Disable non-temporal hint on Cortex-A53/57
The LDNP/STNP instructions as implemented on Cortex-A53 and
Cortex-A57 do not behave in a way most programmers expect, and will
most probably result in a significant speed degradation to any code
that employs them. The ARMv8-A architecture (see Document ARM DDI
0487A.h, section D3.4.3) allows cores to ignore the non-temporal hint
and treat LDNP/STNP as LDP/STP instead.
This patch introduces 2 new build flags:
A53_DISABLE_NON_TEMPORAL_HINT and A57_DISABLE_NON_TEMPORAL_HINT
to enforce this behaviour on Cortex-A53 and Cortex-A57. They are
enabled by default.
The string printed in debug builds when a specific CPU errata
workaround is compiled in but skipped at runtime has been
generalised, so that it can be reused for the non-temporal hint use
case as well.
Change-Id: I3e354f4797fd5d3959872a678e160322b13867a1
diff --git a/lib/cpus/aarch64/cpu_helpers.S b/lib/cpus/aarch64/cpu_helpers.S
index e8a1392..e41d95b 100644
--- a/lib/cpus/aarch64/cpu_helpers.S
+++ b/lib/cpus/aarch64/cpu_helpers.S
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2014, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2014-2016, 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:
@@ -205,16 +205,17 @@
endfunc get_cpu_ops_ptr
#if DEBUG
- /*
- * This function prints a warning message to the crash console
- * if the CPU revision/part number does not match the errata
- * workaround enabled in the build.
- * Clobber: x30, x0 - x5
- */
.section .rodata.rev_warn_str, "aS"
rev_warn_str:
- .asciz "Warning: Skipping Errata workaround for non matching CPU revision number.\n"
+ .asciz "Warning: Skipping CPU specific reset operation for non-matching CPU revision number.\n"
+ /*
+ * This function prints the above warning message to the crash console.
+ * It should be called when a CPU specific operation is enabled in the
+ * build but doesn't apply to this CPU revision/part number.
+ *
+ * Clobber: x30, x0 - x5
+ */
.globl print_revision_warning
func print_revision_warning
mov x5, x30