parisc/unaligned: Rewrite 64-bit inline assembly of emulate_ldd()

Convert to use real temp variables instead of clobbering processor
registers. This aligns the 64-bit inline assembly code with the 32-bit
assembly code which was rewritten with commit 427c107
("parisc/unaligned: Rewrite 32-bit inline assembly of emulate_ldd()").

While at it, fix comment in 32-bit rewrite code. Temporary variables are
now used for both 32-bit and 64-bit code, so move their declarations
to the function header.

No functional change intended.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Cc: stable@vger.kernel.org # v6.0+
Signed-off-by: Helge Deller <deller@gmx.de>

Author: groeck

arch/parisc/kernel/unaligned.c

@@ -169,6 +169,7 @@ static int emulate_ldw(struct pt_regs *regs, int toreg, int flop)
 static int emulate_ldd(struct pt_regs *regs, int toreg, int flop)
 {
 	unsigned long saddr = regs->ior;
+	unsigned long shift, temp1;
 	__u64 val = 0;
 	ASM_EXCEPTIONTABLE_VAR(ret);
 
@@ -180,25 +181,22 @@ static int emulate_ldd(struct pt_regs *regs, int toreg, int flop)
 
 #ifdef CONFIG_64BIT
 	__asm__ __volatile__  (
-"	depd,z	%3,60,3,%%r19\n"		/* r19=(ofs&7)*8 */
-"	mtsp	%4, %%sr1\n"
-"	depd	%%r0,63,3,%3\n"
-"1:	ldd	0(%%sr1,%3),%0\n"
-"2:	ldd	8(%%sr1,%3),%%r20\n"
-"	subi	64,%%r19,%%r19\n"
-"	mtsar	%%r19\n"
-"	shrpd	%0,%%r20,%%sar,%0\n"
+"	depd,z	%2,60,3,%3\n"		/* shift=(ofs&7)*8 */
+"	mtsp	%5, %%sr1\n"
+"	depd	%%r0,63,3,%2\n"
+"1:	ldd	0(%%sr1,%2),%0\n"
+"2:	ldd	8(%%sr1,%2),%4\n"
+"	subi	64,%3,%3\n"
+"	mtsar	%3\n"
+"	shrpd	%0,%4,%%sar,%0\n"
 "3:	\n"
 	ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 3b, "%1")
 	ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 3b, "%1")
-	: "=r" (val), "+r" (ret)
-	: "0" (val), "r" (saddr), "r" (regs->isr)
-	: "r19", "r20" );
+	: "+r" (val), "+r" (ret), "+r" (saddr), "=&r" (shift), "=&r" (temp1)
+	: "r" (regs->isr) );
 #else
-    {
-	unsigned long shift, temp1;
 	__asm__ __volatile__  (
-"	zdep	%2,29,2,%3\n"		/* r19=(ofs&3)*8 */
+"	zdep	%2,29,2,%3\n"		/* shift=(ofs&3)*8 */
 "	mtsp	%5, %%sr1\n"
 "	dep	%%r0,31,2,%2\n"
 "1:	ldw	0(%%sr1,%2),%0\n"
@@ -214,7 +212,6 @@ static int emulate_ldd(struct pt_regs *regs, int toreg, int flop)
 	ASM_EXCEPTIONTABLE_ENTRY_EFAULT(3b, 4b, "%1")
 	: "+r" (val), "+r" (ret), "+r" (saddr), "=&r" (shift), "=&r" (temp1)
 	: "r" (regs->isr) );
-    }
 #endif
 
 	DPRINTF("val = 0x%llx\n", val);