The hart ID passed by the previous boot stage is currently stored in register s0. If we divert the control flow inside a function, which is required as part of multi-hart support, the function epilog may not be called, clobbering register s0. Save the hart ID in the unallocatable register tp instead to protect the hart ID.
Signed-off-by: Lukas Auer lukas.auer@aisec.fraunhofer.de ---
Changes in v3: - New patch to save the hart ID in register tp instead of s0
Changes in v2: None
arch/riscv/cpu/start.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/riscv/cpu/start.S b/arch/riscv/cpu/start.S index a30f6f7194..bcc0ff696d 100644 --- a/arch/riscv/cpu/start.S +++ b/arch/riscv/cpu/start.S @@ -36,7 +36,7 @@ .globl _start _start: /* save hart id and dtb pointer */ - mv s0, a0 + mv tp, a0 mv s1, a1
la t0, trap_entry @@ -64,7 +64,7 @@ call_board_init_f_0: jal board_init_f_init_reserve
/* save the boot hart id to global_data */ - SREG s0, GD_BOOT_HART(gp) + SREG tp, GD_BOOT_HART(gp)
/* Enable cache */ jal icache_enable