arch/sparc/kernel/unaligned.c - maze/linux - Git at Google

 /*
  * 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 <linux/module.h>
 #include <asm/ptrace.h>
 #include <asm/processor.h>
 #include <asm/system.h>
 #include <asm/uaccess.h>
 #include <linux/smp.h>
 #include <linux/smp_lock.h>

 /* #define DEBUG_MNA */

 enum direction {
 	load,    /* ld, ldd, ldh, ldsh */
 	store,   /* st, std, sth, stsh */
 	both,    /* Swap, ldstub, etc. */
 	fpload,
 	fpstore,
 	invalid,
 };

 #ifdef DEBUG_MNA
 static char *dirstrings[] = {
   "load", "store", "both", "fpload", "fpstore", "invalid"
 };
 #endif

 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_window *win;

 	if(reg < 16)
 		return (!reg ? 0 : regs->u_regs[reg]);

 	/* Ho hum, the slightly complicated case. */
 	win = (struct reg_window *) 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_window __user *win;
 	unsigned long ret;

 	if (reg < 16)
 		return (!reg ? 0 : regs->u_regs[reg]);

 	/* Ho hum, the slightly complicated case. */
 	win = (struct reg_window __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_window *win;

 	if(reg < 16)
 		return &regs->u_regs[reg];
 	win = (struct reg_window *) 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;

 #ifdef DEBUG_MNA
 		printk("KMNA: pc=%08lx [dir=%s addr=%08lx size=%d] retpc[%08lx]\n",
 		       regs->pc, dirstrings[dir], addr, size, regs->u_regs[UREG_RETPC]);
 #endif
 		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;

 	lock_kernel();
 	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);
 		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:
 	unlock_kernel();
 }
	/*
	* 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 <linux/module.h>
	#include <asm/ptrace.h>
	#include <asm/processor.h>
	#include <asm/system.h>
	#include <asm/uaccess.h>
	#include <linux/smp.h>
	#include <linux/smp_lock.h>

	/* #define DEBUG_MNA */

	enum direction {
	load, /* ld, ldd, ldh, ldsh */
	store, /* st, std, sth, stsh */
	both, /* Swap, ldstub, etc. */
	fpload,
	fpstore,
	invalid,
	};

	#ifdef DEBUG_MNA
	static char *dirstrings[] = {
	"load", "store", "both", "fpload", "fpstore", "invalid"
	};
	#endif

	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_window *win;

	if(reg < 16)
	return (!reg ? 0 : regs->u_regs[reg]);

	/* Ho hum, the slightly complicated case. */
	win = (struct reg_window *) 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_window __user *win;
	unsigned long ret;

	if (reg < 16)
	return (!reg ? 0 : regs->u_regs[reg]);

	/* Ho hum, the slightly complicated case. */
	win = (struct reg_window __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_window *win;

	if(reg < 16)
	return &regs->u_regs[reg];
	win = (struct reg_window *) 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;

	#ifdef DEBUG_MNA
	printk("KMNA: pc=%08lx [dir=%s addr=%08lx size=%d] retpc[%08lx]\n",
	regs->pc, dirstrings[dir], addr, size, regs->u_regs[UREG_RETPC]);
	#endif
	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;

	lock_kernel();
	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);
	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:
	unlock_kernel();
	}