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lib: sbi: Handle the case where MTVAL has illegal instruction address

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The Kendryte K210 follows RISC-V v1.9 spec so MTVAL has instruction
address (instead of instruction encoding) on illegal instruction trap.

To handle above case, we fix sbi_illegal_insn_handler() without any
impact on RISC-V v1.10 (or higher) systems. This achieved by exploiting
the fact that program counter (and instruction address) is always 2-byte
aligned in RISC-V world.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Tested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
This commit is contained in:
Anup Patel
2020-08-15 22:17:58 +05:30
committed by Anup Patel
parent e435ba0524
commit 4f3bad6e43
1 changed files with 15 additions and 6 deletions
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21
lib/sbi/sbi_illegal_insn.c
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@@ -118,13 +118,22 @@ int sbi_illegal_insn_handler(ulong insn, struct sbi_trap_regs *regs)
{
struct sbi_trap_info uptrap;
/*
* We only deal with 32-bit (or longer) illegal instructions. If we
* see instruction is zero OR instruction is 16-bit then we fetch and
* check the instruction encoding using unprivilege access.
*
* The program counter (PC) in RISC-V world is always 2-byte aligned
* so handling only 32-bit (or longer) illegal instructions also help
* the case where MTVAL CSR contains instruction address for illegal
* instruction trap.
*/
if (unlikely((insn & 3) != 3)) {
if (insn == 0) {
insn = sbi_get_insn(regs->mepc, &uptrap);
if (uptrap.cause) {
uptrap.epc = regs->mepc;
return sbi_trap_redirect(regs, &uptrap);
}
insn = sbi_get_insn(regs->mepc, &uptrap);
if (uptrap.cause) {
uptrap.epc = regs->mepc;
return sbi_trap_redirect(regs, &uptrap);
}
if ((insn & 3) != 3)
return truly_illegal_insn(insn, regs);