Report errata workaround status to console

The errata reporting policy is as follows:

  - If an errata workaround is enabled:

    - If it applies (i.e. the CPU is affected by the errata), an INFO
      message is printed, confirming that the errata workaround has been
      applied.

    - If it does not apply, a VERBOSE message is printed, confirming
      that the errata workaround has been skipped.

  - If an errata workaround is not enabled, but would have applied had
    it been, a WARN message is printed, alerting that errata workaround
    is missing.

The CPU errata messages are printed by both BL1 (primary CPU only) and
runtime firmware on debug builds, once for each CPU/errata combination.

Relevant output from Juno r1 console when ARM Trusted Firmware is built
with PLAT=juno LOG_LEVEL=50 DEBUG=1:

  VERBOSE: BL1: cortex_a57: errata workaround for 806969 was not applied
  VERBOSE: BL1: cortex_a57: errata workaround for 813420 was not applied
  INFO:    BL1: cortex_a57: errata workaround for disable_ldnp_overread was applied
  WARNING: BL1: cortex_a57: errata workaround for 826974 was missing!
  WARNING: BL1: cortex_a57: errata workaround for 826977 was missing!
  WARNING: BL1: cortex_a57: errata workaround for 828024 was missing!
  WARNING: BL1: cortex_a57: errata workaround for 829520 was missing!
  WARNING: BL1: cortex_a57: errata workaround for 833471 was missing!
  ...
  VERBOSE: BL31: cortex_a57: errata workaround for 806969 was not applied
  VERBOSE: BL31: cortex_a57: errata workaround for 813420 was not applied
  INFO:    BL31: cortex_a57: errata workaround for disable_ldnp_overread was applied
  WARNING: BL31: cortex_a57: errata workaround for 826974 was missing!
  WARNING: BL31: cortex_a57: errata workaround for 826977 was missing!
  WARNING: BL31: cortex_a57: errata workaround for 828024 was missing!
  WARNING: BL31: cortex_a57: errata workaround for 829520 was missing!
  WARNING: BL31: cortex_a57: errata workaround for 833471 was missing!
  ...
  VERBOSE: BL31: cortex_a53: errata workaround for 826319 was not applied
  INFO:    BL31: cortex_a53: errata workaround for disable_non_temporal_hint was applied

Also update documentation.

Change-Id: Iccf059d3348adb876ca121cdf5207bdbbacf2aba
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

1 files changed, 84 insertions, 1 deletions

diff --git a/lib/cpus/aarch32/cpu_helpers.S b/lib/cpus/aarch32/cpu_helpers.S
index d8cabfe5..c41978ed 100644
--- a/lib/cpus/aarch32/cpu_helpers.S
+++ b/lib/cpus/aarch32/cpu_helpers.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2017, 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:
@@ -172,3 +172,86 @@ func get_cpu_ops_ptr
 error_exit:
 	bx	lr
 endfunc get_cpu_ops_ptr
+
+/*
+ * Extract CPU revision and variant, and combine them into a single numeric for
+ * easier comparison.
+ */
+	.globl	cpu_get_rev_var
+func cpu_get_rev_var
+	ldcopr	r1, MIDR
+
+	/*
+	 * Extract the variant[23:20] and revision[3:0] from r1 and pack it in
+	 * r0[0:7] as variant[7:4] and revision[3:0]:
+	 *
+	 * First extract r1[23:16] to r0[7:0] and zero fill the rest. Then
+	 * extract r1[3:0] into r0[3:0] retaining other bits.
+	 */
+	ubfx	r0, r1, #(MIDR_VAR_SHIFT - MIDR_REV_BITS), #(MIDR_REV_BITS + MIDR_VAR_BITS)
+	bfi	r0, r1, #MIDR_REV_SHIFT, #MIDR_REV_BITS
+	bx	lr
+endfunc cpu_get_rev_var
+
+/*
+ * Compare the CPU's revision-variant (r0) with a given value (r1), for errata
+ * application purposes. If the revision-variant is less than or same as a given
+ * value, indicates that errata applies; otherwise not.
+ */
+	.globl	cpu_rev_var_ls
+func cpu_rev_var_ls
+	cmp	r0, r1
+	movls	r0, #ERRATA_APPLIES
+	movhi	r0, #ERRATA_NOT_APPLIES
+	bx	lr
+endfunc cpu_rev_var_ls
+
+#if REPORT_ERRATA
+/*
+ * void print_errata_status(void);
+ *
+ * Function to print errata status for CPUs of its class. Must be called only:
+ *
+ *   - with MMU and data caches are enabled;
+ *   - after cpu_ops have been initialized in per-CPU data.
+ */
+	.globl print_errata_status
+func print_errata_status
+	push	{r4, lr}
+#ifdef IMAGE_BL1
+	/*
+	 * BL1 doesn't have per-CPU data. So retrieve the CPU operations
+	 * directly.
+	 */
+	bl	get_cpu_ops_ptr
+	ldr	r0, [r0, #CPU_ERRATA_FUNC]
+	cmp	r0, #0
+	blxne	r0
+#else
+	/*
+	 * Retrieve pointer to cpu_ops, and further, the errata printing
+	 * function. If it's non-NULL, jump to the function in turn.
+	 */
+	bl	_cpu_data
+	ldr	r1, [r0, #CPU_DATA_CPU_OPS_PTR]
+	ldr	r0, [r1, #CPU_ERRATA_FUNC]
+	cmp	r0, #0
+	beq	1f
+
+	mov	r4, r0
+
+	/*
+	 * Load pointers to errata lock and printed flag. Call
+	 * errata_needs_reporting to check whether this CPU needs to report
+	 * errata status pertaining to its class.
+	 */
+	ldr	r0, [r1, #CPU_ERRATA_LOCK]
+	ldr	r1, [r1, #CPU_ERRATA_PRINTED]
+	bl	errata_needs_reporting
+	cmp	r0, #0
+	blxne	r4
+1:
+#endif
+	pop	{r4, pc}
+endfunc print_errata_status
+#endif