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linux/arch/riscv/kernel/traps_misaligned.c
Damien Le Moal 956d705dd2
riscv: Unaligned load/store handling for M_MODE 
Add handlers for unaligned load and store traps that may be generated
by applications. Code heavily inspired from the OpenSBI project.
Handling of the unaligned access traps is suitable for applications
compiled with or without compressed instructions and is independent of
the kernel CONFIG_RISCV_ISA_C option value.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2020-04-03 10:45:33 -07:00

371 lines
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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2020 Western Digital Corporation or its affiliates.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/irq.h>
#include <asm/processor.h>
#include <asm/ptrace.h>
#include <asm/csr.h>
#define INSN_MATCH_LB 0x3
#define INSN_MASK_LB 0x707f
#define INSN_MATCH_LH 0x1003
#define INSN_MASK_LH 0x707f
#define INSN_MATCH_LW 0x2003
#define INSN_MASK_LW 0x707f
#define INSN_MATCH_LD 0x3003
#define INSN_MASK_LD 0x707f
#define INSN_MATCH_LBU 0x4003
#define INSN_MASK_LBU 0x707f
#define INSN_MATCH_LHU 0x5003
#define INSN_MASK_LHU 0x707f
#define INSN_MATCH_LWU 0x6003
#define INSN_MASK_LWU 0x707f
#define INSN_MATCH_SB 0x23
#define INSN_MASK_SB 0x707f
#define INSN_MATCH_SH 0x1023
#define INSN_MASK_SH 0x707f
#define INSN_MATCH_SW 0x2023
#define INSN_MASK_SW 0x707f
#define INSN_MATCH_SD 0x3023
#define INSN_MASK_SD 0x707f
#define INSN_MATCH_FLW 0x2007
#define INSN_MASK_FLW 0x707f
#define INSN_MATCH_FLD 0x3007
#define INSN_MASK_FLD 0x707f
#define INSN_MATCH_FLQ 0x4007
#define INSN_MASK_FLQ 0x707f
#define INSN_MATCH_FSW 0x2027
#define INSN_MASK_FSW 0x707f
#define INSN_MATCH_FSD 0x3027
#define INSN_MASK_FSD 0x707f
#define INSN_MATCH_FSQ 0x4027
#define INSN_MASK_FSQ 0x707f
#define INSN_MATCH_C_LD 0x6000
#define INSN_MASK_C_LD 0xe003
#define INSN_MATCH_C_SD 0xe000
#define INSN_MASK_C_SD 0xe003
#define INSN_MATCH_C_LW 0x4000
#define INSN_MASK_C_LW 0xe003
#define INSN_MATCH_C_SW 0xc000
#define INSN_MASK_C_SW 0xe003
#define INSN_MATCH_C_LDSP 0x6002
#define INSN_MASK_C_LDSP 0xe003
#define INSN_MATCH_C_SDSP 0xe002
#define INSN_MASK_C_SDSP 0xe003
#define INSN_MATCH_C_LWSP 0x4002
#define INSN_MASK_C_LWSP 0xe003
#define INSN_MATCH_C_SWSP 0xc002
#define INSN_MASK_C_SWSP 0xe003
#define INSN_MATCH_C_FLD 0x2000
#define INSN_MASK_C_FLD 0xe003
#define INSN_MATCH_C_FLW 0x6000
#define INSN_MASK_C_FLW 0xe003
#define INSN_MATCH_C_FSD 0xa000
#define INSN_MASK_C_FSD 0xe003
#define INSN_MATCH_C_FSW 0xe000
#define INSN_MASK_C_FSW 0xe003
#define INSN_MATCH_C_FLDSP 0x2002
#define INSN_MASK_C_FLDSP 0xe003
#define INSN_MATCH_C_FSDSP 0xa002
#define INSN_MASK_C_FSDSP 0xe003
#define INSN_MATCH_C_FLWSP 0x6002
#define INSN_MASK_C_FLWSP 0xe003
#define INSN_MATCH_C_FSWSP 0xe002
#define INSN_MASK_C_FSWSP 0xe003
#define INSN_LEN(insn) ((((insn) & 0x3) < 0x3) ? 2 : 4)
#if defined(CONFIG_64BIT)
#define LOG_REGBYTES 3
#define XLEN 64
#else
#define LOG_REGBYTES 2
#define XLEN 32
#endif
#define REGBYTES (1 << LOG_REGBYTES)
#define XLEN_MINUS_16 ((XLEN) - 16)
#define SH_RD 7
#define SH_RS1 15
#define SH_RS2 20
#define SH_RS2C 2
#define RV_X(x, s, n) (((x) >> (s)) & ((1 << (n)) - 1))
#define RVC_LW_IMM(x) ((RV_X(x, 6, 1) << 2) | \
(RV_X(x, 10, 3) << 3) | \
(RV_X(x, 5, 1) << 6))
#define RVC_LD_IMM(x) ((RV_X(x, 10, 3) << 3) | \
(RV_X(x, 5, 2) << 6))
#define RVC_LWSP_IMM(x) ((RV_X(x, 4, 3) << 2) | \
(RV_X(x, 12, 1) << 5) | \
(RV_X(x, 2, 2) << 6))
#define RVC_LDSP_IMM(x) ((RV_X(x, 5, 2) << 3) | \
(RV_X(x, 12, 1) << 5) | \
(RV_X(x, 2, 3) << 6))
#define RVC_SWSP_IMM(x) ((RV_X(x, 9, 4) << 2) | \
(RV_X(x, 7, 2) << 6))
#define RVC_SDSP_IMM(x) ((RV_X(x, 10, 3) << 3) | \
(RV_X(x, 7, 3) << 6))
#define RVC_RS1S(insn) (8 + RV_X(insn, SH_RD, 3))
#define RVC_RS2S(insn) (8 + RV_X(insn, SH_RS2C, 3))
#define RVC_RS2(insn) RV_X(insn, SH_RS2C, 5)
#define SHIFT_RIGHT(x, y) \
((y) < 0 ? ((x) << -(y)) : ((x) >> (y)))
#define REG_MASK \
((1 << (5 + LOG_REGBYTES)) - (1 << LOG_REGBYTES))
#define REG_OFFSET(insn, pos) \
(SHIFT_RIGHT((insn), (pos) - LOG_REGBYTES) & REG_MASK)
#define REG_PTR(insn, pos, regs) \
(ulong *)((ulong)(regs) + REG_OFFSET(insn, pos))
#define GET_RM(insn) (((insn) >> 12) & 7)
#define GET_RS1(insn, regs) (*REG_PTR(insn, SH_RS1, regs))
#define GET_RS2(insn, regs) (*REG_PTR(insn, SH_RS2, regs))
#define GET_RS1S(insn, regs) (*REG_PTR(RVC_RS1S(insn), 0, regs))
#define GET_RS2S(insn, regs) (*REG_PTR(RVC_RS2S(insn), 0, regs))
#define GET_RS2C(insn, regs) (*REG_PTR(insn, SH_RS2C, regs))
#define GET_SP(regs) (*REG_PTR(2, 0, regs))
#define SET_RD(insn, regs, val) (*REG_PTR(insn, SH_RD, regs) = (val))
#define IMM_I(insn) ((s32)(insn) >> 20)
#define IMM_S(insn) (((s32)(insn) >> 25 << 5) | \
(s32)(((insn) >> 7) & 0x1f))
#define MASK_FUNCT3 0x7000
#define GET_PRECISION(insn) (((insn) >> 25) & 3)
#define GET_RM(insn) (((insn) >> 12) & 7)
#define PRECISION_S 0
#define PRECISION_D 1
#define STR(x) XSTR(x)
#define XSTR(x) #x
#define DECLARE_UNPRIVILEGED_LOAD_FUNCTION(type, insn) \
static inline type load_##type(const type *addr) \
{ \
type val; \
asm (#insn " %0, %1" \
: "=&r" (val) : "m" (*addr)); \
return val; \
}
#define DECLARE_UNPRIVILEGED_STORE_FUNCTION(type, insn) \
static inline void store_##type(type *addr, type val) \
{ \
asm volatile (#insn " %0, %1\n" \
: : "r" (val), "m" (*addr)); \
}
DECLARE_UNPRIVILEGED_LOAD_FUNCTION(u8, lbu)
DECLARE_UNPRIVILEGED_LOAD_FUNCTION(u16, lhu)
DECLARE_UNPRIVILEGED_LOAD_FUNCTION(s8, lb)
DECLARE_UNPRIVILEGED_LOAD_FUNCTION(s16, lh)
DECLARE_UNPRIVILEGED_LOAD_FUNCTION(s32, lw)
DECLARE_UNPRIVILEGED_STORE_FUNCTION(u8, sb)
DECLARE_UNPRIVILEGED_STORE_FUNCTION(u16, sh)
DECLARE_UNPRIVILEGED_STORE_FUNCTION(u32, sw)
#if defined(CONFIG_64BIT)
DECLARE_UNPRIVILEGED_LOAD_FUNCTION(u32, lwu)
DECLARE_UNPRIVILEGED_LOAD_FUNCTION(u64, ld)
DECLARE_UNPRIVILEGED_STORE_FUNCTION(u64, sd)
DECLARE_UNPRIVILEGED_LOAD_FUNCTION(ulong, ld)
#else
DECLARE_UNPRIVILEGED_LOAD_FUNCTION(u32, lw)
DECLARE_UNPRIVILEGED_LOAD_FUNCTION(ulong, lw)
static inline u64 load_u64(const u64 *addr)
{
return load_u32((u32 *)addr)
+ ((u64)load_u32((u32 *)addr + 1) << 32);
}
static inline void store_u64(u64 *addr, u64 val)
{
store_u32((u32 *)addr, val);
store_u32((u32 *)addr + 1, val >> 32);
}
#endif
static inline ulong get_insn(ulong mepc)
{
register ulong __mepc asm ("a2") = mepc;
ulong val, rvc_mask = 3, tmp;
asm ("and %[tmp], %[addr], 2\n"
"bnez %[tmp], 1f\n"
#if defined(CONFIG_64BIT)
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:"
: [insn] "=&r" (val), [tmp] "=&r" (tmp)
: [addr] "r" (__mepc), [rvc_mask] "r" (rvc_mask),
[xlen_minus_16] "i" (XLEN_MINUS_16));
return val;
}
union reg_data {
u8 data_bytes[8];
ulong data_ulong;
u64 data_u64;
};
int handle_misaligned_load(struct pt_regs *regs)
{
union reg_data val;
unsigned long epc = regs->epc;
unsigned long insn = get_insn(epc);
unsigned long addr = csr_read(mtval);
int i, fp = 0, shift = 0, len = 0;
regs->epc = 0;
if ((insn & INSN_MASK_LW) == INSN_MATCH_LW) {
len = 4;
shift = 8 * (sizeof(unsigned long) - len);
#if defined(CONFIG_64BIT)
} else if ((insn & INSN_MASK_LD) == INSN_MATCH_LD) {
len = 8;
shift = 8 * (sizeof(unsigned long) - len);
} else if ((insn & INSN_MASK_LWU) == INSN_MATCH_LWU) {
len = 4;
#endif
} else if ((insn & INSN_MASK_FLD) == INSN_MATCH_FLD) {
fp = 1;
len = 8;
} else if ((insn & INSN_MASK_FLW) == INSN_MATCH_FLW) {
fp = 1;
len = 4;
} else if ((insn & INSN_MASK_LH) == INSN_MATCH_LH) {
len = 2;
shift = 8 * (sizeof(unsigned long) - len);
} else if ((insn & INSN_MASK_LHU) == INSN_MATCH_LHU) {
len = 2;
#if defined(CONFIG_64BIT)
} else if ((insn & INSN_MASK_C_LD) == INSN_MATCH_C_LD) {
len = 8;
shift = 8 * (sizeof(unsigned long) - 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(unsigned long) - len);
#endif
} else if ((insn & INSN_MASK_C_LW) == INSN_MATCH_C_LW) {
len = 4;
shift = 8 * (sizeof(unsigned long) - 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(unsigned long) - len);
} else if ((insn & INSN_MASK_C_FLD) == INSN_MATCH_C_FLD) {
fp = 1;
len = 8;
insn = RVC_RS2S(insn) << SH_RD;
} else if ((insn & INSN_MASK_C_FLDSP) == INSN_MATCH_C_FLDSP) {
fp = 1;
len = 8;
#if defined(CONFIG_32BIT)
} else if ((insn & INSN_MASK_C_FLW) == INSN_MATCH_C_FLW) {
fp = 1;
len = 4;
insn = RVC_RS2S(insn) << SH_RD;
} else if ((insn & INSN_MASK_C_FLWSP) == INSN_MATCH_C_FLWSP) {
fp = 1;
len = 4;
#endif
} else {
regs->epc = epc;
return -1;
}
val.data_u64 = 0;
for (i = 0; i < len; i++)
val.data_bytes[i] = load_u8((void *)(addr + i));
if (fp)
return -1;
SET_RD(insn, regs, val.data_ulong << shift >> shift);
regs->epc = epc + INSN_LEN(insn);
return 0;
}
int handle_misaligned_store(struct pt_regs *regs)
{
union reg_data val;
unsigned long epc = regs->epc;
unsigned long insn = get_insn(epc);
unsigned long addr = csr_read(mtval);
int i, len = 0;
regs->epc = 0;
val.data_ulong = GET_RS2(insn, regs);
if ((insn & INSN_MASK_SW) == INSN_MATCH_SW) {
len = 4;
#if defined(CONFIG_64BIT)
} else if ((insn & INSN_MASK_SD) == INSN_MATCH_SD) {
len = 8;
#endif
} else if ((insn & INSN_MASK_SH) == INSN_MATCH_SH) {
len = 2;
#if defined(CONFIG_64BIT)
} 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);
} else {
regs->epc = epc;
return -1;
}
for (i = 0; i < len; i++)
store_u8((void *)(addr + i), val.data_bytes[i]);
regs->epc = epc + INSN_LEN(insn);
return 0;
}
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