riscv: avoid Imbalance in RAS

BugLink: https://bugs.launchpad.net/bugs/2097301

[ 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@tenstorrent.com/ [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>
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>

This commit is contained in:

Jisheng Zhang

2024-07-21 01:06:59 +08:00

committed by

Mehmet Basaran

parent 77f5ec4eff

commit 87e9141efd

1 changed files with 2 additions and 2 deletions

									
										arch/riscv/kernel/entry.S
									
		+2
		-2
	
												View File
												
				@@ -232,8 +232,8 @@ 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