With an admittedly exotic choice of configuration options
(CC_OPTIMIZE_FOR_SIZE, THUMB2, some other size-minimizing ones)
and compiler, the proc_info table can end up being misaligned,
and the kernel being unbootable (Error: unrecognized/unsupported
processor variant).
Forcing the alignement to 4 bytes in the linker script fixes the
issue.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The exception fixup table is currently aligned to a 32-byte boundary.
Whilst this won't cause any problems, the exception_table_entry
structures contain only a pair of unsigned longs, so 4-byte alignment
is all that is required. If the table was walked from start to end,
cacheline alignment may bring some performance benefits, but since a
binary search is used, the access pattern is random and will not benefit
from a stricter alignment.
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The linker script assumes a cacheline size of 32 bytes when aligning
the .data..cacheline_aligned and .data..percpu sections.
This patch updates the script to use L1_CACHE_BYTES, which should be set
to 64 on platforms that require it.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
When disabling and re-enabling the MMU, it is necessary to take out an
identity mapping for the code that manipulates the SCTLR in order to
avoid it disappearing from under our feet. This is useful when soft
rebooting and returning from CPU suspend.
This patch allocates a set of page tables during boot and populates them
with an identity mapping for the .idmap.text section. This means that
users of the identity map do not need to manage their own pgd and can
instead annotate their functions with __idmap or, in the case of assembly
code, place them in the correct section.
Acked-by: Dave Martin <dave.martin@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
ARM uses its own BUG() handler which makes its output slightly different
from other archtectures.
One of the problems is that the ARM implementation doesn't report the function
with the BUG() in it, but always reports the PC being in __bug(). The generic
implementation doesn't have this problem.
Currently we get something like:
kernel BUG at fs/proc/breakme.c:35!
Unable to handle kernel NULL pointer dereference at virtual address 00000000
...
PC is at __bug+0x20/0x2c
With this patch it displays:
kernel BUG at fs/proc/breakme.c:35!
Internal error: Oops - undefined instruction: 0 [#1] PREEMPT SMP
...
PC is at write_breakme+0xd0/0x1b4
This implementation uses an undefined instruction to implement BUG, and sets up
a bug table containing the relevant information. Many versions of gcc do not
support %c properly for ARM (inserting a # when they shouldn't) so we work
around this using distasteful macro magic.
v1: Initial version to replace existing ARM BUG() implementation with something
more similar to other architectures.
v2: Add Thumb support, remove backtrace whitespace output changes. Change to
use macros instead of requiring the asm %d flag to work (thanks to
Dave Martin <dave.martin@linaro.org>)
v3: Remove old BUG() implementation in favor of this one.
Remove the Backtrace: message (will submit this separately).
Use ARM_EXIT_KEEP() so that some architectures can dump exit text at link time
thanks to Stephen Boyd <sboyd@codeaurora.org> (although since we always
define GENERIC_BUG this might be academic.)
Rebase to linux-2.6.git master.
v4: Allow BUGS in modules (these were not reported correctly in v3)
(thanks to Stephen Boyd <sboyd@codeaurora.org> for suggesting that.)
Remove __bug() as this is no longer needed.
v5: Add %progbits as the section flags.
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
We are seeing linker errors caused by sections being discarded, despite
the linker script trying to keep them. The result is (eg):
`.exit.text' referenced in section `.alt.smp.init' of drivers/built-in.o: defined in discarded section `.exit.text' of drivers/built-in.o
`.exit.text' referenced in section `.alt.smp.init' of net/built-in.o: defined in discarded section `.exit.text' of net/built-in.o
This is the relevent part of the linker script (reformatted to make it
clearer):
| SECTIONS
| {
| /*
| * unwind exit sections must be discarded before the rest of the
| * unwind sections get included.
| */
| /DISCARD/ : {
| *(.ARM.exidx.exit.text)
| *(.ARM.extab.exit.text)
| }
| ...
| .exit.text : {
| *(.exit.text)
| *(.memexit.text)
| }
| ...
| /DISCARD/ : {
| *(.exit.text)
| *(.memexit.text)
| *(.exit.data)
| *(.memexit.data)
| *(.memexit.rodata)
| *(.exitcall.exit)
| *(.discard)
| *(.discard.*)
| }
| }
Now, this is what the linker manual says about discarded output sections:
| The special output section name `/DISCARD/' may be used to discard
| input sections. Any input sections which are assigned to an output
| section named `/DISCARD/' are not included in the output file.
No questions, no exceptions. It doesn't say "unless they are listed
before the /DISCARD/ section." Now, this is what asn-generic/vmlinux.lds.S
says:
| /*
| * Default discarded sections.
| *
| * Some archs want to discard exit text/data at runtime rather than
| * link time due to cross-section references such as alt instructions,
| * bug table, eh_frame, etc. DISCARDS must be the last of output
| * section definitions so that such archs put those in earlier section
| * definitions.
| */
And guess what - the list _always_ includes .exit.text etc.
Now, what's actually happening is that the linker is reading the script,
and it finds the first /DISCARD/ output section at the beginning of the
script. It continues reading the script, and finds the 'DISCARD' macro
at the end, which having been postprocessed results in another
/DISCARD/ output section. As the linker already contains the earlier
/DISCARD/ output section, it adds it to that existing section, so it
effectively is placed at the start. This can be seen by using the -M
option to ld:
| Linker script and memory map
|
| 0xc037c080 jiffies = jiffies_64
|
| /DISCARD/
| *(.ARM.exidx.exit.text)
| *(.ARM.extab.exit.text)
| *(.exit.text)
| *(.memexit.text)
| *(.exit.data)
| *(.memexit.data)
| *(.memexit.rodata)
| *(.exitcall.exit)
| *(.discard)
| *(.discard.*)
|
| 0xc0008000 . = 0xc0008000
|
| .head.text 0xc0008000 0x1d0
| 0xc0008000 _text = .
| *(.head.text)
| .head.text 0xc0008000 0x1d0 arch/arm/kernel/head.o
| 0xc0008000 stext
|
| .text 0xc0008200 0x2d78d0
| 0xc0008200 _stext = .
| 0xc0008200 __exception_text_start = .
| *(.exception.text)
| .exception.text
| ...
As you can see, all the discarded sections are grouped together - and
as a result of it being the first output section, they all appear before
any other section.
The result is that not only is the unwind information discarded (as
intended), but also the .exit.text, despite us wanting to have the
.exit.text preserved.
We can't move the unwind information elsewhere, because it'll then be
included even when we do actually discard the .exit.text (and similar)
sections.
So, work around this by avoiding the generic DISCARDS macro, and instead
conditionalize the sections to be discarded ourselves. This avoids the
ambiguity in how the linker assigns input sections to output sections,
making our script less dependent on undocumented linker behaviour.
Reported-by: Rob Herring <robherring2@gmail.com>
Tested-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
x86 uses _text to mark the start of the kernel image including the
head text, and _stext to mark the start of the .text section. Change
our vmlinux.lds to conform. An audit of the places which use _stext
and _text in arch/arm indicates no users of either symbol are impacted
by this change. It does mean a slight change to /proc/iomem output.
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Place the init sections between the text and data sections. This
means all code is grouped together at the beginning of the kernel
image, and all data is at the end of the image. This avoids problems
with the 24-bit branch instruction relocations becoming invalid with
large initramfs images.
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Keep the various linker tables as separate output sections rather
than combining them together into one big .init section. This
makes the 'vmlinux' easier to see what is placed where.
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Percpu allocator honors alignment request upto PAGE_SIZE and both the
percpu addresses in the percpu address space and the translated kernel
addresses should be aligned accordingly. The calculation of the
former depends on the alignment of percpu output section in the kernel
image.
The linker script macros PERCPU_VADDR() and PERCPU() are used to
define this output section and the latter takes @align parameter.
Several architectures are using @align smaller than PAGE_SIZE breaking
percpu memory alignment.
This patch removes @align parameter from PERCPU(), renames it to
PERCPU_SECTION() and makes it always align to PAGE_SIZE. While at it,
add PCPU_SETUP_BUG_ON() checks such that alignment problems are
reliably detected and remove percpu alignment comment recently added
in workqueue.c as the condition would trigger BUG way before reaching
there.
For um, this patch raises the alignment of percpu area. As the area
is in .init, there shouldn't be any noticeable difference.
This problem was discovered by David Howells while debugging boot
failure on mn10300.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Cc: uclinux-dist-devel@blackfin.uclinux.org
Cc: David Howells <dhowells@redhat.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: user-mode-linux-devel@lists.sourceforge.net
* 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm: (91 commits)
ARM: 6806/1: irq: introduce entry and exit functions for chained handlers
ARM: 6781/1: Thumb-2: Work around buggy Thumb-2 short branch relocations in gas
ARM: 6747/1: P2V: Thumb2 support
ARM: 6798/1: aout-core: zero thread debug registers in a.out core dump
ARM: 6796/1: Footbridge: Fix I/O mappings for NOMMU mode
ARM: 6784/1: errata: no automatic Store Buffer drain on Cortex-A9
ARM: 6772/1: errata: possible fault MMU translations following an ASID switch
ARM: 6776/1: mach-ux500: activate fix for errata 753970
ARM: 6794/1: SPEAr: Append UL to device address macros.
ARM: 6793/1: SPEAr: Remove unused *_SIZE macros from spear*.h files
ARM: 6792/1: SPEAr: Replace SIZE macro's with SZ_4K macros
ARM: 6791/1: SPEAr3xx: Declare device structures after shirq code
ARM: 6790/1: SPEAr: Clock Framework: Rename usbd clock and align apb_clk entry
ARM: 6789/1: SPEAr3xx: Rename sdio to sdhci
ARM: 6788/1: SPEAr: Include mach/hardware.h instead of mach/spear.h
ARM: 6787/1: SPEAr: Reorder #includes in .h & .c files.
ARM: 6681/1: SPEAr: add debugfs support to clk API
ARM: 6703/1: SPEAr: update clk API support
ARM: 6679/1: SPEAr: make clk API functions more generic
ARM: 6737/1: SPEAr: formalized timer support
...
* 'for-2.6.39' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
percpu, x86: Add arch-specific this_cpu_cmpxchg_double() support
percpu: Generic support for this_cpu_cmpxchg_double()
alpha: use L1_CACHE_BYTES for cacheline size in the linker script
percpu: align percpu readmostly subsection to cacheline
Fix up trivial conflict in arch/x86/kernel/vmlinux.lds.S due to the
percpu alignment having changed ("x86: Reduce back the alignment of the
per-CPU data section")
When SMP_ON_UP is used and the spinlocks are inlined, we end up with
inline spinlocks in the exit code, with references from the SMP
alternatives section to the exit sections. This causes link time
errors. Avoid this by placing the exit sections in the init-discarded
region.
Cc: <stable@kernel.org>
Tested-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Commit 18991197b4 added --build-id
linker option when toolchain supports it. ARM one does, but for some
reason places the section at 0 when linker script doesn't mention it
explicitly.
The 1e621a8e37 worked around the problem
removing this section from binary image with explicit objcopy options,
but it still exists in vmlinux, confusing tools like debuggers and perf.
This problem was discussed here:
http://lists.infradead.org/pipermail/linux-arm-kernel/2010-May/015994.htmlhttp://lists.infradead.org/pipermail/linux-arm-kernel/2010-May/015994.html
but the proposed changes to the linker script were substantial.
This patch simply places NOTES (36 bytes long, at least when compiled
with CodeSourcery toolchain) between data and bss, which seem to be
the right place (and suggested by the sample linker script in
include/asm-generic/vmlinux.lds.h).
It is enough to place it correctly in vmlinux (so debuggers are happy):
Section Headers:
[11] .data PROGBITS c07ce000 7ce000 020fc0 00 WA 0 0 32
[12] .notes NOTE c07eefc0 7eefc0 000024 00 AX 0 0 4
[13] .bss NOBITS c07ef000 7eefe4 01e628 00 WA 0 0 32
Program Headers:
LOAD 0x008000 0xc0008000 0xc0008000 0x7e6fe4 0x805628 RWE 0x8000
NOTE 0x7eefc0 0xc07eefc0 0xc07eefc0 0x00024 0x00024 R E 0x4
Section to Segment mapping:
Segment Sections...
00 <...> .data .notes .bss
01 .notes
and to get it exposed as /sys/kernel/notes used by perf tools.
Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This idea came from Nicolas, Eric Miao produced an initial version,
which was then rewritten into this.
Patch the physical to virtual translations at runtime. As we modify
the code, this makes it incompatible with XIP kernels, but allows us
to achieve this with minimal loss of performance.
As many translations are of the form:
physical = virtual + (PHYS_OFFSET - PAGE_OFFSET)
virtual = physical - (PHYS_OFFSET - PAGE_OFFSET)
we generate an 'add' instruction for __virt_to_phys(), and a 'sub'
instruction for __phys_to_virt(). We calculate at run time (PHYS_OFFSET
- PAGE_OFFSET) by comparing the address prior to MMU initialization with
where it should be once the MMU has been initialized, and place this
constant into the above add/sub instructions.
Once we have (PHYS_OFFSET - PAGE_OFFSET), we can calculate the real
PHYS_OFFSET as PAGE_OFFSET is a build-time constant, and save this for
the C-mode PHYS_OFFSET variable definition to use.
At present, we are unable to support Realview with Sparsemem enabled
as this uses a complex mapping function, and MSM as this requires a
constant which will not fit in our math instruction.
Add a module version magic string for this feature to prevent
incompatible modules being loaded.
Tested-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Currently percpu readmostly subsection may share cachelines with other
percpu subsections which may result in unnecessary cacheline bounce
and performance degradation.
This patch adds @cacheline parameter to PERCPU() and PERCPU_VADDR()
linker macros, makes each arch linker scripts specify its cacheline
size and use it to align percpu subsections.
This is based on Shaohua's x86 only patch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Shaohua Li <shaohua.li@intel.com>
As our SMP implementation uses MESI protocols. Grouping together data
which is mostly only read together means that we avoid unnecessary
cache line bouncing when this code shares a cache line with other data.
In other words, cache lines associated with read-mostly data are
expected to spend most of their time in shared state.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
When FUNCTION_GRAPH_TRACER is enabled, place do_IRQ() and friends in the
IRQ_ENTRY section so that the irq-related features of the function graph
tracer work.
Signed-off-by: Rabin Vincent <rabin@rab.in>
Commit 5085f3ff45 added better support for
CONFIG_HOTPLUG_CPU by keeping proc_info around. However, depending on
the Kconfig options selected, this can make the booting fail mysteriously
early on.
Turns out a data abort can happen in __lookup_processor in ldmia r5 {r3, r4}.
When it happens the address loaded to r5 is not aligned. Fix the problem by
aligning proc_info.
Reported-by: Anand Gadiyar <gadiyar@ti.com>
Tested-by: Anand Gadiyar <gadiyar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
