Commit graph

4 commits

Author SHA1 Message Date
Ralf Baechle
634286f127 MIPS: IP27: Switch from DMA_IP27 to DMA_COHERENT
The special IP27 DMA code selected by DMA_IP27 has been removed a while
ago turning DMA_IP27 into almost a nop.  Also fixup the broken logic of
its last users memcpy.S and memcpy-inatomic.s.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-01-30 21:32:58 +00:00
Ralf Baechle
c5ec1983e4 [MIPS] Eleminate local symbols from the symbol table.
These symbols appear in oprofile output, stacktraces and similar but only
make the output harder to read.  Many identical symbol names such as
"both_aligned" were also being used in multiple source files making it
impossible to see which file actually was meant.  So let's get rid of them.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-01-29 10:14:59 +00:00
Maciej W. Rozycki
619b6e18fc [MIPS] R4000/R4400 daddiu erratum workaround
This complements the generic R4000/R4400 errata workaround code and adds 
bits for the daddiu problem.  In most places it just modifies handwritten 
assembly code so that the assembler is allowed to use a temporary register 
as daddiu may now be treated as a macro that expands to a sequence of li 
and daddu.  It is the AT register or, where AT is unavailable or used 
explicitly for another purpose, an explicitly-named register is selected, 
using the .set at=<reg> feature added recently to gas.  This feature is 
only used if CONFIG_CPU_DADDI_WORKAROUNDS has been set, so if the 
workaround remains disabled, the required version of binutils stays 
unchanged.

 Similarly, daddiu instructions put in branch delay slots in noreorder 
fragments are now taken out of them and the assembler is allowed to 
reorder them itself as possible (which it does making the whole idea of 
scheduling them into delay slots manually questionable).

 Also in the very few places where such a simple conversion was not 
possible, a handcoded longer sequence is implemented.

 Other than that there are changes to code responsible for building the 
TLB fault and page clear/copy handlers to avoid daddiu as appropriate.  
These are only effective if the erratum is verified to be present at the 
run time.

 Finally there is a trivial update to __delay(), because it uses daddiu in 
a branch delay slot.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-01-29 10:14:55 +00:00
Ralf Baechle
e03b526932 [MIPS] Fixup copy_from_user_inatomic
From the 01408c4939 log message:

The problem is that when we write to a file, the copy from userspace to
pagecache is first done with preemption disabled, so if the source
address is not immediately available the copy fails *and* *zeros* *the*
*destination*.

This is a problem because a concurrent read (which admittedly is an odd
thing to do) might see zeros rather that was there before the write, or
what was there after, or some mixture of the two (any of these being a
reasonable thing to see).

If the copy did fail, it will immediately be retried with preemption
re-enabled so any transient problem with accessing the source won't
cause an error.

The first copying does not need to zero any uncopied bytes, and doing
so causes the problem.  It uses copy_from_user_atomic rather than
copy_from_user so the simple expedient is to change copy_from_user_atomic
to *not* zero out bytes on failure.

< --- end cite --- >

This patch finally implements at least a not so pretty solution by
duplicating the relevant part of __copy_user.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-20 01:26:42 +00:00