[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/Makefile b/arch/mips/Makefile
index a1f8d8b..a49127a 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -141,6 +141,10 @@
cflags-$(CONFIG_CPU_R10000) += $(call cc-option,-march=r10000,-march=r8000) \
-Wa,--trap
+cflags-$(CONFIG_CPU_R4000_WORKAROUNDS) += $(call cc-option,-mfix-r4000,)
+cflags-$(CONFIG_CPU_R4400_WORKAROUNDS) += $(call cc-option,-mfix-r4400,)
+cflags-$(CONFIG_CPU_DADDI_WORKAROUNDS) += $(call cc-option,-mno-daddi,)
+
ifdef CONFIG_CPU_SB1
ifdef CONFIG_SB1_PASS_1_WORKAROUNDS
MODFLAGS += -msb1-pass1-workarounds
@@ -602,9 +606,11 @@
endif
endif
- ifeq ($(KBUILD_SYM32), y)
- ifeq ($(call cc-option-yn,-msym32), y)
- cflags-y += -msym32 -DKBUILD_64BIT_SYM32
+ ifeq ($(KBUILD_SYM32)$(call cc-option-yn,-msym32), yy)
+ cflags-y += -msym32 -DKBUILD_64BIT_SYM32
+ else
+ ifeq ($(CONFIG_CPU_DADDI_WORKAROUNDS), y)
+ $(error CONFIG_CPU_DADDI_WORKAROUNDS unsupported without -msym32)
endif
endif
endif