linux-stable.git/arch/powerpc/kernel/vmlinux.lds.S, branch v3.2.73

powerpc: Align TOC to 256 bytes

2015-08-06T23:32:11+00:00

commit 5e95235ccd5442d4a4fe11ec4eb99ba1b7959368 upstream.

Recent toolchains force the TOC to be 256 byte aligned. We need
to enforce this alignment in our linker script, otherwise pointers
to our TOC variables (__toc_start, __prom_init_toc_start) could
be incorrect.

If they are bad, we die a few hundred instructions into boot.

Signed-off-by: Anton Blanchard 
Signed-off-by: Michael Ellerman 
Signed-off-by: Ben Hutchings

powerpc/modules: Module CRC relocation fix causes perf issues

2013-08-02T20:15:07+00:00

commit 0e0ed6406e61434d3f38fb58aa8464ec4722b77e upstream.

Module CRCs are implemented as absolute symbols that get resolved by
a linker script. We build an intermediate .o that contains an
unresolved symbol for each CRC. genksysms parses this .o, calculates
the CRCs and writes a linker script that "resolves" the symbols to
the calculated CRC.

Unfortunately the ppc64 relocatable kernel sees these CRCs as symbols
that need relocating and relocates them at boot. Commit d4703aef
(module: handle ppc64 relocating kcrctabs when CONFIG_RELOCATABLE=y)
added a hook to reverse the bogus relocations. Part of this patch
created a symbol at 0x0:

# head -2 /proc/kallsyms
0000000000000000 T reloc_start
c000000000000000 T .__start

This reloc_start symbol is causing lots of confusion to perf. It
thinks reloc_start is a massive function that stretches from 0x0 to
0xc000000000000000 and we get various cryptic errors out of perf,
including:

problem incrementing symbol count, skipping event

This patch removes the  reloc_start linker script label and instead
defines it as PHYSICAL_START. We also need to wrap it with
CONFIG_PPC64 because the ppc32 kernel can set a non zero
PHYSICAL_START at compile time and we wouldn't want to subtract
it from the CRCs in that case.

Signed-off-by: Anton Blanchard 
Acked-by: Rusty Russell 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Ben Hutchings

percpu: Always align percpu output section to PAGE_SIZE

2011-03-24T17:50:09+00:00

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 
Acked-by: Mike Frysinger 
Cc: uclinux-dist-devel@blackfin.uclinux.org
Cc: David Howells 
Cc: Jeff Dike 
Cc: user-mode-linux-devel@lists.sourceforge.net

percpu: align percpu readmostly subsection to cacheline

2011-01-25T13:26:50+00:00

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 
Cc: Shaohua Li

Rename .data.read_mostly to .data..read_mostly.

2010-03-03T10:26:00+00:00

Signed-off-by: Denys Vlasenko 
Signed-off-by: Michal Marek

Rename .data.page_aligned to .data..page_aligned.

2010-03-03T10:25:59+00:00

Signed-off-by: Tim Abbott 
Cc: Sam Ravnborg 
Signed-off-by: Denys Vlasenko 
Signed-off-by: Michal Marek

Rename .data.init_task to .data..init_task.

2010-03-03T10:25:58+00:00

Signed-off-by: Tim Abbott 
Cc: Sam Ravnborg 
Signed-off-by: Denys Vlasenko 
Signed-off-by: Michal Marek

Rename .data.cacheline_aligned to .data..cacheline_aligned.

2010-03-03T10:25:58+00:00

Signed-off-by: Tim Abbott 
Cc: Sam Ravnborg 
Signed-off-by: Denys Vlasenko 
Signed-off-by: Michal Marek

module: handle ppc64 relocating kcrctabs when CONFIG_RELOCATABLE=y

2009-12-15T05:58:34+00:00

powerpc applies relocations to the kcrctab.  They're absolute symbols,
but it's not completely unreasonable: other archs may too, but the
relocation is often 0.

http://lists.ozlabs.org/pipermail/linuxppc-dev/2009-November/077972.html

Inspired-by: Neil Horman 
Signed-off-by: Rusty Russell 
Tested-by: Neil Horman 
Acked-by: Paul Mackerras

powerpc: warning: allocated section `.data_nosave' not in segment

2009-10-14T05:58:39+00:00

We need to align before the output section. Having the align inside
the output section causes the linker to put some filler in there,
which makes it a non-empty section, but this section isn't assigned to
a segment so you get a warning from the linker.

Signed-off-by: Sean MacLennan 
Acked-by: Segher Boessenkool 
Signed-off-by: Benjamin Herrenschmidt