On 28.05.19 02:15, John David Anglin wrote:
> 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.
Fun part is, that I had prepared exactly the same patch two days ago too.
In addition I added this:
+ /* We currently only support kernel addresses, and sr0 is always 0. */
+ /* BUG_ON(mfsp(0) != sid); */
and explicitely mentioned "%sr0" to make it clear:
asm volatile ("lci %%r0(%sr0,%1), %0" : "=r" (ci) : "r" (vba));
Anyway, your patch is good. Will apply.
Helge
>
> Tested on rp3440, c8000 and c3750.
>
> Signed-off-by: John David Anglin <dave.anglin@xxxxxxxx>
> ---
>
> diff --git a/drivers/parisc/ccio-dma.c b/drivers/parisc/ccio-dma.c
> index acba1f56af3e..d7649a70a0c4 100644
> --- a/drivers/parisc/ccio-dma.c
> +++ b/drivers/parisc/ccio-dma.c
> @@ -565,8 +565,6 @@ 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!
> @@ -597,7 +595,7 @@ 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));
>
> diff --git a/drivers/parisc/sba_iommu.c b/drivers/parisc/sba_iommu.c
> index 0a9c762a70fa..5468490d2298 100644
> --- a/drivers/parisc/sba_iommu.c
> +++ b/drivers/parisc/sba_iommu.c
> @@ -575,8 +575,7 @@ 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 */
>
