/*
* unaligned.c: Unaligned load/store trap handling with special
* cases for the kernel to do them more quickly.
*
* Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
* Copyright (C) 1996 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <asm/ptrace.h>
#include <asm/processor.h>
#include <asm/uaccess.h>
#include <linux/smp.h>
#include <linux/perf_event.h>
enum direction {
load, /* ld, ldd, ldh, ldsh */
store, /* st, std, sth, stsh */
both, /* Swap, ldstub, etc. */
fpload,
fpstore,
invalid,
};
static inline enum direction decode_direction(unsigned int insn)
{
unsigned long tmp = (insn >> 21) & 1;
if(!tmp)
return load;
else {
if(((insn>>19)&0x3f) == 15)
return both;
else
return store;
}
}
/* 8 = double-word, 4 = word, 2 = half-word */
static inline int decode_access_size(unsigned int insn)
{
insn = (insn >> 19) & 3;
if(!insn)
return 4;
else if(insn == 3)
return 8;
else if(insn == 2)
return 2;
else {
printk("Impossible unaligned trap. insn=%08x\n", insn);
die_if_kernel("Byte sized unaligned access?!?!", current->thread.kregs);
return 4; /* just to keep gcc happy. */
}
}
/* 0x400000 = signed, 0 = unsigned */
static inline int decode_signedness(unsigned int insn)
{
return (insn & 0x400000);
}
static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
unsigned int rd)
{
if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
/* Wheee... */
__asm__ __volatile__("save %sp, -0x40, %sp\n\t"
"save %sp, -0x40, %sp\n\t"
"save %sp, -0x40, %sp\n\t"
"save %sp, -0x40, %sp\n\t"
"save %sp, -0x40, %sp\n\t"
"save %sp, -0x40, %sp\n\t"
"save %sp, -0x40, %sp\n\t"
"restore; restore; restore; restore;\n\t"
"restore; restore; restore;\n\t");
}
}
static inline int sign_extend_imm13(int imm)
{
return imm << 19 >> 19;
}
static inline unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
{
struct reg_window32 *win;
if(reg < 16)
return (!reg ? 0 : regs->u_regs[reg]);
/* Ho hum, the slightly complicated case. */
win = (struct reg_window32 *) regs->u_regs[UREG_FP];
return win->locals[reg - 16]; /* yes, I know what this does... */
}
static inline unsigned long safe_fetch_reg(unsigned int reg, struct pt_regs *regs)
{
struct reg_window32 __user *win;
unsigned long ret;
if (reg < 16)
return (!reg ? 0 : regs->u_regs[reg]);
/* Ho hum, the slightly complicated case. */
win = (struct reg_window32 __user *) regs->u_regs[UREG_FP];
if ((unsigned long)win & 3)
return -1;
if (get_user(ret, &win->locals[reg - 16]))
return -1;
return ret;
}
static inline unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs)
{
struct reg_window32 *win;
if(reg < 16)
return ®s->u_regs[reg];
win = (struct reg_window32 *) regs->u_regs[UREG_FP];
return &win->locals[reg - 16];
}
static unsigned long compute_effective_address(struct pt_regs *regs,
unsigned int insn)
{
unsigned int rs1 = (insn >> 14) & 0x1f;
unsigned int rs2 = insn & 0x1f;
unsigned int rd = (insn >> 25) & 0x1f;
if(insn & 0x2000) {
maybe_flush_windows(rs1, 0, rd);
return (fetch_reg(rs1, regs) + sign_extend_imm13(insn));
} else {
maybe_flush_windows(rs1, rs2, rd);
return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs));
}
}
unsigned long safe_compute_effective_address(struct pt_regs *regs,
unsigned int insn)
{
unsigned int rs1 = (insn >> 14) & 0x1f;
unsigned int rs2 = insn & 0x1f;
unsigned int rd = (insn >> 25) & 0x1f;
if(insn & 0x2000) {
maybe_flush_windows(rs1, 0, rd);
return (safe_fetch_reg(rs1, regs) + sign_extend_imm13(insn));
} else {
maybe_flush_windows(rs1, rs2, rd);
return (safe_fetch_reg(rs1, regs) + safe_fetch_reg(rs2, regs));
}
}
/* This is just to make gcc think panic does return... */
static void unaligned_panic(char *str)
{
panic(str);
}
/* una_asm.S */
extern int do_int_load(unsigned long *dest_reg, int size,
unsigned long *saddr, int is_signed);
extern int __do_int_store(unsigned long *dst_addr, int size,
unsigned long *src_val);
static int do_int_store(int reg_num, int size, unsigned long *dst_addr,
struct pt_regs *regs)
{
unsigned long zero[2] = { 0, 0 };
unsigned long *src_val;
if (reg_num)
src_val = fetch_reg_addr(reg_num, regs);
else {
src_val = &zero[0];
if (size == 8)
zero[1] = fetch_reg(1, regs);
}
return __do_int_store(dst_addr, size, src_val);
}
extern void smp_capture(void);
extern void smp_release(void);
static inline void advance(struct pt_regs *regs)
{
regs->pc = regs->npc;
regs->npc += 4;
}
static inline int floating_point_load_or_store_p(unsigned int insn)
{
return (insn >> 24) & 1;
}
static inline int ok_for_kernel(unsigned int insn)
{
return !floating_point_load_or_store_p(insn);
}
static void kernel_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
{
unsigned long g2 = regs->u_regs [UREG_G2];
unsigned long fixup = search_extables_range(regs->pc, &g2);
if (!fixup) {
unsigned long address = compute_effective_address(regs, insn);
if(address < PAGE_SIZE) {
printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference in mna handler");
} else
printk(KERN_ALERT "Unable to handle kernel paging request in mna handler");
printk(KERN_ALERT " at virtual address %08lx\n",address);
printk(KERN_ALERT "current->{mm,active_mm}->context = %08lx\n",
(current->mm ? current->mm->context :
current->active_mm->context));
printk(KERN_ALERT "current->{mm,active_mm}->pgd = %08lx\n",
(current->mm ? (unsigned long) current->mm->pgd :
(unsigned long) current->active_mm->pgd));
die_if_kernel("Oops", regs);
/* Not reached */
}
regs->pc = fixup;
regs->npc = regs->pc + 4;
regs->u_regs [UREG_G2] = g2;
}
asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn)
{
enum direction dir = decode_direction(insn);
int size = decode_access_size(insn);
if(!ok_for_kernel(insn) || dir == both) {
printk("Unsupported unaligned load/store trap for kernel at <%08lx>.\n",
regs->pc);
unaligned_panic("Wheee. Kernel does fpu/atomic unaligned load/store.");
} else {
unsigned long addr = compute_effective_address(regs, insn);
int err;
perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, addr);
switch (dir) {
case load:
err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
regs),
size, (unsigned long *) addr,
decode_signedness(insn));
break;
case store:
err = do_int_store(((insn>>25)&0x1f), size,
(unsigned long *) addr, regs);
break;
default:
panic("Impossible kernel unaligned trap.");
/* Not reached... */
}
if (err)
kernel_mna_trap_fault(regs, insn);
else
advance(regs);
}
}
static inline int ok_for_user(struct pt_regs *regs, unsigned int insn,
enum direction dir)
{
unsigned int reg;
int check = (dir == load) ? VERIFY_READ : VERIFY_WRITE;
int size = ((insn >> 19) & 3) == 3 ? 8 : 4;
if ((regs->pc | regs->npc) & 3)
return 0;
/* Must access_ok() in all the necessary places. */
#define WINREG_ADDR(regnum) \
((void __user *)(((unsigned long *)regs->u_regs[UREG_FP])+(regnum)))
reg = (insn >> 25) & 0x1f;
if (reg >= 16) {
if (!access_ok(check, WINREG_ADDR(reg - 16), size))
return -EFAULT;
}
reg = (insn >> 14) & 0x1f;
if (reg >= 16) {
if (!access_ok(check, WINREG_ADDR(reg - 16), size))
return -EFAULT;
}
if (!(insn & 0x2000)) {
reg = (insn & 0x1f);
if (reg >= 16) {
if (!access_ok(check, WINREG_ADDR(reg - 16), size))
return -EFAULT;
}
}
#undef WINREG_ADDR
return 0;
}
static void user_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
{
siginfo_t info;
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRALN;
info.si_addr = (void __user *)safe_compute_effective_address(regs, insn);
info.si_trapno = 0;
send_sig_info(SIGBUS, &info, current);
}
asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
{
enum direction dir;
if(!(current->thread.flags & SPARC_FLAG_UNALIGNED) ||
(((insn >> 30) & 3) != 3))
goto kill_user;
dir = decode_direction(insn);
if(!ok_for_user(regs, insn, dir)) {
goto kill_user;
} else {
int err, size = decode_access_size(insn);
unsigned long addr;
if(floating_point_load_or_store_p(insn)) {
printk("User FPU load/store unaligned unsupported.\n");
goto kill_user;
}
addr = compute_effective_address(regs, insn);
perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, addr);
switch(dir) {
case load:
err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
regs),
size, (unsigned long *) addr,
decode_signedness(insn));
break;
case store:
err = do_int_store(((insn>>25)&0x1f), size,
(unsigned long *) addr, regs);
break;
case both:
/*
* This was supported in 2.4. However, we question
* the value of SWAP instruction across word boundaries.
*/
printk("Unaligned SWAP unsupported.\n");
err = -EFAULT;
break;
default:
unaligned_panic("Impossible user unaligned trap.");
goto out;
}
if (err)
goto kill_user;
else
advance(regs);
goto out;
}
kill_user:
user_mna_trap_fault(regs, insn);
out:
;
}