svn commit: r276187 - head/sys/arm/arm

[Rui Paulo]

On Dec 24, 2014, at 14:40, Ian Lepore <ian at 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 <ian at 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 <onwahe at gmail.com>,
>>>  		Michal Meloun <meloun at 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