Russell King [Tue, 20 Sep 2011 22:35:15 +0000 (23:35 +0100)]
ARM: fix vmlinux.lds.S discarding sections
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:
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>
Russell King [Thu, 1 Sep 2011 10:57:59 +0000 (11:57 +0100)]
ARM: pm: add L2 cache cleaning for suspend
We need to ensure that state is pushed out from the L2 cache when
suspending so that the resume paths can access their data before the
MMU and caches have been re-initialized. Add the necessary calls to
__cpu_suspend_save().
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Russell King [Thu, 1 Sep 2011 10:52:33 +0000 (11:52 +0100)]
ARM: pm: convert some assembly to C
Convert some of the sleep.S guts to C code, which makes it easier to
use our macros and to add L2 cache handling. We provide a helper
function, __cpu_suspend_save(), which deals with saving the common
state, setting up for resume, and flushing caches.
The remainder left as assembly code is the saving of the CPU general
purpose registers, and allocating space on the stack to save the CPU
specific registers and resume state.
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Russell King [Wed, 31 Aug 2011 22:26:18 +0000 (23:26 +0100)]
ARM: pm: get rid of cpu_resume_turn_mmu_on
We don't require cpu_resume_turn_mmu_on as we can combine the ldr
instruction with the following code provided we ensure that
cpu_resume_mmu is aligned for older CPUs. Note that we also align
to a 32-byte boundary to ensure that the code can't cross a section
boundary.
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Russell King [Sun, 28 Aug 2011 09:30:34 +0000 (10:30 +0100)]
ARM: pm: no need to save/restore context ID register
There is no need to save and restore the context ID register on ARMv6
and ARMv7 with a temporary page table as we write the context ID
register when we switch back to the real page tables for the thread.
Moreover, the temporary page tables do not contain any non-global
mappings, so the context ID value should not be used. To be safe,
initialize the register to a reserved context ID value.
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Russell King [Sat, 27 Aug 2011 21:39:09 +0000 (22:39 +0100)]
ARM: pm: only use preallocated page table during resume
Only use the preallocated page table during the resume, not while
suspending. This avoids the overhead of having to switch unnecessarily
to the resume page table in the suspend path.
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Russell King [Fri, 26 Aug 2011 19:28:52 +0000 (20:28 +0100)]
ARM: pm: preallocate a page table for suspend/resume
Preallocate a page table and setup an identity mapping for the MMU
enable code. This means we don't have to "borrow" a page table to
do this, avoiding complexities with L2 cache coherency.
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Merge branch 'fixes' of git://git.linaro.org/people/arnd/arm-soc
* 'fixes' of git://git.linaro.org/people/arnd/arm-soc:
mach-integrator: fix VGA base regression
arm/dt: Tegra: Update SDHCI nodes to match bindings
ARM: EXYNOS4: fix incorrect pad configuration for keypad row lines
ARM: SAMSUNG: fix to prevent declaring duplicated
ARM: SAMSUNG: fix watchdog reset issue with clk_get()
ARM: S3C64XX: Remove un-used code backlight code on SMDK6410
ARM: EXYNOS4: restart clocksource while system resumes
ARM: EXYNOS4: Fix routing timer interrupt to offline CPU
ARM: EXYNOS4: Fix return type of local_timer_setup()
ARM: EXYNOS4: Fix wrong pll type for vpll
ARM: Dove: fix second SPI initialization call
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