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>

With large kernel builds such as allyesconfig exceeding maximum relative
branch offsets, the init section will be too far away to branch to
directly. This causes veneers to be added by the linker, but veneers
don't work before the MMU is enabled. Fix this by moving __fixup_smp to
the .head.text section as it is not very big.

Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Fix e26a9e00afc482b971afcaef1db8c9034d4d6d7c 'ARM: Better
virt_to_page() handling' replaced __pv_phys_offset with
__pv_phys_pfn_offset. Also note that size of __pv_phys_offset
was quad but size of __pv_phys_pfn_offset is word. Instruction
that used to update __pv_phys_offset which address is in r6
had to update low word of __pv_phys_offset so it used #LOW_OFFSET
macro for store offset. Now when size of __pv_phys_pfn_offset is
word, no difference between little endian and big endian should
exist - i.e no offset should be used when __pv_phys_pfn_offset
is stored.

Note that for little endian image proposed change is noop,
since in little endian case #LOW_OFFSET is defined 0 anyway.

Reported-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>
Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

virt_to_page() is incredibly inefficient when virt-to-phys patching is
enabled.  This is because we end up with this calculation:

  page = &mem_map[asm virt_to_phys(addr) >> 12 - __pv_phys_offset >> 12]

in assembly.  The asm virt_to_phys() is equivalent this this operation:

  addr - PAGE_OFFSET + __pv_phys_offset

and we can see that because this is assembly, the compiler has no chance
to optimise some of that away.  This should reduce down to:

  page = &mem_map[(addr - PAGE_OFFSET) >> 12]

for the common cases.  Permit the compiler to make this optimisation by
giving it more of the information it needs - do this by providing a
virt_to_pfn() macro.

Another issue which makes this more complex is that __pv_phys_offset is
a 64-bit type on all platforms.  This is needlessly wasteful - if we
store the physical offset as a PFN, we can save a lot of work having
to deal with 64-bit values, which sometimes ends up producing incredibly
horrid code:

     a4c:       e3009000        movw    r9, #0
                        a4c: R_ARM_MOVW_ABS_NC  __pv_phys_offset
     a50:       e3409000        movt    r9, #0          ; r9 = &__pv_phys_offset
                        a50: R_ARM_MOVT_ABS     __pv_phys_offset
     a54:       e3002000        movw    r2, #0
                        a54: R_ARM_MOVW_ABS_NC  __pv_phys_offset
     a58:       e3402000        movt    r2, #0          ; r2 = &__pv_phys_offset
                        a58: R_ARM_MOVT_ABS     __pv_phys_offset
     a5c:       e5999004        ldr     r9, [r9, #4]    ; r9 = high word of __pv_phys_offset
     a60:       e3001000        movw    r1, #0
                        a60: R_ARM_MOVW_ABS_NC  mem_map
     a64:       e592c000        ldr     ip, [r2]        ; ip = low word of __pv_phys_offset

Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

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>

The pgtbl macro couldn't handle the specific
(TEXT_OFFSET - PG_DIR_SIZE) value that the combination of
MSM platforms and LPAE created:

head.S:163: Error: invalid constant (203000) after fixup

Regardless of whether this combination of configuration options
will work on currently support platforms at run time, make it
at least assemble properly.

Signed-off-by: Christopher Covington <cov@codeaurora.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Jason Gunthorpe reports a build failure when ARM_PATCH_PHYS_VIRT is
not defined:

In file included from arch/arm/include/asm/page.h:163:0,
                 from include/linux/mm_types.h:16,
                 from include/linux/sched.h:24,
                 from arch/arm/kernel/asm-offsets.c:13:
arch/arm/include/asm/memory.h: In function '__virt_to_phys':
arch/arm/include/asm/memory.h:244:40: error: 'PHYS_OFFSET' undeclared (first use in this function)
arch/arm/include/asm/memory.h:244:40: note: each undeclared identifier is reported only once for each function it appears in
arch/arm/include/asm/memory.h: In function '__phys_to_virt':
arch/arm/include/asm/memory.h:249:13: error: 'PHYS_OFFSET' undeclared (first use in this function)

Fixes: ca5a45c06cd4 ("ARM: mm: use phys_addr_t appropriately in p2v and v2p conversions")
Tested-By: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Fix patching code to convert mov instruction into mvn instruction
in case of CONFIG_ARCH_PHYS_ADDR_T_64BIT and CONFIG_ARM_PATCH_PHYS_VIRT.

In BE case store into r0 proper bits so byte swapped instruction
could be modified correctly.

Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
Reviewed-by: R Sricharan <r.sricharan@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>