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lib: sbi: fix system_opcode_insn

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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 <wxjstz@126.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Xiang W
2022-05-26 22:14:44 +08:00
committed by Anup Patel
parent 1bc67db80c
commit f067bb84cf
1 changed files with 8 additions and 0 deletions
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8
lib/sbi/sbi_illegal_insn.c
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@@ -16,6 +16,7 @@
#include <sbi/sbi_pmu.h>
#include <sbi/sbi_trap.h>
#include <sbi/sbi_unpriv.h>
#include <sbi/sbi_console.h>
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))