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linux/arch/sh/kernel/traps.c
Paul Mundt 1f666587db sh: Fix exception_handling_table alignment. 
With the recent change ripping out interrupt_table, explicit
padding of the table was missing, causing bad things to happen
when manually inserting handlers in to the table. This problem
particularly showed up in relation to do_fpu_state_restore()
which was inserted quite deeply in to the table and ended up
scribbling over a slab object.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2006-10-19 16:30:32 +09:00

811 lines
18 KiB
C
Raw Blame History

/*
* '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 - 2006 Paul Mundt
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/io.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#ifdef CONFIG_SH_KGDB
#include <asm/kgdb.h>
#define CHK_REMOTE_DEBUG(regs) \
{ \
if (kgdb_debug_hook && !user_mode(regs))\
(*kgdb_debug_hook)(regs); \
}
#else
#define CHK_REMOTE_DEBUG(regs)
#endif
#ifdef CONFIG_CPU_SH2
#define TRAP_RESERVED_INST 4
#define TRAP_ILLEGAL_SLOT_INST 6
#else
#define TRAP_RESERVED_INST 12
#define TRAP_ILLEGAL_SLOT_INST 13
#endif
static void dump_mem(const char *str, unsigned long bottom, unsigned long top)
{
unsigned long p;
int i;
printk("%s(0x%08lx to 0x%08lx)\n", str, bottom, top);
for (p = bottom & ~31; p < top; ) {
printk("%04lx: ", p & 0xffff);
for (i = 0; i < 8; i++, p += 4) {
unsigned int val;
if (p < bottom || p >= top)
printk(" ");
else {
if (__get_user(val, (unsigned int __user *)p)) {
printk("\n");
return;
}
printk("%08x ", val);
}
}
printk("\n");
}
}
DEFINE_SPINLOCK(die_lock);
void die(const char * str, struct pt_regs * regs, long err)
{
static int die_counter;
console_verbose();
spin_lock_irq(&die_lock);
bust_spinlocks(1);
printk("%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
CHK_REMOTE_DEBUG(regs);
print_modules();
show_regs(regs);
printk("Process: %s (pid: %d, stack limit = %p)\n",
current->comm, current->pid, task_stack_page(current) + 1);
if (!user_mode(regs) || in_interrupt())
dump_mem("Stack: ", regs->regs[15], THREAD_SIZE +
(unsigned long)task_stack_page(current));
bust_spinlocks(0);
spin_unlock_irq(&die_lock);
do_exit(SIGSEGV);
}
static inline void die_if_kernel(const char *str, struct pt_regs *regs,
long err)
{
if (!user_mode(regs))
die(str, regs, err);
}
static int handle_unaligned_notify_count = 10;
/*
* try and fix up kernelspace address errors
* - userspace errors just cause EFAULT to be returned, resulting in SEGV
* - kernel/userspace interfaces cause a jump to an appropriate handler
* - other kernel errors are bad
* - return 0 if fixed-up, -EFAULT if non-fatal (to the kernel) fault
*/
static int die_if_no_fixup(const char * str, struct pt_regs * regs, long err)
{
if (!user_mode(regs)) {
const struct exception_table_entry *fixup;
fixup = search_exception_tables(regs->pc);
if (fixup) {
regs->pc = fixup->fixup;
return 0;
}
die(str, regs, err);
}
return -EFAULT;
}
/*
* 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(u16 instruction, struct pt_regs *regs)
{
int ret, index, count;
unsigned long *rm, *rn;
unsigned char *src, *dst;
index = (instruction>>8)&15; /* 0x0F00 */
rn = &regs->regs[index];
index = (instruction>>4)&15; /* 0x00F0 */
rm = &regs->regs[index];
count = 1<<(instruction&3);
ret = -EFAULT;
switch (instruction>>12) {
case 0: /* mov.[bwl] to/from memory via r0+rn */
if (instruction & 8) {
/* from memory */
src = (unsigned char*) *rm;
src += regs->regs[0];
dst = (unsigned char*) rn;
*(unsigned long*)dst = 0;
#ifdef __LITTLE_ENDIAN__
if (copy_from_user(dst, src, count))
goto fetch_fault;
if ((count == 2) && dst[1] & 0x80) {
dst[2] = 0xff;
dst[3] = 0xff;
}
#else
dst += 4-count;
if (__copy_user(dst, src, count))
goto fetch_fault;
if ((count == 2) && dst[2] & 0x80) {
dst[0] = 0xff;
dst[1] = 0xff;
}
#endif
} else {
/* to memory */
src = (unsigned char*) rm;
#if !defined(__LITTLE_ENDIAN__)
src += 4-count;
#endif
dst = (unsigned char*) *rn;
dst += regs->regs[0];
if (copy_to_user(dst, src, count))
goto fetch_fault;
}
ret = 0;
break;
case 1: /* mov.l Rm,@(disp,Rn) */
src = (unsigned char*) rm;
dst = (unsigned char*) *rn;
dst += (instruction&0x000F)<<2;
if (copy_to_user(dst,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;
dst = (unsigned char*) *rn;
#if !defined(__LITTLE_ENDIAN__)
src += 4-count;
#endif
if (copy_to_user(dst, src, count))
goto fetch_fault;
ret = 0;
break;
case 5: /* mov.l @(disp,Rm),Rn */
src = (unsigned char*) *rm;
src += (instruction&0x000F)<<2;
dst = (unsigned char*) rn;
*(unsigned long*)dst = 0;
if (copy_from_user(dst,src,4))
goto fetch_fault;
ret = 0;
break;
case 6: /* mov.[bwl] from memory, possibly with post-increment */
src = (unsigned char*) *rm;
if (instruction & 4)
*rm += count;
dst = (unsigned char*) rn;
*(unsigned long*)dst = 0;
#ifdef __LITTLE_ENDIAN__
if (copy_from_user(dst, src, count))
goto fetch_fault;
if ((count == 2) && dst[1] & 0x80) {
dst[2] = 0xff;
dst[3] = 0xff;
}
#else
dst += 4-count;
if (copy_from_user(dst, src, count))
goto fetch_fault;
if ((count == 2) && dst[2] & 0x80) {
dst[0] = 0xff;
dst[1] = 0xff;
}
#endif
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
dst = (unsigned char*) *rm; /* called Rn in the spec */
dst += (instruction&0x000F)<<1;
if (copy_to_user(dst, src, 2))
goto fetch_fault;
ret = 0;
break;
case 0x85: /* mov.w @(disp,Rm),R0 */
src = (unsigned char*) *rm;
src += (instruction&0x000F)<<1;
dst = (unsigned char*) &regs->regs[0];
*(unsigned long*)dst = 0;
#if !defined(__LITTLE_ENDIAN__)
dst += 2;
#endif
if (copy_from_user(dst, src, 2))
goto fetch_fault;
#ifdef __LITTLE_ENDIAN__
if (dst[1] & 0x80) {
dst[2] = 0xff;
dst[3] = 0xff;
}
#else
if (dst[2] & 0x80) {
dst[0] = 0xff;
dst[1] = 0xff;
}
#endif
ret = 0;
break;
}
break;
}
return ret;
fetch_fault:
/* Argh. Address not only misaligned but also non-existent.
* Raise an EFAULT and see if it's trapped
*/
return die_if_no_fixup("Fault in unaligned fixup", regs, 0);
}
/*
* emulate the instruction in the delay slot
* - fetches the instruction from PC+2
*/
static inline int handle_unaligned_delayslot(struct pt_regs *regs)
{
u16 instruction;
if (copy_from_user(&instruction, (u16 *)(regs->pc+2), 2)) {
/* 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);
}
/*
* 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)
static int handle_unaligned_access(u16 instruction, struct pt_regs *regs)
{
u_int rm;
int ret, index;
index = (instruction>>8)&15; /* 0x0F00 */
rm = regs->regs[index];
/* shout about the first ten userspace fixups */
if (user_mode(regs) && handle_unaligned_notify_count>0) {
handle_unaligned_notify_count--;
printk("Fixing up unaligned userspace access in \"%s\" pid=%d pc=0x%p ins=0x%04hx\n",
current->comm,current->pid,(u16*)regs->pc,instruction);
}
ret = -EFAULT;
switch (instruction&0xF000) {
case 0x0000:
if (instruction==0x000B) {
/* rts */
ret = handle_unaligned_delayslot(regs);
if (ret==0)
regs->pc = regs->pr;
}
else if ((instruction&0x00FF)==0x0023) {
/* braf @Rm */
ret = handle_unaligned_delayslot(regs);
if (ret==0)
regs->pc += rm + 4;
}
else if ((instruction&0x00FF)==0x0003) {
/* bsrf @Rm */
ret = handle_unaligned_delayslot(regs);
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_unaligned_delayslot(regs);
if (ret==0)
regs->pc = rm;
}
else if ((instruction&0x00FF)==0x000B) {
/* jsr @Rm */
ret = handle_unaligned_delayslot(regs);
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*/
break;
case 0x0F00: /* bf/s lab */
ret = handle_unaligned_delayslot(regs);
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 */
break;
case 0x0D00: /* bt/s lab */
ret = handle_unaligned_delayslot(regs);
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 0xA000: /* bra label */
ret = handle_unaligned_delayslot(regs);
if (ret==0)
regs->pc += SH_PC_12BIT_OFFSET(instruction);
break;
case 0xB000: /* bsr label */
ret = handle_unaligned_delayslot(regs);
if (ret==0) {
regs->pr = regs->pc + 4;
regs->pc += SH_PC_12BIT_OFFSET(instruction);
}
break;
}
return ret;
/* handle non-delay-slot instruction */
simple:
ret = handle_unaligned_ins(instruction,regs);
if (ret==0)
regs->pc += 2;
return ret;
}
/*
* Handle various address error exceptions
*/
asmlinkage void do_address_error(struct pt_regs *regs,
unsigned long writeaccess,
unsigned long address)
{
unsigned long error_code;
mm_segment_t oldfs;
u16 instruction;
int tmp;
asm volatile("stc r2_bank,%0": "=r" (error_code));
oldfs = get_fs();
if (user_mode(regs)) {
local_irq_enable();
current->thread.error_code = error_code;
current->thread.trap_no = (writeaccess) ? 8 : 7;
/* bad PC is not something we can fix */
if (regs->pc & 1)
goto uspace_segv;
set_fs(USER_DS);
if (copy_from_user(&instruction, (u16 *)(regs->pc), 2)) {
/* Argh. Fault on the instruction itself.
This should never happen non-SMP
*/
set_fs(oldfs);
goto uspace_segv;
}
tmp = handle_unaligned_access(instruction, regs);
set_fs(oldfs);
if (tmp==0)
return; /* sorted */
uspace_segv:
printk(KERN_NOTICE "Killing process \"%s\" due to unaligned access\n", current->comm);
force_sig(SIGSEGV, current);
} else {
if (regs->pc & 1)
die("unaligned program counter", regs, error_code);
set_fs(KERNEL_DS);
if (copy_from_user(&instruction, (u16 *)(regs->pc), 2)) {
/* Argh. Fault on the instruction itself.
This should never happen non-SMP
*/
set_fs(oldfs);
die("insn faulting in do_address_error", regs, 0);
}
handle_unaligned_access(instruction, regs);
set_fs(oldfs);
}
}
#ifdef CONFIG_SH_DSP
/*
* SH-DSP support gerg@snapgear.com.
*/
int is_dsp_inst(struct pt_regs *regs)
{
unsigned short inst;
/*
* Safe guard if DSP mode is already enabled or we're lacking
* the DSP altogether.
*/
if (!(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 */
/* arch/sh/kernel/cpu/sh4/fpu.c */
extern int do_fpu_inst(unsigned short, struct pt_regs *);
extern asmlinkage void do_fpu_state_restore(unsigned long r4, unsigned long r5,
unsigned long r6, unsigned long r7, struct pt_regs regs);
asmlinkage void do_reserved_inst(unsigned long r4, unsigned long r5,
unsigned long r6, unsigned long r7,
struct pt_regs regs)
{
unsigned long error_code;
struct task_struct *tsk = current;
#ifdef CONFIG_SH_FPU_EMU
unsigned short inst;
int err;
get_user(inst, (unsigned short*)regs.pc);
err = do_fpu_inst(inst, &regs);
if (!err) {
regs.pc += 2;
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;
return;
}
#endif
asm volatile("stc r2_bank, %0": "=r" (error_code));
local_irq_enable();
tsk->thread.error_code = error_code;
tsk->thread.trap_no = TRAP_RESERVED_INST;
CHK_REMOTE_DEBUG(&regs);
force_sig(SIGILL, tsk);
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 & 0xfd00) == 0x8d00) {
regs->pc += SH_PC_8BIT_OFFSET(inst);
return 0;
}
if ((inst & 0xe000) == 0xa000) {
regs->pc += SH_PC_12BIT_OFFSET(inst);
return 0;
}
if ((inst & 0xf0df) == 0x0003) {
regs->pc += regs->regs[(inst & 0x0f00) >> 8] + 4;
return 0;
}
if ((inst & 0xf0df) == 0x400b) {
regs->pc = regs->regs[(inst & 0x0f00) >> 8];
return 0;
}
if ((inst & 0xffff) == 0x000b) {
regs->pc = regs->pr;
return 0;
}
return 1;
}
#endif
asmlinkage void do_illegal_slot_inst(unsigned long r4, unsigned long r5,
unsigned long r6, unsigned long r7,
struct pt_regs regs)
{
unsigned long error_code;
struct task_struct *tsk = current;
#ifdef CONFIG_SH_FPU_EMU
unsigned short inst;
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
asm volatile("stc r2_bank, %0": "=r" (error_code));
local_irq_enable();
tsk->thread.error_code = error_code;
tsk->thread.trap_no = TRAP_RESERVED_INST;
CHK_REMOTE_DEBUG(&regs);
force_sig(SIGILL, tsk);
die_if_no_fixup("illegal slot instruction", &regs, error_code);
}
asmlinkage void do_exception_error(unsigned long r4, unsigned long r5,
unsigned long r6, unsigned long r7,
struct pt_regs regs)
{
long ex;
asm volatile("stc r2_bank, %0" : "=r" (ex));
die_if_kernel("exception", &regs, ex);
}
#if defined(CONFIG_SH_STANDARD_BIOS)
void *gdb_vbr_vector;
static inline void __init gdb_vbr_init(void)
{
register unsigned long vbr;
/*
* Read the old value of the VBR register to initialise
* the vector through which debug and BIOS traps are
* delegated by the Linux trap handler.
*/
asm volatile("stc vbr, %0" : "=r" (vbr));
gdb_vbr_vector = (void *)(vbr + 0x100);
printk("Setting GDB trap vector to 0x%08lx\n",
(unsigned long)gdb_vbr_vector);
}
#endif
void __init per_cpu_trap_init(void)
{
extern void *vbr_base;
#ifdef CONFIG_SH_STANDARD_BIOS
gdb_vbr_init();
#endif
/* 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");
}
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, do_fpu_state_restore);
set_exception_table_evt(0x820, do_fpu_state_restore);
#endif
/* Setup VBR for boot cpu */
per_cpu_trap_init();
}
void show_trace(struct task_struct *tsk, unsigned long *sp,
struct pt_regs *regs)
{
unsigned long addr;
if (regs && user_mode(regs))
return;
printk("\nCall trace: ");
#ifdef CONFIG_KALLSYMS
printk("\n");
#endif
while (!kstack_end(sp)) {
addr = *sp++;
if (kernel_text_address(addr))
print_ip_sym(addr);
}
printk("\n");
}
void show_stack(struct task_struct *tsk, unsigned long *sp)
{
unsigned long stack;
if (!tsk)
tsk = current;
if (tsk == current)
sp = (unsigned long *)current_stack_pointer;
else
sp = (unsigned long *)tsk->thread.sp;
stack = (unsigned long)sp;
dump_mem("Stack: ", stack, THREAD_SIZE +
(unsigned long)task_stack_page(tsk));
show_trace(tsk, sp, NULL);
}
void dump_stack(void)
{
show_stack(NULL, NULL);
}
EXPORT_SYMBOL(dump_stack);
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