patch-2.1.9 linux/arch/sparc/kernel/unaligned.c

• Lines: 396
• Date: Sun Nov 10 23:25:55 1996
• Orig file: v2.1.8/linux/arch/sparc/kernel/unaligned.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v2.1.8/linux/arch/sparc/kernel/unaligned.c linux/arch/sparc/kernel/unaligned.c
@@ -0,0 +1,395 @@
+/* $Id: unaligned.c,v 1.10 1996/11/10 21:25:47 davem Exp $
+ * 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)
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <asm/ptrace.h>
+#include <asm/processor.h>
+#include <asm/system.h>
+#include <asm/uaccess.h>
+
+/* #define DEBUG_MNA */
+
+extern void die_if_kernel(char *, struct pt_regs *);
+
+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->tss.kregs);
+		return 4; /* just to keep gcc happy. */
+	}
+}
+
+/* 1 = signed, 0 = unsigned */
+static inline int decode_signedness(unsigned int insn)
+{
+	return (insn >> 22) & 1;
+}
+
+static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
+				       unsigned int rd)
+{
+	int yep;
+
+	if(rs2 >= 16 || rs1 >= 16 || rd >= 16)
+		yep = 1;
+	else
+		yep = 0;
+	if(yep) {
+		/* 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_halfword(int hword)
+{
+	return hword << 16 >> 16;
+}
+
+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 *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 inline 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;
+	unsigned int imm13 = (insn & 0x1fff);
+
+	if(insn & 0x2000) {
+		maybe_flush_windows(rs1, 0, rd);
+		return (fetch_reg(rs1, regs) + sign_extend_imm13(imm13));
+	} else {
+		maybe_flush_windows(rs1, rs2, rd);
+		return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs));
+	}
+}
+
+static inline void do_integer_load(unsigned long *dest_reg, int size,
+				   unsigned long *saddr, int is_signed)
+{
+	unsigned char bytes[4];
+
+	switch(size) {
+	case 2:
+		bytes[0] = *((unsigned char *)saddr + 1);
+		bytes[1] = *((unsigned char *)saddr + 0);
+		*dest_reg = (bytes[0] | (bytes[1] << 8));
+		if(is_signed)
+			*dest_reg = sign_extend_halfword(*dest_reg);
+		break;
+
+	case 4:
+		bytes[0] = *((unsigned char *)saddr + 3);
+		bytes[1] = *((unsigned char *)saddr + 2);
+		bytes[2] = *((unsigned char *)saddr + 1);
+		bytes[3] = *((unsigned char *)saddr + 0);
+		*dest_reg = (bytes[0] | (bytes[1] << 8) |
+			     (bytes[2] << 16) | (bytes[3] << 24));
+		break;
+
+	case 8:
+		bytes[0] = *((unsigned char *)saddr + 3);
+		bytes[1] = *((unsigned char *)saddr + 2);
+		bytes[2] = *((unsigned char *)saddr + 1);
+		bytes[3] = *((unsigned char *)saddr + 0);
+		*dest_reg++ = (bytes[0] | (bytes[1] << 8) |
+			     (bytes[2] << 16) | (bytes[3] << 24));
+		saddr++;
+		bytes[0] = *((unsigned char *)saddr + 3);
+		bytes[1] = *((unsigned char *)saddr + 2);
+		bytes[2] = *((unsigned char *)saddr + 1);
+		bytes[3] = *((unsigned char *)saddr + 0);
+		*dest_reg = (bytes[0] | (bytes[1] << 8) |
+			     (bytes[2] << 16) | (bytes[3] << 24));
+		break;
+
+	default:
+		panic("Impossible unaligned load.");
+	};
+}
+
+static inline void store_common(unsigned long *src_val,
+				int size, unsigned long *dst_addr)
+{
+	unsigned char *daddr = (unsigned char *) dst_addr;
+	switch(size) {
+	case 2:
+		daddr[0] = ((*src_val) >> 8) & 0xff;
+		daddr[1] = (*src_val & 0xff);
+		break;
+
+	case 4:
+		daddr[0] = ((*src_val) >> 24) & 0xff;
+		daddr[1] = ((*src_val) >> 16) & 0xff;
+		daddr[2] = ((*src_val) >> 8) & 0xff;
+		daddr[3] = (*src_val & 0xff);
+		break;
+
+	case 8:
+		daddr[0] = ((*src_val) >> 24) & 0xff;
+		daddr[1] = ((*src_val) >> 16) & 0xff;
+		daddr[2] = ((*src_val) >> 8) & 0xff;
+		daddr[3] = (*src_val & 0xff);
+		daddr += 4;
+		src_val++;
+		daddr[0] = ((*src_val) >> 24) & 0xff;
+		daddr[1] = ((*src_val) >> 16) & 0xff;
+		daddr[2] = ((*src_val) >> 8) & 0xff;
+		daddr[3] = (*src_val & 0xff);
+		break;
+
+	default:
+		panic("Impossible unaligned store.");
+	}
+}
+
+static inline void do_integer_store(int reg_num, int size,
+				    unsigned long *dst_addr,
+				    struct pt_regs *regs)
+{
+	unsigned long *src_val;
+	static unsigned long zero[2] = { 0, 0 };
+
+	if(reg_num)
+		src_val = fetch_reg_addr(reg_num, regs);
+	else
+		src_val = &zero[0];
+	store_common(src_val, size, dst_addr);
+}
+
+static inline void do_atomic(unsigned long *srcdest_reg, unsigned long *mem)
+{
+	unsigned long flags, tmp;
+
+#ifdef __SMP__
+	/* XXX Need to capture/release other cpu's around this. */
+#endif
+	save_and_cli(flags);
+	tmp = *srcdest_reg;
+	do_integer_load(srcdest_reg, 4, mem, 0);
+	store_common(&tmp, 4, mem);
+	restore_flags(flags);
+}
+
+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);
+}
+
+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);
+		panic("Wheee. Kernel does fpu/atomic unaligned load/store.");
+		/* Not reached... */
+	} else {
+		unsigned long addr = compute_effective_address(regs, insn);
+
+#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:
+			do_integer_load(fetch_reg_addr(((insn>>25)&0x1f), regs),
+					size, (unsigned long *) addr,
+					decode_signedness(insn));
+			break;
+
+		case store:
+			do_integer_store(((insn>>25)&0x1f), size,
+					 (unsigned long *) addr, regs);
+			break;
+		case both:
+#if 0 /* unsupported */
+			do_atomic(fetch_reg_addr(((insn>>25)&0x1f), regs),
+				  (unsigned long *) addr);
+			break;
+#endif
+		default:
+			panic("Impossible kernel unaligned trap.");
+			/* Not reached... */
+		}
+		advance(regs);
+	}
+}
+
+static inline int ok_for_user(struct pt_regs *regs, unsigned int insn,
+			      enum direction dir)
+{
+	unsigned int reg;
+	int retval, check = (dir == load) ? VERIFY_READ : VERIFY_WRITE;
+	int size = ((insn >> 19) & 3) == 3 ? 8 : 4;
+
+	if((regs->pc | regs->npc) & 3)
+		return 0;
+
+	/* Must verify_area() in all the necessary places. */
+#define WINREG_ADDR(regnum) ((void *)(((unsigned long *)regs->u_regs[UREG_FP])+(regnum)))
+	retval = 0;
+	reg = (insn >> 25) & 0x1f;
+	if(reg >= 16) {
+		retval = verify_area(check, WINREG_ADDR(reg - 16), size);
+		if(retval)
+			return retval;
+	}
+	reg = (insn >> 14) & 0x1f;
+	if(reg >= 16) {
+		retval = verify_area(check, WINREG_ADDR(reg - 16), size);
+		if(retval)
+			return retval;
+	}
+	if(!(insn & 0x2000)) {
+		reg = (insn & 0x1f);
+		if(reg >= 16) {
+			retval = verify_area(check, WINREG_ADDR(reg - 16), size);
+			if(retval)
+				return retval;
+		}
+	}
+	return retval;
+#undef WINREG_ADDR
+}
+
+asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
+{
+	enum direction dir;
+
+	if(!(current->tss.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 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:
+			do_integer_load(fetch_reg_addr(((insn>>25)&0x1f), regs),
+					size, (unsigned long *) addr,
+					decode_signedness(insn));
+			break;
+
+		case store:
+			do_integer_store(((insn>>25)&0x1f), size,
+					 (unsigned long *) addr, regs);
+			break;
+
+		case both:
+			do_atomic(fetch_reg_addr(((insn>>25)&0x1f), regs),
+				  (unsigned long *) addr);
+			break;
+
+		default:
+			panic("Impossible user unaligned trap.");
+		}
+		advance(regs);
+		return;
+	}
+
+kill_user:
+	current->tss.sig_address = regs->pc;
+	current->tss.sig_desc = SUBSIG_PRIVINST;
+	send_sig(SIGBUS, current, 1);
+}