linux-toradex.git/arch/x86/include/asm/vdso.h, branch v4.9.76

x86/arch_prctl/vdso: Add ARCH_MAP_VDSO_*

2016-09-14T19:28:09+00:00

Add API to change vdso blob type with arch_prctl.
As this is usefull only by needs of CRIU, expose
this interface under CONFIG_CHECKPOINT_RESTORE.

Signed-off-by: Dmitry Safonov 
Acked-by: Andy Lutomirski 
Cc: 0x7f454c46@gmail.com
Cc: oleg@redhat.com
Cc: linux-mm@kvack.org
Cc: gorcunov@openvz.org
Cc: xemul@virtuozzo.com
Link: http://lkml.kernel.org/r/20160905133308.28234-4-dsafonov@virtuozzo.com
Signed-off-by: Thomas Gleixner

x86/vdso: Use .fault for the vDSO text mapping

2016-01-12T10:59:34+00:00

The old scheme for mapping the vDSO text is rather complicated.
vdso2c generates a struct vm_special_mapping and a blank .pages
array of the correct size for each vdso image.  Init code in
vdso/vma.c populates the .pages array for each vDSO image, and
the mapping code selects the appropriate struct
vm_special_mapping.

With .fault, we can use a less roundabout approach: vdso_fault()
just returns the appropriate page for the selected vDSO image.

Signed-off-by: Andy Lutomirski 
Reviewed-by: Kees Cook 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Dave Hansen 
Cc: Fenghua Yu 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Oleg Nesterov 
Cc: Peter Zijlstra 
Cc: Quentin Casasnovas 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/f886954c186bafd74e1b967c8931d852ae199aa2.1451446564.git.luto@kernel.org
Signed-off-by: Ingo Molnar

x86/vdso: Get pvclock data from the vvar VMA instead of the fixmap

2015-12-11T07:56:03+00:00

Signed-off-by: Andy Lutomirski 
Reviewed-by: Paolo Bonzini 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/9d37826fdc7e2d2809efe31d5345f97186859284.1449702533.git.luto@kernel.org
Signed-off-by: Ingo Molnar

x86/vdso/32: Save extra registers in the INT80 vsyscall path

2015-10-09T07:41:06+00:00

The goal is to integrate the SYSENTER and SYSCALL32 entry paths
with the INT80 path.  SYSENTER clobbers ESP and EIP.  SYSCALL32
clobbers ECX (and, invisibly, R11).  SYSRETL (long mode to
compat mode) clobbers ECX and, invisibly, R11.  SYSEXIT (which
we only need for native 32-bit) clobbers ECX and EDX.

This means that we'll need to provide ESP to the kernel in a
register (I chose ECX, since it's only needed for SYSENTER) and
we need to provide the args that normally live in ECX and EDX in
memory.

The epilogue needs to restore ECX and EDX, since user code
relies on regs being preserved.

We don't need to do anything special about EIP, since the kernel
already knows where we are.  The kernel will eventually need to
know where int $0x80 lands, so add a vdso_image entry for it.

The only user-visible effect of this code is that ptrace-induced
changes to ECX and EDX during fast syscalls will be lost.  This
is already the case for the SYSENTER path.

Signed-off-by: Andy Lutomirski 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/b860925adbee2d2627a0671fbfe23a7fd04127f8.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar

x86/vdso: Remove runtime 32-bit vDSO selection

2015-10-07T09:34:08+00:00

32-bit userspace will now always see the same vDSO, which is
exactly what used to be the int80 vDSO.  Subsequent patches will
clean it up and make it support SYSENTER and SYSCALL using
alternatives.

Signed-off-by: Andy Lutomirski 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/e7e6b3526fa442502e6125fe69486aab50813c32.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar

x86, vdso: Move the vvar area before the vdso text

2014-07-11T23:57:51+00:00

Putting the vvar area after the vdso text is rather complicated: it
only works of the total length of the vdso text mapping is known at
vdso link time, and the linker doesn't allow symbol addresses to
depend on the sizes of non-allocatable data after the PT_LOAD
segment.

Moving the vvar area before the vdso text will allow is to safely
map non-allocatable data after the vdso text, which is a nice
simplification.

Signed-off-by: Andy Lutomirski 
Link: http://lkml.kernel.org/r/156c78c0d93144ff1055a66493783b9e56813983.1405040914.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin

x86, mm: Improve _install_special_mapping and fix x86 vdso naming

2014-05-20T18:38:42+00:00

Using arch_vma_name to give special mappings a name is awkward.  x86
currently implements it by comparing the start address of the vma to
the expected address of the vdso.  This requires tracking the start
address of special mappings and is probably buggy if a special vma
is split or moved.

Improve _install_special_mapping to just name the vma directly.  Use
it to give the x86 vvar area a name, which should make CRIU's life
easier.

As a side effect, the vvar area will show up in core dumps.  This
could be considered weird and is fixable.

[hpa: I say we accept this as-is but be prepared to deal with knocking
 out the vvars from core dumps if this becomes a problem.]

Cc: Cyrill Gorcunov 
Cc: Pavel Emelyanov 
Signed-off-by: Andy Lutomirski 
Link: http://lkml.kernel.org/r/276b39b6b645fb11e345457b503f17b83c2c6fd0.1400538962.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin

x86, vdso: Move the 32-bit vdso special pages after the text

2014-05-05T20:18:56+00:00

This unifies the vdso mapping code and teaches it how to map special
pages at addresses corresponding to symbols in the vdso image.  The
new code is used for all vdso variants, but so far only the 32-bit
variants use the new vvar page position.

Signed-off-by: Andy Lutomirski 
Link: http://lkml.kernel.org/r/b6d7858ad7b5ac3fd3c29cab6d6d769bc45d195e.1399317206.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin

x86, vdso: Reimplement vdso.so preparation in build-time C

2014-05-05T20:18:51+00:00

Currently, vdso.so files are prepared and analyzed by a combination
of objcopy, nm, some linker script tricks, and some simple ELF
parsers in the kernel. Replace all of that with plain C code that
runs at build time.

All five vdso images now generate .c files that are compiled and
linked in to the kernel image.

This should cause only one userspace-visible change: the loaded vDSO
images are stripped more heavily than they used to be. Everything
outside the loadable segment is dropped. In particular, this causes
the section table and section name strings to be missing. This
should be fine: real dynamic loaders don't load or inspect these
tables anyway. The result is roughly equivalent to eu-strip's
--strip-sections option.

The purpose of this change is to enable the vvar and hpet mappings
to be moved to the page following the vDSO load segment. Currently,
it is possible for the section table to extend into the page after
the load segment, so, if we map it, it risks overlapping the vvar or
hpet page. This happens whenever the load segment is just under a
multiple of PAGE_SIZE.

The only real subtlety here is that the old code had a C file with
inline assembler that did 'call VDSO32_vsyscall' and a linker script
that defined 'VDSO32_vsyscall = __kernel_vsyscall'. This most
likely worked by accident: the linker script entry defines a symbol
associated with an address as opposed to an alias for the real
dynamic symbol __kernel_vsyscall. That caused ld to relocate the
reference at link time instead of leaving an interposable dynamic
relocation. Since the VDSO32_vsyscall hack is no longer needed, I
now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it
work. vdso2c will generate an error and abort the build if the
resulting image contains any dynamic relocations, so we won't
silently generate bad vdso images.

(Dynamic relocations are a problem because nothing will even attempt
to relocate the vdso.)

Signed-off-by: Andy Lutomirski
Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin

x86, vdso: Finish removing VDSO32_PRELINK

2014-03-21T03:20:18+00:00

It's a declaration of a nonexistent symbol.  We can get rid of the
64-bit versions, too, but that's more intrusive.

Signed-off-by: Andy Lutomirski 
Cc: Stefani Seibold 
Link: http://lkml.kernel.org/r/2ce2ce18447d8a0b78d44a278a066b6c0af06b32.1395366931.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin