zynq: k4.19: fix kernel panic on smp bring-up

This fixes a kernel panic when validating the
arguments of memcpy at runtime, which is enabled
by generic's CONFIG_FORTIFY_SOURCE for k4.19

This wasn't triggered on 4.14, as ARCH_HAS_FORTIFY_SOURCE
was added on k4.17 for the ARM architecture

Signed-off-by: Luis Araneda <luaraneda@gmail.com>

target/linux/zynq/patches-4.19/110-ARM-zynq-Use-memcpy_toio-instead-of-memcpy.patch

@@ -0,0 +1,35 @@
+From a801d4aa6000f7ba0ffc5ba9d841af62ec7e0bb1 Mon Sep 17 00:00:00 2001
+From: Luis Araneda <luaraneda@gmail.com>
+Date: Tue, 30 Jul 2019 00:29:03 -0400
+Subject: [RFC PATCH] ARM: zynq: Use memcpy_toio instead of memcpy on smp bring-up
+
+This fixes a kernel panic (read overflow) on memcpy when
+FORTIFY_SOURCE is enabled.
+
+The computed size of memcpy args are:
+- p_size (dst): 4294967295 = (size_t) -1
+- q_size (src): 1
+- size (len): 8
+
+Additionally, the memory is marked as __iomem, so one of
+the memcpy_* functions should be used for read/write
+
+Signed-off-by: Luis Araneda <luaraneda@gmail.com>
+---
+As of 2019-08-03, this patch is under review and waiting
+comments from the maintainer / author
+--
+ arch/arm/mach-zynq/platsmp.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/arch/arm/mach-zynq/platsmp.c
++++ b/arch/arm/mach-zynq/platsmp.c
+@@ -65,7 +65,7 @@ int zynq_cpun_start(u32 address, int cpu
+ 			* 0x4: Jump by mov instruction
+ 			* 0x8: Jumping address
+ 			*/
+-			memcpy((__force void *)zero, &zynq_secondary_trampoline,
++			memcpy_toio(zero, &zynq_secondary_trampoline,
+ 							trampoline_size);
+ 			writel(address, zero + trampoline_size);
+