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lib: Handle page/access fault caused by unpriv load/store

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The unpriv load/store instruction from M-mode can cause page/access
fault to M-mode if S-mode page table did not have mappings OR it did
not have PMP access permission.

To tackle this, we redirect trap back to S-mode if unpriv load/store
instruction traps in M-mode.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
This commit is contained in:
Anup Patel
2019-05-23 13:30:58 +05:30
committed by Anup Patel
parent bb915780ac
commit a6395acd6c
9 changed files with 131 additions and 44 deletions
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13
lib/sbi_ecall.c
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@@ -34,6 +34,7 @@ int sbi_ecall_handler(u32 hartid, ulong mcause, struct sbi_trap_regs *regs,
struct sbi_scratch *scratch)
{
int ret = SBI_ENOTSUPP;
struct unpriv_trap uptrap;
struct sbi_tlb_info tlb_info;
switch (regs->a7) {
@@ -59,11 +60,11 @@ int sbi_ecall_handler(u32 hartid, ulong mcause, struct sbi_trap_regs *regs,
ret = 0;
break;
case SBI_ECALL_SEND_IPI:
ret = sbi_ipi_send_many(scratch, (ulong *)regs->a0,
ret = sbi_ipi_send_many(scratch, &uptrap, (ulong *)regs->a0,
SBI_IPI_EVENT_SOFT, NULL);
break;
case SBI_ECALL_REMOTE_FENCE_I:
ret = sbi_ipi_send_many(scratch, (ulong *)regs->a0,
ret = sbi_ipi_send_many(scratch, &uptrap, (ulong *)regs->a0,
SBI_IPI_EVENT_FENCE_I, NULL);
break;
case SBI_ECALL_REMOTE_SFENCE_VMA:
@@ -71,7 +72,7 @@ int sbi_ecall_handler(u32 hartid, ulong mcause, struct sbi_trap_regs *regs,
tlb_info.size = (unsigned long)regs->a2;
tlb_info.type = SBI_TLB_FLUSH_VMA;
ret = sbi_ipi_send_many(scratch, (ulong *)regs->a0,
ret = sbi_ipi_send_many(scratch, &uptrap, (ulong *)regs->a0,
SBI_IPI_EVENT_SFENCE_VMA, &tlb_info);
break;
case SBI_ECALL_REMOTE_SFENCE_VMA_ASID:
@@ -80,7 +81,7 @@ int sbi_ecall_handler(u32 hartid, ulong mcause, struct sbi_trap_regs *regs,
tlb_info.asid = (unsigned long)regs->a3;
tlb_info.type = SBI_TLB_FLUSH_VMA_ASID;
ret = sbi_ipi_send_many(scratch, (ulong *)regs->a0,
ret = sbi_ipi_send_many(scratch, &uptrap, (ulong *)regs->a0,
SBI_IPI_EVENT_SFENCE_VMA_ASID,
&tlb_info);
break;
@@ -96,6 +97,10 @@ int sbi_ecall_handler(u32 hartid, ulong mcause, struct sbi_trap_regs *regs,
if (!ret) {
regs->mepc += 4;
} else if (ret == SBI_ETRAP) {
ret = 0;
sbi_trap_redirect(regs, scratch, regs->mepc,
uptrap.cause, uptrap.tval);
}
return ret;