parse_cache_info() parse device tree to detect various [i/d] cache properties.
But if no cache nodes found in device tree, these properties are set to zero
as default in init_cache_info().
Having a zero value could cause a infinite loop in rfi_flush_callback() since
l1d_size is used to determine the lid_flush_set parameter which is used as
the upper bounce in L1D cache flush loop. So default the l1d_size to 64K if
it is zero.
Fixes: aa8a5e0062ac9 ('powerpc/64s: Add support for RFI flush of L1-D cache')
Signed-off-by: Madhavan Srinivasan <ma...@linux.vnet.ibm.com>
---
arch/powerpc/include/asm/setup.h | 2 ++
arch/powerpc/kernel/setup_64.c | 16 ++++++++++++++++
2 files changed, 18 insertions(+)
diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h
index 469b7fdc9be4..12954bf2d3fe 100644
--- a/arch/powerpc/include/asm/setup.h
+++ b/arch/powerpc/include/asm/setup.h
@@ -41,6 +41,8 @@ static inline void pseries_little_endian_exceptions(void) {}
void rfi_flush_enable(bool enable);
+#define DEFAULT_L1D_SIZE (1024 * 64)
+
/* These are bit flags */
enum l1d_flush_type {
L1D_FLUSH_NONE = 0x1,
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 491be4179ddd..7a3077a2cd5c 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -856,6 +856,22 @@ static void init_fallback_flush(void)
int cpu;
l1d_size = ppc64_caches.l1d.size;
+
+ /*
+ * If there is no cache node in cpus/ device tree,
+ * l1d_size could be zero. This in turn make l1d_flush_sets as
+ * zero, which will be an issue in RFI_FLUSH_CALLBACK.
+ *
+ * RFI_FLUSH_CALLBACK use the l1d_flush_sets value as upper bounce
+ * (loaded in CTR) and loop with a `bdnz` instruction. If the CTR
+ * happen to zero, instruction (as per definition) will decrement
+ * CTR first and then compare. So we end up in a really big
+ * loop (becos of negative value in CTR). Avoid this by defaulting
+ * to a sane value (64kb).
+ */
+ if (!l1d_size)
+ l1d_size = DEFAULT_L1D_SIZE;
+
limit = min(safe_stack_limit(), ppc64_rma_size);
/*
--
2.7.4
