Messages in this thread | | | Date | Thu, 31 Jan 2008 08:29:06 -0800 | From | Arjan van de Ven <> | Subject | Re: [RFC PATCH v2] x86: mmiotrace - trace memory mapped IO |
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On Thu, 31 Jan 2008 18:16:30 +0200 Pekka Paalanen <pq@iki.fi> wrote:
> > > could you please send us a patch for the whole mmiotrace > > > kernel-side feature, so that we can have a look at the general > > > structure of this? (and the interaction with change_page_attr(), > > > etc.) Even if it's not functional (and wont even build/boot) at > > > the moment. Thanks, > > And here's mmiotrace. This works for me (amd64), but not for a test > user who has 32-bit x86. We have not had the chance to debug it yet. > The symptom is "everything locked up" after insmodding > testmmiotrace.ko, targeting the mid-point of his VRAM. And there's > the "undefined symbol init_mm" problem on 32-bit, but we just put the > export back in (not included in these patches). > > No-one has tried this on SMP. I have a Core 2 Duo laptop where I will > test this when I get the chance.
+static void print_pte(unsigned long address) > +{ > + pgd_t *pgd = pgd_offset_k(address); > + pud_t *pud = pud_offset(pgd, address); > + pmd_t *pmd = pmd_offset(pud, address); > + if (pmd_large(*pmd)) { > + printk(KERN_EMERG MODULE_NAME ": 4MB pages are not " > + "currently > supported: %lx\n", > + address); > + BUG(); > + } > + printk(KERN_DEBUG MODULE_NAME ": pte for 0x%lx: 0x%lx > 0x%lx\n", > + address, > + pte_val(*pte_offset_kernel(pmd, address)), > + pte_val(*pte_offset_kernel(pmd, address)) & > _PAGE_PRESENT); +}
ok this wants to use some of the page_address() and other helpers from pageattr.c; that should be easy to solve during integration (I can even see a more generic version of this function moving there)
> +/* file_create() callback. Creates relay file in debugfs. */ > +static struct dentry *create_buf_file_handler(const char *filename, > + struct dentry > *parent, > + int mode, > + struct rchan_buf > *buf, > + int *is_global) > +{ > + struct dentry *buf_file; > + > + mmio_fops.read = relay_file_operations.read; > + mmio_fops.open = relay_file_operations.open; > + mmio_fops.poll = relay_file_operations.poll; > + mmio_fops.mmap = relay_file_operations.mmap; > + mmio_fops.release = relay_file_operations.release; > + mmio_fops.splice_read = relay_file_operations.splice_read;
can't we do this at compile time?
> + > +void __iomem *ioremap_cache_trace(unsigned long offset, unsigned > long size) +{ > + void __iomem *p = ioremap_cache(offset, size); > + printk(KERN_DEBUG MODULE_NAME ": ioremap_cache(0x%lx, 0x%lx) > = %p\n", > + offset, > size, p); > + ioremap_trace_core(offset, size, p); > + return p; > +} > +EXPORT_SYMBOL(ioremap_cache_trace); > + > +void __iomem *ioremap_nocache_trace(unsigned long offset, unsigned > long size) +{ > + void __iomem *p = ioremap_nocache(offset, size); > + printk(KERN_DEBUG MODULE_NAME ": ioremap_nocache(0x%lx, > 0x%lx) = %p\n", > + offset, > size, p); > + ioremap_trace_core(offset, size, p); > + return p; > +} > +EXPORT_SYMBOL(ioremap_nocache_trace);
I would rather keep the split I think and make the trace call explicit
or.. even nicer, we could go fancy and allow the mmio tracer to "subscribe" to, say, a PCI bar, and auto-enable tracing when the bar gets ioremap'd
about the isntruction decoding.. would be nice if we can share that with kvm so that we can debug that stuff once ;-)
other than that I think the code is quite nice already, seems getting this merge ready isn't going to be an enormous deal in terms of complexity
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