[PATCH] powerpc/kernel: Fix L1D_SIZE to a non-zero value on missing cache nodes
From: Madhavan Srinivasan <hidden>
Date: 2018-01-17 19:03:51
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
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 <redacted>
---
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