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Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull x86 vdso updates from Ingo Molnar:
 "Various vDSO updates from Andy Lutomirski, mostly cleanups and
  reorganization to improve maintainability, but also some
  micro-optimizations and robustization changes"

* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86_64/vsyscall: Restore orig_ax after vsyscall seccomp
  x86_64: Add a comment explaining the TASK_SIZE_MAX guard page
  x86_64,vsyscall: Make vsyscall emulation configurable
  x86_64, vsyscall: Rewrite comment and clean up headers in vsyscall code
  x86_64, vsyscall: Turn vsyscalls all the way off when vsyscall==none
  x86,vdso: Use LSL unconditionally for vgetcpu
  x86: vdso: Fix build with older gcc
  x86_64/vdso: Clean up vgetcpu init and merge the vdso initcalls
  x86_64/vdso: Remove jiffies from the vvar page
  x86/vdso: Make the PER_CPU segment 32 bits
  x86/vdso: Make the PER_CPU segment start out accessed
  x86/vdso: Change the PER_CPU segment to use struct desc_struct
  x86_64/vdso: Move getcpu code from vsyscall_64.c to vdso/vma.c
  x86_64/vsyscall: Move all of the gate_area code to vsyscall_64.c
This commit is contained in:
Linus Torvalds 2014-12-10 14:24:20 -08:00
commit 3100e448e7
16 changed files with 190 additions and 200 deletions
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8
arch/x86/include/asm/processor.h
View file

@ -894,7 +894,13 @@ extern unsigned long thread_saved_pc(struct task_struct *tsk);
#else
/*
* User space process size. 47bits minus one guard page.
* User space process size. 47bits minus one guard page. The guard
* page is necessary on Intel CPUs: if a SYSCALL instruction is at
* the highest possible canonical userspace address, then that
* syscall will enter the kernel with a non-canonical return
* address, and SYSRET will explode dangerously. We avoid this
* particular problem by preventing anything from being mapped
* at the maximum canonical address.
*/
#define TASK_SIZE_MAX ((1UL << 47) - PAGE_SIZE)