From 63104c06a9eddf53f88f6d16196bb036c62967b2 Mon Sep 17 00:00:00 2001 From: Stefan Kristiansson Date: Mon, 3 Nov 2014 14:28:14 +0200 Subject: [PATCH] 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 [shorne@gmail.com: Added delay slot pc adjust logic] Signed-off-by: Stafford Horne --- arch/openrisc/kernel/entry.S | 22 +++- arch/openrisc/kernel/process.c | 3 + arch/openrisc/kernel/traps.c | 183 +++++++++++++++++++++++++++++++++ 3 files changed, 206 insertions(+), 2 deletions(-) diff --git a/arch/openrisc/kernel/entry.S b/arch/openrisc/kernel/entry.S index aac0bde3330c..ba1a361c9a1e 100644 --- a/arch/openrisc/kernel/entry.S +++ b/arch/openrisc/kernel/entry.S @@ -173,6 +173,11 @@ handler: ;\ l.j _ret_from_exception ;\ l.nop +/* clobbers 'reg' */ +#define CLEAR_LWA_FLAG(reg) \ + l.movhi reg,hi(lwa_flag) ;\ + l.ori reg,reg,lo(lwa_flag) ;\ + l.sw 0(reg),r0 /* * NOTE: one should never assume that SPR_EPC, SPR_ESR, SPR_EEAR * contain the same values as when exception we're handling @@ -193,6 +198,7 @@ EXCEPTION_ENTRY(_tng_kernel_start) /* ---[ 0x200: BUS exception ]------------------------------------------- */ EXCEPTION_ENTRY(_bus_fault_handler) + CLEAR_LWA_FLAG(r3) /* r4: EA of fault (set by EXCEPTION_HANDLE) */ l.jal do_bus_fault l.addi r3,r1,0 /* pt_regs */ @@ -202,11 +208,13 @@ EXCEPTION_ENTRY(_bus_fault_handler) /* ---[ 0x300: Data Page Fault exception ]------------------------------- */ EXCEPTION_ENTRY(_dtlb_miss_page_fault_handler) + CLEAR_LWA_FLAG(r3) l.and r5,r5,r0 l.j 1f l.nop EXCEPTION_ENTRY(_data_page_fault_handler) + CLEAR_LWA_FLAG(r3) /* set up parameters for do_page_fault */ l.ori r5,r0,0x300 // exception vector 1: @@ -282,11 +290,13 @@ EXCEPTION_ENTRY(_data_page_fault_handler) /* ---[ 0x400: Insn Page Fault exception ]------------------------------- */ EXCEPTION_ENTRY(_itlb_miss_page_fault_handler) + CLEAR_LWA_FLAG(r3) l.and r5,r5,r0 l.j 1f l.nop EXCEPTION_ENTRY(_insn_page_fault_handler) + CLEAR_LWA_FLAG(r3) /* set up parameters for do_page_fault */ l.ori r5,r0,0x400 // exception vector 1: @@ -304,6 +314,7 @@ EXCEPTION_ENTRY(_insn_page_fault_handler) /* ---[ 0x500: Timer exception ]----------------------------------------- */ EXCEPTION_ENTRY(_timer_handler) + CLEAR_LWA_FLAG(r3) l.jal timer_interrupt l.addi r3,r1,0 /* pt_regs */ @@ -313,6 +324,7 @@ EXCEPTION_ENTRY(_timer_handler) /* ---[ 0x600: Aligment exception ]-------------------------------------- */ EXCEPTION_ENTRY(_alignment_handler) + CLEAR_LWA_FLAG(r3) /* r4: EA of fault (set by EXCEPTION_HANDLE) */ l.jal do_unaligned_access l.addi r3,r1,0 /* pt_regs */ @@ -509,6 +521,7 @@ EXCEPTION_ENTRY(_external_irq_handler) // l.sw PT_SR(r1),r4 1: #endif + CLEAR_LWA_FLAG(r3) l.addi r3,r1,0 l.movhi r8,hi(do_IRQ) l.ori r8,r8,lo(do_IRQ) @@ -556,8 +569,12 @@ ENTRY(_sys_call_handler) * they should be clobbered, otherwise */ l.sw PT_GPR3(r1),r3 - /* r4 already saved */ - /* r4 holds the EEAR address of the fault, load the original r4 */ + /* + * r4 already saved + * r4 holds the EEAR address of the fault, use it as screatch reg and + * then load the original r4 + */ + CLEAR_LWA_FLAG(r4) l.lwz r4,PT_GPR4(r1) l.sw PT_GPR5(r1),r5 l.sw PT_GPR6(r1),r6 @@ -776,6 +793,7 @@ UNHANDLED_EXCEPTION(_vector_0xd00,0xd00) /* ---[ 0xe00: Trap exception ]------------------------------------------ */ EXCEPTION_ENTRY(_trap_handler) + CLEAR_LWA_FLAG(r3) /* r4: EA of fault (set by EXCEPTION_HANDLE) */ l.jal do_trap l.addi r3,r1,0 /* pt_regs */ diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c index d7990df9025a..c49350b200e1 100644 --- a/arch/openrisc/kernel/process.c +++ b/arch/openrisc/kernel/process.c @@ -226,6 +226,7 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu) extern struct thread_info *_switch(struct thread_info *old_ti, struct thread_info *new_ti); +extern int lwa_flag; struct task_struct *__switch_to(struct task_struct *old, struct task_struct *new) @@ -243,6 +244,8 @@ struct task_struct *__switch_to(struct task_struct *old, new_ti = new->stack; old_ti = old->stack; + lwa_flag = 0; + current_thread_info_set[smp_processor_id()] = new_ti; last = (_switch(old_ti, new_ti))->task; diff --git a/arch/openrisc/kernel/traps.c b/arch/openrisc/kernel/traps.c index a4574cb4b0fb..7907b6cf5d8a 100644 --- a/arch/openrisc/kernel/traps.c +++ b/arch/openrisc/kernel/traps.c @@ -40,6 +40,8 @@ extern char _etext, _stext; int kstack_depth_to_print = 0x180; +int lwa_flag; +unsigned long __user *lwa_addr; static inline int valid_stack_ptr(struct thread_info *tinfo, void *p) { @@ -334,10 +336,191 @@ asmlinkage void do_bus_fault(struct pt_regs *regs, unsigned long 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 regs->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) { siginfo_t info; + 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 */ -- 2.45.2