PERFORCE change 140994 for review

[John Baldwin]

On Thursday 01 May 2008 01:38:21 pm Peter Wemm wrote:
> http://perforce.freebsd.org/chv.cgi?CH=140994
> 
> Change 140994 by peter at peter_daintree on 2008/05/01 17:37:28
> 
> 	Update.  Use the correct fields.  Look for pcpu_size in the kernel
> 	to adapt to any layout changes.  (Let the consumer deal with variance
> 	rather than guaranteeing that libkvm breaks first)

You do know about this MI array in kern/subr_pcpu.c?

struct pcpu *cpuid_to_pcpu[MAXCPU];
struct cpuhead cpuhead = SLIST_HEAD_INITIALIZER(cpuhead);

You can use that to make this all MI instead of reading __pcpu.  Either walk 
the cpuhead list or the array and just read the pcpu structs one at a time.
 
> Affected files ...
> 
> .. //depot/projects/hammer/lib/libkvm/kvm_amd64.c#24 edit
> 
> Differences ...
> 
> ==== //depot/projects/hammer/lib/libkvm/kvm_amd64.c#24 (text+ko) ====
> 
> @@ -76,7 +76,8 @@
>  	size_t		mmapsize;
>  	pml4_entry_t	*PML4;
>  	int		mp_maxcpus;
> -	struct pcpu	*pcpu;
> +	int		pcpu_recsize;
> +	char		*pcpu;
>  };
>  
>  /*
> @@ -375,9 +376,23 @@
>  		/* UP system; symbol doesn't exist */
>  		vmst->mp_maxcpus = 1;
>  	}
> -	vm->pcpu = _kvm_malloc(kd, sizeof(struct pcpu) * vm->mp_maxcpus);
> +	/*
> +	 * The __pcpu array may have different inter-record padding or may
> +	 * grow additional fields.  We have to adapt the best we can.
> +	 */
> +	nlist[0].n_name = "pcpu_size";
> +	nlist[1].n_name = 0;
> +	if (kvm_nlist(kd, nlist) == 0) {
> +		if (kvm_read(kd, nlist[0].n_value, &vm->pcpu_recsize,
> +		    sizeof(vm->pcpu_recsize)) != sizeof(vm->pcpu_recsize)) {
> +			_kvm_err(kd, kd->program, "cannot read pcpu_size");
> +	} else {
> +		/* Older kernel's dont have it. Hope for the best. */
> +		vmst->pcpu_recsize = sizeof(struct pcpu);
> +	}
> +	vm->pcpu = _kvm_malloc(kd, vm->pcpu_recsize * vm->mp_maxcpus);
>  
> -	nlist[0].n_name = "pcpu";
> +	nlist[0].n_name = "__pcpu";
>  	nlist[1].n_name = 0;
>  
>  	if (kvm_nlist(kd, nlist) != 0) {
> @@ -385,8 +400,8 @@
>  		return (-1);
>  	}
>  	if (kvm_read(kd, nlist[0].n_value, vm->pcpu,
> -	    sizeof(struct pcpu) * vm->mp_maxcpus) !=
> -	    sizeof(struct pcpu) * vm->mp_maxcpus) {
> +	    vm->pcpu_recsize * vm->mp_maxcpus) !=
> +	    vm->pcpu_recsize * vm->mp_maxcpus) {
>  		_kvm_err(kd, kd->program, "cannot read pcpu chunk");
>  		return (-1);
>  	}
> @@ -407,8 +422,8 @@
>  			return (NULL);
>  	}
>  
> -	if (cpu < 0 ||  cpu > vm->vm_maxcpus)
> +	if (cpu < 0 || cpu > vm->vm_maxcpus)
>  		_kvm_err(kd, kd->program, "
>  		return (NULL);	/* EDOOFUS actually */
> -	return (&vm->pcpu[cpu]);
> +	return ((struct pcpu *)&vm->pcpu[cpu * vm->pcpu_recsize]);
>  }
> 



-- 
John Baldwin