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alistair23-linux/arch/openrisc/kernel/traps.c
Stafford Horne ae15a41a64 openrisc: entry: Fix delay slot exception detection 
Originally in patch e6d20c55a4 ("openrisc: entry: Fix delay slot
detection") I fixed delay slot detection, but only for QEMU.  We missed
that hardware delay slot detection using delay slot exception flag (DSX)
was still broken.  This was because QEMU set the DSX flag in both
pre-exception supervision register (ESR) and supervision register (SR)
register, but on real hardware the DSX flag is only set on the SR
register during exceptions.

Fix this by carrying the DSX flag into the SR register during exception.
We also update the DSX flag read locations to read the value from the SR
register not the pt_regs SR register which represents ESR.  The ESR
should never have the DSX flag set.

In the process I updated/removed a few comments to match the current
state.  Including removing a comment saying that the DSX detection logic
was inefficient and needed to be rewritten.

I have tested this on QEMU with a patch ensuring it matches the hardware
specification.

Link: https://lists.gnu.org/archive/html/qemu-devel/2018-07/msg00000.html
Fixes: e6d20c55a4 ("openrisc: entry: Fix delay slot detection")
Signed-off-by: Stafford Horne <shorne@gmail.com>
2018-07-01 16:48:24 +09:00

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/*
* OpenRISC traps.c
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* Modifications for the OpenRISC architecture:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Here we handle the break vectors not used by the system call
* mechanism, as well as some general stack/register dumping
* things.
*
*/
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/kernel.h>
#include <linux/extable.h>
#include <linux/kmod.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/kallsyms.h>
#include <linux/uaccess.h>
#include <asm/segment.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/unwinder.h>
#include <asm/sections.h>
int kstack_depth_to_print = 0x180;
int lwa_flag;
unsigned long __user *lwa_addr;
void print_trace(void *data, unsigned long addr, int reliable)
{
pr_emerg("[<%p>] %s%pS\n", (void *) addr, reliable ? "" : "? ",
(void *) addr);
}
/* displays a short stack trace */
void show_stack(struct task_struct *task, unsigned long *esp)
{
if (esp == NULL)
esp = (unsigned long *)&esp;
pr_emerg("Call trace:\n");
unwind_stack(NULL, esp, print_trace);
}
void show_trace_task(struct task_struct *tsk)
{
/*
* TODO: SysRq-T trace dump...
*/
}
void show_registers(struct pt_regs *regs)
{
int i;
int in_kernel = 1;
unsigned long esp;
esp = (unsigned long)(regs->sp);
if (user_mode(regs))
in_kernel = 0;
printk("CPU #: %d\n"
" PC: %08lx SR: %08lx SP: %08lx\n",
smp_processor_id(), regs->pc, regs->sr, regs->sp);
printk("GPR00: %08lx GPR01: %08lx GPR02: %08lx GPR03: %08lx\n",
0L, regs->gpr[1], regs->gpr[2], regs->gpr[3]);
printk("GPR04: %08lx GPR05: %08lx GPR06: %08lx GPR07: %08lx\n",
regs->gpr[4], regs->gpr[5], regs->gpr[6], regs->gpr[7]);
printk("GPR08: %08lx GPR09: %08lx GPR10: %08lx GPR11: %08lx\n",
regs->gpr[8], regs->gpr[9], regs->gpr[10], regs->gpr[11]);
printk("GPR12: %08lx GPR13: %08lx GPR14: %08lx GPR15: %08lx\n",
regs->gpr[12], regs->gpr[13], regs->gpr[14], regs->gpr[15]);
printk("GPR16: %08lx GPR17: %08lx GPR18: %08lx GPR19: %08lx\n",
regs->gpr[16], regs->gpr[17], regs->gpr[18], regs->gpr[19]);
printk("GPR20: %08lx GPR21: %08lx GPR22: %08lx GPR23: %08lx\n",
regs->gpr[20], regs->gpr[21], regs->gpr[22], regs->gpr[23]);
printk("GPR24: %08lx GPR25: %08lx GPR26: %08lx GPR27: %08lx\n",
regs->gpr[24], regs->gpr[25], regs->gpr[26], regs->gpr[27]);
printk("GPR28: %08lx GPR29: %08lx GPR30: %08lx GPR31: %08lx\n",
regs->gpr[28], regs->gpr[29], regs->gpr[30], regs->gpr[31]);
printk(" RES: %08lx oGPR11: %08lx\n",
regs->gpr[11], regs->orig_gpr11);
printk("Process %s (pid: %d, stackpage=%08lx)\n",
current->comm, current->pid, (unsigned long)current);
/*
* When in-kernel, we also print out the stack and code at the
* time of the fault..
*/
if (in_kernel) {
printk("\nStack: ");
show_stack(NULL, (unsigned long *)esp);
printk("\nCode: ");
if (regs->pc < PAGE_OFFSET)
goto bad;
for (i = -24; i < 24; i++) {
unsigned char c;
if (__get_user(c, &((unsigned char *)regs->pc)[i])) {
bad:
printk(" Bad PC value.");
break;
}
if (i == 0)
printk("(%02x) ", c);
else
printk("%02x ", c);
}
}
printk("\n");
}
void nommu_dump_state(struct pt_regs *regs,
unsigned long ea, unsigned long vector)
{
int i;
unsigned long addr, stack = regs->sp;
printk("\n\r[nommu_dump_state] :: ea %lx, vector %lx\n\r", ea, vector);
printk("CPU #: %d\n"
" PC: %08lx SR: %08lx SP: %08lx\n",
0, regs->pc, regs->sr, regs->sp);
printk("GPR00: %08lx GPR01: %08lx GPR02: %08lx GPR03: %08lx\n",
0L, regs->gpr[1], regs->gpr[2], regs->gpr[3]);
printk("GPR04: %08lx GPR05: %08lx GPR06: %08lx GPR07: %08lx\n",
regs->gpr[4], regs->gpr[5], regs->gpr[6], regs->gpr[7]);
printk("GPR08: %08lx GPR09: %08lx GPR10: %08lx GPR11: %08lx\n",
regs->gpr[8], regs->gpr[9], regs->gpr[10], regs->gpr[11]);
printk("GPR12: %08lx GPR13: %08lx GPR14: %08lx GPR15: %08lx\n",
regs->gpr[12], regs->gpr[13], regs->gpr[14], regs->gpr[15]);
printk("GPR16: %08lx GPR17: %08lx GPR18: %08lx GPR19: %08lx\n",
regs->gpr[16], regs->gpr[17], regs->gpr[18], regs->gpr[19]);
printk("GPR20: %08lx GPR21: %08lx GPR22: %08lx GPR23: %08lx\n",
regs->gpr[20], regs->gpr[21], regs->gpr[22], regs->gpr[23]);
printk("GPR24: %08lx GPR25: %08lx GPR26: %08lx GPR27: %08lx\n",
regs->gpr[24], regs->gpr[25], regs->gpr[26], regs->gpr[27]);
printk("GPR28: %08lx GPR29: %08lx GPR30: %08lx GPR31: %08lx\n",
regs->gpr[28], regs->gpr[29], regs->gpr[30], regs->gpr[31]);
printk(" RES: %08lx oGPR11: %08lx\n",
regs->gpr[11], regs->orig_gpr11);
printk("Process %s (pid: %d, stackpage=%08lx)\n",
((struct task_struct *)(__pa(current)))->comm,
((struct task_struct *)(__pa(current)))->pid,
(unsigned long)current);
printk("\nStack: ");
printk("Stack dump [0x%08lx]:\n", (unsigned long)stack);
for (i = 0; i < kstack_depth_to_print; i++) {
if (((long)stack & (THREAD_SIZE - 1)) == 0)
break;
stack++;
printk("%lx :: sp + %02d: 0x%08lx\n", stack, i * 4,
*((unsigned long *)(__pa(stack))));
}
printk("\n");
printk("Call Trace: ");
i = 1;
while (((long)stack & (THREAD_SIZE - 1)) != 0) {
addr = *((unsigned long *)__pa(stack));
stack++;
if (kernel_text_address(addr)) {
if (i && ((i % 6) == 0))
printk("\n ");
printk(" [<%08lx>]", addr);
i++;
}
}
printk("\n");
printk("\nCode: ");
for (i = -24; i < 24; i++) {
unsigned char c;
c = ((unsigned char *)(__pa(regs->pc)))[i];
if (i == 0)
printk("(%02x) ", c);
else
printk("%02x ", c);
}
printk("\n");
}
/* This is normally the 'Oops' routine */
void die(const char *str, struct pt_regs *regs, long err)
{
console_verbose();
printk("\n%s#: %04lx\n", str, err & 0xffff);
show_registers(regs);
#ifdef CONFIG_JUMP_UPON_UNHANDLED_EXCEPTION
printk("\n\nUNHANDLED_EXCEPTION: entering infinite loop\n");
/* shut down interrupts */
local_irq_disable();
__asm__ __volatile__("l.nop 1");
do {} while (1);
#endif
do_exit(SIGSEGV);
}
/* This is normally the 'Oops' routine */
void die_if_kernel(const char *str, struct pt_regs *regs, long err)
{
if (user_mode(regs))
return;
die(str, regs, err);
}
void unhandled_exception(struct pt_regs *regs, int ea, int vector)
{
printk("Unable to handle exception at EA =0x%x, vector 0x%x",
ea, vector);
die("Oops", regs, 9);
}
void __init trap_init(void)
{
/* Nothing needs to be done */
}
asmlinkage void do_trap(struct pt_regs *regs, unsigned long address)
{
force_sig_fault(SIGTRAP, TRAP_TRACE, (void __user *)address, current);
regs->pc += 4;
}
asmlinkage void do_unaligned_access(struct pt_regs *regs, unsigned long address)
{
if (user_mode(regs)) {
/* Send a SIGBUS */
force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)address, current);
} else {
printk("KERNEL: Unaligned Access 0x%.8lx\n", address);
show_registers(regs);
die("Die:", regs, address);
}
}
asmlinkage void do_bus_fault(struct pt_regs *regs, unsigned long address)
{
if (user_mode(regs)) {
/* Send a SIGBUS */
force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, current);
} else { /* Kernel mode */
printk("KERNEL: Bus error (SIGBUS) 0x%.8lx\n", address);
show_registers(regs);
die("Die:", regs, address);
}
}
static inline int in_delay_slot(struct pt_regs *regs)
{
#ifdef CONFIG_OPENRISC_NO_SPR_SR_DSX
/* No delay slot flag, do the old way */
unsigned int op, insn;
insn = *((unsigned int *)regs->pc);
op = insn >> 26;
switch (op) {
case 0x00: /* l.j */
case 0x01: /* l.jal */
case 0x03: /* l.bnf */
case 0x04: /* l.bf */
case 0x11: /* l.jr */
case 0x12: /* l.jalr */
return 1;
default:
return 0;
}
#else
return mfspr(SPR_SR) & SPR_SR_DSX;
#endif
}
static inline void adjust_pc(struct pt_regs *regs, unsigned long address)
{
int displacement;
unsigned int rb, op, jmp;
if (unlikely(in_delay_slot(regs))) {
/* In delay slot, instruction at pc is a branch, simulate it */
jmp = *((unsigned int *)regs->pc);
displacement = sign_extend32(((jmp) & 0x3ffffff) << 2, 27);
rb = (jmp & 0x0000ffff) >> 11;
op = jmp >> 26;
switch (op) {
case 0x00: /* l.j */
regs->pc += displacement;
return;
case 0x01: /* l.jal */
regs->pc += displacement;
regs->gpr[9] = regs->pc + 8;
return;
case 0x03: /* l.bnf */
if (regs->sr & SPR_SR_F)
regs->pc += 8;
else
regs->pc += displacement;
return;
case 0x04: /* l.bf */
if (regs->sr & SPR_SR_F)
regs->pc += displacement;
else
regs->pc += 8;
return;
case 0x11: /* l.jr */
regs->pc = regs->gpr[rb];
return;
case 0x12: /* l.jalr */
regs->pc = regs->gpr[rb];
regs->gpr[9] = regs->pc + 8;
return;
default:
break;
}
} else {
regs->pc += 4;
}
}
static inline void simulate_lwa(struct pt_regs *regs, unsigned long address,
unsigned int insn)
{
unsigned int ra, rd;
unsigned long value;
unsigned long orig_pc;
long imm;
const struct exception_table_entry *entry;
orig_pc = regs->pc;
adjust_pc(regs, address);
ra = (insn >> 16) & 0x1f;
rd = (insn >> 21) & 0x1f;
imm = (short)insn;
lwa_addr = (unsigned long __user *)(regs->gpr[ra] + imm);
if ((unsigned long)lwa_addr & 0x3) {
do_unaligned_access(regs, address);
return;
}
if (get_user(value, lwa_addr)) {
if (user_mode(regs)) {
force_sig(SIGSEGV, current);
return;
}
if ((entry = search_exception_tables(orig_pc))) {
regs->pc = entry->fixup;
return;
}
/* kernel access in kernel space, load it directly */
value = *((unsigned long *)lwa_addr);
}
lwa_flag = 1;
regs->gpr[rd] = value;
}
static inline void simulate_swa(struct pt_regs *regs, unsigned long address,
unsigned int insn)
{
unsigned long __user *vaddr;
unsigned long orig_pc;
unsigned int ra, rb;
long imm;
const struct exception_table_entry *entry;
orig_pc = regs->pc;
adjust_pc(regs, address);
ra = (insn >> 16) & 0x1f;
rb = (insn >> 11) & 0x1f;
imm = (short)(((insn & 0x2200000) >> 10) | (insn & 0x7ff));
vaddr = (unsigned long __user *)(regs->gpr[ra] + imm);
if (!lwa_flag || vaddr != lwa_addr) {
regs->sr &= ~SPR_SR_F;
return;
}
if ((unsigned long)vaddr & 0x3) {
do_unaligned_access(regs, address);
return;
}
if (put_user(regs->gpr[rb], vaddr)) {
if (user_mode(regs)) {
force_sig(SIGSEGV, current);
return;
}
if ((entry = search_exception_tables(orig_pc))) {
regs->pc = entry->fixup;
return;
}
/* kernel access in kernel space, store it directly */
*((unsigned long *)vaddr) = regs->gpr[rb];
}
lwa_flag = 0;
regs->sr |= SPR_SR_F;
}
#define INSN_LWA 0x1b
#define INSN_SWA 0x33
asmlinkage void do_illegal_instruction(struct pt_regs *regs,
unsigned long address)
{
unsigned int op;
unsigned int insn = *((unsigned int *)address);
op = insn >> 26;
switch (op) {
case INSN_LWA:
simulate_lwa(regs, address, insn);
return;
case INSN_SWA:
simulate_swa(regs, address, insn);
return;
default:
break;
}
if (user_mode(regs)) {
/* Send a SIGILL */
force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)address, current);
} else { /* Kernel mode */
printk("KERNEL: Illegal instruction (SIGILL) 0x%.8lx\n",
address);
show_registers(regs);
die("Die:", regs, address);
}
}
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