linux-stable.git/arch/powerpc/kernel/misc_64.S, branch linux-4.1.y

powerpc: Simplify module TOC handling

2018-03-01T03:09:48+00:00

[ Upstream commit c153693d7eb9eeb28478aa2deaaf0b4e7b5ff5e9 ]

PowerPC64 uses the symbol .TOC. much as other targets use
_GLOBAL_OFFSET_TABLE_. It identifies the value of the GOT pointer (or in
powerpc parlance, the TOC pointer). Global offset tables are generally
local to an executable or shared library, or in the kernel, module. Thus
it does not make sense for a module to resolve a relocation against
.TOC. to the kernel's .TOC. value. A module has its own .TOC., and
indeed the powerpc64 module relocation processing ignores the kernel
value of .TOC. and instead calculates a module-local value.

This patch removes code involved in exporting the kernel .TOC., tweaks
modpost to ignore an undefined .TOC., and the module loader to twiddle
the section symbol so that .TOC. isn't seen as undefined.

Note that if the kernel was compiled with -msingle-pic-base then ELFv2
would not have function global entry code setting up r2. In that case
the module call stubs would need to be modified to set up r2 using the
kernel .TOC. value, requiring some of this code to be reinstated.

mpe: Furthermore a change in binutils master (not yet released) causes
the current way we handle the TOC to no longer work when building with
MODVERSIONS=y and RELOCATABLE=n. The symptom is that modules can not be
loaded due to there being no version found for TOC.

Cc: stable@vger.kernel.org # 3.16+
Signed-off-by: Alan Modra 
Signed-off-by: Michael Ellerman 
Signed-off-by: Sasha Levin

powerpc/64: Fix flush_(d|i)cache_range() called from modules

2018-03-01T03:09:48+00:00

[ Upstream commit 8f5f525d5b83f7d76a6baf9c4e94d4bf312ea7f6 ]

When the kernel is compiled to use 64bit ABIv2 the _GLOBAL() macro does
not include a global entry point. A function's global entry point is
used when the function is called from a different TOC context and in the
kernel this typically means a call from a module into the vmlinux (or
vice-versa).

There are a few exported asm functions declared with _GLOBAL() and
calling them from a module will likely crash the kernel since any TOC
relative load will yield garbage.

flush_icache_range() and flush_dcache_range() are both exported to
modules, and use the TOC, so must use _GLOBAL_TOC().

Fixes: 721aeaa9fdf3 ("powerpc: Build little endian ppc64 kernel with ABIv2")
Cc: stable@vger.kernel.org # v3.16+
Signed-off-by: Oliver O'Halloran 
Signed-off-by: Michael Ellerman 
Signed-off-by: Sasha Levin

powerpc: module: handle MODVERSION for .TOC.

2014-04-23T00:05:28+00:00

For the ELFv2 ABI, powerpc introduces a magic symbol ".TOC.".  If we
don't create a CRC for it (minus the leading ".", since we strip that)
we get a modpost warning about missing CRC and the CRC array seems to
be displaced by 1 so other CRCs mismatch too.

Signed-off-by: Rusty Russell

powerpc: EXPORT_SYMBOL(.TOC.)

2014-04-23T00:05:28+00:00

For the ELFv2 ABI, powerpc introduces a magic symbol ".TOC.".  depmod
then complains that this doesn't resolve (so does modpost, but we could
easily fix that).  To export this, we need to use asm.

modpost and depmod both strip "." from symbols for the old PPC64 ELFv1
ABI, so we actually export a "TOC.".

Signed-off-by: Rusty Russell

powerpc: ABIv2 function calls must place target address in r12

2014-04-23T00:05:20+00:00

To establish addressability quickly, ABIv2 requires the target
address of the function being called to be in r12. Fix a number of
places in assembly code that we do indirect function calls.

We need to avoid function descriptors on ABIv2 too.

Signed-off-by: Anton Blanchard

powerpc: No need to use dot symbols when branching to a function

2014-04-23T00:05:16+00:00

binutils is smart enough to know that a branch to a function
descriptor is actually a branch to the functions text address.

Alan tells me that binutils has been doing this for 9 years.

Signed-off-by: Anton Blanchard

Merge branch 'merge' into next

2013-12-30T04:19:31+00:00

Merge a pile of fixes that went into the "merge" branch (3.13-rc's) such
as Anton Little Endian fixes.

Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix build break with PPC_EARLY_DEBUG_BOOTX=y

2013-12-10T00:25:03+00:00

A kernel configured with PPC_EARLY_DEBUG_BOOTX=y but PPC_PMAC=n and
PPC_MAPLE=n will fail to link:

  btext.c:(.text+0x2d0fc): undefined reference to `.rmci_off'
  btext.c:(.text+0x2d214): undefined reference to `.rmci_on'

Fix it by making the build of rmci_on/off() depend on
PPC_EARLY_DEBUG_BOOTX, which also enable the only code that uses them.

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

powerpc: purge all the prefetched instructions for the coherent icache flush

2013-12-02T03:13:47+00:00

As Benjamin Herrenschmidt has indicated, we still need a dummy icbi to
purge all the prefetched instructions from the ifetch buffers for the
snooping icache. We also need a sync before the icbi to order the
actual stores to memory that might have modified instructions with
the icbi.

Signed-off-by: Kevin Hao 
Signed-off-by: Benjamin Herrenschmidt

powerpc/irq: Run softirqs off the top of the irq stack

2013-09-25T04:15:36+00:00

Nowadays, irq_exit() calls __do_softirq() pretty much directly
instead of calling do_softirq() which switches to the decicated
softirq stack.

This has lead to observed stack overflows on powerpc since we call
irq_enter() and irq_exit() outside of the scope that switches to
the irq stack.

This fixes it by moving the stack switching up a level, making
irq_enter() and irq_exit() run off the irq stack.

Signed-off-by: Benjamin Herrenschmidt