Introduce unified API to zero memory
Introduce zeromem_dczva function on AArch64 that can handle unaligned
addresses and make use of DC ZVA instruction to zero a whole block at a
time. This zeroing takes place directly in the cache to speed it up
without doing external memory access.
Remove the zeromem16 function on AArch64 and replace it with an alias to
zeromem. This zeromem16 function is now deprecated.
Remove the 16-bytes alignment constraint on __BSS_START__ in
firmware-design.md as it is now not mandatory anymore (it used to comply
with zeromem16 requirements).
Change the 16-bytes alignment constraints in SP min's linker script to a
8-bytes alignment constraint as the AArch32 zeromem implementation is now
more efficient on 8-bytes aligned addresses.
Introduce zero_normalmem and zeromem helpers in platform agnostic header
that are implemented this way:
* AArch32:
* zero_normalmem: zero using usual data access
* zeromem: alias for zero_normalmem
* AArch64:
* zero_normalmem: zero normal memory using DC ZVA instruction
(needs MMU enabled)
* zeromem: zero using usual data access
Usage guidelines: in most cases, zero_normalmem should be preferred.
There are 2 scenarios where zeromem (or memset) must be used instead:
* Code that must run with MMU disabled (which means all memory is
considered device memory for data accesses).
* Code that fills device memory with null bytes.
Optionally, the following rule can be applied if performance is
important:
* Code zeroing small areas (few bytes) that are not secrets should use
memset to take advantage of compiler optimizations.
Note: Code zeroing security-related critical information should use
zero_normalmem/zeromem instead of memset to avoid removal by
compilers' optimizations in some cases or misbehaving versions of GCC.
Fixes ARM-software/tf-issues#408
Change-Id: Iafd9663fc1070413c3e1904e54091cf60effaa82
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
diff --git a/plat/nvidia/tegra/common/drivers/memctrl/memctrl.c b/plat/nvidia/tegra/common/drivers/memctrl/memctrl.c
index 40d1bab..689f2d7 100644
--- a/plat/nvidia/tegra/common/drivers/memctrl/memctrl.c
+++ b/plat/nvidia/tegra/common/drivers/memctrl/memctrl.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
@@ -37,8 +37,6 @@
#include <tegra_def.h>
#include <xlat_tables.h>
-extern void zeromem16(void *mem, unsigned int length);
-
#define TEGRA_GPU_RESET_REG_OFFSET 0x28c
#define GPU_RESET_BIT (1 << 24)
@@ -114,13 +112,13 @@
* Perform cache maintenance to ensure that the non-overlapping area is
* zeroed out. The first invalidation of this range ensures that
* possible evictions of dirty cache lines do not interfere with the
- * 'zeromem16' operation. Other CPUs could speculatively prefetch the
+ * 'zeromem' operation. Other CPUs could speculatively prefetch the
* main memory contents of this area between the first invalidation and
- * the 'zeromem16' operation. The second invalidation ensures that any
+ * the 'zeromem' operation. The second invalidation ensures that any
* such cache lines are removed as well.
*/
inv_dcache_range(non_overlap_area_start, non_overlap_area_size);
- zeromem16((void *)non_overlap_area_start, non_overlap_area_size);
+ zeromem((void *)non_overlap_area_start, non_overlap_area_size);
inv_dcache_range(non_overlap_area_start, non_overlap_area_size);
}