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lib: Handle traps when doing unpriv load/store in get_insn()

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We can get a page/access trap when doing unpriv load/store in
get_insn() function because on a SMP system Linux swapper running
on HART A can unmap pages from page table used by HART B.

To tackle this we extend get_insn() implementation so that if
we get trap in get_insn() then we redirect it to S-mode as fetch
page/access fault.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
This commit is contained in:
Anup Patel
2019-08-12 11:50:22 +05:30
parent 2e0f3ac758
commit a88e424f6c
4 changed files with 65 additions and 46 deletions
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71
lib/sbi/riscv_unpriv.c
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@@ -97,11 +97,20 @@ void store_u64(u64 *addr, u64 val,
}
#endif
ulong get_insn(ulong mepc, ulong *mstatus)
ulong get_insn(ulong mepc, struct sbi_scratch *scratch,
struct unpriv_trap *trap)
{
register ulong __mepc asm("a2") = mepc;
register ulong __mstatus asm("a3");
ulong val;
ulong __mstatus = 0, val = 0;
#ifdef __riscv_compressed
ulong rvc_mask = 3, tmp;
#endif
if (trap) {
trap->ilen = 4;
trap->cause = 0;
trap->tval = 0;
sbi_hart_set_trap_info(scratch, trap);
}
#ifndef __riscv_compressed
asm("csrrs %[mstatus], " STR(CSR_MSTATUS) ", %[mprv]\n"
#if __riscv_xlen == 64
@@ -109,37 +118,37 @@ ulong get_insn(ulong mepc, ulong *mstatus)
#else
STR(LW) " %[insn], (%[addr])\n"
#endif
"csrw " STR(CSR_MSTATUS) ", %[mstatus]"
"csrw " STR(CSR_MSTATUS) ", %[mstatus]"
: [mstatus] "+&r"(__mstatus), [insn] "=&r"(val)
: [mprv] "r"(MSTATUS_MPRV | MSTATUS_MXR), [addr] "r"(__mepc));
: [mprv] "r"(MSTATUS_MPRV | MSTATUS_MXR), [addr] "r"(mepc));
#else
ulong rvc_mask = 3, tmp;
asm("csrrs %[mstatus], " STR(CSR_MSTATUS) ", %[mprv]\n"
"and %[tmp], %[addr], 2\n"
"bnez %[tmp], 1f\n"
#if __riscv_xlen == 64
STR(LWU) " %[insn], (%[addr])\n"
#else
STR(LW) " %[insn], (%[addr])\n"
#endif
"and %[tmp], %[insn], %[rvc_mask]\n"
"beq %[tmp], %[rvc_mask], 2f\n"
"sll %[insn], %[insn], %[xlen_minus_16]\n"
"srl %[insn], %[insn], %[xlen_minus_16]\n"
"j 2f\n"
"1:\n"
"lhu %[insn], (%[addr])\n"
"and %[tmp], %[insn], %[rvc_mask]\n"
"bne %[tmp], %[rvc_mask], 2f\n"
"lhu %[tmp], 2(%[addr])\n"
"sll %[tmp], %[tmp], 16\n"
"add %[insn], %[insn], %[tmp]\n"
"2: csrw " STR(CSR_MSTATUS) ", %[mstatus]"
"lhu %[insn], (%[addr])\n"
"and %[tmp], %[insn], %[rvc_mask]\n"
"bne %[tmp], %[rvc_mask], 2f\n"
"lhu %[tmp], 2(%[addr])\n"
"sll %[tmp], %[tmp], 16\n"
"add %[insn], %[insn], %[tmp]\n"
"2: csrw " STR(CSR_MSTATUS) ", %[mstatus]"
: [mstatus] "+&r"(__mstatus), [insn] "=&r"(val), [tmp] "=&r"(tmp)
: [mprv] "r"(MSTATUS_MPRV | MSTATUS_MXR), [addr] "r"(__mepc),
[rvc_mask] "r"(rvc_mask), [xlen_minus_16] "i"(__riscv_xlen - 16));
: [mprv] "r"(MSTATUS_MPRV | MSTATUS_MXR), [addr] "r"(mepc),
[rvc_mask] "r"(rvc_mask));
#endif
if (mstatus)
*mstatus = __mstatus;
if (trap) {
sbi_hart_set_trap_info(scratch, NULL);
switch (trap->cause) {
case CAUSE_LOAD_ACCESS:
trap->cause = CAUSE_FETCH_ACCESS;
trap->tval = mepc;
break;
case CAUSE_LOAD_PAGE_FAULT:
trap->cause = CAUSE_FETCH_PAGE_FAULT;
trap->tval = mepc;
break;
default:
break;
};
}
return val;
}