[MIPS] R4000/R4400 errata workarounds
This is the gereric part of R4000/R4400 errata workarounds. They include
compiler and assembler support as well as some source code modifications
to address the problems with some combinations of multiply/divide+shift
instructions as well as the daddi and daddiu instructions.
Changes included are as follows:
1. New Kconfig options to select workarounds by platforms as necessary.
2. Arch top-level Makefile to pass necessary options to the compiler; also
incompatible configurations are detected (-mno-sym32 unsupported as
horribly intrusive for little gain).
3. Bug detection updated and shuffled -- the multiply/divide+shift problem
is lethal enough that if not worked around it makes the kernel crash in
time_init() because of a division by zero; the daddiu erratum might
also trigger early potentially, though I have not observed it. On the
other hand the daddi detection code requires the exception subsystem to
have been initialised (and is there mainly for information).
4. r4k_daddiu_bug() added so that the existence of the erratum can be
queried by code at the run time as necessary; useful for generated code
like TLB fault and copy/clear page handlers.
5. __udelay() updated as it uses multiplication in inline assembly.
Note that -mdaddi requires modified toolchain (which has been maintained
by myself and available from my site for ~4years now -- versions covered
are GCC 2.95.4 - 4.1.2 and binutils from 2.13 onwards). The -mfix-r4000
and -mfix-r4400 have been standard for a while though.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 12bf963..11bc17c 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -91,6 +91,9 @@
select BOOT_ELF32
select CEVT_R4K
select CSRC_R4K
+ select CPU_DADDI_WORKAROUNDS if 64BIT
+ select CPU_R4000_WORKAROUNDS if 64BIT
+ select CPU_R4400_WORKAROUNDS if 64BIT
select DMA_NONCOHERENT
select NO_IOPORT
select IRQ_CPU
@@ -1606,6 +1609,19 @@
bool
#
+# CPU non-features
+#
+config CPU_DADDI_WORKAROUNDS
+ bool
+
+config CPU_R4000_WORKAROUNDS
+ bool
+ select CPU_R4400_WORKAROUNDS
+
+config CPU_R4400_WORKAROUNDS
+ bool
+
+#
# Use the generic interrupt handling code in kernel/irq/:
#
config GENERIC_HARDIRQS