[U-Boot] [PATCH 2/2] arm: Fix _start for CONFIG_SYS_DV_NOR_BOOT_CFG

[Benoît Thébaudeau]

The boards using CONFIG_SYS_DV_NOR_BOOT_CFG (i.e. calimain,
da850evm_direct_nor and enbw_cmc) had the _start symbol defined after
the CONFIG_SYS_DV_NOR_BOOT_CFG word rather than before it in
arch/arm/lib/vectors.S. Because of that, if by lack of luck
'gd->mon_len = (ulong)&__bss_end - (ulong)_start' (see setup_mon_len())
was a multiple of 4 kiB (see reserve_uboot()), then the last BSS word
overlapped the first word of the following reserved RAM area (or went
beyond the top of RAM without such an area) after relocation because
__image_copy_start did not match _start (see relocate_code()).

This was broken by commit 41623c9 'arm: move exception handling out of
start.S files', which defined _start twice (before and after the
CONFIG_SYS_DV_NOR_BOOT_CFG word), then by commit 0a26e1d 'arm: fix a
double-definition error of _start symbol', which kept the definition of
the _start symbol after the CONFIG_SYS_DV_NOR_BOOT_CFG word. This new
commit fixes this issue by restoring the original behavior, i.e. by
defining the _start symbol before the CONFIG_SYS_DV_NOR_BOOT_CFG word.

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau.dev at gmail.com>
Cc: Albert Aribaud <albert.u.boot at aribaud.net>
Cc: Manfred Rudigier <manfred.rudigier at omicron.at>
Cc: Christian Riesch <christian.riesch at omicron.at>
Cc: Sudhakar Rajashekhara <sudhakar.raj at ti.com>
Cc: Heiko Schocher <hs at denx.de>
---
 arch/arm/lib/vectors.S |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm/lib/vectors.S b/arch/arm/lib/vectors.S
index 843b18f..0cb87ce 100644
--- a/arch/arm/lib/vectors.S
+++ b/arch/arm/lib/vectors.S
@@ -45,11 +45,12 @@
  *************************************************************************
  */
 
+_start:
+
 #ifdef CONFIG_SYS_DV_NOR_BOOT_CFG
 	.word	CONFIG_SYS_DV_NOR_BOOT_CFG
 #endif
 
-_start:
 	b	reset
 	ldr	pc, _undefined_instruction
 	ldr	pc, _software_interrupt
-- 
1.7.10.4