Re: [PATCH] riscv,entry: fix misaligned base for excp_vect_table

From: Palmer Dabbelt
Date: Tue Mar 30 2021 - 01:55:24 EST


On Wed, 17 Mar 2021 01:17:25 PDT (-0700), yuzihao@xxxxxxxxx wrote:
* 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@xxxxxxxxx>
---
arch/riscv/kernel/entry.S | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 744f3209c..76274a4a1 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -447,6 +447,7 @@ ENDPROC(__switch_to)
#endif

.section ".rodata"
+ .align LGREG
/* Exception vector table */
ENTRY(excp_vect_table)
RISCV_PTR do_trap_insn_misaligned

Thanks, this is on fixes.