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lib: Add misaligned load/store trap handling

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We generally don't get misaligned load/store traps from Linux/U-Boot
compiled using GCC 8.2 or higher but this is not true with older
GCC toolchains. To tackle this we add misaligned load/store trap
handling adopted from BBL sources but much more simpler.
(Note: BBL sources can be found at https://github.com/riscv/riscv-pk.git)

Signed-off-by: Anup Patel <anup.patel@wdc.com>
This commit is contained in:
Anup Patel 2018-12-24 16:49:01 +05:30 • committed by Anup Patel
parent 96f66f79ca
commit b5ae8e8a65
4 changed files with 166 additions and 1 deletions
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26
include/sbi/sbi_misaligned_ldst.h Normal file
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@ -0,0 +1,26 @@
/*
* Copyright (c) 2018 Western Digital Corporation or its affiliates.
*
* Authors:
* Anup Patel <anup.patel@wdc.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#ifndef __SBI_MISALIGNED_LDST_H__
#define __SBI_MISALIGNED_LDST_H__
#include <sbi/sbi_types.h>
struct sbi_trap_regs;
struct sbi_scratch;
int sbi_misaligned_load_handler(u32 hartid, ulong mcause,
struct sbi_trap_regs *regs,
struct sbi_scratch *scratch);
int sbi_misaligned_store_handler(u32 hartid, ulong mcause,
struct sbi_trap_regs *regs,
struct sbi_scratch *scratch);
#endif

1
lib/objects.mk
View file

@ -18,6 +18,7 @@ lib-objs-y += sbi_hart.o
lib-objs-y += sbi_illegal_insn.o
lib-objs-y += sbi_init.o
lib-objs-y += sbi_ipi.o
lib-objs-y += sbi_misaligned_ldst.o
lib-objs-y += sbi_system.o
lib-objs-y += sbi_timer.o
lib-objs-y += sbi_trap.o

129
lib/sbi_misaligned_ldst.c Normal file
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@ -0,0 +1,129 @@
/*
* Copyright (c) 2018 Western Digital Corporation or its affiliates.
*
* Authors:
* Anup Patel <anup.patel@wdc.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <sbi/riscv_asm.h>
#include <sbi/riscv_encoding.h>
#include <sbi/sbi_error.h>
#include <sbi/sbi_misaligned_ldst.h>
#include <sbi/sbi_trap.h>
#include <sbi/sbi_unpriv.h>
union reg_data {
u8 data_bytes[8];
ulong data_ulong;
u64 data_u64;
};
int sbi_misaligned_load_handler(u32 hartid, ulong mcause,
struct sbi_trap_regs *regs,
struct sbi_scratch *scratch)
{
union reg_data val;
ulong mstatus = csr_read(mstatus);
ulong insn = get_insn(regs->mepc, &mstatus);
ulong addr = csr_read(mtval);
int i, shift = 0, len = 0;
if ((insn & INSN_MASK_LW) == INSN_MATCH_LW) {
len = 4;
shift = 8 * (sizeof(ulong) - len);
#if __riscv_xlen == 64
} else if ((insn & INSN_MASK_LD) == INSN_MATCH_LD) {
len = 8;
shift = 8 * (sizeof(ulong) - len);
} else if ((insn & INSN_MASK_LWU) == INSN_MATCH_LWU) {
len = 4;
#endif
} else if ((insn & INSN_MASK_LH) == INSN_MATCH_LH) {
len = 2;
shift = 8 * (sizeof(ulong) - len);
} else if ((insn & INSN_MASK_LHU) == INSN_MATCH_LHU) {
len = 2;
#ifdef __riscv_compressed
# if __riscv_xlen >= 64
} else if ((insn & INSN_MASK_C_LD) == INSN_MATCH_C_LD) {
len = 8;
shift = 8 * (sizeof(ulong) - len);
insn = RVC_RS2S(insn) << SH_RD;
} else if ((insn & INSN_MASK_C_LDSP) == INSN_MATCH_C_LDSP &&
((insn >> SH_RD) & 0x1f)) {
len = 8;
shift = 8 * (sizeof(ulong) - len);
# endif
} else if ((insn & INSN_MASK_C_LW) ==INSN_MATCH_C_LW) {
len = 4;
shift = 8 * (sizeof(ulong) - len);
insn = RVC_RS2S(insn) << SH_RD;
} else if ((insn & INSN_MASK_C_LWSP) == INSN_MATCH_C_LWSP &&
((insn >> SH_RD) & 0x1f)) {
len = 4;
shift = 8 * (sizeof(ulong) - len);
#endif
} else
return SBI_EILL;
val.data_u64 = 0;
for (i = 0; i < len; i++)
val.data_bytes[i] = load_u8((void *)(addr + i), regs->mepc);
SET_RD(insn, regs, val.data_ulong << shift >> shift);
regs->mepc += INSN_LEN(insn);
return 0;
}
int sbi_misaligned_store_handler(u32 hartid, ulong mcause,
struct sbi_trap_regs *regs,
struct sbi_scratch *scratch)
{
union reg_data val;
ulong mstatus = csr_read(mstatus);
ulong insn = get_insn(regs->mepc, &mstatus);
ulong addr = csr_read(mtval);
int i, len = 0;
val.data_ulong = GET_RS2(insn, regs);
if ((insn & INSN_MASK_SW) == INSN_MATCH_SW) {
len = 4;
#if __riscv_xlen == 64
} else if ((insn & INSN_MASK_SD) == INSN_MATCH_SD) {
len = 8;
#endif
} else if ((insn & INSN_MASK_SH) == INSN_MATCH_SH) {
len = 2;
#ifdef __riscv_compressed
# if __riscv_xlen >= 64
} else if ((insn & INSN_MASK_C_SD) == INSN_MATCH_C_SD) {
len = 8;
val.data_ulong = GET_RS2S(insn, regs);
} else if ((insn & INSN_MASK_C_SDSP) == INSN_MATCH_C_SDSP &&
((insn >> SH_RD) & 0x1f)) {
len = 8;
val.data_ulong = GET_RS2C(insn, regs);
# endif
} else if ((insn & INSN_MASK_C_SW) == INSN_MATCH_C_SW) {
len = 4;
val.data_ulong = GET_RS2S(insn, regs);
} else if ((insn & INSN_MASK_C_SWSP) == INSN_MATCH_C_SWSP &&
((insn >> SH_RD) & 0x1f)) {
len = 4;
val.data_ulong = GET_RS2C(insn, regs);
#endif
} else
return SBI_EILL;
for (i = 0; i < len; i++)
store_u8((void *)(addr + i), val.data_bytes[i], regs->mepc);
regs->mepc += INSN_LEN(insn);
return 0;
}

11
lib/sbi_trap.c
View file

@ -12,9 +12,10 @@
#include <sbi/sbi_console.h>
#include <sbi/sbi_ecall.h>
#include <sbi/sbi_error.h>
#include <sbi/sbi_illegal_insn.h>
#include <sbi/sbi_hart.h>
#include <sbi/sbi_illegal_insn.h>
#include <sbi/sbi_ipi.h>
#include <sbi/sbi_misaligned_ldst.h>
#include <sbi/sbi_timer.h>
#include <sbi/sbi_trap.h>
@ -95,6 +96,14 @@ void sbi_trap_handler(struct sbi_trap_regs *regs,
rc = sbi_illegal_insn_handler(hartid, mcause, regs, scratch);
msg = "illegal instruction handler failed";
break;
case CAUSE_MISALIGNED_LOAD:
rc = sbi_misaligned_load_handler(hartid, mcause, regs, scratch);
msg = "misaligned load handler failed";
break;
case CAUSE_MISALIGNED_STORE:
rc = sbi_misaligned_store_handler(hartid, mcause, regs, scratch);
msg = "misaligned store handler failed";
break;
case CAUSE_SUPERVISOR_ECALL:
case CAUSE_HYPERVISOR_ECALL:
rc = sbi_ecall_handler(hartid, mcause, regs, scratch);