linux-toradex.git/arch/powerpc/kernel/vdso32, branch v2.6.27.31

powerpc: Fixup lwsync at runtime

2008-07-03T06:58:10+00:00

To allow for a single kernel image on e500 v1/v2/mc we need to fixup lwsync
at runtime.  On e500v1/v2 lwsync causes an illop so we need to patch up
the code.  We default to 'sync' since that is always safe and if the cpu
is capable we will replace 'sync' with 'lwsync'.

We introduce CPU_FTR_LWSYNC as a way to determine at runtime if this is
needed.  This flag could be moved elsewhere since we dont really use it
for the normal CPU_FTR purpose.

Finally we only store the relative offset in the fixup section to keep it
as small as possible rather than using a full fixup_entry.

Signed-off-by: Kumar Gala 
Signed-off-by: Paul Mackerras

powerpc: Introduce infrastructure for feature sections with alternatives

2008-07-01T01:28:28+00:00

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 
Signed-off-by: Paul Mackerras

[POWERPC] vdso: Fixes for cache block sizes

2007-11-20T02:56:31+00:00

The current VDSO implementation is hardcoded to 128 byte cache blocks,
which are only used on IBM's 64-bit processors.

Convert it to get the cache block sizes out of vdso_data instead,
similar to how the ppc64 in-kernel cache flush does it.

Signed-off-by: Olof Johansson 
Signed-off-by: Paul Mackerras

powerpc32 vDSO: linker script indentation

2007-10-16T17:01:50+00:00

This cleans up the formatting in the vDSO linker script, mostly just the
use of whitespace.  It's intended to approximate the kernel standard
conventions for indenting C, treating elements of the linker script about
like initialized variable definitions.

Signed-off-by: Roland McGrath 
Acked-by: Benjamin Herrenschmidt 
Cc: Sam Ravnborg 
Signed-off-by: Linus Torvalds

[POWERPC] Update .gitignore for new vdso generated files

2007-10-08T13:38:12+00:00

We now generate vdso[32,64].so.dbg as part of the build so
add them to .gitignore

Signed-off-by: Kumar Gala

[POWERPC] powerpc vDSO: install unstripped copies on disk

2007-10-03T02:02:43+00:00

This keeps an unstripped copy of the vDSO images built before they are
stripped and embedded in the kernel.  The unstripped copies get installed in
$(MODLIB)/vdso/ by "make install".  These files can be useful when they
contain source-level debugging information.

Signed-off-by: Roland McGrath 
Cc: Sam Ravnborg 
Cc: Benjamin Herrenschmidt 
Signed-off-by: Andrew Morton 
Signed-off-by: Paul Mackerras

[POWERPC] Fix VDSO gettimeofday() when called with NULL struct timeval

2007-06-26T04:41:19+00:00

Consider the prototype for gettimeofday():
	int gettimofday(struct timeval *tv, struct timezone *tz);

Although it is valid to call with /either/ tv or tz being NULL, and
the C version of sys_gettimeofday() supports this, the current version
of gettimeofday() in the VDSO will SEGV if called with a NULL tv.

This adds a check for tv being NULL so that it doesn't SEGV.

Signed-off-by: Tony Breeds 
Acked-by: Benjamin Herrenschmidt 
Signed-off-by: Paul Mackerras

[POWERPC] Support feature fixups in vdso's

2006-10-25T01:54:07+00:00

This patch reworks the feature fixup mecanism so vdso's can be fixed up.
The main issue was that the construct:

        .long   label  (or .llong on 64 bits)

will not work in the case of a shared library like the vdso. It will
generate an empty placeholder in the fixup table along with a reloc,
which is not something we can deal with in the vdso.

The idea here (thanks Alan Modra !) is to instead use something like:

1:
        .long   label - 1b

That is, the feature fixup tables no longer contain addresses of bits of
code to patch, but offsets of such code from the fixup table entry
itself. That is properly resolved by ld when building the .so's. I've
modified the fixup mecanism generically to use that method for the rest
of the kernel as well.

Another trick is that the 32 bits vDSO included in the 64 bits kernel
need to have a table in the 64 bits format. However, gas does not
support 32 bits code with a statement of the form:

        .llong  label - 1b  (Or even just .llong label)

That is, it cannot emit the right fixup/relocation for the linker to use
to assign a 32 bits address to an .llong field. Thus, in the specific
case of the 32 bits vdso built as part of the 64 bits kernel, we are
using a modified macro that generates:

        .long   0xffffffff
        .llong  label - 1b

Note that is assumes that the value is negative which is enforced by
the .lds (those offsets are always negative as the .text is always
before the fixup table and gas doesn't support emiting the reloc the
other way around).

Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Paul Mackerras

[PATCH] vDSO hash-style fix

2006-07-31T20:28:43+00:00

The latest toolchains can produce a new ELF section in DSOs and
dynamically-linked executables.  The new section ".gnu.hash" replaces
".hash", and allows for more efficient runtime symbol lookups by the
dynamic linker.  The new ld option --hash-style={sysv|gnu|both} controls
whether to produce the old ".hash", the new ".gnu.hash", or both.  In some
new systems such as Fedora Core 6, gcc by default passes --hash-style=gnu
to the linker, so that a standard invocation of "gcc -shared" results in
producing a DSO with only ".gnu.hash".  The new ".gnu.hash" sections need
to be dealt with the same way as ".hash" sections in all respects; only the
dynamic linker cares about their contents.  To work with older dynamic
linkers (i.e.  preexisting releases of glibc), a binary must have the old
".hash" section.  The --hash-style=both option produces binaries that a new
dynamic linker can use more efficiently, but an old dynamic linker can
still handle.

The new section runs afoul of the custom linker scripts used to build vDSO
images for the kernel.  On ia64, the failure mode for this is a boot-time
panic because the vDSO's PT_IA_64_UNWIND segment winds up ill-formed.

This patch addresses the problem in two ways.

First, it mentions ".gnu.hash" in all the linker scripts alongside ".hash".
 This produces correct vDSO images with --hash-style=sysv (or old tools),
with --hash-style=gnu, or with --hash-style=both.

Second, it passes the --hash-style=sysv option when building the vDSO
images, so that ".gnu.hash" is not actually produced.  This is the most
conservative choice for compatibility with any old userland.  There is some
concern that some ancient glibc builds (though not any known old production
system) might choke on --hash-style=both binaries.  The optimizations
provided by the new style of hash section do not really matter for a DSO
with a tiny number of symbols, as the vDSO has.  If someone wants to use
=gnu or =both for their vDSO builds and worry less about that
compatibility, just change the option and the linker script changes will
make any choice work fine.

Signed-off-by: Roland McGrath 
Cc: "Luck, Tony" 
Cc: Kyle McMartin 
Cc: Paul Mackerras 
Cc: Benjamin Herrenschmidt 
Cc: Jeff Dike 
Cc: Andi Kleen 
Cc: Sam Ravnborg 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Remove obsolete #include

2006-06-30T17:25:36+00:00

Signed-off-by: Jörn Engel 
Signed-off-by: Adrian Bunk