On Dec 24, 2014, at 14:40, Ian Lepore <i...@freebsd.org> wrote:
> 
> On Wed, 2014-12-24 at 22:26 +0000, Andrew Turner wrote:
>> On Wed, 24 Dec 2014 17:12:52 +0000 (UTC)
>> Ian Lepore <i...@freebsd.org> wrote:
>> 
>>> Author: ian
>>> Date: Wed Dec 24 17:12:51 2014
>>> New Revision: 276187
>>> URL: https://svnweb.freebsd.org/changeset/base/276187
>>> 
>>> Log:
>>>  Eliminate unnecessary references to pte.h internals by using the
>>> standard pmap_kenter_temporary() to map pages while dumping.
>>> 
>>>  Submitted by:      Svatopluk Kraus <onw...@gmail.com>,
>>>             Michal Meloun <mel...@miracle.cz>
>>> 
>>> Modified:
>>>  head/sys/arm/arm/dump_machdep.c
>>> 
>>> Modified: head/sys/arm/arm/dump_machdep.c
>>> ==============================================================================
>>> --- head/sys/arm/arm/dump_machdep.c Wed Dec 24 16:11:15
>>> 2014        (r276186) +++ head/sys/arm/arm/dump_machdep.c   Wed
>>> Dec 24 17:12:51 2014        (r276187) @@ -160,11 +160,13 @@ static int
>>> cb_dumpdata(struct md_pa *mdp, int seqnr, void *arg)
>>> {
>>>     struct dumperinfo *di = (struct dumperinfo*)arg;
>>> -   vm_paddr_t pa;
>>> +   vm_paddr_t a, pa;
>>> +   void *va;
>>>     uint32_t pgs;
>>>     size_t counter, sz, chunk;
>>> -   int c, error;
>>> +   int i, c, error;
>>> 
>>> +   va = 0;
>>>     error = 0;      /* catch case in which chunk size is 0 */
>>>     counter = 0;
>>>     pgs = mdp->md_size / PAGE_SIZE;
>>> @@ -194,16 +196,14 @@ cb_dumpdata(struct md_pa *mdp, int seqnr
>>>                     printf(" %d", pgs * PAGE_SIZE);
>>>                     counter &= (1<<24) - 1;
>>>             }
>>> -           if (pa == (pa & L1_ADDR_BITS)) {
>>> -                   pmap_kenter_section(0, pa & L1_ADDR_BITS, 0);
>>> -                   cpu_tlb_flushID_SE(0);
>>> -                   cpu_cpwait();
>>> +           for (i = 0; i < chunk; i++) {
>>> +                   a = pa + i * PAGE_SIZE;
>>> +                   va = pmap_kenter_temporary(trunc_page(a), i);
>> 
>> Is this correct? It may map multiple chunks here.
>>>             }
>>> #ifdef SW_WATCHDOG
>>>             wdog_kern_pat(WD_LASTVAL);
>>> #endif
>>> -           error = dump_write(di,
>>> -               (void *)(pa - (pa & L1_ADDR_BITS)),0, dumplo,
>>> sz);
>>> +           error = dump_write(di, va, 0, dumplo, sz);
>> 
>> Then uses the last virtual address to dump the data here. Wouldn't this
>> miss the chunks mapped other than the last one?
> 
> Yeah, but a quirk of pmap_kenter_temporary() is that its return value is
> constant, so this wrong-looking code is actually right.

I'm a bit surprised about this.  This most likely warrants a comment.


--
Rui Paulo



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