From: Jisheng Zhang jszhang@kernel.org
[ 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@tensto... [1] Signed-off-by: Jisheng Zhang jszhang@kernel.org Reviewed-by: Cyril Bur cyrilbur@tenstorrent.com Link: https://lore.kernel.org/r/20240720170659.1522-1-jszhang@kernel.org Signed-off-by: Palmer Dabbelt palmer@rivosinc.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 ed7baf2cf7e87..1f90fee24a8ba 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -219,8 +219,8 @@ 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)
/*