The mstatus CSR includes WPRI (writes preserve values, reads ignore values) fields and must therefore not be set to zero without preserving these fields. It is not apparent why mstatus is set to zero here since it is not required for U-Boot to run. Remove it.
This instruction and others encode zero as an immediate. RISC-V has the zero register for this purpose. Replace the immediates with the zero register.
Signed-off-by: Lukas Auer lukas.auer@aisec.fraunhofer.de Reviewed-by: Bin Meng bmeng.cn@gmail.com Reviewed-by: Rick Chen rick@andestech.com ---
Changes in v4: None Changes in v3: None Changes in v2: None
arch/riscv/cpu/start.S | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/riscv/cpu/start.S b/arch/riscv/cpu/start.S index c313477ae0..b01ea6e224 100644 --- a/arch/riscv/cpu/start.S +++ b/arch/riscv/cpu/start.S @@ -38,8 +38,9 @@ _start: SREG a2, 0(t0) la t0, trap_entry csrw mtvec, t0 - csrwi mstatus, 0 - csrwi mie, 0 + + /* mask all interrupts */ + csrw mie, zero
/* * Set stackpointer in internal/ex RAM to call board_init_f @@ -160,11 +161,10 @@ clear_bss: add t0, t0, t6 /* t0 <- rel __bss_start in RAM */ la t1, __bss_end /* t1 <- rel __bss_end in FLASH */ add t1, t1, t6 /* t1 <- rel __bss_end in RAM */ - li t2, 0x00000000 /* clear */ beq t0, t1, call_board_init_r
clbss_l: - SREG t2, 0(t0) /* clear loop... */ + SREG zero, 0(t0) /* clear loop... */ addi t0, t0, REGBYTES bne t0, t1, clbss_l