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authorPaul Burton <paul.burton@imgtec.com>2015-09-25 08:59:38 -0700
committerRalf Baechle <ralf@linux-mips.org>2015-09-27 14:15:26 +0200
commite060f6ed281669b6d2f22d8dafd664b532386918 (patch)
treefa74247359834941661b76a318ca6ad790b01041
parent651ca7f4dab77f07fdac9cfb68bcab6bd2b7f827 (diff)
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MIPS: Initialise MAARs on secondary CPUs
MAARs should be initialised on each CPU (or rather, core) in the system in order to achieve consistent behaviour & performance. Previously they have only been initialised on the boot CPU which leads to performance problems if tasks are later scheduled on a secondary CPU, particularly if those tasks make use of unaligned vector accesses where some CPUs don't handle any cases in hardware for non-speculative memory regions. Fix this by recording the MAAR configuration from the boot CPU and applying it to secondary CPUs as part of their bringup. Reported-by: Doug Gilmore <doug.gilmore@imgtec.com> Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Steven J. Hill <Steven.Hill@imgtec.com> Cc: Andrew Bresticker <abrestic@chromium.org> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: David Hildenbrand <dahi@linux.vnet.ibm.com> Cc: linux-kernel@vger.kernel.org Cc: Aaro Koskinen <aaro.koskinen@iki.fi> Cc: James Hogan <james.hogan@imgtec.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Markos Chandras <markos.chandras@imgtec.com> Cc: Hemmo Nieminen <hemmo.nieminen@iki.fi> Cc: Alex Smith <alex.smith@imgtec.com> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Patchwork: https://patchwork.linux-mips.org/patch/11239/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
-rw-r--r--arch/mips/include/asm/maar.h9
-rw-r--r--arch/mips/kernel/smp.c2
-rw-r--r--arch/mips/mm/init.c28
3 files changed, 36 insertions, 3 deletions
diff --git a/arch/mips/include/asm/maar.h b/arch/mips/include/asm/maar.h
index b02891f9caaf..21d9607c80d7 100644
--- a/arch/mips/include/asm/maar.h
+++ b/arch/mips/include/asm/maar.h
@@ -66,6 +66,15 @@ static inline void write_maar_pair(unsigned idx, phys_addr_t lower,
}
/**
+ * maar_init() - initialise MAARs
+ *
+ * Performs initialisation of MAARs for the current CPU, making use of the
+ * platforms implementation of platform_maar_init where necessary and
+ * duplicating the setup it provides on secondary CPUs.
+ */
+extern void maar_init(void);
+
+/**
* struct maar_config - MAAR configuration data
* @lower: The lowest address that the MAAR pair will affect. Must be
* aligned to a 2^16 byte boundary.
diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index a31896c33716..bd4385a8e6e8 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -42,6 +42,7 @@
#include <asm/mmu_context.h>
#include <asm/time.h>
#include <asm/setup.h>
+#include <asm/maar.h>
cpumask_t cpu_callin_map; /* Bitmask of started secondaries */
@@ -157,6 +158,7 @@ asmlinkage void start_secondary(void)
mips_clockevent_init();
mp_ops->init_secondary();
cpu_report();
+ maar_init();
/*
* XXX parity protection should be folded in here when it's converted
diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 023c164b9eb6..8770e619185e 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -44,6 +44,7 @@
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/fixmap.h>
+#include <asm/maar.h>
/*
* We have up to 8 empty zeroed pages so we can map one of the right colour
@@ -288,10 +289,14 @@ unsigned __weak platform_maar_init(unsigned num_pairs)
return num_configured;
}
-static void maar_init(void)
+void maar_init(void)
{
unsigned num_maars, used, i;
phys_addr_t lower, upper, attr;
+ static struct {
+ struct maar_config cfgs[3];
+ unsigned used;
+ } recorded = { { { 0 } }, 0 };
if (!cpu_has_maar)
return;
@@ -304,8 +309,14 @@ static void maar_init(void)
/* MAARs should be in pairs */
WARN_ON(num_maars % 2);
- /* Configure the required MAARs */
- used = platform_maar_init(num_maars / 2);
+ /* Set MAARs using values we recorded already */
+ if (recorded.used) {
+ used = maar_config(recorded.cfgs, recorded.used, num_maars / 2);
+ BUG_ON(used != recorded.used);
+ } else {
+ /* Configure the required MAARs */
+ used = platform_maar_init(num_maars / 2);
+ }
/* Disable any further MAARs */
for (i = (used * 2); i < num_maars; i++) {
@@ -315,6 +326,9 @@ static void maar_init(void)
back_to_back_c0_hazard();
}
+ if (recorded.used)
+ return;
+
pr_info("MAAR configuration:\n");
for (i = 0; i < num_maars; i += 2) {
write_c0_maari(i);
@@ -341,6 +355,14 @@ static void maar_init(void)
pr_cont(" speculate");
pr_cont("\n");
+
+ /* Record the setup for use on secondary CPUs */
+ if (used <= ARRAY_SIZE(recorded.cfgs)) {
+ recorded.cfgs[recorded.used].lower = lower;
+ recorded.cfgs[recorded.used].upper = upper;
+ recorded.cfgs[recorded.used].attrs = attr;
+ recorded.used++;
+ }
}
}