Messages in this thread | | | Date | Fri, 03 Oct 2008 20:11:27 +0200 | From | Jiri Slaby <> | Subject | Re: [PATCH -tip] x86: fix virt_addr_valid() with CONFIG_DEBUG_VIRTUAL=y (try 2) |
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Vegard Nossum napsal(a): > Is this what you had in mind? If not, then I don't know how to do it :-)
Yeah, something like that, but I am not the one you need ACK from ;).
Few notes below.
> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c > index 835e062..b20389d 100644 > --- a/arch/x86/mm/ioremap.c > +++ b/arch/x86/mm/ioremap.c > @@ -45,6 +45,28 @@ unsigned long __phys_addr(unsigned long x) > } > EXPORT_SYMBOL(__phys_addr); > > +bool __virt_addr_valid(unsigned long x) > +{ > + if (x >= __START_KERNEL_map) { > + x -= __START_KERNEL_map; > + if (x >= KERNEL_IMAGE_SIZE) > + return false; > + x += phys_base; > + } else { > + if (x < PAGE_OFFSET) > + return false; > + x -= PAGE_OFFSET; > + if (system_state == SYSTEM_BOOTING > + ? x > MAXMEM : !phys_addr_valid(x)) > + { > + return false; > + } > + } > + > + return pfn_valid(x >> PAGE_SHIFT); > +} > +EXPORT_SYMBOL(__virt_addr_valid);
Just an implementation note. Still don't expect address for which __virt_addr_valid() returns true to not cause a page fault. If it is called e.g. for address between __START_KERNEL_map and __START_KERNEL_map+KERNEL_IMAGE_SIZE and its pte entry has present bit unset, it will crash when dereferenced -- unused pages above kernel image are unmapped during boot.
> + > #else [...] > +bool __virt_addr_valid(unsigned long x) > +{ > + if (x < PAGE_OFFSET) > + return false; > + if (system_state != SYSTEM_BOOTING && is_vmalloc_addr((void *) x)) > + return false; > + return pfn_valid((x - PAGE_OFFSET) >> PAGE_SHIFT); > +}
Here too, the mappings at the top are probably returned as true? Absolutely not sure about this (what returns pfn_valid on those corresponding physical addresses).
> #endif > > int page_is_ram(unsigned long pagenr)
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