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lib: sbi_trap: Redirect exception based on hedeleg

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HS-mode software can choose what exceptions to delegate to VS-mode using
the hedeleg CSR. Synthetic VS/VU-mode exceptions should also honor
hedeleg. They should be redirected to VS-mode if and only if delegated
by HS-mode.

Signed-off-by: dramforever <dramforever@live.com>
Reviewed-by: Xiang W <wxjstz@126.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
dramforever
2022-06-12 13:57:37 +08:00
committed by Anup Patel
parent cb8271c8e4
commit adc3388d76
1 changed files with 6 additions and 9 deletions
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15
lib/sbi/sbi_trap.c
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@@ -99,17 +99,14 @@ int sbi_trap_redirect(struct sbi_trap_regs *regs,
if (prev_mode != PRV_S && prev_mode != PRV_U)
return SBI_ENOTSUPP;
/* For certain exceptions from VS/VU-mode we redirect to VS-mode */
/* If exceptions came from VS/VU-mode, redirect to VS-mode if
* delegated in hedeleg
*/
if (misa_extension('H') && prev_virt) {
switch (trap->cause) {
case CAUSE_FETCH_PAGE_FAULT:
case CAUSE_LOAD_PAGE_FAULT:
case CAUSE_STORE_PAGE_FAULT:
if ((trap->cause < __riscv_xlen) &&
(csr_read(CSR_HEDELEG) & BIT(trap->cause))) {
next_virt = TRUE;
break;
default:
break;
};
}
}
/* Update MSTATUS MPV bits */