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The vsyscall page is weird. It is in what is traditionally part of the kernel address space. But, it has user permissions and we handle faults on it like we would on a user page: interrupts on. Right now, we handle vsyscall emulation in the "bad_area" code, which is used for both user-address-space and kernel-address-space faults. Move the handling to the user-address-space code *only* and ensure we get there by "excluding" the vsyscall page from the kernel address space via a check in fault_in_kernel_space(). Since the fault_in_kernel_space() check is used on 32-bit, also add a 64-bit check to make it clear we only use this path on 64-bit. Also move the unlikely() to be in is_vsyscall_vaddr() itself. This helps clean up the kernel fault handling path by removing a case that can happen in normal[1] operation. (Yeah, yeah, we can argue about the vsyscall page being "normal" or not.) This also makes sanity checks easier, like the "we never take pkey faults in the kernel address space" check in the next patch. Cc: x86@kernel.org Cc: Jann Horn <jannh@google.com> Cc: Sean Christopherson <sean.j.christopherson@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: http://lkml.kernel.org/r/20180928160230.6E9336EE@viggo.jf.intel.com |
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| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.