On Sun, Jan 12, 2014 at 05:20:00PM +0800, Qiaowei Ren wrote:
> An access to an invalid bound directory entry will cause a #BR
> exception. This patch hook #BR exception handler to allocate
> one bound table and bind it with that buond directory entry.
>
> This will avoid the need of forwarding the #BR exception
> to the user space when bound directory has invalid entry.
>
> Signed-off-by: Qiaowei Ren <qiaowei....@intel.com>
> ---
> arch/x86/include/asm/mpx.h | 35 +++++++++++++++++++++++++++++++++
> arch/x86/kernel/Makefile | 1 +
> arch/x86/kernel/mpx.c | 44 ++++++++++++++++++++++++++++++++++++++++++
> arch/x86/kernel/traps.c | 46
> +++++++++++++++++++++++++++++++++++++++++++-
> 4 files changed, 125 insertions(+), 1 deletions(-)
> create mode 100644 arch/x86/include/asm/mpx.h
> create mode 100644 arch/x86/kernel/mpx.c
...
> diff --git a/arch/x86/kernel/mpx.c b/arch/x86/kernel/mpx.c
> new file mode 100644
> index 0000000..767b3bf
> --- /dev/null
> +++ b/arch/x86/kernel/mpx.c
> @@ -0,0 +1,44 @@
> +#include <linux/kernel.h>
> +#include <linux/syscalls.h>
> +#include <asm/processor.h>
> +#include <asm/mpx.h>
> +#include <asm/mman.h>
> +#include <asm/i387.h>
> +#include <asm/fpu-internal.h>
> +#include <asm/alternative.h>
> +
> +static bool allocate_bt(unsigned long bd_entry)
> +{
> + unsigned long bt_size = 1UL << (MPX_L2_BITS+MPX_L2_SHIFT);
> + unsigned long bt_addr, old_val;
> +
> + bt_addr = sys_mmap_pgoff(0, bt_size, PROT_READ | PROT_WRITE,
> + MAP_ANONYMOUS | MAP_PRIVATE | MAP_POPULATE, -1, 0);
Are we sure about this? We can do a possible memory allocation in
mmap_region() in this exception handler context. And yes, we do a
conditional_sti(), which makes it all the more susceptible.
Have you run this with lockdep enabled?
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
--
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
