Merge branch '2021-06-07-arm-cache-cp15-improvements' into next

To quote the series author, Patrick Delaunay:

On STM32MP15x platform we can use OP-TEE, loaded in DDR in a region
protected by a firewall. This region is reserved in the device with
the "no-map" property as defined in the binding file
doc/device-tree-bindings/reserved-memory/reserved-memory.txt.

Sometime the platform boot failed in U-Boot on a Cortex A7 access to
this region (depending of the binary and the issue can change with compiler
version or with code alignment), then the firewall raise an error,
for example:

E/TC:0   tzc_it_handler:19 TZC permission failure
E/TC:0   dump_fail_filter:420 Permission violation on filter 0
E/TC:0   dump_fail_filter:425 Violation @0xde5c6bf0, non-secure privileged read,
         AXI ID 5c0
E/TC:0   Panic

After investigation, the forbidden access is a speculative request performed
by the Cortex A7 because all the DDR is mapped as MEMORY with CACHEABLE
property.

The issue is solved only when the region reserved by OP-TEE is no more
mapped in U-Boot as it is already done in Linux kernel.

Tested on DK2 board with OP-TEE 3.12 / TF-A 2.4:

With hard-coded address for OP-TEE reserved memory,
the error doesn't occur.

 void dram_bank_mmu_setup(int bank)
 {
 ....

    	for (i = start >> MMU_SECTION_SHIFT;
 	     i < (start >> MMU_SECTION_SHIFT) + (size >> MMU_SECTION_SHIFT);
 	     i++) {
 		option = DCACHE_DEFAULT_OPTION;
 		if (i >= 0xde0)
 			option = INVALID_ENTRY;
 		set_section_dcache(i, option);
 	}
 }

Just by modifying the test on 0xde0 to 0xdf0, the OP-TEE memory protected
by firewall is mapped cacheable and the error occurs.

I think that it can be a general issue for ARM architecture: the "no-map" tag
of reserved memory in device should be respected by U-Boot if firewall
is configured before U-Boot execution.

But I don't propose a generic solution in
arm/lib/cache-cp15.c:dram_bank_mmu_setup()
because the device tree parsing done in lmb_init_and_reserve() takes a
long time when it is executed without data cache.

1 files changed, 38 insertions, 0 deletions

diff --git a/include/lmb.h b/include/lmb.h
index 541e17093c6..3c4afdf9f06 100644
--- a/include/lmb.h
+++ b/include/lmb.h
@@ -13,6 +13,16 @@
  */
 
 /**
+ * enum lmb_flags - definition of memory region attributes
+ * @LMB_NONE: no special request
+ * @LMB_NOMAP: don't add to mmu configuration
+ */
+enum lmb_flags {
+	LMB_NONE		= 0x0,
+	LMB_NOMAP		= 0x4,
+};
+
+/**
  * struct lmb_property - Description of one region.
  *
  * @base: Base address of the region.
@@ -21,6 +31,7 @@
 struct lmb_property {
 	phys_addr_t base;
 	phys_size_t size;
+	enum lmb_flags flags;
 };
 
 /**
@@ -69,6 +80,17 @@ extern void lmb_init_and_reserve_range(struct lmb *lmb, phys_addr_t base,
 				       phys_size_t size, void *fdt_blob);
 extern long lmb_add(struct lmb *lmb, phys_addr_t base, phys_size_t size);
 extern long lmb_reserve(struct lmb *lmb, phys_addr_t base, phys_size_t size);
+/**
+ * lmb_reserve_flags - Reserve one region with a specific flags bitfield.
+ *
+ * @lmb		the logical memory block struct
+ * @base	base address of the memory region
+ * @size	size of the memory region
+ * @flags	flags for the memory region
+ * @return 0 if OK, > 0 for coalesced region or a negative error code.
+ */
+long lmb_reserve_flags(struct lmb *lmb, phys_addr_t base,
+		       phys_size_t size, enum lmb_flags flags);
 extern phys_addr_t lmb_alloc(struct lmb *lmb, phys_size_t size, ulong align);
 extern phys_addr_t lmb_alloc_base(struct lmb *lmb, phys_size_t size, ulong align,
 			    phys_addr_t max_addr);
@@ -78,6 +100,15 @@ extern phys_addr_t lmb_alloc_addr(struct lmb *lmb, phys_addr_t base,
 				  phys_size_t size);
 extern phys_size_t lmb_get_free_size(struct lmb *lmb, phys_addr_t addr);
 extern int lmb_is_reserved(struct lmb *lmb, phys_addr_t addr);
+/**
+ * lmb_is_reserved_flags - test if tha address is in reserved region with a bitfield flag
+ *
+ * @lmb		the logical memory block struct
+ * @addr	address to be tested
+ * @flags	flags bitfied to be tested
+ * @return 0 if not reserved or reserved without the requested flag else 1
+ */
+int lmb_is_reserved_flags(struct lmb *lmb, phys_addr_t addr, int flags);
 extern long lmb_free(struct lmb *lmb, phys_addr_t base, phys_size_t size);
 
 extern void lmb_dump_all(struct lmb *lmb);
@@ -92,6 +123,13 @@ lmb_size_bytes(struct lmb_region *type, unsigned long region_nr)
 void board_lmb_reserve(struct lmb *lmb);
 void arch_lmb_reserve(struct lmb *lmb);
 
+/* Low level functions */
+
+static inline bool lmb_is_nomap(struct lmb_property *m)
+{
+	return m->flags & LMB_NOMAP;
+}
+
 #endif /* __KERNEL__ */
 
 #endif /* _LINUX_LMB_H */