path: root/Documentation
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authorLinus Torvalds <>2011-08-12 20:46:24 -0700
committerLinus Torvalds <>2011-08-12 20:46:24 -0700
commit06e727d2a5d9d889fabad35223ad77205a9bebb9 (patch)
tree2a2d4ec9ed95c95f044c8d69e87ab47195a1d2ed /Documentation
parente68ff9cd15552e46e0f993eace25af0947b1222d (diff)
parent3ae36655b97a03fa1decf72f04078ef945647c1a (diff)
Merge branch 'x86-vdso-for-linus' of git://
* 'x86-vdso-for-linus' of git:// x86-64: Rework vsyscall emulation and add vsyscall= parameter x86-64: Wire up getcpu syscall x86: Remove unnecessary compile flag tweaks for vsyscall code x86-64: Add vsyscall:emulate_vsyscall trace event x86-64: Add user_64bit_mode paravirt op x86-64, xen: Enable the vvar mapping x86-64: Work around gold bug 13023 x86-64: Move the "user" vsyscall segment out of the data segment. x86-64: Pad vDSO to a page boundary
Diffstat (limited to 'Documentation')
1 files changed, 21 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index e279b7242912..78926aa2531c 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2680,6 +2680,27 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
vmpoff= [KNL,S390] Perform z/VM CP command after power off.
Format: <command>
+ vsyscall= [X86-64]
+ Controls the behavior of vsyscalls (i.e. calls to
+ fixed addresses of 0xffffffffff600x00 from legacy
+ code). Most statically-linked binaries and older
+ versions of glibc use these calls. Because these
+ functions are at fixed addresses, they make nice
+ targets for exploits that can control RIP.
+ emulate [default] Vsyscalls turn into traps and are
+ emulated reasonably safely.
+ native Vsyscalls are native syscall instructions.
+ This is a little bit faster than trapping
+ and makes a few dynamic recompilers work
+ better than they would in emulation mode.
+ It also makes exploits much easier to write.
+ none Vsyscalls don't work at all. This makes
+ them quite hard to use for exploits but
+ might break your system.
vt.cur_default= [VT] Default cursor shape.
Format: 0xCCBBAA, where AA, BB, and CC are the same as
the parameters of the <Esc>[?A;B;Cc escape sequence;