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Commit b478b782e110fdb4135caa3062b6d687e989d994 "kallsyms, tracing: output
more proper symbol name" introduces a "bugfix" that introduces a segfault
in kallsyms in my configurations.
The cause is the introduction of prefix_underscores_count() which attempts
to count underscores, even in symbols that do not have them. As a result,
it just uselessly runs past the end of the buffer until it crashes:
CC init/version.o
LD init/built-in.o
LD .tmp_vmlinux1
KSYM .tmp_kallsyms1.S
/bin/sh: line 1: 16934 Done sh-linux-gnu-nm -n .tmp_vmlinux1
16935 Segmentation fault | scripts/kallsyms > .tmp_kallsyms1.S
make: *** [.tmp_kallsyms1.S] Error 139
This simplifies the logic and just does a straightforward count.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Paulo Marques <pmarques@grupopie.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org> [2.6.30.x, 2.6.31.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The previous commit (17b1f0de) introduced a slightly broken consolidation
of the memory text range checking.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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The Blackfin arch has a discontiguous .text layout due to having on-chip
instruction memory and no virtual memory support. As such, we need to
add explicit checks for these additional .text regions.
Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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Impact: bugfix, output more reliable symbol lookup result
Debug tools(dump_stack(), ftrace...) are like to print out symbols.
But it is always print out the first aliased symbol.(Aliased symbols
are symbols with the same address), and the first aliased symbol is
sometime not proper.
# echo function_graph > current_tracer
# cat trace
......
1) 1.923 us | select_nohz_load_balancer();
1) + 76.692 us | }
1) | default_idle() {
1) ==========> | __irqentry_text_start() {
1) 0.000 us | native_apic_mem_write();
1) | irq_enter() {
1) 0.000 us | idle_cpu();
1) | tick_check_idle() {
1) 0.000 us | tick_check_oneshot_broadcast();
1) | tick_nohz_stop_idle() {
......
It's very embarrassing, it ouputs "__irqentry_text_start()",
actually, it should output "smp_apic_timer_interrupt()".
(these two symbol are the same address, but "__irqentry_text_start"
is deemed to the first aliased symbol by scripts/kallsyms)
This patch puts symbols like "__irqentry_text_start" to the second
aliased symbols. And a more proper symbol name becomes the first.
Aliased symbols mostly come from linker script. The solution is
guessing "is this symbol defined in linker script", the symbols
defined in linker script will not become the first aliased symbol.
And if symbols are found to be equal in this "linker script provided"
criteria, symbols are sorted by the number of prefix underscores.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Paulo Marques <pmarques@grupopie.com>
LKML-Reference: <49BA06E2.7080807@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This reverts commit ad7a953c522ceb496611d127e51e278bfe0ff483.
And commit: ("allow stripping of generated symbols under CONFIG_KALLSYMS_ALL")
9bb482476c6c9d1ae033306440c51ceac93ea80c
These stripping patches has caused a set of issues:
1) People have reported compatibility issues with binutils due to
lack of support for `--strip-unneeded-symbols' with objcopy 2.15.92.0.2
Reported by: Wenji
2) ccache and distcc no longer works as expeced
Reported by: Ted, Roland, + others
3) The installed modules increased a lot in size
Reported by: Ted, Davej + others
Reported-by: Wenji Huang <wenji.huang@oracle.com>
Reported-by: "Theodore Ts'o" <tytso@mit.edu>
Reported-by: Dave Jones <davej@redhat.com>
Reported-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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Building upon parts of the module stripping patch, this patch
introduces similar stripping for vmlinux when CONFIG_KALLSYMS_ALL=y.
Using CONFIG_KALLSYMS_STRIP_GENERATED reduces the overhead of
CONFIG_KALLSYMS_ALL from 245k/310k to 65k/80k for the (i386/x86-64)
kernels I tested with.
The patch also does away with the need to special case the kallsyms-
internal symbols by making them available even in the first linking
stage.
While it is a generated file, the patch includes the changes to
scripts/genksyms/keywords.c_shipped, as I'm unsure what the procedure
here is.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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Andi Kleen <andi@firstfloor.org>
reported that he saw a lot of symbols like this:
0000000000000b24 N DW.aio.h.903a6d92.2
0000000000000bce N DW.task_io_accounting.h.8d8de327.0
0000000000000bec N DW.hrtimer.h.c23659c6.0
in his System.map / kallsyms output.
Simple solution is to skip all debugging
symbols (they are marked 'N').
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Paulo Marques <pmarques@grupopie.com>
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Pointed out by Paulo:
"When I wrote this initially, it was a mistake to add a Changelog in
the first place, but I didn't know better at the time.
If you're going to make changes to this file, please remove all the
Changelog, instead of adding more entries to it. The 'Changelog'
should be kept by the version control system, and not the source code
itself."
Cc: Paulo Marques <pmarques@grupopie.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Acked-by: Paulo Marques <pmarques@grupopie.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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When resolving symbol names from addresses with aliased symbol names,
kallsyms_lookup always returns the first symbol, even if it is a weak
symbol.
This patch changes this by sorting the symbols with the weak symbols last
before feeding them to the kernel. This way the kernel runtime isn't
changed at all, only the kallsyms build system is changed.
Another side effect is that the symbols get sorted by address, too. So,
even if future binutils version have some bug in "nm" that makes it fail to
correctly sort symbols by address, the kernel won't be affected by this.
Mathieu says:
I created a module in LTTng that uses kallsyms to get the symbol
corresponding to a specific system call address. Unfortunately, all the
unimplemented syscalls were all referring to the (same) weak symbol
identifying an unrelated system call rather that sys_ni (or whatever
non-weak symbol would be expected). Kallsyms was dumbly returning the first
symbol that matched.
This patch makes sure kallsyms returns the non-weak symbol when there is
one, which seems to be the expected result.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Looks-great-to: Rusty Russell <rusty@rustcorp.com.au>
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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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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* git://git.kernel.org/pub/scm/linux/kernel/git/sam/kbuild: (33 commits)
xtensa: use DATA_DATA in xtensa
powerpc: add missing DATA_DATA to powerpc
cris: use DATA_DATA in cris
kallsyms: remove usage of memmem and _GNU_SOURCE from scripts/kallsyms.c
kbuild: use -fno-optimize-sibling-calls unconditionally
kconfig: reset generated values only if Kconfig and .config agree.
kbuild: fix the warning when running make tags
kconfig: strip 'CONFIG_' automatically in kernel configuration search
kbuild: use POSIX BRE in headers install target
Whitelist references from __dbe_table to .init
modpost white list pattern adjustment
kbuild: do section mismatch check on full vmlinux
kbuild: whitelist references from variables named _timer to .init.text
kbuild: remove hardcoded _logo names from modpost
kbuild: remove hardcoded apic_es7000 from modpost
kbuild: warn about references from .init.text to .exit.text
kbuild: consolidate section checks
kbuild: refactor code in modpost to improve maintainability
kbuild: ignore section mismatch warnings originating from .note section
kbuild: .paravirtprobe section is obsolete, so modpost doesn't need to handle it
...
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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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The only in-kernel user of "memmem" is scripts/kallsyms.c and it only
uses it to find tokens that are 2 bytes in size. It is trivial to
replace it with a simple function that finds 2-byte tokens.
This should help users from systems that don't have the memmem GNU
extension available.
Signed-off-by: Paulo Marques <pmarques@grupopie.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.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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changes
o On some platforms like avr32, section init comes before .text and
not necessarily a symbol's relative position w.r.t _text is positive.
In such cases assembler detects the overflow and emits warning. This
patch fixes it.
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
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Print the addresses of non-absolute symbols relative to _text
so that ld will generate relocations. Allowing a relocatable
kernel to relocate them. We can't actually use the symbol names
because kallsyms includes static symbols that are not exported
from their object files.
Add the _text symbol definitions to the architectures which don't
define it otherwise linker will fail.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
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This fixes coverity bugs #398 and #397
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Local symbols generated by gcc start with a `$'; no point in including them
in the kernel.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch changes the way the compression algorithm works. The base
algorithm is similiar to the previous but we force the compressed token
size to 2.
Having a fixed size compressed token allows for a lot of optimizations, and
that in turn allows this code to run over *all* the symbols faster than it
did before over just a subset.
Having it work over all the symbols will make it behave better when symbols
change positions between passes, and the "inconsistent kallsyms" messages
should become less frequent.
In my tests the compression ratio was degraded by about 0.5%, but the
results will depend greatly on the number of symbols to compress.
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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This time I did not break anything... and they shut up gcc4 ;)
Signed-off-by: Sam Ravnborg <sam@ravnborg.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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kallsyms does not consider SYMBOL_PREFIX of C. Consequently it does not
work on architectures using that prefix character (h8300, v850).
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Avoid kallsyms corner case on _etext and _einittext with
CONFIG_KALLSYMS_ALL=n.
Signed-off-by: Keith Owens <kaos@ocs.com.au>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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Some absolute symbols are useful, they can even appear in back traces.
Tweak kallsyms to retain the useful absolute symbols.
This list is from ia64, add absolute symbols from other architectures
as required.
Signed-off-by: Keith Owens <kaos@sgi.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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All ARM binutils versions post 2.11.90 contains an extra "feature" which
interferes with the kernel in various ways - extra "mapping symbols"
in the ELF symbol table '$a', '$t' and '$d'. This causes two problems:
1. Since '$a' symbols have the same value as function names, this
causes anything which uses the kallsyms infrastructure to report
wrong values.
2. programs which parse System.map do not expect symbols to start with
'$'.
Signed-off-by: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
===== kernel/module.c 1.120 vs edited =====
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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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PPC small data area base symbols shift between kallsyms phases 1 and 2, which
makes the kallsyms data unstable. Exclude them from the kallsyms list.
Signed-off-by: Keith Owens <kaos@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Exclude symbols added by kallsyms itself, so .tmp_kallsyms[12].S have
the same list of symbols.
Signed-off-by: Keith Owens <kaos@sgi.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>
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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From: James Bottomley <James.Bottomley@steeleye.com>
kallsyms is broken in parisc on 2.5.56 again because of assembler syntax
subtleties. This is the offending line:
printf("\t.byte 0x%02x ; .asciz\t\"%s\"\n"
Note the `;' separating the two statements. On some platforms `;' is a
comment in assembly code, and thus the following .asciz is ignored.
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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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The generated .tmp_kallsyms.S needs to use .long / .quad for
32/64 bit archs. To know which arch we're compiling for, we
use the preprocessor and BITS_PER_LONG from <asm/types.h>.
Unfortunately, asm/types.h was not safe to include from assembler
files, so lots of #ifndef __ASSEMBLY__ needed to be added - should
be fine now, untested for != i386, though.
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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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kallsyms.c generates the symbol table in a .S file using the assembler .string
macro. Unfortunately, the .string macro is implemented in a platform specific
way (it may or may not zero terminate the string). On parisc, it doesn't zero
terminate, so the symbol table search doesn't work.
The solution is to replace .string with .asciz which is guaranteed to do the
correct thing on all platforms.
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Argh, missed one line in the generated assembly, which is kinda important.
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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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