[PATCH] MIPS: SGI-IP27: Install the cache error vector on every CPU

[Imre Kaloz <kaloz@kernel.org>]

The hub flips the low 128K of the CKSEG1 (attribute 0) uncached alias
per CPU slice, and the cache error vector is fetched through it.
trap_init() writes the vector through TO_UNCAC(), which is not flipped,
so only slice 0 sees it. Copy it to each secondary CPU's slot as it
comes up.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Imre Kaloz <kaloz@kernel.org>
---
 arch/mips/sgi-ip27/ip27-smp.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/mips/sgi-ip27/ip27-smp.c b/arch/mips/sgi-ip27/ip27-smp.c
index 62733e049570..0fef66b86959 100644
--- a/arch/mips/sgi-ip27/ip27-smp.c
+++ b/arch/mips/sgi-ip27/ip27-smp.c
@@ -7,11 +7,13 @@
  * Copyright (C) 2000 - 2001 by Silicon Graphics, Inc.
  */
 #include <linux/init.h>
+#include <linux/string.h>
 #include <linux/sched.h>
 #include <linux/sched/task_stack.h>
 #include <linux/topology.h>
 #include <linux/nodemask.h>
 
+#include <asm/addrspace.h>
 #include <asm/page.h>
 #include <asm/processor.h>
 #include <asm/ptrace.h>
@@ -133,6 +135,18 @@ static void ip27_init_cpu(void)
 	per_cpu_init();
 }
 
+static void ip27_init_secondary(void)
+{
+	/*
+	 * The hub flips the low 128K of the attribute 0 uncached alias per
+	 * CPU slice and the cache error vector is fetched through that alias,
+	 * so the copy trap_init() made through TO_UNCAC() only serves slice 0.
+	 */
+	memcpy((void *)CKSEG1ADDR(0x100), (void *)TO_UNCAC(0x100), 0x80);
+
+	ip27_init_cpu();
+}
+
 static void ip27_smp_finish(void)
 {
 	hub_rt_clock_event_init();
@@ -182,7 +196,7 @@ static void __init ip27_prepare_cpus(unsigned int max_cpus)
 const struct plat_smp_ops ip27_smp_ops = {
 	.send_ipi_single	= ip27_send_ipi_single,
 	.send_ipi_mask		= ip27_send_ipi_mask,
-	.init_secondary		= ip27_init_cpu,
+	.init_secondary		= ip27_init_secondary,
 	.smp_finish		= ip27_smp_finish,
 	.boot_secondary		= ip27_boot_secondary,
 	.smp_setup		= ip27_smp_setup,

base-commit: 24a19b953e2a3d0ea5a8c4951a0ab8f32720c907
-- 
2.47.3