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@xxxxxxxxxx>
Reported-by: Sudip Mukherjee <sudipm.mukherjee@xxxxxxxxx>
Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxx>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@xxxxxxxxxxxxxxx # v2.6.12+
---
Hi,
I'm assuming this won't go back beyond commit 2a11c8ea20bf ("kconfig:
Introduce IS_ENABLED(), IS_BUILTIN() and IS_MODULE()") or any backport
will have to be rewritten to avoid IS_ENABLED.
The original actual change named to fix ought to be commit dd82ef87e4c9
("PROM interface rework to support a 64-bit kernel.") from the LMO repo:
<https://git.kernel.org/pub/scm/linux/kernel/git/ralf/linux.git/commit/?id=dd82ef87e4c9>,
which introduced the `prom_is_rex' macro, which guards this code. Said
commit predates the history of our main repository though.
This change has actually been verified at runtime with a PMIN system
(effectively a PMAX, but with a slower R2000 CPU) and a 4MAX+ system (an
R4400SC-based machine), and naturally throughout the three possible build
configurations: R3k, R4k/32-bit, R4k/64-bit.
It took longer than expected, but oh well... Sorry for the inconvenience
caused.
Please apply,
Maciej
---
arch/mips/dec/prom/Makefile | 2 +-
arch/mips/include/asm/dec/prom.h | 15 +++++----------
2 files changed, 6 insertions(+), 11 deletions(-)
linux-dec-locore-r3000.diff
Index: linux-macro/arch/mips/dec/prom/Makefile
===================================================================
--- linux-macro.orig/arch/mips/dec/prom/Makefile
+++ linux-macro/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
Index: linux-macro/arch/mips/include/asm/dec/prom.h
===================================================================
--- linux-macro.orig/arch/mips/include/asm/dec/prom.h
+++ linux-macro/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
