From f067bb84cf2dd6493ff3fa49294d3ec80481ad75 Mon Sep 17 00:00:00 2001 From: Xiang W Date: Thu, 26 May 2022 22:14:44 +0800 Subject: [PATCH] lib: sbi: fix system_opcode_insn If the csr's operation comes from M mode, it should not be forwarded to low-privilege processing, this patch fixes this problem. Signed-off-by: Xiang W Reviewed-by: Anup Patel --- lib/sbi/sbi_illegal_insn.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/lib/sbi/sbi_illegal_insn.c b/lib/sbi/sbi_illegal_insn.c index bfe7d619..388ad55d 100644 --- a/lib/sbi/sbi_illegal_insn.c +++ b/lib/sbi/sbi_illegal_insn.c @@ -16,6 +16,7 @@ #include #include #include +#include typedef int (*illegal_insn_func)(ulong insn, struct sbi_trap_regs *regs); @@ -37,8 +38,15 @@ static int system_opcode_insn(ulong insn, struct sbi_trap_regs *regs) int do_write, rs1_num = (insn >> 15) & 0x1f; ulong rs1_val = GET_RS1(insn, regs); int csr_num = (u32)insn >> 20; + ulong prev_mode = (regs->mstatus & MSTATUS_MPP) >> MSTATUS_MPP_SHIFT; ulong csr_val, new_csr_val; + if (prev_mode == PRV_M) { + sbi_printf("%s: Failed to access CSR %#x from M-mode", + __func__, csr_num); + return SBI_EFAIL; + } + /* TODO: Ensure that we got CSR read/write instruction */ if (sbi_emulate_csr_read(csr_num, regs, &csr_val))