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This patchset throws out tt mode, which has been non-functional for a while.
This is done in phases, interspersed with code cleanups on the affected files.
The removal is done as follows:
remove all code, config options, and files which depend on
CONFIG_MODE_TT
get rid of the CHOOSE_MODE macro, which decided whether to
call tt-mode or skas-mode code, and replace invocations with their
skas portions
replace all now-trivial procedures with their skas equivalents
There are now a bunch of now-redundant pieces of data structures, including
mode-specific pieces of the thread structure, pt_regs, and mm_context. These
are all replaced with their skas-specific contents.
As part of the ongoing style compliance project, I made a style pass over all
files that were changed. There are three such patches, one for each phase,
covering the files affected by that phase but no later ones.
I noticed that we weren't freeing the LDT state associated with a process when
it exited, so that's fixed in one of the later patches.
The last patch is a tidying patch which I've had for a while, but which caused
inexplicable crashes under tt mode. Since that is no longer a problem, this
can now go in.
This patch:
Start getting rid of tt mode support.
This patch throws out CONFIG_MODE_TT and all config options, code, and files
which depend on it.
CONFIG_MODE_SKAS is gone and everything that depends on it is included
unconditionally.
The few changed lines are in re-written Kconfig help, lines which needed
something skas-related removed from them, and a few more which weren't
strictly deletions.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Replaced task_protections with stack_protections since they do the same
thing, and task_protections was misnamed anyway.
This needs THREAD_SIZE, so that's imported via common-offsets.h
Also tidied up the code in the vicinity.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Rename os_{read_write}_file_k back to os_{read_write}_file, delete
the originals and their bogus infrastructure, and fix all the callers.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This patch starts the removal of a very old, very broken piece of code. This
stems from the problem of passing a userspace buffer into read() or write() on
the host. If that buffer had not yet been faulted in, read and write will
return -EFAULT.
To avoid this problem, the solution was to fault the buffer in before the
system call by touching the pages that hold the buffer by doing a copy-user of
a byte to each page. This is obviously bogus, but it does usually work, in tt
mode, since the kernel and process are in the same address space and userspace
addresses can be accessed directly in the kernel.
In skas mode, where the kernel and process are in separate address spaces, it
is completely bogus because the userspace address, which is invalid in the
kernel, is passed into the system call instead of the corresponding physical
address, which would be valid. Here, it appears that this code, on every host
read() or write(), tries to fault in a random process page. This doesn't seem
to cause any correctness problems, but there is a performance impact. This
patch, and the ones following, result in a 10-15% performance gain on a kernel
build.
This code can't be immediately tossed out because when it is, you can't log
in. Apparently, there is some code in the console driver which depends on
this somehow.
However, we can start removing it by switching the code which does I/O using
kernel addresses to using plain read() and write(). This patch introduces
os_read_file_k and os_write_file_k for use with kernel buffers and converts
all call locations which use obvious kernel buffers to use them. These
include I/O using buffers which are local variables which are on the stack or
kmalloc-ed. Later patches will handle the less obvious cases, followed by a
mass conversion back to the original interface.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Acked-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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user_util.h isn't needed any more, so delete it and remove all includes of it.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Get rid of a bunch of unused stuff -
cpu_feature had no users
linux_prog is little-used, so its declaration is moved to the
user for easy deletion when the whole file goes away
a long-unused debugging aid in helper.c is gone
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Locking fixes. Locking was totally lacking for the mconsole_devices, which
got a spin lock, and the unplugged pages data, which got a mutex.
The locking of the mconsole console output code was confused. Now, the
console_lock (renamed to client_lock) protects the clients list.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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I noticed that errors happening while hotplugging devices from the host were
never returned back to the mconsole client. In some cases, success was
returned instead of even an information-free error.
This patch cleans that up by having the low-level configuration code pass back
an error string along with an error code. At the top level, which knows
whether it is early boot time or responding to an mconsole request, the string
is printk'd or returned to the mconsole client.
There are also whitespace and trivial code cleanups in the surrounding code.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix a small memory leak in ubd_config, and clearify the confusion which lead
to it.
Then, some little changes not affecting operations -
* move init functions together,
* add a comment about a potential problem in case of some evolution in the block layer,
* mark all initcalls as static __init functions
* mark an used once little function as inline
* document that mconsole methods are all called in process context (was
triggered when checking ubd mconsole methods).
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Make TT mode compile after the introduction of klibc's implementation of
setjmp.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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kbuild explicitly includes this at build time.
Signed-off-by: Dave Jones <davej@redhat.com>
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Eliminate an unused debug option.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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It turns out that init_new_thread_signals is always called with altstack == 1,
so we can eliminate the parameter.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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When UML is built as a static binary, it segfaults when run. The reason is
that a memory hole that is present in dynamic binaries isn't there in static
binaries, and it contains essential stuff.
This fix removes the code which maps some anonymous memory into that hole and
cleans up some related code.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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I was looking at the code of the UML and more precisely at the functions
set_task_sizes_tt and set_task_sizes_skas. I noticed that these 2 functions
take a paramater (arg) which is not used : the function is always called with
the value 0.
I suppose that this value might change in the future (or even can be
configured), so I added a constant in mem_user.h file.
Also, I rounded CONFIG_HOST_TASk_SIZE to a 4M.
Signed-off-by: Tyler <tyler@agat.net>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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cleanup: remove task_t and convert all the uses to struct task_struct. I
introduced it for the scheduler anno and it was a mistake.
Conversion was mostly scripted, the result was reviewed and all
secondary whitespace and style impact (if any) was fixed up by hand.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Call arch_switch also in switch_to_skas, even if it's, for now, a no-op for
that case (and mark this in the comment); this will change soon.
Also, arch_switch for TT mode is actually useless when the PT proxy (a
complicate debugging instrumentation for TT mode) is not enabled. In fact, it
only calls update_debugregs, which checks debugregs_seq against seq (to check
if the registers are up-to-date - seq here means a "version number" of the
registers).
If the ptrace proxy is not enabled, debugregs_seq always stays 0 and
update_debugregs will be a no-op. So, optimize this out (the compiler can't
do it).
Also, I've been disappointed by the fact that it would make a lot of sense if,
after calling a successful
update_debugregs(current->thread.arch.debugregs_seq),
current->thread.arch.debugregs_seq were updated with the new debugregs_seq.
But this is not done. Is this a bug or a feature? For all purposes, it seems
a bug (otherwise the whole mechanism does not make sense, which is also a
possibility to check), which causes some performance only problems (not
correctness), since we write_debugregs when not needed.
Also, as suggested by Jeff, remove a redundant enabling of SIGVTALRM,
comprised in the subsequent local_irq_enable(). I'm just a bit dubious if
ordering matters there...
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Fixes a bug introduced in commit e32dacb9f481fd6decb41adb28e720c923d34f54 -
index is initialized based on syscall before syscall is calculated.
I'm bothering with this mainly because it gives a correct warning when the
config option is enabled, even if the code is for a almost unused debugging
option.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Some fixes to make softints work in tt mode.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The serial UML OS-abstraction layer patch (um/kernel dir).
This moves skas headers to arch/um/include.
Signed-off-by: Gennady Sharapov <Gennady.V.Sharapov@intel.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The serial UML OS-abstraction layer patch (um/kernel dir).
This moves all systemcalls from time.c file under os-Linux dir and joins
time.c and tine_kernel.c files
Signed-off-by: Gennady Sharapov <Gennady.V.Sharapov@intel.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The serial UML OS-abstraction layer patch (um/kernel dir).
This moves all systemcalls from user_util.c file under os-Linux dir
Signed-off-by: Gennady Sharapov <Gennady.V.Sharapov@intel.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The serial UML OS-abstraction layer patch (um/kernel dir).
This moves all systemcalls from trap_user.c file under os-Linux dir
Signed-off-by: Gennady Sharapov <Gennady.V.Sharapov@intel.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The serial UML OS-abstraction layer patch (um/kernel dir).
This moves all systemcalls from signal_user.c file under os-Linux dir
Signed-off-by: Gennady Sharapov <Gennady.V.Sharapov@intel.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The access_ok_tt() macro is bogus, in that a read access is unconditionally
considered valid.
I couldn't find in SCM logs the introduction of this check, but I went back to
2.4.20-1um and the definition was the same.
Possibly this was done to avoid problems with missing set_fs() calls, but
there can't be any I think because they would fail with SKAS mode.
TT-specific code is still to check.
Also, this patch joins common code together, and makes the "address range
wrapping" check happen for all cases, rather than for only some.
This may, possibly, be reoptimized at some time, but the current code doesn't
seem clever, just confused.
* Important: I've also had to change references to access_ok_{tt,skas} back to
access_ok - the kernel wasn't that happy otherwise.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The serial UML OS-abstraction layer patch (um/kernel dir).
This moves all systemcalls from uaccess_user.c file under os-Linux dir
Signed-off-by: Gennady Sharapov <Gennady.V.Sharapov@intel.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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In worrying over the various pte operations in different architectures, I came
across some unused functions in UML: remove mprotect_kernel_vm,
protect_vm_page and addr_pte.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The current code doesn't handle well general protection faults on the host -
it thinks that cr2 is always the address of a page fault. While actually, on
general protection faults, that address is not accessible, so we'd better
assume we couldn't satisfy the fault. Currently instead we think we've fixed
it, so we go back, retry the instruction and fault again endlessly.
This leads to the kernel hanging when doing copy_from_user(dest, -1, ...) in
TT mode, since reading *(-1) causes a GFP, and we don't support kernel
preemption.
Thanks to Luo Xin for testing UML with LTP and reporting the failures he got.
Cc: Luo Xin <luothing@sina.com>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The header declaring this function wasn't included, so the function declaration
was totally bogus wrt. the proto - even if this wasn't going to fail at all.
It was so bad that the compile warning I got was "control reaches end of
non-void function", i.e. missing return. Actually, this has been there for ages,
the consolidation patch just added the warning which was needed to clean it up.
Nice. Really.
Cc: Allan Graves <allan.graves@gmail.com>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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When removing verify_area, verify_area_{tt,skas} were forgotten.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The serial UML OS-abstraction layer patch (um/kernel dir).
This moves all system calls from mem_user.c and tempfile.c files under
os-Linux dir.
Signed-off-by: Gennady Sharapov <Gennady.V.Sharapov@intel.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch moves code that is in both switch_to_tt and switch_to_skas to the
top level _switch_to function, keeping us from duplicating code. It is
required for the stack trace patch to work properly.
Signed-off-by: Allan Graves <allan.graves@gmail.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Change syscall-stub's data to include a "expected retval".
Stub now checks syscalls retval and aborts execution of syscall list, if
retval != expected retval.
run_syscall_stub prints the data of the failed syscall, using the data pointer
and retval written by the stub to the beginning of the stack.
one_syscall_stub is removed, to simplify code, because only some instructions
are saved by one_syscall_stub, no host-syscall.
Using the stub with additional data (modify_ldt via stub)
is prepared also.
Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This merges two sets of files which had no business being split apart in the
first place.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This adds VM op batching to skas0. Rather than having a context switch to and
from the userspace stub for each address space change, we write a number of
operations to the stub data page and invoke a different stub which loops over
them and executes them all in one go.
The operations are stored as [ system call number, arg1, arg2, ... ] tuples.
The set is terminated by a system call number of 0. Single operations, i.e.
page faults, are handled in the old way, since that is slightly more
efficient.
For a kernel build, a minority (~1/4) of the operations are part of a set.
These sets averaged ~100 in length, so for this quarter, the context switching
overhead is greatly reduced.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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UML has had two modes of operation - an insecure, slow mode (tt mode) in
which the kernel is mapped into every process address space which requires
no host kernel modifications, and a secure, faster mode (skas mode) in
which the UML kernel is in a separate host address space, which requires a
patch to the host kernel.
This patch implements something very close to skas mode for hosts which
don't support skas - I'm calling this skas0. It provides the security of
the skas host patch, and some of the performance gains.
The two main things that are provided by the skas patch, /proc/mm and
PTRACE_FAULTINFO, are implemented in a way that require no host patch.
For the remote address space changing stuff (mmap, munmap, and mprotect),
we set aside two pages in the process above its stack, one of which
contains a little bit of code which can call mmap et al.
To update the address space, the system call information (system call
number and arguments) are written to the stub page above the code. The
%esp is set to the beginning of the data, the %eip is set the the start of
the stub, and it repeatedly pops the information into its registers and
makes the system call until it sees a system call number of zero. This is
to amortize the cost of the context switch across multiple address space
updates.
When the updates are done, it SIGSTOPs itself, and the kernel process
continues what it was doing.
For a PTRACE_FAULTINFO replacement, we set up a SIGSEGV handler in the
child, and let it handle segfaults rather than nullifying them. The
handler is in the same page as the mmap stub. The second page is used as
the stack. The handler reads cr2 and err from the sigcontext, sticks them
at the base of the stack in a faultinfo struct, and SIGSTOPs itself. The
kernel then reads the faultinfo and handles the fault.
A complication on x86_64 is that this involves resetting the registers to
the segfault values when the process is inside the kill system call. This
breaks on x86_64 because %rcx will contain %rip because you tell SYSRET
where to return to by putting the value in %rcx. So, this corrupts $rcx on
return from the segfault. To work around this, I added an
arch_finish_segv, which on x86 does nothing, but which on x86_64 ptraces
the child back through the sigreturn. This causes %rcx to be restored by
sigreturn and avoids the corruption. Ultimately, I think I will replace
this with the trick of having it send itself a blocked signal which will be
unblocked by the sigreturn. This will allow it to be stopped just after
the sigreturn, and PTRACE_SYSCALLed without all the back-and-forth of
PTRACE_SYSCALLing it through sigreturn.
This runs on a stock host, so theoretically (and hopefully), tt mode isn't
needed any more. We need to make sure that this is better in every way
than tt mode, though. I'm concerned about the speed of address space
updates and page fault handling, since they involve extra round-trips to
the child. We can amortize the round-trip cost for large address space
updates by writing all of the operations to the data page and having the
child execute them all at the same time. This will help fork and exec, but
not page faults, since they involve only one page.
I can't think of any way to help page faults, except to add something like
PTRACE_FAULTINFO to the host. There is PTRACE_SIGINFO, but UML doesn't use
siginfo for SIGSEGV (or anything else) because there isn't enough
information in the siginfo struct to handle page faults (the faulting
operation type is missing). Adding that would make PTRACE_SIGINFO a usable
equivalent to PTRACE_FAULTINFO.
As for the code itself:
- The system call stub is in arch/um/kernel/sys-$(SUBARCH)/stub.S. It is
put in its own section of the binary along with stub_segv_handler in
arch/um/kernel/skas/process.c. This is manipulated with run_syscall_stub
in arch/um/kernel/skas/mem_user.c. syscall_stub will execute any system
call at all, but it's only used for mmap, munmap, and mprotect.
- The x86_64 stub calls sigreturn by hand rather than allowing the normal
sigreturn to happen, because the normal sigreturn is a SA_RESTORER in
UML's address space provided by libc. Needless to say, this is not
available in the child's address space. Also, it does a couple of odd
pops before that which restore the stack to the state it was in at the
time the signal handler was called.
- There is a new field in the arch mmu_context, which is now a union.
This is the pid to be manipulated rather than the /proc/mm file
descriptor. Code which deals with this now checks proc_mm to see whether
it should use the usual skas code or the new code.
- userspace_tramp is now used to create a new host process for every UML
process, rather than one per UML processor. It checks proc_mm and
ptrace_faultinfo to decide whether to map in the pages above its stack.
- start_userspace now makes CLONE_VM conditional on proc_mm since we need
separate address spaces now.
- switch_mm_skas now just sets userspace_pid[0] to the new pid rather
than PTRACE_SWITCH_MM. There is an addition to userspace which updates
its idea of the pid being manipulated each time around the loop. This is
important on exec, when the pid will change underneath userspace().
- The stub page has a pte, but it can't be mapped in using tlb_flush
because it is part of tlb_flush. This is why it's required for it to be
mapped in by userspace_tramp.
Other random things:
- The stub section in uml.lds.S is page aligned. This page is written
out to the backing vm file in setup_physmem because it is mapped from
there into user processes.
- There's some confusion with TASK_SIZE now that there are a couple of
extra pages that the process can't use. TASK_SIZE is considered by the
elf code to be the usable process memory, which is reasonable, so it is
decreased by two pages. This confuses the definition of
USER_PGDS_IN_LAST_PML4, making it too small because of the rounding down
of the uneven division. So we round it to the nearest PGDIR_SIZE rather
than the lower one.
- I added a missing PT_SYSCALL_ARG6_OFFSET macro.
- um_mmu.h was made into a userspace-usable file.
- proc_mm and ptrace_faultinfo are globals which say whether the host
supports these features.
- There is a bad interaction between the mm.nr_ptes check at the end of
exit_mmap, stack randomization, and skas0. exit_mmap will stop freeing
pages at the PGDIR_SIZE boundary after the last vma. If the stack isn't
on the last page table page, the last pte page won't be freed, as it
should be since the stub ptes are there, and exit_mmap will BUG because
there is an unfreed page. To get around this, TASK_SIZE is set to the
next lowest PGDIR_SIZE boundary and mm->nr_ptes is decremented after the
calls to init_stub_pte. This ensures that we know the process stack (and
all other process mappings) will be below the top page table page, and
thus we know that mm->nr_ptes will be one too many, and can be
decremented.
Things that need fixing:
- We may need better assurrences that the stub code is PIC.
- The stub pte is set up in init_new_context_skas.
- alloc_pgdir is probably the right place.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Clean up the hot-unplugging code. There is now an id procedure which is
called to figure out what device we're talking to. The error messages from
that are now done from mconsole_remove instead of the driver. remove is now
called with the device number, after it has been checked, so doesn't need to
do sanity checking on it.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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user_time_init_skas and user_time_init_tt were essentially the same. So, this
merges them, deleting the mode-specific functions and declarations.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Fix the do_fork calling convention: normal arch pass the regs and the new sp
value to do_fork instead of NULL.
Currently the arch-independent code ignores these values, while the UML code
(actually it's copy_thread) gets the right values by itself.
With this patch, things are fixed up.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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With Al Viro <viro@parcelfarce.linux.theplanet.co.uk>
To make sure switcheroo() can execute when we remap all the executable
image, we used a trick to make it use a local copy of errno... this trick
does not work with NPTL glibc, only with LinuxThreads, so use another
(simpler) one to make it work anyway.
Hopefully, a lot improved thanks to merging with the version of Al Viro
(which had his part of problems, though, i.e. removing a fix to another
bug and not fixing the problem on i386).
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This var is currently useless, as it's apparent from reading the code. Until
2.6.11 it was used in some code related to jail mode, in the same proc.:
if(jail){
while(!reading) sched_yield();
}
jail mode has been dropped, together with that use, so let's finish dropping
this.
Also, remove some other useless definitions I met.
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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From: Oleg Drokin: This patch is needed to support kernel modules that want to
use clear_user() (that is exported symbol on all other architectures).
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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tt-mode closes switch_pipes in exit_thread_tt and kills processes in
switch_to_tt, if the exit_state is EXIT_DEAD or EXIT_ZOMBIE.
In very rare cases the exiting process can be scheduled out after having set
exit_state and closed switch_pipes (from release_task it calls proc_pid_flush,
which might sleep). If this process is to be restarted, UML failes in
switch_to_tt with:
write of switch_pipe failed, err = 9
We fix this by closing switch_pipes not in exit_thread_tt, but later in
release_thread_tt. Additionally, we set switch_pipe[0] = 0 after closing.
switch_to_tt must not kill "from" process depending on its exit_state, but
must kill it after release_thread was processed only, so it examines
switch_pipe[0] for its decision.
Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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tt/mem.c still uses hardcoded TOP for i386 instead of CONFIG_TOP_ADDR provided
by subarch's Kconfig_XXXX, which would be right.
Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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s390 tt-mode needs to save not only syscall number, but an further register
also.
Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Remove the __deprecated from verify_area_skas and verify_area_tt. Since
verify_area is itself marked __deprecated, and it is the only caller of
these, then they don't need to be marked. Marking them only makes the
build noisier.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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