From: Jisheng Zhang <jszhang@xxxxxxxxxx> [ Upstream commit 8f1534e7440382d118c3d655d3a6014128b2086d ] Inspired by[1], modify the code to remove the code of modifying ra to avoid imbalance RAS (return address stack) which may lead to incorret predictions on return. Link: https://lore.kernel.org/linux-riscv/20240607061335.2197383-1-cyrilbur@xxxxxxxxxxxxxxx/ [1] Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxx> Reviewed-by: Cyril Bur <cyrilbur@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20240720170659.1522-1-jszhang@xxxxxxxxxx Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- arch/riscv/kernel/entry.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index ac2e908d4418d..fefb8e7d957a0 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -239,8 +239,8 @@ SYM_CODE_START(ret_from_fork) jalr s0 1: move a0, sp /* pt_regs */ - la ra, ret_from_exception - tail syscall_exit_to_user_mode + call syscall_exit_to_user_mode + j ret_from_exception SYM_CODE_END(ret_from_fork) #ifdef CONFIG_IRQ_STACKS -- 2.43.0
