The ARM ABI requires that the stack be aligned to 8 bytes as it is noted in Procedure Call Standard for the ARM Architecture: http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042d/index.html
Unaligned SP also causes the problem with variable-length arrays allocation when VLA address becomes less than stack pointer during aligning of this address, so the further 'push' into the stack overwrites first 4 bytes of VLA.
Signed-off-by: Vitaly Kuzmichev vkuzmichev@mvista.com Signed-off-by: George G. Davis gdavis@mvista.com --- arch/arm/cpu/arm1136/start.S | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/arch/arm/cpu/arm1136/start.S b/arch/arm/cpu/arm1136/start.S index 957f438..d0c5717 100644 --- a/arch/arm/cpu/arm1136/start.S +++ b/arch/arm/cpu/arm1136/start.S @@ -185,6 +185,7 @@ stack_setup: #endif sub sp, r0, #12 /* leave 3 words for abort-stack */ #endif /* CONFIG_PRELOADER */ + bic sp, sp, #7 /* 8-byte alignment */
clear_bss: ldr r0, _bss_start /* find start of bss segment */