kernel_optimize_test/arch/powerpc/lib
Michael Ellerman fac23fe4be powerpc: Introduce infrastructure for feature sections with alternatives
The current feature section logic only supports nop'ing out code, this means
if you want to choose at runtime between instruction sequences, one or both
cases will have to execute the nop'ed out contents of the other section, eg:

BEGIN_FTR_SECTION
	or	1,1,1
END_FTR_SECTION_IFSET(FOO)
BEGIN_FTR_SECTION
	or	2,2,2
END_FTR_SECTION_IFCLR(FOO)

and the resulting code will be either,

	or	1,1,1
	nop

or,
	nop
	or	2,2,2

For small code segments this is fine, but for larger code blocks and in
performance criticial code segments, it would be nice to avoid the nops.
This commit starts to implement logic to allow the following:

BEGIN_FTR_SECTION
	or	1,1,1
FTR_SECTION_ELSE
	or	2,2,2
ALT_FTR_SECTION_END_IFSET(FOO)

and the resulting code will be:

	or	1,1,1
or,
	or	2,2,2

We achieve this by extending the existing FTR macros. The current feature
section semantic just becomes a special case, ie. if the else case is empty
we nop out the default case.

The key limitation is that the size of the else case must be less than or
equal to the size of the default case. If the else case is smaller the
remainder of the section is nop'ed.

We let the linker put the else case code in with the rest of the text,
so that relative branches from the else case are more likley to link,
this has the disadvantage that we can't free the unused else cases.

This commit introduces the required macro and linker script changes, but
does not enable the patching of the alternative sections.

We also need to update two hand-made section entries in reg.h and timex.h

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-07-01 11:28:28 +10:00
..
alloc.c [POWERPC] Limit range of __init_ref_ok somewhat 2007-10-03 11:48:44 +10:00
checksum_32.S
checksum_64.S
code-patching.c powerpc: Add tests of the code patching routines 2008-07-01 11:28:22 +10:00
copy_32.S
copypage_64.S
copyuser_64.S
crtsavres.S [POWERPC] Fix -Os kernel builds with newer gcc versions 2008-06-16 15:00:54 +10:00
devres.c [POWERPC] devres: Add devm_ioremap_prot() 2008-05-05 16:47:14 +10:00
div64.S
dma-noncoherent.c [POWERPC] Remove use of 4level-fixup.h for ppc32 2007-05-08 13:40:31 +10:00
feature-fixups.c powerpc: Introduce infrastructure for feature sections with alternatives 2008-07-01 11:28:28 +10:00
locks.c
Makefile powerpc: Split out do_feature_fixups() from cputable.c 2008-07-01 11:28:24 +10:00
mem_64.S
memcpy_64.S
rheap.c [POWERPC] Make rheap safe for spinlocks 2008-04-17 09:50:38 -05:00
sstep.c
string.S [POWERPC] Add hand-coded assembly strcmp 2008-04-07 10:03:03 +10:00
usercopy_64.c