Messages in this thread Patch in this message | | | Date | Sat, 26 Apr 2008 21:07:07 +0200 | From | Ingo Molnar <> | Subject | [patch] x86, PAT: disable /dev/mem mmap RAM with PAT |
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* Venki Pallipadi <venkatesh.pallipadi@intel.com> wrote:
> OK. Below is the quick to disable /dev/mem mmap of RAM with PAT. This > should go along with Ingo's patch that removes PAT dependency on > NONPROMISC_DEVMEM. It makes things safer and eliminates aliasing. > Still somewhat unclean as the range_is_allowed is duplicated. And > also, just compile tested right now.
thanks, i've queued up the patch below. I'll do some testing and then send it to Linus.
Ingo
---------------> Subject: x86, PAT: disable /dev/mem mmap RAM with PAT From: Venki Pallipadi <venkatesh.pallipadi@intel.com> Date: Sat, 26 Apr 2008 11:32:12 -0700
disable /dev/mem mmap of RAM with PAT. It makes things safer and eliminates aliasing. A future improvement would be to avoid the range_is_allowed duplication.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- arch/x86/mm/pat.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+)
Index: linux-x86.q/arch/x86/mm/pat.c =================================================================== --- linux-x86.q.orig/arch/x86/mm/pat.c +++ linux-x86.q/arch/x86/mm/pat.c @@ -16,6 +16,7 @@ #include <asm/msr.h> #include <asm/tlbflush.h> #include <asm/processor.h> +#include <asm/page.h> #include <asm/pgtable.h> #include <asm/pat.h> #include <asm/e820.h> @@ -477,6 +478,33 @@ pgprot_t phys_mem_access_prot(struct fil return vma_prot; } +#ifdef CONFIG_NONPROMISC_DEVMEM +/* This check is done in drivers/char/mem.c in case of NONPROMISC_DEVMEM*/ +static inline int range_is_allowed(unsigned long pfn, unsigned long size) +{ + return 1; +} +#else +static inline int range_is_allowed(unsigned long pfn, unsigned long size) +{ + u64 from = ((u64)pfn) << PAGE_SHIFT; + u64 to = from + size; + u64 cursor = from; + + while (cursor < to) { + if (!devmem_is_allowed(pfn)) { + printk(KERN_INFO + "Program %s tried to access /dev/mem between %Lx->%Lx.\n", + current->comm, from, to); + return 0; + } + cursor += PAGE_SIZE; + pfn++; + } + return 1; +} +#endif /* CONFIG_NONPROMISC_DEVMEM */ + int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn, unsigned long size, pgprot_t *vma_prot) { @@ -485,6 +513,9 @@ int phys_mem_access_prot_allowed(struct unsigned long ret_flags; int retval; + if (!range_is_allowed(pfn, size)) + return 0; + if (file->f_flags & O_SYNC) { flags = _PAGE_CACHE_UC; }
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