Hi Bo Gan,

From: Bo Gan ganboing@gmail.com Sent: Tuesday, May 09, 2023 9:46 AM To: u-boot@lists.denx.de Cc: Bo Gan ganboing@gmail.com; Rick Jian-Zhi Chen(陳建志) rick@andestech.com; Leo Yu-Chi Liang(梁育齊) ycliang@andestech.com Subject: [PATCH] riscv: setup per-hart stack earlier

Harts need to use per-hart stack before any function call, even if that function is a simple one. When the callee uses stack for register save/ restore, especially RA, if nested call, concurrent access by multiple harts on the same stack will cause data-race.

This patch sets up SP before `board_init_f_alloc_reserve`. A side effect of this is that the memory layout has changed as the following:

+----------------+ +----------------+ <----- SPL_STACK/ | ...... | | hart 0 stack | SYS_INIT_SP_ADDR | malloc_base | +----------------+ +----------------+ | hart 1 stack | | GD | +----------------+ If not SMP, N=1 +----------------+ | ...... | | hart 0 stack | +----------------+ +----------------+ ==> | hart N-1 stack| | hart 1 stack | +----------------+ +----------------+ | ...... | | ...... | | malloc_base | +----------------+ +----------------+ | hart N-1 stack| | GD | +----------------+ +----------------+ | | | |

Signed-off-by: Bo Gan ganboing@gmail.com Cc: Rick Chen rick@andestech.com Cc: Leo ycliang@andestech.com

---

arch/riscv/cpu/start.S | 37 ++++++++++++++++++++++++------------- 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/arch/riscv/cpu/start.S b/arch/riscv/cpu/start.S index dad22bf..90015c2 100644 --- a/arch/riscv/cpu/start.S +++ b/arch/riscv/cpu/start.S @@ -91,16 +91,35 @@ _start:

• Set stackpointer in internal/ex RAM to call board_init_f

*/ call_board_init_f:

•   li      t0, -16
  

#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)

•   li      t1, CONFIG_SPL_STACK
  

•   li      t0, CONFIG_SPL_STACK
  

#else

•   li      t1, SYS_INIT_SP_ADDR
  

•   li      t0, CONFIG_SYS_INIT_SP_ADDR
  

It builds fail as below:

arch/riscv/cpu/start.S:97: Error: illegal operands `li t0,CONFIG_SYS_INIT_SP_ADDR'

Thanks, Rick