Looks good! An alternative would of course be to add a COP2 kernel config that are selected by some MIPS machines.
/Mikael
________________________________________
Från: Ralf Baechle [ralf@xxxxxxxxxxxxxx]
Skickat: den 24 november 2009 19:17
Till: Mikael Starvik
Kopia: linux-mips@xxxxxxxxxxxxxx; David Daney
Ämne: Re: COP2 unaligned -> SIGBUS
On Mon, Nov 23, 2009 at 11:56:19AM +0000, Ralf Baechle wrote:
>
> > > Since there are now at least two users of cop2 I propose the following:
> >
> > Yes, the comment is not quite correct. CP2 has always been available for
> > application specific extensions and a few imlementations have made use of
> > that. I'll update the comment. Oh and the Praystation has a TLB.
>
> On 2nd thought - there is one user of CU2 in the kernel - the Cavium support.
>
> Nothing else in the stock Linux/MIPS kernel will ever enable c0_status.cu2,
> so the attempt to execute a CP2 load or store instruction would result in a
> Coprocessor Unusable exception which whould result in a SIGILL being
> delivered to the offending process. On Cavium the instructions COP2 is
> documented to not deliver any exceptions so there isn't really anything
> that would need to be changed.
>
> David - I think we should try to get rid of the processor specifics from
> this core code so probably having notifiers to run on Address Error or
> Coprocessor Unusable exceptions would be a solution? I also want to get
> rid of the Cavium #ifdef from traps.c.
So how about this patch below? It uses notifiers as a halfway clean and
reasonably fast hook mechanism. Might be over-engineered though :-)
Compiles but not runtime tested.
Ralf
From: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
MIPS: COP2 cleanups.
Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
diff --git a/arch/mips/cavium-octeon/Makefile b/arch/mips/cavium-octeon/Makefile
index 1394362..3e98763 100644
--- a/arch/mips/cavium-octeon/Makefile
+++ b/arch/mips/cavium-octeon/Makefile
@@ -9,7 +9,7 @@
# Copyright (C) 2005-2009 Cavium Networks
#
-obj-y := setup.o serial.o octeon-platform.o octeon-irq.o csrc-octeon.o
+obj-y := cpu.o setup.o serial.o octeon-platform.o octeon-irq.o csrc-octeon.o
obj-y += dma-octeon.o flash_setup.o
obj-y += octeon-memcpy.o
diff --git a/arch/mips/cavium-octeon/cpu.c b/arch/mips/cavium-octeon/cpu.c
new file mode 100644
index 0000000..b6df538
--- /dev/null
+++ b/arch/mips/cavium-octeon/cpu.c
@@ -0,0 +1,52 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2009 Wind River Systems,
+ * written by Ralf Baechle <ralf@xxxxxxxxxxxxxx>
+ */
+#include <linux/init.h>
+#include <linux/irqflags.h>
+#include <linux/notifier.h>
+#include <linux/prefetch.h>
+#include <linux/sched.h>
+
+#include <asm/cop2.h>
+#include <asm/current.h>
+#include <asm/mipsregs.h>
+#include <asm/page.h>
+#include <asm/octeon/octeon.h>
+
+static int cnmips_cu2_call(struct notifier_block *nfb, unsigned long action,
+ void *data)
+{
+ unsigned long flags;
+ unsigned int status;
+
+ switch (action) {
+ case CU2_EXCEPTION:
+ prefetch(¤t->thread.cp2);
+ local_irq_save(flags);
+ KSTK_STATUS(current) |= ST0_CU2;
+ status = read_c0_status();
+ write_c0_status(status | ST0_CU2);
+ octeon_cop2_restore(&(current->thread.cp2));
+ write_c0_status(status & ~ST0_CU2);
+ local_irq_restore(flags);
+
+ return NOTIFY_BAD; /* Don't call default notifier */
+ }
+
+ return NOTIFY_OK; /* Let default notifier send signals */
+}
+
+static struct notifier_block cnmips_cu2_notifier = {
+ .notifier_call = cnmips_cu2_call,
+};
+
+static int cnmips_cu2_setup(void)
+{
+ return register_cu2_notifier(&cnmips_cu2_notifier);
+}
+early_initcall(cnmips_cu2_setup);
diff --git a/arch/mips/include/asm/cop2.h b/arch/mips/include/asm/cop2.h
new file mode 100644
index 0000000..6b04c98
--- /dev/null
+++ b/arch/mips/include/asm/cop2.h
@@ -0,0 +1,23 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2009 Wind River Systems,
+ * written by Ralf Baechle <ralf@xxxxxxxxxxxxxx>
+ */
+#ifndef __ASM_COP2_H
+#define __ASM_COP2_H
+
+enum cu2_ops {
+ CU2_EXCEPTION,
+ CU2_LWC2_OP,
+ CU2_LDC2_OP,
+ CU2_SWC2_OP,
+ CU2_SDC2_OP,
+};
+
+extern int register_cu2_notifier(struct notifier_block *nb);
+extern int cu2_notifier_call_chain(unsigned long val, void *v);
+
+#endif /* __ASM_COP2_H */
diff --git a/arch/mips/include/asm/octeon/octeon.h b/arch/mips/include/asm/octeon/octeon.h
index cac9b1a..4d0a8c6 100644
--- a/arch/mips/include/asm/octeon/octeon.h
+++ b/arch/mips/include/asm/octeon/octeon.h
@@ -47,6 +47,7 @@ struct octeon_cop2_state;
extern unsigned long octeon_crypto_enable(struct octeon_cop2_state *state);
extern void octeon_crypto_disable(struct octeon_cop2_state *state,
unsigned long flags);
+extern asmlinkage void octeon_cop2_restore(struct octeon_cop2_state *task);
extern void octeon_init_cvmcount(void);
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 0a18b4c..2c5c3a2 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -25,10 +25,12 @@
#include <linux/ptrace.h>
#include <linux/kgdb.h>
#include <linux/kdebug.h>
+#include <linux/notifier.h>
#include <asm/bootinfo.h>
#include <asm/branch.h>
#include <asm/break.h>
+#include <asm/cop2.h>
#include <asm/cpu.h>
#include <asm/dsp.h>
#include <asm/fpu.h>
@@ -79,10 +81,6 @@ extern asmlinkage void handle_reserved(void);
extern int fpu_emulator_cop1Handler(struct pt_regs *xcp,
struct mips_fpu_struct *ctx, int has_fpu);
-#ifdef CONFIG_CPU_CAVIUM_OCTEON
-extern asmlinkage void octeon_cop2_restore(struct octeon_cop2_state *task);
-#endif
-
void (*board_be_init)(void);
int (*board_be_handler)(struct pt_regs *regs, int is_fixup);
void (*board_nmi_handler_setup)(void);
@@ -857,6 +855,44 @@ static void mt_ase_fp_affinity(void)
#endif /* CONFIG_MIPS_MT_FPAFF */
}
+/*
+ * No lock; only written during early bootup by CPU 0.
+ */
+static RAW_NOTIFIER_HEAD(cu2_chain);
+
+int __ref register_cu2_notifier(struct notifier_block *nb)
+{
+ return raw_notifier_chain_register(&cu2_chain, nb);
+}
+
+int cu2_notifier_call_chain(unsigned long val, void *v)
+{
+ return raw_notifier_call_chain(&cu2_chain, val, v);
+}
+
+static int default_cu2_call(struct notifier_block *nfb, unsigned long action,
+ void *data)
+{
+ struct pt_regs *regs = data;
+
+ switch (action) {
+ default:
+ die_if_kernel("Unhandled kernel unaligned access or invalid "
+ "instruction", regs);
+ /* Fall through */
+
+ case CU2_EXCEPTION:
+ force_sig(SIGILL, current);
+ }
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block default_cu2_notifier = {
+ .notifier_call = default_cu2_call,
+ .priority = 0x80000000, /* Run last */
+};
+
asmlinkage void do_cpu(struct pt_regs *regs)
{
unsigned int __user *epc;
@@ -920,17 +956,9 @@ asmlinkage void do_cpu(struct pt_regs *regs)
return;
case 2:
-#ifdef CONFIG_CPU_CAVIUM_OCTEON
- prefetch(¤t->thread.cp2);
- local_irq_save(flags);
- KSTK_STATUS(current) |= ST0_CU2;
- status = read_c0_status();
- write_c0_status(status | ST0_CU2);
- octeon_cop2_restore(&(current->thread.cp2));
- write_c0_status(status & ~ST0_CU2);
- local_irq_restore(flags);
- return;
-#endif
+ raw_notifier_call_chain(&cu2_chain, CU2_EXCEPTION, regs);
+ break;
+
case 3:
break;
}
@@ -1760,4 +1788,6 @@ void __init trap_init(void)
flush_tlb_handlers();
sort_extable(__start___dbe_table, __stop___dbe_table);
+
+ register_cu2_notifier(&default_cu2_notifier);
}
diff --git a/arch/mips/kernel/unaligned.c b/arch/mips/kernel/unaligned.c
index 67bd626..69b039c 100644
--- a/arch/mips/kernel/unaligned.c
+++ b/arch/mips/kernel/unaligned.c
@@ -81,6 +81,7 @@
#include <asm/asm.h>
#include <asm/branch.h>
#include <asm/byteorder.h>
+#include <asm/cop2.h>
#include <asm/inst.h>
#include <asm/uaccess.h>
#include <asm/system.h>
@@ -451,17 +452,27 @@ static void emulate_load_store_insn(struct pt_regs *regs,
*/
goto sigbus;
+ /*
+ * COP2 is available to implementor for application specific use.
+ * It's up to applications to register a notifier chain and do
+ * whatever they have to do, including possible sending of signals.
+ */
case lwc2_op:
+ cu2_notifier_call_chain(CU2_LWC2_OP, regs);
+ break;
+
case ldc2_op:
+ cu2_notifier_call_chain(CU2_LDC2_OP, regs);
+ break;
+
case swc2_op:
+ cu2_notifier_call_chain(CU2_SWC2_OP, regs);
+ break;
+
case sdc2_op:
- /*
- * These are the coprocessor 2 load/stores. The current
- * implementations don't use cp2 and cp2 should always be
- * disabled in c0_status. So send SIGILL.
- * (No longer true: The Sony Praystation uses cp2 for
- * 3D matrix operations. Dunno if that thingy has a MMU ...)
- */
+ cu2_notifier_call_chain(CU2_SDC2_OP, regs);
+ break;
+
default:
/*
* Pheeee... We encountered an yet unknown instruction or
