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linux/linux-5.4.31/arch/sh/kernel/traps_32.c

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// SPDX-License-Identifier: GPL-2.0
/*
* 'traps.c' handles hardware traps and faults after we have saved some
* state in 'entry.S'.
*
* SuperH version: Copyright (C) 1999 Niibe Yutaka
* Copyright (C) 2000 Philipp Rumpf
* Copyright (C) 2000 David Howells
* Copyright (C) 2002 - 2010 Paul Mundt
*/
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/hardirq.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/kallsyms.h>
#include <linux/io.h>
#include <linux/bug.h>
#include <linux/debug_locks.h>
#include <linux/kdebug.h>
#include <linux/limits.h>
#include <linux/sysfs.h>
#include <linux/uaccess.h>
#include <linux/perf_event.h>
#include <linux/sched/task_stack.h>
#include <asm/alignment.h>
#include <asm/fpu.h>
#include <asm/kprobes.h>
#include <asm/traps.h>
#include <asm/bl_bit.h>
#ifdef CONFIG_CPU_SH2
# define TRAP_RESERVED_INST 4
# define TRAP_ILLEGAL_SLOT_INST 6
# define TRAP_ADDRESS_ERROR 9
# ifdef CONFIG_CPU_SH2A
# define TRAP_UBC 12
# define TRAP_FPU_ERROR 13
# define TRAP_DIVZERO_ERROR 17
# define TRAP_DIVOVF_ERROR 18
# endif
#else
#define TRAP_RESERVED_INST 12
#define TRAP_ILLEGAL_SLOT_INST 13
#endif
static inline void sign_extend(unsigned int count, unsigned char *dst)
{
#ifdef __LITTLE_ENDIAN__
if ((count == 1) && dst[0] & 0x80) {
dst[1] = 0xff;
dst[2] = 0xff;
dst[3] = 0xff;
}
if ((count == 2) && dst[1] & 0x80) {
dst[2] = 0xff;
dst[3] = 0xff;
}
#else
if ((count == 1) && dst[3] & 0x80) {
dst[2] = 0xff;
dst[1] = 0xff;
dst[0] = 0xff;
}
if ((count == 2) && dst[2] & 0x80) {
dst[1] = 0xff;
dst[0] = 0xff;
}
#endif
}
static struct mem_access user_mem_access = {
copy_from_user,
copy_to_user,
};
/*
* handle an instruction that does an unaligned memory access by emulating the
* desired behaviour
* - note that PC _may not_ point to the faulting instruction
* (if that instruction is in a branch delay slot)
* - return 0 if emulation okay, -EFAULT on existential error
*/
static int handle_unaligned_ins(insn_size_t instruction, struct pt_regs *regs,
struct mem_access *ma)
{
int ret, index, count;
unsigned long *rm, *rn;
unsigned char *src, *dst;
unsigned char __user *srcu, *dstu;
index = (instruction>>8)&15; /* 0x0F00 */
rn = &regs->regs[index];
index = (instruction>>4)&15; /* 0x00F0 */
rm = &regs->regs[index];
count = 1<<(instruction&3);
switch (count) {
case 1: inc_unaligned_byte_access(); break;
case 2: inc_unaligned_word_access(); break;
case 4: inc_unaligned_dword_access(); break;
case 8: inc_unaligned_multi_access(); break;
}
ret = -EFAULT;
switch (instruction>>12) {
case 0: /* mov.[bwl] to/from memory via r0+rn */
if (instruction & 8) {
/* from memory */
srcu = (unsigned char __user *)*rm;
srcu += regs->regs[0];
dst = (unsigned char *)rn;
*(unsigned long *)dst = 0;
#if !defined(__LITTLE_ENDIAN__)
dst += 4-count;
#endif
if (ma->from(dst, srcu, count))
goto fetch_fault;
sign_extend(count, dst);
} else {
/* to memory */
src = (unsigned char *)rm;
#if !defined(__LITTLE_ENDIAN__)
src += 4-count;
#endif
dstu = (unsigned char __user *)*rn;
dstu += regs->regs[0];
if (ma->to(dstu, src, count))
goto fetch_fault;
}
ret = 0;
break;
case 1: /* mov.l Rm,@(disp,Rn) */
src = (unsigned char*) rm;
dstu = (unsigned char __user *)*rn;
dstu += (instruction&0x000F)<<2;
if (ma->to(dstu, src, 4))
goto fetch_fault;
ret = 0;
break;
case 2: /* mov.[bwl] to memory, possibly with pre-decrement */
if (instruction & 4)
*rn -= count;
src = (unsigned char*) rm;
dstu = (unsigned char __user *)*rn;
#if !defined(__LITTLE_ENDIAN__)
src += 4-count;
#endif
if (ma->to(dstu, src, count))
goto fetch_fault;
ret = 0;
break;
case 5: /* mov.l @(disp,Rm),Rn */
srcu = (unsigned char __user *)*rm;
srcu += (instruction & 0x000F) << 2;
dst = (unsigned char *)rn;
*(unsigned long *)dst = 0;
if (ma->from(dst, srcu, 4))
goto fetch_fault;
ret = 0;
break;
case 6: /* mov.[bwl] from memory, possibly with post-increment */
srcu = (unsigned char __user *)*rm;
if (instruction & 4)
*rm += count;
dst = (unsigned char*) rn;
*(unsigned long*)dst = 0;
#if !defined(__LITTLE_ENDIAN__)
dst += 4-count;
#endif
if (ma->from(dst, srcu, count))
goto fetch_fault;
sign_extend(count, dst);
ret = 0;
break;
case 8:
switch ((instruction&0xFF00)>>8) {
case 0x81: /* mov.w R0,@(disp,Rn) */
src = (unsigned char *) &regs->regs[0];
#if !defined(__LITTLE_ENDIAN__)
src += 2;
#endif
dstu = (unsigned char __user *)*rm; /* called Rn in the spec */
dstu += (instruction & 0x000F) << 1;
if (ma->to(dstu, src, 2))
goto fetch_fault;
ret = 0;
break;
case 0x85: /* mov.w @(disp,Rm),R0 */
srcu = (unsigned char __user *)*rm;
srcu += (instruction & 0x000F) << 1;
dst = (unsigned char *) &regs->regs[0];
*(unsigned long *)dst = 0;
#if !defined(__LITTLE_ENDIAN__)
dst += 2;
#endif
if (ma->from(dst, srcu, 2))
goto fetch_fault;
sign_extend(2, dst);
ret = 0;
break;
}
break;
case 9: /* mov.w @(disp,PC),Rn */
srcu = (unsigned char __user *)regs->pc;
srcu += 4;
srcu += (instruction & 0x00FF) << 1;
dst = (unsigned char *)rn;
*(unsigned long *)dst = 0;
#if !defined(__LITTLE_ENDIAN__)
dst += 2;
#endif
if (ma->from(dst, srcu, 2))
goto fetch_fault;
sign_extend(2, dst);
ret = 0;
break;
case 0xd: /* mov.l @(disp,PC),Rn */
srcu = (unsigned char __user *)(regs->pc & ~0x3);
srcu += 4;
srcu += (instruction & 0x00FF) << 2;
dst = (unsigned char *)rn;
*(unsigned long *)dst = 0;
if (ma->from(dst, srcu, 4))
goto fetch_fault;
ret = 0;
break;
}
return ret;
fetch_fault:
/* Argh. Address not only misaligned but also non-existent.
* Raise an EFAULT and see if it's trapped
*/
die_if_no_fixup("Fault in unaligned fixup", regs, 0);
return -EFAULT;
}
/*
* emulate the instruction in the delay slot
* - fetches the instruction from PC+2
*/
static inline int handle_delayslot(struct pt_regs *regs,
insn_size_t old_instruction,
struct mem_access *ma)
{
insn_size_t instruction;
void __user *addr = (void __user *)(regs->pc +
instruction_size(old_instruction));
if (copy_from_user(&instruction, addr, sizeof(instruction))) {
/* the instruction-fetch faulted */
if (user_mode(regs))
return -EFAULT;
/* kernel */
die("delay-slot-insn faulting in handle_unaligned_delayslot",
regs, 0);
}
return handle_unaligned_ins(instruction, regs, ma);
}
/*
* handle an instruction that does an unaligned memory access
* - have to be careful of branch delay-slot instructions that fault
* SH3:
* - if the branch would be taken PC points to the branch
* - if the branch would not be taken, PC points to delay-slot
* SH4:
* - PC always points to delayed branch
* - return 0 if handled, -EFAULT if failed (may not return if in kernel)
*/
/* Macros to determine offset from current PC for branch instructions */
/* Explicit type coercion is used to force sign extension where needed */
#define SH_PC_8BIT_OFFSET(instr) ((((signed char)(instr))*2) + 4)
#define SH_PC_12BIT_OFFSET(instr) ((((signed short)(instr<<4))>>3) + 4)
int handle_unaligned_access(insn_size_t instruction, struct pt_regs *regs,
struct mem_access *ma, int expected,
unsigned long address)
{
u_int rm;
int ret, index;
/*
* XXX: We can't handle mixed 16/32-bit instructions yet
*/
if (instruction_size(instruction) != 2)
return -EINVAL;
index = (instruction>>8)&15; /* 0x0F00 */
rm = regs->regs[index];
/*
* Log the unexpected fixups, and then pass them on to perf.
*
* We intentionally don't report the expected cases to perf as
* otherwise the trapped I/O case will skew the results too much
* to be useful.
*/
if (!expected) {
unaligned_fixups_notify(current, instruction, regs);
perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1,
regs, address);
}
ret = -EFAULT;
switch (instruction&0xF000) {
case 0x0000:
if (instruction==0x000B) {
/* rts */
ret = handle_delayslot(regs, instruction, ma);
if (ret==0)
regs->pc = regs->pr;
}
else if ((instruction&0x00FF)==0x0023) {
/* braf @Rm */
ret = handle_delayslot(regs, instruction, ma);
if (ret==0)
regs->pc += rm + 4;
}
else if ((instruction&0x00FF)==0x0003) {
/* bsrf @Rm */
ret = handle_delayslot(regs, instruction, ma);
if (ret==0) {
regs->pr = regs->pc + 4;
regs->pc += rm + 4;
}
}
else {
/* mov.[bwl] to/from memory via r0+rn */
goto simple;
}
break;
case 0x1000: /* mov.l Rm,@(disp,Rn) */
goto simple;
case 0x2000: /* mov.[bwl] to memory, possibly with pre-decrement */
goto simple;
case 0x4000:
if ((instruction&0x00FF)==0x002B) {
/* jmp @Rm */
ret = handle_delayslot(regs, instruction, ma);
if (ret==0)
regs->pc = rm;
}
else if ((instruction&0x00FF)==0x000B) {
/* jsr @Rm */
ret = handle_delayslot(regs, instruction, ma);
if (ret==0) {
regs->pr = regs->pc + 4;
regs->pc = rm;
}
}
else {
/* mov.[bwl] to/from memory via r0+rn */
goto simple;
}
break;
case 0x5000: /* mov.l @(disp,Rm),Rn */
goto simple;
case 0x6000: /* mov.[bwl] from memory, possibly with post-increment */
goto simple;
case 0x8000: /* bf lab, bf/s lab, bt lab, bt/s lab */
switch (instruction&0x0F00) {
case 0x0100: /* mov.w R0,@(disp,Rm) */
goto simple;
case 0x0500: /* mov.w @(disp,Rm),R0 */
goto simple;
case 0x0B00: /* bf lab - no delayslot*/
ret = 0;
break;
case 0x0F00: /* bf/s lab */
ret = handle_delayslot(regs, instruction, ma);
if (ret==0) {
#if defined(CONFIG_CPU_SH4) || defined(CONFIG_SH7705_CACHE_32KB)
if ((regs->sr & 0x00000001) != 0)
regs->pc += 4; /* next after slot */
else
#endif
regs->pc += SH_PC_8BIT_OFFSET(instruction);
}
break;
case 0x0900: /* bt lab - no delayslot */
ret = 0;
break;
case 0x0D00: /* bt/s lab */
ret = handle_delayslot(regs, instruction, ma);
if (ret==0) {
#if defined(CONFIG_CPU_SH4) || defined(CONFIG_SH7705_CACHE_32KB)
if ((regs->sr & 0x00000001) == 0)
regs->pc += 4; /* next after slot */
else
#endif
regs->pc += SH_PC_8BIT_OFFSET(instruction);
}
break;
}
break;
case 0x9000: /* mov.w @(disp,Rm),Rn */
goto simple;
case 0xA000: /* bra label */
ret = handle_delayslot(regs, instruction, ma);
if (ret==0)
regs->pc += SH_PC_12BIT_OFFSET(instruction);
break;
case 0xB000: /* bsr label */
ret = handle_delayslot(regs, instruction, ma);
if (ret==0) {
regs->pr = regs->pc + 4;
regs->pc += SH_PC_12BIT_OFFSET(instruction);
}
break;
case 0xD000: /* mov.l @(disp,Rm),Rn */
goto simple;
}
return ret;
/* handle non-delay-slot instruction */
simple:
ret = handle_unaligned_ins(instruction, regs, ma);
if (ret==0)
regs->pc += instruction_size(instruction);
return ret;
}
/*
* Handle various address error exceptions:
* - instruction address error:
* misaligned PC
* PC >= 0x80000000 in user mode
* - data address error (read and write)
* misaligned data access
* access to >= 0x80000000 is user mode
* Unfortuntaly we can't distinguish between instruction address error
* and data address errors caused by read accesses.
*/
asmlinkage void do_address_error(struct pt_regs *regs,
unsigned long writeaccess,
unsigned long address)
{
unsigned long error_code = 0;
mm_segment_t oldfs;
insn_size_t instruction;
int tmp;
/* Intentional ifdef */
#ifdef CONFIG_CPU_HAS_SR_RB
error_code = lookup_exception_vector();
#endif
oldfs = get_fs();
if (user_mode(regs)) {
int si_code = BUS_ADRERR;
unsigned int user_action;
local_irq_enable();
inc_unaligned_user_access();
set_fs(USER_DS);
if (copy_from_user(&instruction, (insn_size_t *)(regs->pc & ~1),
sizeof(instruction))) {
set_fs(oldfs);
goto uspace_segv;
}
set_fs(oldfs);
/* shout about userspace fixups */
unaligned_fixups_notify(current, instruction, regs);
user_action = unaligned_user_action();
if (user_action & UM_FIXUP)
goto fixup;
if (user_action & UM_SIGNAL)
goto uspace_segv;
else {
/* ignore */
regs->pc += instruction_size(instruction);
return;
}
fixup:
/* bad PC is not something we can fix */
if (regs->pc & 1) {
si_code = BUS_ADRALN;
goto uspace_segv;
}
set_fs(USER_DS);
tmp = handle_unaligned_access(instruction, regs,
&user_mem_access, 0,
address);
set_fs(oldfs);
if (tmp == 0)
return; /* sorted */
uspace_segv:
printk(KERN_NOTICE "Sending SIGBUS to \"%s\" due to unaligned "
"access (PC %lx PR %lx)\n", current->comm, regs->pc,
regs->pr);
force_sig_fault(SIGBUS, si_code, (void __user *)address);
} else {
inc_unaligned_kernel_access();
if (regs->pc & 1)
die("unaligned program counter", regs, error_code);
set_fs(KERNEL_DS);
if (copy_from_user(&instruction, (void __user *)(regs->pc),
sizeof(instruction))) {
/* Argh. Fault on the instruction itself.
This should never happen non-SMP
*/
set_fs(oldfs);
die("insn faulting in do_address_error", regs, 0);
}
unaligned_fixups_notify(current, instruction, regs);
handle_unaligned_access(instruction, regs, &user_mem_access,
0, address);
set_fs(oldfs);
}
}
#ifdef CONFIG_SH_DSP
/*
* SH-DSP support gerg@snapgear.com.
*/
int is_dsp_inst(struct pt_regs *regs)
{
unsigned short inst = 0;
/*
* Safe guard if DSP mode is already enabled or we're lacking
* the DSP altogether.
*/
if (!(current_cpu_data.flags & CPU_HAS_DSP) || (regs->sr & SR_DSP))
return 0;
get_user(inst, ((unsigned short *) regs->pc));
inst &= 0xf000;
/* Check for any type of DSP or support instruction */
if ((inst == 0xf000) || (inst == 0x4000))
return 1;
return 0;
}
#else
#define is_dsp_inst(regs) (0)
#endif /* CONFIG_SH_DSP */
#ifdef CONFIG_CPU_SH2A
asmlinkage void do_divide_error(unsigned long r4)
{
int code;
switch (r4) {
case TRAP_DIVZERO_ERROR:
code = FPE_INTDIV;
break;
case TRAP_DIVOVF_ERROR:
code = FPE_INTOVF;
break;
default:
/* Let gcc know unhandled cases don't make it past here */
return;
}
force_sig_fault(SIGFPE, code, NULL);
}
#endif
asmlinkage void do_reserved_inst(void)
{
struct pt_regs *regs = current_pt_regs();
unsigned long error_code;
#ifdef CONFIG_SH_FPU_EMU
unsigned short inst = 0;
int err;
get_user(inst, (unsigned short*)regs->pc);
err = do_fpu_inst(inst, regs);
if (!err) {
regs->pc += instruction_size(inst);
return;
}
/* not a FPU inst. */
#endif
#ifdef CONFIG_SH_DSP
/* Check if it's a DSP instruction */
if (is_dsp_inst(regs)) {
/* Enable DSP mode, and restart instruction. */
regs->sr |= SR_DSP;
/* Save DSP mode */
current->thread.dsp_status.status |= SR_DSP;
return;
}
#endif
error_code = lookup_exception_vector();
local_irq_enable();
force_sig(SIGILL);
die_if_no_fixup("reserved instruction", regs, error_code);
}
#ifdef CONFIG_SH_FPU_EMU
static int emulate_branch(unsigned short inst, struct pt_regs *regs)
{
/*
* bfs: 8fxx: PC+=d*2+4;
* bts: 8dxx: PC+=d*2+4;
* bra: axxx: PC+=D*2+4;
* bsr: bxxx: PC+=D*2+4 after PR=PC+4;
* braf:0x23: PC+=Rn*2+4;
* bsrf:0x03: PC+=Rn*2+4 after PR=PC+4;
* jmp: 4x2b: PC=Rn;
* jsr: 4x0b: PC=Rn after PR=PC+4;
* rts: 000b: PC=PR;
*/
if (((inst & 0xf000) == 0xb000) || /* bsr */
((inst & 0xf0ff) == 0x0003) || /* bsrf */
((inst & 0xf0ff) == 0x400b)) /* jsr */
regs->pr = regs->pc + 4;
if ((inst & 0xfd00) == 0x8d00) { /* bfs, bts */
regs->pc += SH_PC_8BIT_OFFSET(inst);
return 0;
}
if ((inst & 0xe000) == 0xa000) { /* bra, bsr */
regs->pc += SH_PC_12BIT_OFFSET(inst);
return 0;
}
if ((inst & 0xf0df) == 0x0003) { /* braf, bsrf */
regs->pc += regs->regs[(inst & 0x0f00) >> 8] + 4;
return 0;
}
if ((inst & 0xf0df) == 0x400b) { /* jmp, jsr */
regs->pc = regs->regs[(inst & 0x0f00) >> 8];
return 0;
}
if ((inst & 0xffff) == 0x000b) { /* rts */
regs->pc = regs->pr;
return 0;
}
return 1;
}
#endif
asmlinkage void do_illegal_slot_inst(void)
{
struct pt_regs *regs = current_pt_regs();
unsigned long inst;
if (kprobe_handle_illslot(regs->pc) == 0)
return;
#ifdef CONFIG_SH_FPU_EMU
get_user(inst, (unsigned short *)regs->pc + 1);
if (!do_fpu_inst(inst, regs)) {
get_user(inst, (unsigned short *)regs->pc);
if (!emulate_branch(inst, regs))
return;
/* fault in branch.*/
}
/* not a FPU inst. */
#endif
inst = lookup_exception_vector();
local_irq_enable();
force_sig(SIGILL);
die_if_no_fixup("illegal slot instruction", regs, inst);
}
asmlinkage void do_exception_error(void)
{
long ex;
ex = lookup_exception_vector();
die_if_kernel("exception", current_pt_regs(), ex);
}
void per_cpu_trap_init(void)
{
extern void *vbr_base;
/* NOTE: The VBR value should be at P1
(or P2, virtural "fixed" address space).
It's definitely should not in physical address. */
asm volatile("ldc %0, vbr"
: /* no output */
: "r" (&vbr_base)
: "memory");
/* disable exception blocking now when the vbr has been setup */
clear_bl_bit();
}
void *set_exception_table_vec(unsigned int vec, void *handler)
{
extern void *exception_handling_table[];
void *old_handler;
old_handler = exception_handling_table[vec];
exception_handling_table[vec] = handler;
return old_handler;
}
void __init trap_init(void)
{
set_exception_table_vec(TRAP_RESERVED_INST, do_reserved_inst);
set_exception_table_vec(TRAP_ILLEGAL_SLOT_INST, do_illegal_slot_inst);
#if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SH_FPU) || \
defined(CONFIG_SH_FPU_EMU)
/*
* For SH-4 lacking an FPU, treat floating point instructions as
* reserved. They'll be handled in the math-emu case, or faulted on
* otherwise.
*/
set_exception_table_evt(0x800, do_reserved_inst);
set_exception_table_evt(0x820, do_illegal_slot_inst);
#elif defined(CONFIG_SH_FPU)
set_exception_table_evt(0x800, fpu_state_restore_trap_handler);
set_exception_table_evt(0x820, fpu_state_restore_trap_handler);
#endif
#ifdef CONFIG_CPU_SH2
set_exception_table_vec(TRAP_ADDRESS_ERROR, address_error_trap_handler);
#endif
#ifdef CONFIG_CPU_SH2A
set_exception_table_vec(TRAP_DIVZERO_ERROR, do_divide_error);
set_exception_table_vec(TRAP_DIVOVF_ERROR, do_divide_error);
#ifdef CONFIG_SH_FPU
set_exception_table_vec(TRAP_FPU_ERROR, fpu_error_trap_handler);
#endif
#endif
#ifdef TRAP_UBC
set_exception_table_vec(TRAP_UBC, breakpoint_trap_handler);
#endif
}
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