[U-Boot] [PATCH] arm: use common instructions applicable to armv7m & other arm archs

Vikas Manocha
2016-01-19T02:52:57Z

BIC instruction to clear the SP is not allowed in armv7m & is deprecated
in ARMv6T2 & above. This patch cleans the code by using instructions allowed
for armv7m as well as other Arm archs.

Signed-off-by: Vikas Manocha <vikas.manocha@st.com>
---
arch/arm/lib/crt0.S | 25 +++++++------------------
1 file changed, 7 insertions(+), 18 deletions(-)

diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S
index 2f4c14e..3731d0c 100644
--- a/arch/arm/lib/crt0.S
+++ b/arch/arm/lib/crt0.S
@@ -71,18 +71,12 @@ ENTRY(_main)
*/

#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
- ldr sp, =(CONFIG_SPL_STACK)
+ ldr r0, =(CONFIG_SPL_STACK)
#else
- ldr sp, =(CONFIG_SYS_INIT_SP_ADDR)
+ ldr r0, =(CONFIG_SYS_INIT_SP_ADDR)
#endif
-#if defined(CONFIG_CPU_V7M) /* v7M forbids using SP as BIC destination */
- mov r3, sp
- bic r3, r3, #7
- mov sp, r3
-#else
- bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
-#endif
- mov r0, sp
+ bic r0, r0, #7 /* 8-byte alignment for ABI compliance */
+ mov sp, r0
bl board_init_f_alloc_reserve
mov sp, r0
/* set up gd here, outside any C code */
@@ -100,14 +94,9 @@ ENTRY(_main)
* 'here' but relocated.
*/

- ldr sp, [r9, #GD_START_ADDR_SP] /* sp = gd->start_addr_sp */
-#if defined(CONFIG_CPU_V7M) /* v7M forbids using SP as BIC destination */
- mov r3, sp
- bic r3, r3, #7
- mov sp, r3
-#else
- bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
-#endif
+ ldr r0, [r9, #GD_START_ADDR_SP] /* sp = gd->start_addr_sp */
+ bic r0, r0, #7
+ mov sp, r0 /* 8-byte alignment for ABI compliance */
ldr r9, [r9, #GD_BD] /* r9 = gd->bd */
sub r9, r9, #GD_SIZE /* new GD is below bd */

--
1.9.1