DEC: Limit PMAX memory probing to R3k systems

Recent tightening of the opcode table in binutils so as to consistently
disallow the assembly or disassembly of CP0 instructions not supported
by the processor architecture chosen has caused a regression like below:

arch/mips/dec/prom/locore.S: Assembler messages:
arch/mips/dec/prom/locore.S:29: Error: opcode not supported on this processor: r4600 (mips3) `rfe'

in a piece of code used to probe for memory with PMAX DECstation models,
which have non-REX firmware.  Those computers always have an R2000 CPU
and consequently the exception handler used in memory probing uses the
RFE instruction, which those processors use.

While adding 64-bit support this code was correctly excluded for 64-bit
configurations, however it should have also been excluded for irrelevant
32-bit configurations.  Do this now then, and only enable PMAX memory
probing for R3k systems.

Reported-by: Jan-Benedict Glaw <jbglaw@lug-owl.de>
Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org # v2.6.12+
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

diff --git a/arch/mips/dec/prom/Makefile b/arch/mips/dec/prom/Makefile
index d95016016b42bef365d7b8bb6348888df9e386f2..2bad87551203b2714529f7bbd38a832bf2b30a1e 100644 (file)
--- a/arch/mips/dec/prom/Makefile
+++ b/arch/mips/dec/prom/Makefile
@@ -6,4 +6,4 @@
 
 lib-y                  += init.o memory.o cmdline.o identify.o console.o
 
-lib-$(CONFIG_32BIT)    += locore.o
+lib-$(CONFIG_CPU_R3000)        += locore.o

diff --git a/arch/mips/include/asm/dec/prom.h b/arch/mips/include/asm/dec/prom.h
index 62c7dfb90e06c35afa168fa999e408f3b240004d..1e1247add1cf802b9abe3a5216b3a785f83e5988 100644 (file)
--- a/arch/mips/include/asm/dec/prom.h
+++ b/arch/mips/include/asm/dec/prom.h
@@ -43,16 +43,11 @@
  */
 #define REX_PROM_MAGIC         0x30464354
 
-#ifdef CONFIG_64BIT
-
-#define prom_is_rex(magic)     1       /* KN04 and KN05 are REX PROMs.  */
-
-#else /* !CONFIG_64BIT */
-
-#define prom_is_rex(magic)     ((magic) == REX_PROM_MAGIC)
-
-#endif /* !CONFIG_64BIT */
-
+/* KN04 and KN05 are REX PROMs, so only do the check for R3k systems.  */
+static inline bool prom_is_rex(u32 magic)
+{
+       return !IS_ENABLED(CONFIG_CPU_R3000) || magic == REX_PROM_MAGIC;
+}
 
 /*
  * 3MIN/MAXINE PROM entry points for DS5000/1xx's, DS5000/xx's and