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SubjectRe: [PATCH 01/01][retry 2] x86: L3 cache index disable for 2.6.26
Hi!
> diff -r e683983d4dd0 Documentation/ABI/testing/sysfs-devices-cache_disable
> --- /dev/null Thu Jan 01 00:00:00 1970 +0000
> +++ b/Documentation/ABI/testing/sysfs-devices-cache_disable Wed Aug 13 09:06:52 2008 -0500
> @@ -0,0 +1,18 @@
> +What: /sys/devices/system/cpu/cpu*/cache/index*/cache_disable_X
> +Date: Augsust 2008
> +KernelVersion: 2.6.27
> +Contact: osrc-kernel@elbe.amd.com
> +Description: These files exist in every cpu's cache index directories.
> + There are currently 2 cache_disable_# files in each
> + directory. Reading from these files on a supported
> + processor will return that cache disable index value
> + for that processor and node. Writing to one of these
> + files will cause the specificed cache index to be disable.

disabled.

> +#if defined(CONFIG_PCI) && defined(CONFIG_K8_NB)
> +#include <linux/pci.h>
> +#include <asm/k8.h>
> +static struct pci_dev *get_k8_northbridge(int node)
> +{
> + return k8_northbridges[node];
> +}
> +#else
> +static inline int pci_write_config_dword(struct pci_dev *dev, int where,
> + u32 val)
> +{
> + return 0;
> +}

Spaces vs. tabs problem visible here. ...

> +static ssize_t show_cache_disable(struct _cpuid4_info *this_leaf, char *buf,
> + unsigned int index)
> +{
> + int node = cpu_to_node(first_cpu(this_leaf->shared_cpu_map));
> + struct pci_dev *dev = get_k8_northbridge(node);
> + unsigned int reg = 0;
> +
> + if (!this_leaf->can_disable)
> + return 0;
> +
> + pci_read_config_dword(dev, 0x1BC + index * 4, &reg);
> + return sprintf(buf, "%x\n", reg);
> +}

...and getting serious here.


> +#define SHOW_CACHE_DISABLE(index) \
> +static ssize_t \
> +show_cache_disable_##index(struct _cpuid4_info *this_leaf, char *buf) \
> +{ \
> + return show_cache_disable(this_leaf, buf, index); \
> +}
> +
> +static ssize_t
> +store_cache_disable(struct _cpuid4_info *this_leaf, const char *buf,
> + size_t count, unsigned int index)
> +{
> + int node = cpu_to_node(first_cpu(this_leaf->shared_cpu_map));
> + struct pci_dev *dev = get_k8_northbridge(node);
> + ssize_t ret = 0;
> + unsigned int val;
> +
> + if (!this_leaf->can_disable)
> + return 0;

So if someone asks you to disable part of cache you can't disable, you
return success?

> + if (strlen(buf) > 10)
> + return -EINVAL;
> +
> + ret = sscanf(buf, "%x\n", &val);
> + if (ret != 1)
> + return -EINVAL;
....
> + return strlen(buf);

Is this safe to do? What if buf is not null-terminated?

return count?

Actually, the sscanf is problematic, too, right?


Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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