[PATCH 0/2] metag: cache aliasing detection fixes

[PATCH 0/2] metag: cache aliasing detection fixes

[James Hogan]

A couple of metag cache aliasing detection fixes I intend on applying
for v3.11.

James Hogan (2):
  metag: panic if cache aliasing possible
  metag: don't check for cache aliasing on smp cpu boot

 arch/metag/kernel/cachepart.c | 13 +++++++------
 arch/metag/kernel/smp.c       |  6 ------
 2 files changed, 7 insertions(+), 12 deletions(-)

-- 
1.8.1.2

[PATCH 1/2] metag: panic if cache aliasing possible

[James Hogan]

If the cache and page size configuration allows for cache aliasing to
occur we warn on boot, but the log messages are easy to miss and will
result is random crashes occuring in userland. Let's panic too in this
case so that the user immediately knows they need to fix the cache
configuration or configured page size.

Also fix the warning messages which display the cache and page sizes to
include newlines, and add the word "Potential" since an actual cache
alias hasn't been detected.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
---
 arch/metag/kernel/cachepart.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/metag/kernel/cachepart.c b/arch/metag/kernel/cachepart.c
index 954548b..0a2385f 100644
--- a/arch/metag/kernel/cachepart.c
+++ b/arch/metag/kernel/cachepart.c
@@ -100,22 +100,23 @@ void check_for_cache_aliasing(int thread_id)
 		thread_cache_size =
 				get_thread_cache_size(cache_type, thread_id);
 		if (thread_cache_size < 0)
-			pr_emerg("Can't read %s cache size", \
+			pr_emerg("Can't read %s cache size\n",
 				 cache_type ? "DCACHE" : "ICACHE");
 		else if (thread_cache_size == 0)
 			/* Cache is off. No need to check for aliasing */
 			continue;
 		if (thread_cache_size / CACHE_ASSOCIATIVITY > PAGE_SIZE) {
-			pr_emerg("Cache aliasing detected in %s on Thread %d",
+			pr_emerg("Potential cache aliasing detected in %s on Thread %d\n",
 				 cache_type ? "DCACHE" : "ICACHE", thread_id);
-			pr_warn("Total %s size: %u bytes",
-				cache_type ? "DCACHE" : "ICACHE ",
+			pr_warn("Total %s size: %u bytes\n",
+				cache_type ? "DCACHE" : "ICACHE",
 				cache_type ? get_dcache_size()
 				: get_icache_size());
-			pr_warn("Thread %s size: %d bytes",
+			pr_warn("Thread %s size: %d bytes\n",
 				cache_type ? "CACHE" : "ICACHE",
 				thread_cache_size);
-			pr_warn("Page Size: %lu bytes", PAGE_SIZE);
+			pr_warn("Page Size: %lu bytes\n", PAGE_SIZE);
+			panic("Potential cache aliasing detected");
 		}
 	}
 }
-- 
1.8.1.2

[PATCH 2/2] metag: don't check for cache aliasing on smp cpu boot

[James Hogan]

The cache configuration of the boot cpu is now duplicated to secondary
cpus, so there's no need to check for cache aliasing again when a
secondary cpu is booted. Therefore remove the check from
secondary_start_kernel().

Signed-off-by: James Hogan <james.hogan@imgtec.com>
---
 arch/metag/kernel/smp.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/metag/kernel/smp.c b/arch/metag/kernel/smp.c
index f443ec9..86fdda4 100644
--- a/arch/metag/kernel/smp.c
+++ b/arch/metag/kernel/smp.c
@@ -404,12 +404,6 @@ asmlinkage void secondary_start_kernel(void)
 	set_cpu_online(cpu, true);
 
 	/*
-	 * Check for cache aliasing.
-	 * Preemption is disabled
-	 */
-	check_for_cache_aliasing(cpu);
-
-	/*
 	 * OK, it's off to the idle thread for us
 	 */
 	cpu_startup_entry(CPUHP_ONLINE);
-- 
1.8.1.2