openrisc: add l.lwa/l.swa emulation
This adds an emulation layer for implementations that lack the l.lwa and l.swa instructions. It handles these instructions both in kernel space and user space. Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> [shorne@gmail.com: Added delay slot pc adjust logic] Signed-off-by: Stafford Horne <shorne@gmail.com>
This commit is contained in:
Stefan Kristiansson
committed by
Stafford Horne
Stafford Horne
parent
8c9b7db0de
commit
63104c06a9
@@ -40,6 +40,8 @@
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extern char _etext, _stext;
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int kstack_depth_to_print = 0x180;
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int lwa_flag;
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unsigned long __user *lwa_addr;
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static inline int valid_stack_ptr(struct thread_info *tinfo, void *p)
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{
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@@ -334,10 +336,191 @@ asmlinkage void do_bus_fault(struct pt_regs *regs, unsigned long address)
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}
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}
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static inline int in_delay_slot(struct pt_regs *regs)
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{
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#ifdef CONFIG_OPENRISC_NO_SPR_SR_DSX
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/* No delay slot flag, do the old way */
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unsigned int op, insn;
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insn = *((unsigned int *)regs->pc);
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op = insn >> 26;
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switch (op) {
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case 0x00: /* l.j */
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case 0x01: /* l.jal */
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case 0x03: /* l.bnf */
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case 0x04: /* l.bf */
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case 0x11: /* l.jr */
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case 0x12: /* l.jalr */
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return 1;
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default:
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return 0;
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}
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#else
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return regs->sr & SPR_SR_DSX;
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#endif
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}
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static inline void adjust_pc(struct pt_regs *regs, unsigned long address)
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{
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int displacement;
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unsigned int rb, op, jmp;
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if (unlikely(in_delay_slot(regs))) {
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/* In delay slot, instruction at pc is a branch, simulate it */
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jmp = *((unsigned int *)regs->pc);
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displacement = sign_extend32(((jmp) & 0x3ffffff) << 2, 27);
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rb = (jmp & 0x0000ffff) >> 11;
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op = jmp >> 26;
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switch (op) {
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case 0x00: /* l.j */
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regs->pc += displacement;
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return;
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case 0x01: /* l.jal */
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regs->pc += displacement;
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regs->gpr[9] = regs->pc + 8;
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return;
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case 0x03: /* l.bnf */
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if (regs->sr & SPR_SR_F)
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regs->pc += 8;
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else
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regs->pc += displacement;
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return;
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case 0x04: /* l.bf */
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if (regs->sr & SPR_SR_F)
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regs->pc += displacement;
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else
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regs->pc += 8;
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return;
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case 0x11: /* l.jr */
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regs->pc = regs->gpr[rb];
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return;
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case 0x12: /* l.jalr */
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regs->pc = regs->gpr[rb];
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regs->gpr[9] = regs->pc + 8;
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return;
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default:
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break;
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}
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} else {
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regs->pc += 4;
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}
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}
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static inline void simulate_lwa(struct pt_regs *regs, unsigned long address,
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unsigned int insn)
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{
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unsigned int ra, rd;
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unsigned long value;
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unsigned long orig_pc;
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long imm;
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const struct exception_table_entry *entry;
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orig_pc = regs->pc;
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adjust_pc(regs, address);
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ra = (insn >> 16) & 0x1f;
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rd = (insn >> 21) & 0x1f;
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imm = (short)insn;
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lwa_addr = (unsigned long __user *)(regs->gpr[ra] + imm);
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if ((unsigned long)lwa_addr & 0x3) {
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do_unaligned_access(regs, address);
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return;
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}
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if (get_user(value, lwa_addr)) {
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if (user_mode(regs)) {
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force_sig(SIGSEGV, current);
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return;
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}
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if ((entry = search_exception_tables(orig_pc))) {
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regs->pc = entry->fixup;
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return;
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}
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/* kernel access in kernel space, load it directly */
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value = *((unsigned long *)lwa_addr);
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}
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lwa_flag = 1;
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regs->gpr[rd] = value;
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}
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static inline void simulate_swa(struct pt_regs *regs, unsigned long address,
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unsigned int insn)
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{
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unsigned long __user *vaddr;
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unsigned long orig_pc;
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unsigned int ra, rb;
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long imm;
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const struct exception_table_entry *entry;
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orig_pc = regs->pc;
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adjust_pc(regs, address);
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ra = (insn >> 16) & 0x1f;
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rb = (insn >> 11) & 0x1f;
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imm = (short)(((insn & 0x2200000) >> 10) | (insn & 0x7ff));
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vaddr = (unsigned long __user *)(regs->gpr[ra] + imm);
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if (!lwa_flag || vaddr != lwa_addr) {
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regs->sr &= ~SPR_SR_F;
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return;
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}
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if ((unsigned long)vaddr & 0x3) {
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do_unaligned_access(regs, address);
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return;
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}
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if (put_user(regs->gpr[rb], vaddr)) {
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if (user_mode(regs)) {
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force_sig(SIGSEGV, current);
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return;
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}
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if ((entry = search_exception_tables(orig_pc))) {
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regs->pc = entry->fixup;
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return;
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}
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/* kernel access in kernel space, store it directly */
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*((unsigned long *)vaddr) = regs->gpr[rb];
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}
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lwa_flag = 0;
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regs->sr |= SPR_SR_F;
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}
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#define INSN_LWA 0x1b
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#define INSN_SWA 0x33
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asmlinkage void do_illegal_instruction(struct pt_regs *regs,
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unsigned long address)
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{
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siginfo_t info;
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unsigned int op;
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unsigned int insn = *((unsigned int *)address);
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op = insn >> 26;
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switch (op) {
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case INSN_LWA:
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simulate_lwa(regs, address, insn);
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return;
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case INSN_SWA:
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simulate_swa(regs, address, insn);
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return;
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default:
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break;
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}
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if (user_mode(regs)) {
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/* Send a SIGILL */
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