riscv,entry: fix misaligned base for excp_vect_table

BugLink: https://bugs.launchpad.net/bugs/1926490
[ Upstream commit ac8d0b901f0033b783156ab2dc1a0e73ec42409b ]

In RV64, the size of each entry in excp_vect_table is 8 bytes. If the
base of the table is not 8-byte aligned, loading an entry in the table
will raise a misaligned exception. Although such exception will be
handled by opensbi/bbl, this still causes performance degradation.

Signed-off-by: Zihao Yu <yuzihao@ict.ac.cn>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index c92217497b381c046fd8196d13d4d439722af3b2..06c133cc958175dc8a24f82dc1d38b553ed7696e 100644 (file)
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -411,6 +411,7 @@ ENTRY(__switch_to)
 ENDPROC(__switch_to)
 
        .section ".rodata"
+       .align LGREG
        /* Exception vector table */
 ENTRY(excp_vect_table)
        RISCV_PTR do_trap_insn_misaligned