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Russell King 6ebbf2ce43 ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+
ARMv6 and greater introduced a new instruction ("bx") which can be used
to return from function calls.  Recent CPUs perform better when the
"bx lr" instruction is used rather than the "mov pc, lr" instruction,
and this sequence is strongly recommended to be used by the ARM
architecture manual (section A.4.1.1).

We provide a new macro "ret" with all its variants for the condition
code which will resolve to the appropriate instruction.

Rather than doing this piecemeal, and miss some instances, change all
the "mov pc" instances to use the new macro, with the exception of
the "movs" instruction and the kprobes code.  This allows us to detect
the "mov pc, lr" case and fix it up - and also gives us the possibility
of deploying this for other registers depending on the CPU selection.

Reported-by: Will Deacon <will.deacon@arm.com>
Tested-by: Stephen Warren <swarren@nvidia.com> # Tegra Jetson TK1
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> # mioa701_bootresume.S
Tested-by: Andrew Lunn <andrew@lunn.ch> # Kirkwood
Tested-by: Shawn Guo <shawn.guo@freescale.com>
Tested-by: Tony Lindgren <tony@atomide.com> # OMAPs
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com> # Armada XP, 375, 385
Acked-by: Sekhar Nori <nsekhar@ti.com> # DaVinci
Acked-by: Christoffer Dall <christoffer.dall@linaro.org> # kvm/hyp
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com> # PXA3xx
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> # Xen
Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> # ARMv7M
Tested-by: Simon Horman <horms+renesas@verge.net.au> # Shmobile
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-07-18 12:29:04 +01:00
Russell King 0aeb3408ca ARM: remove global cr_no_alignment
cr_no_alignment is really only used by the alignment code.  Since we no
longer change the setting of cr_alignment after boot, we can localise
this to alignment.c

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-06-02 09:20:18 +01:00
Thomas Petazzoni b363457593 ARM: 7980/1: kernel: improve error message when LPAE config doesn't match CPU
Currently, when the kernel is configured with LPAE support, but the
CPU doesn't support it, the error message is fairly cryptic:

  Error: unrecognized/unsupported processor variant (0x561f5811).

This messages is normally shown when there is an issue when comparing
the processor ID (CP15 0, c0, c0) with the values/masks described in
proc-v7.S. However, the same message is displayed when LPAE support is
enabled in the kernel configuration, but not available in the CPU,
after looking at ID_MMFR0 (CP15 0, c0, c1, 4). Having the same error
message is highly misleading.

This commit improves this by showing a different error message when
this situation occurs:

  Error: Kernel with LPAE support, but CPU does not support LPAE.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-02-21 11:56:32 +00:00
Paul Gortmaker 8bd26e3a7e arm: delete __cpuinit/__CPUINIT usage from all ARM users
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
and are flagged as __cpuinit  -- so if we remove the __cpuinit from
the arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
related content into no-ops as early as possible, since that will get
rid of these warnings.  In any case, they are temporary and harmless.

This removes all the ARM uses of the __cpuinit macros from C code,
and all __CPUINIT from assembly code.  It also had two ".previous"
section statements that were paired off against __CPUINIT
(aka .section ".cpuinit.text") that also get removed here.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: Russell King <linux@arm.linux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2013-07-14 19:36:52 -04:00
Stephen Warren 8c69d7af12 ARM: 7780/1: add missing linker section markup to head-common.S
Macro __INIT is used to place various code in head-common.S into the init
section. This should be matched by a closing __FINIT. Also, add an
explicit ".text" to ensure subsequent code is placed into the correct
section; __FINIT is simply a closing marker to match __INIT and doesn't
guarantee to revert to .text.

This historically caused no problem, because macro __CPUINIT was used at
the exact location where __FINIT was missing, which then placed following
code into the cpuinit section. However, with commit 22f0a2736 "init.h:
remove __cpuinit sections from the kernel" applied, __CPUINIT becomes a
no-op, thus leaving all this code in the init section, rather than the
regular text section. This caused issues such as secondary CPU boot
failures or crashes.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-07-09 09:51:35 +01:00
Uwe Kleine-König b849a60e09 ARM: make cr_alignment read-only #ifndef CONFIG_CPU_CP15
This makes cr_alignment a constant 0 to break code that tries to modify
the value as it's likely that it's built on wrong assumption when
CONFIG_CPU_CP15 isn't defined. For code that is only reading the value 0
is more or less a fine value to report.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Message-Id: 1358413196-5609-2-git-send-email-u.kleine-koenig@pengutronix.de (v8)
2013-01-31 21:44:45 +01:00
Grant Likely 4c2896e88d arm/dt: Make __vet_atags also accept a dtb image
The dtb is passed to the kernel via register r2, which is the same
method that is used to pass an atags pointer.  This patch modifies
__vet_atags to not clear r2 when it encounters a dtb image.

v2: fixed bugs pointed out by Nicolas Pitre

Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2011-05-11 15:12:32 +02:00
Russell King 6fc31d5444 ARM: Defer lookup of machine_type to setup.c
Since the debug macros no longer depend on the machine type information,
the machine type lookup can be deferred to setup_arch() in setup.c which
simplifies the code somewhat.

We also move the __error_a functionality into setup.c for displaying a
message when a bad machine ID is passed to the kernel via the LL debug
code.  We also log this into the kernel ring buffer which makes it
possible to retrieve the message via a debugger.

Original idea from Grant Likely.

Acked-by: Grant Likely <grant.likely@secretlab.ca>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-02-15 16:36:44 +00:00
Russell King cb4d3eaebb ARM: fix missing branch in __error_a
When DEBUG_LL is not set, we don't want __error_a re-entering
__lookup_machine_type - we want it to go to the error function.  This
used to be the case before we reorganized the layout for hotplug cpu,
as we used to fall through to __error.  With the changed layout, we
need an explicit branch here instead.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-01-15 11:19:19 +00:00
Russell King a0a55682b8 Merge branch 'hotplug' into devel
Conflicts:
	arch/arm/kernel/head-common.S
2010-10-18 22:34:47 +01:00
Russell King 80924ac595 ARM: cleanup lookup_machine_type data and ensure these are placed in __HEAD
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-10-08 10:07:34 +01:00
Russell King c083c6609b ARM: hotplug cpu: move __error and __error_p to cpuinit section
__error and __error_p may be used by secondary CPUs, so these
need to be in the cpuinit section.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-10-08 10:07:33 +01:00
Russell King 17bb5e2c17 ARM: move __mmap_switched, C-API functions to init section
Move these functions, which are only ever used during boot CPU
initialization, to the init section.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-10-08 10:07:33 +01:00
Russell King a4ae41341f ARM: cleanup boot cpu calling __mmap_switched
This allows us to relocate __mmap_switched and associated data away
from the head section.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-10-08 10:07:32 +01:00
Russell King 5085f3ff45 ARM: hotplug cpu: Keep processor information, startup code & __lookup_processor_type
When hotplug CPU is enabled, we need to keep the list of supported CPUs,
their setup functions, and __lookup_processor_type in place so that we
can find and initialize secondary CPUs.  Move these into the __CPUINIT
section.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-10-08 10:07:32 +01:00
Russell King 842eab40b6 ARM: vmlinux.lds: Refer to start of .data using _sdata rather than _data
Use _sdata as the start of the data section, rather than _data.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-10-08 10:02:24 +01:00
Nicolas Pitre 158bc5af3d ARM: 5784/1: fix early boot machine ID mismatch error display
That code was refactored a long time ago, but one particular label
didn't get adjusted properly which broke the listing of supported
machines.

Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2009-11-08 11:58:54 +00:00
David Brown 31abdb7441 ARM: 5739/1: ARM: allow empty ATAG_CORE
From: David Brown <davidb@quicinc.com>

The ATAG_CORE is allowed to be empty.  Although this is handled
by parse_tag_core(), __vet_atags during startup rejects this tag
unless it contains data.  Allow the initial tag to be either the
full size, or empty.

Signed-off-by: David Brown <davidb@quicinc.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2009-10-02 22:32:34 +01:00
Catalin Marinas b86040a59f Thumb-2: Implementation of the unified start-up and exceptions code
This patch implements the ARM/Thumb-2 unified kernel start-up and
exception handling code.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-24 12:32:54 +01:00
Catalin Marinas 88987ef91b Thumb-2: Add some .align statements to the .S files
Since the Thumb-2 instructions can be 16-bit wide, data in the .text
sections may not be aligned to a 32-bit word and this leads to unaligned
exceptions. This patch does not affect the ARM code generation.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2009-07-24 12:32:52 +01:00
Russell King 37efe6427d [ARM] use asm/sections.h
Update to use the asm/sections.h header rather than declaring these
symbols ourselves.  Change __data_start to _data to conform with the
naming found within asm/sections.h.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2008-12-01 11:53:07 +00:00
Catalin Marinas 93ed397011 [ARM] 5227/1: Add the ENDPROC declarations to the .S files
This declaration specifies the "function" type and size for various
assembly functions, mainly needed for generating the correct branch
instructions in Thumb-2.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2008-09-01 12:06:34 +01:00
Russell King 4baa992243 [ARM] move include/asm-arm to arch/arm/include/asm
Move platform independent header files to arch/arm/include/asm, leaving
those in asm/arch* and asm/plat* alone.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2008-08-02 21:32:35 +01:00
Lennert Buytenhek 84081bd220 [ARM] 4881/1: print unrecognised processor ID as part of failure message
If we fail to boot due to an unsupported processor ID, print the
processor ID as part of the failure message.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Acked-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2008-04-19 11:28:08 +01:00
Greg Ungerer 9c4c9f3879 [ARM] 4849/1: move ATAGS asm definitions
Move the definitions of ATAG_CORE and ATAG_CORE_SIZE in head.S to
head-common.S. There is no use of these in head.S itself, but they
are used in head-common.S. When building for the !CONFIG_MMU case
these were not defined when compiling head-nommu.S (which includes
head-common.S).

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2008-03-06 12:18:18 +00:00
Bill Gatliff 9d20fdd58e [ARM] 4423/1: add ATAGS support
Examines the ATAGS pointer (r2) at boot, and interprets
a nonzero value as a reference to an ATAGS structure. A
suitable ATAGS structure replaces the kernel's command line.

Signed-off-by: Bill Gatliff <bgat@billgatliff.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2007-07-12 11:13:33 +01:00
Hyok S. Choi 75d90832d5 [ARM] nommu: start-up code
This patch adds nommu version start-up code head-nommu.S.
The common part of the start-up codes is moved to head-common.S.

Signed-off-by: Hyok S. Choi <hyok.choi@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-03-27 14:58:25 +01:00