MIPS: Rewrite sysmips(MIPS_ATOMIC_SET, ...) in C with inline assembler

This way it doesn't have to use CONFIG_CPU_HAS_LLSC anymore.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/system.h

@@ -32,6 +32,9 @@ extern asmlinkage void *resume(void *last, void *next, void *next_ti);
 
 struct task_struct;
 
+extern unsigned int ll_bit;
+extern struct task_struct *ll_task;
+
 #ifdef CONFIG_MIPS_MT_FPAFF
 
 /*

arch/mips/kernel/scall32-o32.S

@@ -187,78 +187,6 @@ illegal_syscall:
 	j	o32_syscall_exit
 	END(handle_sys)
 
-	LEAF(mips_atomic_set)
-	andi	v0, a1, 3			# must be word aligned
-	bnez	v0, bad_alignment
-
-	lw	v1, TI_ADDR_LIMIT($28)		# in legal address range?
-	addiu	a0, a1, 4
-	or	a0, a0, a1
-	and	a0, a0, v1
-	bltz	a0, bad_address
-
-#ifdef CONFIG_CPU_HAS_LLSC
-	/* Ok, this is the ll/sc case.  World is sane :-)  */
-1:	ll	v0, (a1)
-	move	a0, a2
-2:	sc	a0, (a1)
-#if R10000_LLSC_WAR
-	beqzl	a0, 1b
-#else
-	beqz	a0, 1b
-#endif
-
-	.section __ex_table,"a"
-	PTR	1b, bad_stack
-	PTR	2b, bad_stack
-	.previous
-#else
-	sw	a1, 16(sp)
-	sw	a2, 20(sp)
-
-	move	a0, sp
-	move	a2, a1
-	li	a1, 1
-	jal	do_page_fault
-
-	lw	a1, 16(sp)
-	lw	a2, 20(sp)
-
-	/*
-	 * At this point the page should be readable and writable unless
-	 * there was no more memory available.
-	 */
-1:	lw	v0, (a1)
-2:	sw	a2, (a1)
-
-	.section __ex_table,"a"
-	PTR	1b, no_mem
-	PTR	2b, no_mem
-	.previous
-#endif
-
-	sw	zero, PT_R7(sp)		# success
-	sw	v0, PT_R2(sp)		# result
-
-	j	o32_syscall_exit	# continue like a normal syscall
-
-no_mem:	li	v0, -ENOMEM
-	jr	ra
-
-bad_address:
-	li	v0, -EFAULT
-	jr	ra
-
-bad_alignment:
-	li	v0, -EINVAL
-	jr	ra
-	END(mips_atomic_set)
-
-	LEAF(sys_sysmips)
-	beq	a0, MIPS_ATOMIC_SET, mips_atomic_set
-	j	_sys_sysmips
-	END(sys_sysmips)
-
 	LEAF(sys_syscall)
 	subu	t0, a0, __NR_O32_Linux	# check syscall number
 	sltiu	v0, t0, __NR_O32_Linux_syscalls + 1

arch/mips/kernel/scall64-64.S

@@ -124,78 +124,6 @@ illegal_syscall:
 	j	n64_syscall_exit
 	END(handle_sys64)
 
-	LEAF(mips_atomic_set)
-	andi	v0, a1, 3			# must be word aligned
-	bnez	v0, bad_alignment
-
-	LONG_L	v1, TI_ADDR_LIMIT($28)		# in legal address range?
-	LONG_ADDIU	a0, a1, 4
-	or	a0, a0, a1
-	and	a0, a0, v1
-	bltz	a0, bad_address
-
-#ifdef CONFIG_CPU_HAS_LLSC
-	/* Ok, this is the ll/sc case.  World is sane :-)  */
-1:	ll	v0, (a1)
-	move	a0, a2
-2:	sc	a0, (a1)
-#if R10000_LLSC_WAR
-	beqzl	a0, 1b
-#else
-	beqz	a0, 1b
-#endif
-
-	.section __ex_table,"a"
-	PTR	1b, bad_stack
-	PTR	2b, bad_stack
-	.previous
-#else
-	sw	a1, 16(sp)
-	sw	a2, 20(sp)
-
-	move	a0, sp
-	move	a2, a1
-	li	a1, 1
-	jal	do_page_fault
-
-	lw	a1, 16(sp)
-	lw	a2, 20(sp)
-
-	/*
-	 * At this point the page should be readable and writable unless
-	 * there was no more memory available.
-	 */
-1:	lw	v0, (a1)
-2:	sw	a2, (a1)
-
-	.section __ex_table,"a"
-	PTR	1b, no_mem
-	PTR	2b, no_mem
-	.previous
-#endif
-
-	sd	zero, PT_R7(sp)		# success
-	sd	v0, PT_R2(sp)		# result
-
-	j	n64_syscall_exit	# continue like a normal syscall
-
-no_mem:	li	v0, -ENOMEM
-	jr	ra
-
-bad_address:
-	li	v0, -EFAULT
-	jr	ra
-
-bad_alignment:
-	li	v0, -EINVAL
-	jr	ra
-	END(mips_atomic_set)
-
-	LEAF(sys_sysmips)
-	beq	a0, MIPS_ATOMIC_SET, mips_atomic_set
-	j	_sys_sysmips
-	END(sys_sysmips)
-
 	.align	3
 sys_call_table:
 	PTR	sys_read			/* 5000 */

arch/mips/kernel/syscall.c

@@ -28,7 +28,9 @@
 #include <linux/compiler.h>
 #include <linux/module.h>
 #include <linux/ipc.h>
+#include <linux/uaccess.h>
 
+#include <asm/asm.h>
 #include <asm/branch.h>
 #include <asm/cachectl.h>
 #include <asm/cacheflush.h>
@@ -290,12 +292,116 @@ SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
 	return 0;
 }
 
-asmlinkage int _sys_sysmips(long cmd, long arg1, long arg2, long arg3)
+static inline int mips_atomic_set(struct pt_regs *regs,
+	unsigned long addr, unsigned long new)
 {
+	unsigned long old, tmp;
+	unsigned int err;
+
+	if (unlikely(addr & 3))
+		return -EINVAL;
+
+	if (unlikely(!access_ok(VERIFY_WRITE, addr, 4)))
+		return -EINVAL;
+
+	if (cpu_has_llsc && R10000_LLSC_WAR) {
+		__asm__ __volatile__ (
+		"	li	%[err], 0				\n"
+		"1:	ll	%[old], (%[addr])			\n"
+		"	move	%[tmp], %[new]				\n"
+		"2:	sc	%[tmp], (%[addr])			\n"
+		"	beqzl	%[tmp], 1b				\n"
+		"3:							\n"
+		"	.section .fixup,\"ax\"				\n"
+		"4:	li	%[err], %[efault]			\n"
+		"	j	3b					\n"
+		"	.previous					\n"
+		"	.section __ex_table,\"a\"			\n"
+		"	"STR(PTR)"	1b, 4b				\n"
+		"	"STR(PTR)"	2b, 4b				\n"
+		"	.previous					\n"
+		: [old] "=&r" (old),
+		  [err] "=&r" (err),
+		  [tmp] "=&r" (tmp)
+		: [addr] "r" (addr),
+		  [new] "r" (new),
+		  [efault] "i" (-EFAULT)
+		: "memory");
+	} else if (cpu_has_llsc) {
+		__asm__ __volatile__ (
+		"	li	%[err], 0				\n"
+		"1:	ll	%[old], (%[addr])			\n"
+		"	move	%[tmp], %[new]				\n"
+		"2:	sc	%[tmp], (%[addr])			\n"
+		"	bnez	%[tmp], 4f				\n"
+		"3:							\n"
+		"	.subsection 2					\n"
+		"4:	b	1b					\n"
+		"	.previous					\n"
+		"							\n"
+		"	.section .fixup,\"ax\"				\n"
+		"5:	li	%[err], %[efault]			\n"
+		"	j	3b					\n"
+		"	.previous					\n"
+		"	.section __ex_table,\"a\"			\n"
+		"	"STR(PTR)"	1b, 5b				\n"
+		"	"STR(PTR)"	2b, 5b				\n"
+		"	.previous					\n"
+		: [old] "=&r" (old),
+		  [err] "=&r" (err),
+		  [tmp] "=&r" (tmp)
+		: [addr] "r" (addr),
+		  [new] "r" (new),
+		  [efault] "i" (-EFAULT)
+		: "memory");
+	} else {
+		do {
+			preempt_disable();
+			ll_bit = 1;
+			ll_task = current;
+			preempt_enable();
+
+			err = __get_user(old, (unsigned int *) addr);
+			err |= __put_user(new, (unsigned int *) addr);
+			if (err)
+				break;
+			rmb();
+		} while (!ll_bit);
+	}
+
+	if (unlikely(err))
+		return err;
+
+	regs->regs[2] = old;
+	regs->regs[7] = 0;	/* No error */
+
+	/*
+	 * Don't let your children do this ...
+	 */
+	__asm__ __volatile__(
+	"	move	$29, %0						\n"
+	"	j	syscall_exit					\n"
+	: /* no outputs */
+	: "r" (regs));
+
+	/* unreached.  Honestly.  */
+	while (1);
+}
+
+save_static_function(sys_sysmips);
+static int __used noinline
+_sys_sysmips(nabi_no_regargs struct pt_regs regs)
+{
+	long cmd, arg1, arg2, arg3;
+
+	cmd = regs.regs[4];
+	arg1 = regs.regs[5];
+	arg2 = regs.regs[6];
+	arg3 = regs.regs[7];
+
 	switch (cmd) {
 	case MIPS_ATOMIC_SET:
-		printk(KERN_CRIT "How did I get here?\n");
-		return -EINVAL;
+		return mips_atomic_set(&regs, arg1, arg2);
 
 	case MIPS_FIXADE:
 		if (arg1 & ~3)

arch/mips/kernel/traps.c

@@ -466,9 +466,8 @@ asmlinkage void do_be(struct pt_regs *regs)
  * The ll_bit is cleared by r*_switch.S
  */
 
-unsigned long ll_bit;
-
-static struct task_struct *ll_task = NULL;
+unsigned int ll_bit;
+struct task_struct *ll_task;
 
 static inline int simulate_ll(struct pt_regs *regs, unsigned int opcode)
 {