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 #endif - and sp, t1, t0 /* force 16 byte alignment */ + and t0, t0, -16 /* force 16 byte alignment */ + + /* setup stack */ +#if CONFIG_IS_ENABLED(SMP) + /* tp: hart id */ + slli t1, tp, CONFIG_STACK_SIZE_SHIFT + sub sp, t0, t1 +#else + mv sp, t0 +#endif +/* + * Now sp points to the right stack belonging to current CPU. + * It's essential before any function call, otherwise, we get data-race. + */
call_board_init_f_0: - mv a0, sp + /* find top of reserve space */ +#if CONFIG_IS_ENABLED(SMP) + li t1, CONFIG_NR_CPUS +#else + li t1, 1 +#endif + slli t1, t1, CONFIG_STACK_SIZE_SHIFT + sub a0, t0, t1 /* t1 -> size of all CPU stacks */ jal board_init_f_alloc_reserve
/* @@ -109,14 +128,6 @@ call_board_init_f_0: */ mv s0, a0
- /* setup stack */ -#if CONFIG_IS_ENABLED(SMP) - /* tp: hart id */ - slli t0, tp, CONFIG_STACK_SIZE_SHIFT - sub sp, a0, t0 -#else - mv sp, a0 -#endif
/* Configure proprietary settings and customized CSRs of harts */ call_harts_early_init: