[U-Boot] [PATCH] ARM: armv7: Add early stack for erratum workarounds

[Andrew F. Davis]

Some erratum workarounds call into C code before the stack
is setup, this can lead to values pushed onto the stack
being lost, firewall exceptions, and other undefined behavior.

Setup a temporary stack to allow these functions to work
correctly.

Signed-off-by: Andrew F. Davis <afd at ti.com>
---
 arch/arm/cpu/armv7/start.S | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
index 81edec01bf..0cb6dd39cc 100644
--- a/arch/arm/cpu/armv7/start.S
+++ b/arch/arm/cpu/armv7/start.S
@@ -205,6 +205,15 @@ ENTRY(cpu_init_cp15)
 	mov	r2, r3, lsl #4		@ shift variant field for combined value
 	orr	r2, r4, r2		@ r2 has combined CPU variant + revision
 
+/* Early stack for ERRATA that needs into call C code */
+#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
+	ldr	r0, =(CONFIG_SPL_STACK)
+#else
+	ldr	r0, =(CONFIG_SYS_INIT_SP_ADDR)
+#endif
+	bic	r0, r0, #7	/* 8-byte alignment for ABI compliance */
+	mov	sp, r0
+
 #ifdef CONFIG_ARM_ERRATA_798870
 	cmp	r2, #0x30		@ Applies to lower than R3p0
 	bge	skip_errata_798870      @ skip if not affected rev
-- 
2.19.1