock

2013-12-09T00:40:26+00:00

Currently, the slb_shadow buffer is our largest symbol:

  [jk@pablo linux]$ nm --size-sort -r -S obj/vmlinux | head -1
  c000000000da0000 0000000000040000 d slb_shadow

- we allocate 128 bytes per cpu; so 256k with NR_CPUS=2048. As we have
constant initialisers, it's allocated in .text, causing a larger vmlinux
image. We may also allocate unecessary slb_shadow buffers (> no. pacas),
since we use the build-time NR_CPUS rather than the run-time nr_cpu_ids.

We could move this to the bss, but then we still have the NR_CPUS vs
nr_cpu_ids potential for overallocation.

This change dynamically allocates the slb_shadow array, during
initialise_pacas(). At a cost of 104 bytes of text, we save 256k of
data:

  [jk@pablo linux]$ size obj/vmlinux{.orig,}
     text     data      bss       dec     hex	filename
  9202795  5244676  1169576  15617047  ee4c17	obj/vmlinux.orig
  9202899  4982532  1169576  15355007  ea4c7f	obj/vmlinux

Tested on pseries.

Signed-off-by: Jeremy Kerr 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Make slb_shadow a local

2013-12-09T00:40:25+00:00

The only external user of slb_shadow is the pseries lpar code, and it
can access through the paca array instead.

Signed-off-by: Jeremy Kerr 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix section mismatch warning in free_lppacas

2013-10-11T05:49:26+00:00

While cross-building for PPC64 I've got bunch of

WARNING: arch/powerpc/kernel/built-in.o(.text.unlikely+0x2d2): Section
mismatch in reference from the function .free_lppacas() to the variable
.init.data:lppaca_size The function .free_lppacas() references the variable
__initdata lppaca_size. This is often because .free_lppacas lacks a __initdata
annotation or the annotation of lppaca_size is wrong.

Fix it by using proper annotation for free_lppacas. Additionally, annotate
{allocate,new}_llpcas properly.

Signed-off-by: Vladimir Murzin 
Acked-by: Michael Ellerman 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix little endian lppaca, slb_shadow and dtl_entry

2013-08-14T05:33:35+00:00

The lppaca, slb_shadow and dtl_entry hypervisor structures are
big endian, so we have to byte swap them in little endian builds.

LE KVM hosts will also need to be fixed but for now add an #error
to remind us.

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Move boot_paca into early_setup

2013-02-15T05:54:48+00:00

The powerpc boot_paca symbol is now only used within the
early_setup() routine, so move it from its global definition
into early_setup().

Signed-off-by: Geoff Levand 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Initialise paca.data_offset with poison

2012-09-09T23:35:27+00:00

It's possible for the cpu_possible_mask to change between the time we
initialise the pacas and the time we setup per_cpu areas.

Obviously impossible cpus shouldn't ever be running, but stranger things
have happened. So be paranoid and initialise data_offset with a poison
value in case we don't set it up later.

Based on a patch from Anton Blanchard.

Signed-off-by: Michael Ellerman 
Signed-off-by: Benjamin Herrenschmidt