parisc: Use implicit space register selection for loading the coherence index of I/O pdirs

BugLink: https://bugs.launchpad.net/bugs/1832661

commit 63923d2c upstream.

We only support I/O to kernel space. Using %sr1 to load the coherence
index may be racy unless interrupts are disabled. This patch changes the
code used to load the coherence index to use implicit space register
selection. This saves one instruction and eliminates the race.

Tested on rp3440, c8000 and c3750.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/parisc/ccio-dma.c

@@ -563,8 +563,6 @@ ccio_io_pdir_entry(u64 *pdir_ptr, space_t sid, unsigned long vba,
 	/* We currently only support kernel addresses */
 	BUG_ON(sid != KERNEL_SPACE);
 
-	mtsp(sid,1);
-
 	/*
 	** WORD 1 - low order word
 	** "hints" parm includes the VALID bit!
@@ -595,7 +593,7 @@ ccio_io_pdir_entry(u64 *pdir_ptr, space_t sid, unsigned long vba,
 	** Grab virtual index [0:11]
 	** Deposit virt_idx bits into I/O PDIR word
 	*/
-	asm volatile ("lci %%r0(%%sr1, %1), %0" : "=r" (ci) : "r" (vba));
+	asm volatile ("lci %%r0(%1), %0" : "=r" (ci) : "r" (vba));
 	asm volatile ("extru %1,19,12,%0" : "+r" (ci) : "r" (ci));
 	asm volatile ("depw  %1,15,12,%0" : "+r" (pa) : "r" (ci));
 

drivers/parisc/sba_iommu.c

@@ -573,8 +573,7 @@ sba_io_pdir_entry(u64 *pdir_ptr, space_t sid, unsigned long vba,
 	pa = virt_to_phys(vba);
 	pa &= IOVP_MASK;
 
-	mtsp(sid,1);
-	asm("lci 0(%%sr1, %1), %0" : "=r" (ci) : "r" (vba));
+	asm("lci 0(%1), %0" : "=r" (ci) : "r" (vba));
 	pa |= (ci >> PAGE_SHIFT) & 0xff;  /* move CI (8 bits) into lowest byte */
 
 	pa |= SBA_PDIR_VALID_BIT;	/* set "valid" bit */