[PATCH] riscv: setup per-hart stack earlier
Bo Gan
ganboing at gmail.com
Tue May 9 03:45:41 CEST 2023
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 at gmail.com>
Cc: Rick Chen <rick at andestech.com>
Cc: Leo <ycliang at 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:
--
2.7.4
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