This is a note to let you know that I've just added the patch titled
riscv: avoid Imbalance in RAS
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
riscv-avoid-imbalance-in-ras.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit fd5f564b7e141c987bed00ddc3c7459fe8aa92f3
Author: Jisheng Zhang <jszhang@xxxxxxxxxx>
Date: Sun Jul 21 01:06:59 2024 +0800
riscv: avoid Imbalance in RAS
[ 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>
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)
/*
