On 15 January 2015 at 06:42, Akshay Saraswat akshay.s@samsung.com wrote:
When compiled SPL for Thumb secondary cores failed to boot at the kernel boot up. Only one core came up out of 4. This was happening because the code relocated to the address 0x02073000 by the primary core was an ARM asm code which was executed by the secondary cores as if it was a thumb code. This patch fixes the issue of secondary cores considering relocated code as Thumb instructions and not ARM instructions by jumping to the relocated with the help of "bx" ARM instruction. "bx" instruction changes the 5th bit of CPSR which allows execution unit to consider the following instructions as ARM instructions.
Signed-off-by: Akshay Saraswat akshay.s@samsung.com
arch/arm/cpu/armv7/exynos/lowlevel_init.c | 2 +- arch/arm/include/asm/arch-exynos/system.h | 3 +++ 2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/arm/cpu/armv7/exynos/lowlevel_init.c b/arch/arm/cpu/armv7/exynos/lowlevel_init.c index 57b4c66..d9f3f4b 100644 --- a/arch/arm/cpu/armv7/exynos/lowlevel_init.c +++ b/arch/arm/cpu/armv7/exynos/lowlevel_init.c @@ -110,7 +110,7 @@ static void secondary_cpu_start(void) { enable_smp(); svc32_mode_en();
set_pc(CONFIG_EXYNOS_RELOCATE_CODE_BASE);
branch_bx(CONFIG_EXYNOS_RELOCATE_CODE_BASE);}
/* diff --git a/arch/arm/include/asm/arch-exynos/system.h b/arch/arm/include/asm/arch-exynos/system.h index 86903c3..a9fd5e6 100644 --- a/arch/arm/include/asm/arch-exynos/system.h +++ b/arch/arm/include/asm/arch-exynos/system.h @@ -75,6 +75,9 @@ struct exynos5_sysreg { /* Set program counter with the given value */ #define set_pc(x) __asm__ __volatile__ ("mov pc, %0\n\t" : : "r"(x))
+/* Branch to the given location */ +#define branch_bx(x) __asm__ __volatile__ ("bx %0\n\t" : : "r"(x))
/* Read Main Id register */ #define mrc_midr(x) __asm__ __volatile__ \ ("mrc p15, 0, %0, c0, c0, 0\n\t" : "=r"(x) : ) -- 1.9.1
Reviewed-by: Simon Glass sjg@chromium.org
Tested on snow, pit, pi Tested-by: Simon Glass sjg@chromium.org