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This will probably never trigger... but it won't hurt to be careful.
http://googleresearch.blogspot.com/2006/06/extra-extra-read-all-about-it-nearly.html
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Joshua Bloch <jjb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Use proc_create()/proc_create_data() to make sure that ->proc_fops and ->data
be setup before gluing PDE to main tree.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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When passing a zero address to kallsyms_lookup(), the kernel thought it was
a valid kernel address, even if it is not. This is because is_ksym_addr()
called is_kernel_extratext() and checked against labels that don't exist on
many archs (which default as zero). Since PPC was the only kernel which
defines _extra_text, (in 2005), and no longer needs it, this patch removes
_extra_text support.
For some history (provided by Jon):
http://ozlabs.org/pipermail/linuxppc-dev/2005-September/019734.html
http://ozlabs.org/pipermail/linuxppc-dev/2005-September/019736.html
http://ozlabs.org/pipermail/linuxppc-dev/2005-September/019751.html
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Jon Loeliger <jdl@freescale.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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module_address_lookup releases preemption then returns a pointer into
the module space. The only user (kallsyms) copies the result, so just
do that under the preempt disable.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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Fix the extern declaration of kallsyms_num_syms to indicate that the symbol
does not reside in the small-data storage space, and so may not be accessed
relative to the small data base register.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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KSYM_NAME_LEN is peculiar in that it does not include the space for the
trailing '\0', forcing all users to use KSYM_NAME_LEN + 1 when allocating
buffer. This is nonsense and error-prone. Moreover, when the caller
forgets that it's very likely to subtly bite back by corrupting the stack
because the last position of the buffer is always cleared to zero.
This patch increments KSYM_NAME_LEN by one and updates code accordingly.
* off-by-one bug in asm-powerpc/kprobes.h::kprobe_lookup_name() macro
is fixed.
* Where MODULE_NAME_LEN and KSYM_NAME_LEN were used together,
MODULE_NAME_LEN was treated as if it didn't include space for the
trailing '\0'. Fix it.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Acked-by: Paulo Marques <pmarques@grupopie.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Remove pointless `else'.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ugh, this function gets called by our unwinder. recursive backtrace for
the win... bisection to find this one was "fun."
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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We can save some lines of code by using seq_release_private().
Signed-off-by: Martin Peschke <mp3@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Same story as with cat /proc/*/wchan race vs rmmod race, only
/proc/slab_allocators want more info than just symbol name.
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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kallsyms_lookup() can go iterating over modules list unprotected which is OK
for emergency situations (oops), but not OK for regular stuff like
/proc/*/wchan.
Introduce lookup_symbol_name()/lookup_module_symbol_name() which copy symbol
name into caller-supplied buffer or return -ERANGE. All copying is done with
module_mutex held, so...
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Several kallsyms_lookup() pass dummy arguments but only need, say, module's
name. Make kallsyms_lookup() accept NULLs where possible.
Also, makes picture clearer about what interfaces are needed for all symbol
resolving business.
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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module_get_kallsym() leaks "struct module *" outside of module_mutex which is
no-no, because module can dissapear right after mutex unlock.
Copy all needed information from inside module_mutex into caller-supplied
space.
[bunk@stusta.de: is_exported() can now become static]
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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module_get_kallsym() could in theory truncate module symbol name to fit in
buffer, but nobody does this. Always use KSYM_NAME_LEN + 1 bytes for name.
Suggested by lg^WRusty.
Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Today's print_symbol function dumps a kernel symbol with printk. This
patch extends the functionality of kallsyms.c so that the symbol lookup
function may be used without the printk. This is useful for modules that
want to dump symbols elsewhere, for example, to debugfs. I intend to use
the new function call in the GFS2 file system (which will be a separate
patch).
[akpm@linux-foundation.org: build fix]
[clameter@sgi.com: sprint_symbol should return length of string like sprintf]
Signed-off-by: Robert Peterson <rpeterso@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Cc: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Paulo Marques <pmarques@grupopie.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Kallsyms data is never written to, so it can as well benefit from
CONFIG_DEBUG_RODATA.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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- move some file_operations structs into the .rodata section
- move static strings from policy_types[] array into the .rodata section
- fix generic seq_operations usages, so that those structs may be defined
as "const" as well
[akpm@osdl.org: couple of fixes]
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch addresses incorrect symbol type information reported through
/proc/kallsyms. A lowercase character should designate the symbol as local
(or non-exported). An uppercase character should designate the symbol as
global (or external).
Without this patch, some non-exported symbols are incorrectly assigned an
upper-case designation in /proc/kallsyms. This patch corrects this
condition by converting non-exported symbols types to lower case when
appropriate and eliminates the superfluous upcase_if_global function
Signed-off-by: Adam B. Jerome <abj@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Some uses of kallsyms_lookup() do not need to find out the name of a symbol
and its module's name it belongs. This is specially true in arch specific
code, which needs to unwind the stack to show the back trace during oops
(mips is an example). In this specific case, we just need to retreive the
function's size and the offset of the active intruction inside it.
Adds a new entry "kallsyms_lookup_size_offset()" This new entry does
exactly the same as kallsyms_lookup() but does not require any buffers to
store any names.
It returns 0 if it fails otherwise 1.
Signed-off-by: Franck Bui-Huu <vagabon.xyz@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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In an effort to make kprobe modules more portable, here is a patch that:
o Introduces the "symbol_name" field to struct kprobe.
The symbol->address resolution now happens in the kernel in an
architecture agnostic manner. 64-bit powerpc users no longer have
to specify the ".symbols"
o Introduces the "offset" field to struct kprobe to allow a user to
specify an offset into a symbol.
o The legacy mechanism of specifying the kprobe.addr is still supported.
However, if both the kprobe.addr and kprobe.symbol_name are specified,
probe registration fails with an -EINVAL.
o The symbol resolution code uses kallsyms_lookup_name(). So
CONFIG_KPROBES now depends on CONFIG_KALLSYMS
o Apparantly kprobe modules were the only legitimate out-of-tree user of
the kallsyms_lookup_name() EXPORT. Now that the symbol resolution
happens in-kernel, remove the EXPORT as suggested by Christoph Hellwig
o Modify tcp_probe.c that uses the kprobe interface so as to make it
work on multiple platforms (in its earlier form, the code wouldn't
work, say, on powerpc)
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Got a customer bug report (https://bugzilla.novell.com/190296) about kernel
symbols longer than 127 characters which end up in a string buffer that is
not NULL terminated, leading to garbage in /proc/kallsyms. Using strlcpy
prevents this from happening, even though such symbols still won't come out
right.
A better fix would be to not use a fixed-size buffer, but it's probably not
worth the trouble. (Modversion'ed symbols even have a length limit of 60.)
[bunk@stusta.de: build fix]
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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I recently picked up my older work to remove unnecessary #includes of
sched.h, starting from a patch by Dave Jones to not include sched.h
from module.h. This reduces the number of indirect includes of sched.h
by ~300. Another ~400 pointless direct includes can be removed after
this disentangling (patch to follow later).
However, quite a few indirect includes need to be fixed up for this.
In order to feed the patches through -mm with as little disturbance as
possible, I've split out the fixes I accumulated up to now (complete for
i386 and x86_64, more archs to follow later) and post them before the real
patch. This way this large part of the patch is kept simple with only
adding #includes, and all hunks are independent of each other. So if any
hunk rejects or gets in the way of other patches, just drop it. My scripts
will pick it up again in the next round.
Signed-off-by: Tim Schmielau <tim@physik3.uni-rostock.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The PPC32 kernel puts platform-specific functions into separate sections so
that unneeded parts of it can be freed when we've booted and actually
worked out what we're running on today.
This makes kallsyms ignore those functions, because they're not between
_[se]text or _[se]inittext. Rather than teaching kallsyms about the
various pmac/chrp/etc sections, this patch adds '_[se]extratext' markers
for kallsyms.
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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into mars.ravnborg.org:/home/sam/bk/kbuild
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Export kallsyms_lookup_name() for kprobe/jprobe module use.
(akpm: modules which use kprobes/jrobes are usually problem-specific and
will not be merged into the mainline kernel, so we we're actually to see
actual users of this patch merged)
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The attached patch fixes a race between kallsyms and insmod/rmmod.
The problem is this:
(1) The various kallsyms functions poke around in the module list without any
locking so that they can be called from the oops handler.
(2) Although insmod and rmmod use locks to exclude each other, these have no
effect on the kallsyms function.
(3) Although rmmod modifies the module state with the machine "stopped", it
hasn't removed the metadata from the module metadata list, meaning that
as soon as the machine is "restarted", the metadata can be observed by
kallsyms.
It's not possible to say that an item in that list should be ignored if
it's state is marked as inactive - you can't get at the state information
because you can't trust the metadata in which it is embedded.
Furthermore, list linkage information is embedded in the metadata too, so
you can't trust that either...
(4) kallsyms may be walking the module list without a lock whilst either
insmod or rmmod are busy changing it. insmod probably isn't a problem
since nothing is going a way, but rmmod is as it's deleting an entry.
(5) Therefore nothing that uses these functions can in any way trust any
pointers to "static" data (such as module symbol names or module names)
that are returned.
(6) On ppc64 the problems are exacerbated since the hypervisor may reschedule
bits of the kernel, making operations that appear adjacent occur a long
time apart.
This patch fixes the race by only linking/unlinking modules into/from the
master module list with the machine in the "stopped" state. This means that
any "static" information can be trusted as far as the next kernel reschedule
on any given CPU without the need to hold any locks.
However, I'm not sure how this is affected by preemption. I suspect more work
may need to be done in that case, but I'm not entirely sure.
This also means that rmmod has to bump the machine into the stopped state
twice... but since that shouldn't be a common operation, I don't think that's
a problem.
I've amended this patch to not get spinlocks whilst in the machine locked
state - there's no point as nothing else can be holding spinlocks.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch makes some needlessly global code static.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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Anton Blanchard wrote:
>Your recent patch looks to break module kallsyms lookups....
>It looks like if CONFIG_KALLSYMS_ALL is set then we never look up module
>addresses.
Separate lookups for kernel and modules when CONFIG_KALLSYMS_ALL=y.
Signed-off-by: Keith Owens <kaos@ocs.com.au>
Acked-by: Chris Wedgwood <cw@f00f.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The attached patch makes it possible to support gp-rel addressing for small
variables. Since the FR-V cpu's have fixed-length instructions and plenty of
general-purpose registers, one register is nominated as a base for the small
data area. This makes it possible to use single-insn accesses to access
global and static variables instead of having to use multiple instructions.
This, however, causes problems with small variables used to pinpoint the
beginning and end of sections. The compiler assumes it can use gp-rel
addressing for these, but the linker then complains because the displacement
is out of range.
By declaring certain variables as arrays or by forcing them into named
sections, the compiler is persuaded to access them as if they can be outside
the displacement range. Declaring the variables as "const void" type also
works.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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* Treat the gate page as part of the kernel, to improve kernel backtraces.
* Honour CONFIG_KALLSYMS_ALL, all symbols are valid, not just text.
Signed-off-by: Keith Owens <kaos@ocs.com.au>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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This patch is an improvement over my first kallsyms speedup patch posted about
2 weeks ago.
It changes scripts/kallsyms as to produce a different format for
kallsyms_names and extra data to speedup lookups. The compression algorithm
is quite simple: it uses all the char codes not actually used in symbols to
build a lookup table that translates these codes into small strings. For
instance, in my test runs the code 0xFE was being translated into "acpi_"
giving a 4 byte save on every translation.
The advantage of this algorithm is that to translate a symbol we only require
information that is stored on that symbol position, and never need to go back
on the compressed stream to get information from other symbols.
To give an idea about the benefits of this algorithm here are some benchmark
results on a P4 2.8GHz with a symbol table with 10000 entries:
kallsyms_lookup average time:
vanilla 1346.0 us
speedup 14.4 us
with this patch 0.5 us
total data produced by scripts/kallsyms:
uncompressed 169 Kb
vanilla 134 Kb
with this patch 91 Kb
(speedup was my latest patch, that only changed the way kallsyms_lookup worked
and not the data format)
I removed a cond_resched() from the proc/kallsyms handling code path, because
using stem compression, if the current position went backwards, the hole
stream would be uncompressed up to the current position. It seemed that by
removing this loop it would be safe to remove the conditional reschedule
altogether.
There is just one catch with this patch: the time it takes to compile the
kernel goes up just a bit (about 0.8s on a P4 2.8GHz with defconfig). If this
delay is not acceptable I can change the compression algorithm so that it can
use the previous table (calculating a new table is what consumes most of the
time, and not doing the actual compression) and check to see if it obtains a
similar compression ratio. If it does, then this is a sign that the symbol
patterns haven't changed that much and this table is still good to use. This
would not only cut the time down to half on any compilation (because of the 2
pass symbol build method), but in frequent cases where a developer is
compiling a single file and linking everything over and over again, the table
optimization process would never run.
I'm CC'ing Brent Casavant on this email, because last june he sent a patch
trying a different approach that used a 32 entry symbol cache, because there
was a problem with the time "top" took to read "proc/<pid>/wchan". I was
hopping he would be willing to test this patch and comment on the results.
Signed-off-by: Paulo Marques <pmarques@grupopie.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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kernel/kallsyms.c
CHECK kernel/kallsyms.c
kernel/kallsyms.c:136:7: warning: bad constant expression
kernel/kallsyms.c:136:7: warning: bad constant expression
kernel/kallsyms.c:136:7: warning: bad constant expression
kernel/kallsyms.c:143:22: warning: bad constant expression
kernel/kallsyms.c:143:22: warning: bad constant expression
kernel/kallsyms.c:143:22: warning: bad constant expression
Now the cause of sparse warnings is that it does not handle runtime array
dimensioning (which I take it is a sparse problem), but in this particular
case it _might_ make sense to change the runtime allocation to compile
time, as the upper size of the array is known, because the code in
kernel/kallsyms.c clearly uses 127 (or 128) as "magic constant" for kernel
symbol (array) length, and in the other hand in include/linux/module.h
there is: #define MODULE_NAME_LEN (64 - sizeof(unsigned long))
The only concern is that the array become quite big (the original comment
of it being "pretty small" no longer applies ...). One way to help that
would be to use buffer[] also in place of namebuf[], but that would be
little tricky as the format string should be before the symbol name ...
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Distros have started to ship kernels with this patch, as it seems that some
unnamed binary module authors are already abusing this function (as well as
some open source modules, like the openib code.) I could not find any valid
reason why this symbol should be exported, so here's a patch against 2.6.7
that removes it.
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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From: Rusty Russell <rusty@rustcorp.com.au>
kallsyms contains only function names, but some debuggers (eg. xmon on
PPC/PPC64) use it to lookup symbols: it'd be much nicer if it included data
symbols too.
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From: Rusty Russell <rusty@rustcorp.com.au>
Kallsyms discards symbols with the same address, but these are sometimes
useful. Skip this minor optimization and make kallsyms_lookup deal with
aliases
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From: Rusty Russell <rusty@rustcorp.com.au>
The current code doesn't show the last symbol (usually _einittext) in
/proc/kallsyms. The reason for this is subtle: s_start() returns an empty
string for position 0 (ignored by s_show()), and s_next() returns the first
symbol for position 1.
What should happen is that update_iter() for position 0 should fill in the
first symbol. Unfortunately, the get_ksymbol_core() fills in the symbol
information, *and* updates the iterator: we have to split these functions,
which we do by making it return the length of the name offset.
Then we can call get_ksymbol_core() without moving the iterator, meaning
that we can call it at position 0 (ie. s_start()).
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From: Rusty Russell <rusty@au1.ibm.com>
Attached patch adds a kallsyms_lookupname() function for lookups of a
symbol name to an address. Debuggers such as ppc[64] xmon can use this.
It's intentionally not exported as a symbol for module use, since it
can be used to circumvent other symbol export restrictions.
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From: Rusty Russell <rusty@rustcorp.com.au>
Change the permissions on /proc/kallsyms. As David M-T points out,
it's nice for analysis tools not to need root. Place
cond_resched() to avoid starvation problems on non-preempt.
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From: Rusty Russell <rusty@rustcorp.com.au>
Out by one error broke caching of results in /proc/kallsyms, slowing
reading to a crawl.
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From David Mosberger:
> We definitely are seeing some strange crashes in get_ksymbol_core().
> I think the reason is the lack of iterator initialization.
Yes, looks good: reset the iterator at allocation.
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Spelling fix
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This adds a /proc/kallsyms if you have CONFIG_KALLSYMS in your
kernel. The output is nm-like, with symbols in caps (global) if
exported using EXPORT_SYMBOL, rather than the normal static
vs. non-static differentiation.
This is useful for things like performance monitoring tools (profiling
etc) that want to match addresses to names in user space.
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From: Rusty Russell <rusty@rustcorp.com.au>
Introduce _sinittext and _einittext (cf. _stext and _etext), so kallsyms
includes __init functions.
TODO: Use huffman name compression and 16-bit offsets (see IDE
oopser patch)
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There's no need to alias the kallsyms-related symbols to a dummy
variable, we can as well just do the sanity check against NULL.
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version before looking at more complicated changes.
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The attached patch fixes the crash top or cat /proc/*/wchan produces
when using KALLSYMS it's a buffer overrun that should not happen.
Based on patch by andi kleen.
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This patch implements simple stem compression for the kallsyms symbol
table. Each symbol has as first byte a count on how many characters
are identical to the previous symbol. This compresses the often
common repetive prefixes (like subsys_) fairly effectively.
On a fairly full featured monolithic i386 kernel this saves about 60k in
the kallsyms symbol table.
The changes are very simple, so the 60k are not shabby.
One visible change is that the caller of kallsyms_lookup has to pass in
a buffer now, because it has to be modified. I added an arbitary
127 character limit to it.
Still >210k left in the symbol table unfortunately. Another idea would be to
delta encode the addresses in 16bits (functions are all likely to be smaller
than 64K). This would especially help on 64bit hosts. Not done yet, however.
No, before someone asks, I don't want to use zlib for that. Far too fragile
during an oops and overkill too and it would require to link it into all
kernels.
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This patch basically just replaces the scripts/kallsyms script by
a scripts/kallsyms.c C program, which does the same thing much faster.
It also removes duplicates and entries which are not between _stext and
_etext, as they would not get used anyway. This saves about 290KB in
vmlinux with my .config, more than 50% of the kallsyms bloat ;)
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Since I believe kallsyms is important, this reimplements it sanely,
using the current module infrastructure, and not using an external
kallsyms script.
FYI, the previous interface was:
int kallsyms_symbol_to_address(
const char *name, /* Name to lookup */
unsigned long *token, /* Which module to start with */
const char **mod_name, /* Set to module name or "kernel" */
unsigned long *mod_start, /* Set to start address of module */
unsigned long *mod_end, /* Set to end address of module */
const char **sec_name, /* Set to section name */
unsigned long *sec_start, /* Set to start address of section */
unsigned long *sec_end, /* Set to end address of section */
const char **sym_name, /* Set to full symbol name */
unsigned long *sym_start, /* Set to start address of symbol */
unsigned long *sym_end /* Set to end address of symbol */
);
The new one is:
/* Lookup an address. modname is set to NULL if it's in the kernel. */
const char *kallsyms_lookup(unsigned long addr,
unsigned long *symbolsize,
unsigned long *offset,
char **modname);
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The kallsyms patches added __kallsyms as last section into vmlinux,
behind .bss.
This was done to save two additional kallsyms passes, since as the
added section was last, it did not change the symbols before it.
With the new infrastructure in the top-level Makefile, we do not need
to do full relinks for these passes, so they are cheaper. We now
use one additional link/kallsyms run to be able to place the __kallsyms
section before .bss. The other pass is saved by adding an empty but
allocated __kallsyms section in kernel/kallsyms.c, so the first kallsyms
pass already generates a section of the final size.
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