31 May, 2019
1 commit
-
Based on 1 normalized pattern(s):
licensed under the terms of the gnu gpl license version 2
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 62 file(s).
Signed-off-by: Thomas Gleixner
Reviewed-by: Allison Randal
Reviewed-by: Kate Stewart
Reviewed-by: Richard Fontana
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.929121379@linutronix.de
Signed-off-by: Greg Kroah-Hartman
09 May, 2019
1 commit
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Pull Kbuild updates from Masahiro Yamada:
- allow users to invoke 'make' out of the source tree
- refactor scripts/mkmakefile
- deprecate KBUILD_SRC, which was used to track the source tree
location for O= build.- fix recordmcount.pl in case objdump output is localized
- turn unresolved symbols in external modules to errors from warnings
by default; pass KBUILD_MODPOST_WARN=1 to get them back to warnings- generate modules.builtin.modinfo to collect .modinfo data from
built-in modules- misc Makefile cleanups
* tag 'kbuild-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (21 commits)
.gitignore: add more all*.config patterns
moduleparam: Save information about built-in modules in separate file
Remove MODULE_ALIAS() calls that take undefined macro
.gitignore: add leading and trailing slashes to generated directories
scripts/tags.sh: fix direct execution of scripts/tags.sh
scripts: override locale from environment when running recordmcount.pl
samples: kobject: allow CONFIG_SAMPLE_KOBJECT to become y
samples: seccomp: turn CONFIG_SAMPLE_SECCOMP into a bool option
kbuild: move Documentation to vmlinux-alldirs
kbuild: move samples/ to KBUILD_VMLINUX_OBJS
modpost: make KBUILD_MODPOST_WARN also configurable for external modules
kbuild: check arch/$(SRCARCH)/include/generated before out-of-tree build
kbuild: remove unneeded dependency for include/config/kernel.release
memory: squash drivers/memory/Makefile.asm-offsets
kbuild: use $(srctree) instead of KBUILD_SRC to check out-of-tree build
kbuild: mkmakefile: generate a simple wrapper of top Makefile
kbuild: mkmakefile: do not check the generated Makefile marker
kbuild: allow Kbuild to start from any directory
kbuild: pass $(MAKECMDGOALS) to sub-make as is
kbuild: fix warning "overriding recipe for target 'Makefile'"
...
03 May, 2019
1 commit
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recordmcount.pl uses a set of regular expressions to parse the output of
objdump(1). However, if objdump(1) output is localized, it may not match
the regular expressions, thereby preventing recordmcount.pl from parsing
object files correctly.In order to allow recordmcount.pl to function correctly regardless of the
current locale settings, set LANG=C when running objdump(1). LC_ALL is
already unset in the top-level Makefile, so it is not necessary to also
override that environment variable.Signed-off-by: Daniel Dadap
Reviewed-by: Robert Morell
Signed-off-by: Masahiro Yamada
22 Apr, 2019
1 commit
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Support dynamic ftrace including dynamic graph tracer. Gcc-csky with -pg
will produce call site in every function prologue and we can use these
call site to hook trace function.gcc with -pg origin call site:
push lr
jbsr _mcount
nop32
nop32If the (callee - caller)'s offset is in range of bsr instruction, we'll
modify code with:
push lr
bsr _mcount
nop32
nop32
Else if the (callee - caller)'s offset is out of bsr instrunction, we'll
modify code with:
push lr
movih r26, ...
ori r26, ...
jsr r26(r26 is reserved for jsr link reg in csky abiv2 spec.)
Signed-off-by: Guo Ren
09 Dec, 2018
1 commit
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When building with -ffunction-sections, the compiler will place each
function into its own ELF section, prefixed with ".text". For example,
a simple test module with functions test_module_do_work() and
test_module_wq_func():% objdump --section-headers test_module.o | awk '/\.text/{print $2}'
.text
.text.test_module_do_work
.text.test_module_wq_func
.init.text
.exit.textAdjust the recordmcount scripts to look for ".text" as a section name
prefix. This will ensure that those functions will be included in the
__mcount_loc relocations:% objdump --reloc --section __mcount_loc test_module.o
OFFSET TYPE VALUE
0000000000000000 R_X86_64_64 .text.test_module_do_work
0000000000000008 R_X86_64_64 .text.test_module_wq_func
0000000000000010 R_X86_64_64 .init.textLink: http://lkml.kernel.org/r/1542745158-25392-2-git-send-email-joe.lawrence@redhat.com
Signed-off-by: Joe Lawrence
Signed-off-by: Steven Rostedt (VMware)
04 Sep, 2018
1 commit
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Recognize NDS32 object files in recordmcount.pl.
Signed-off-by: Zong Li
Acked-by: Greentime Hu
Signed-off-by: Greentime Hu
01 Jun, 2018
1 commit
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The powerpc toolchain can compile combinations of 32/64 bit and
big/little endian, so it's convenient to consider, e.g.,`CC -m64 -mbig-endian`
To be the C compiler for the purpose of invoking it to build target
artifacts. So overriding the CC variable to include these flags works
for this purpose.Unfortunately that is not compatible with the way the proposed new
Kconfig macro language will work.After previous patches in this series, these flags can be carefully
passed in using flags instead.Signed-off-by: Nicholas Piggin
Signed-off-by: Michael Ellerman
05 Apr, 2018
1 commit
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…l/git/palmer/riscv-linux
Pull RISC-V updates from Palmer Dabbelt:
"This contains the new features we'd like to incorporate into the
RISC-V port for 4.17. We might have a bit more stuff land later in the
merge window, but I wanted to get this out earlier just so everyone
can see where we currently stand.A short summary of the changes is:
- We've added support for dynamic ftrace on RISC-V targets.
- There have been a handful of cleanups to our atomic and locking
routines. They now more closely match the released RISC-V memory
model draft.- Our module loading support has been cleaned up and is now enabled
by default, despite some limitations still existing.- A patch to define COMMANDLINE_FORCE instead of COMMANDLINE_OVERRIDE
so the generic device tree code picks up handling all our command
line stuff.There's more information in the merge commits for each patch set"
* tag 'riscv-for-linus-4.17-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/palmer/riscv-linux: (21 commits)
RISC-V: Rename CONFIG_CMDLINE_OVERRIDE to CONFIG_CMDLINE_FORCE
RISC-V: Add definition of relocation types
RISC-V: Enable module support in defconfig
RISC-V: Support SUB32 relocation type in kernel module
RISC-V: Support ADD32 relocation type in kernel module
RISC-V: Support ALIGN relocation type in kernel module
RISC-V: Support RVC_BRANCH/JUMP relocation type in kernel modulewq
RISC-V: Support HI20/LO12_I/LO12_S relocation type in kernel module
RISC-V: Support CALL relocation type in kernel module
RISC-V: Support GOT_HI20/CALL_PLT relocation type in kernel module
RISC-V: Add section of GOT.PLT for kernel module
RISC-V: Add sections of PLT and GOT for kernel module
riscv/atomic: Strengthen implementations with fences
riscv/spinlock: Strengthen implementations with fences
riscv/barrier: Define __smp_{store_release,load_acquire}
riscv/ftrace: Add HAVE_FUNCTION_GRAPH_RET_ADDR_PTR support
riscv/ftrace: Add DYNAMIC_FTRACE_WITH_REGS support
riscv/ftrace: Add ARCH_SUPPORTS_FTRACE_OPS support
riscv/ftrace: Add dynamic function graph tracer support
riscv/ftrace: Add dynamic function tracer support
...
03 Apr, 2018
1 commit
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Now recordmcount.pl recognizes RISC-V object files. For the mechanism to
work, we have to disable the linker relaxation.Cc: Greentime Hu
Signed-off-by: Alan Kao
Signed-off-by: Palmer Dabbelt
26 Mar, 2018
1 commit
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These two architectures are getting removed, so we no longer
need the special cases.Acked-by: Steven Rostedt (VMware)
Signed-off-by: Arnd Bergmann
14 May, 2017
1 commit
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The default NetBSD package manager is pkgsrc and it installs Perl
along other third party programs under custom and configurable prefix.
The default prefix for binary prebuilt packages is /usr/pkg, and the
Perl executable lands in /usr/pkg/bin/perl.This change switches "/usr/bin/perl" to "/usr/bin/env perl" as it's
the most portable solution that should work for almost everybody.
Perl's executable is detected automatically.This change switches -w option passed to the executable with more
modern "use warnings;" approach. There is no functional change to the
default behavior.While there, drop "require 5" from scripts/namespace.pl (Perl from 1994?).
Signed-off-by: Kamil Rytarowski
Signed-off-by: Masahiro Yamada
25 Mar, 2017
1 commit
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Adding a hook into free_reserve_area() that informs ftrace that boot up init
text is being free, lets ftrace safely remove those init functions from its
records, which keeps ftrace from trying to modify text that no longer
exists.Note, this still does not allow for tracing .init text of modules, as
modules require different work for freeing its init code.Link: http://lkml.kernel.org/r/1488502497.7212.24.camel@linux.intel.com
Cc: linux-mm@kvack.org
Cc: Vlastimil Babka
Cc: Mel Gorman
Cc: Peter Zijlstra
Requested-by: Todd Brandt
Signed-off-by: Steven Rostedt (VMware)
28 Feb, 2017
1 commit
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Fix typos and add the following to the scripts/spelling.txt:
swith||switch
swithable||switchable
swithed||switched
swithing||switchingWhile we are here, fix the "update" to "updates" in the touched hunk in
drivers/net/wireless/marvell/mwifiex/wmm.c.Link: http://lkml.kernel.org/r/1481573103-11329-2-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
08 Oct, 2016
1 commit
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When doing an nmi backtrace of many cores, most of which are idle, the
output is a little overwhelming and very uninformative. Suppress
messages for cpus that are idling when they are interrupted and just
emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN".We do this by grouping all the cpuidle code together into a new
.cpuidle.text section, and then checking the address of the interrupted
PC to see if it lies within that section.This commit suitably tags x86 and tile idle routines, and only adds in
the minimal framework for other architectures.Link: http://lkml.kernel.org/r/1472487169-14923-5-git-send-email-cmetcalf@mellanox.com
Signed-off-by: Chris Metcalf
Acked-by: Peter Zijlstra (Intel)
Tested-by: Peter Zijlstra (Intel)
Tested-by: Daniel Thompson [arm]
Tested-by: Petr Mladek
Cc: Aaron Tomlin
Cc: Peter Zijlstra (Intel)
Cc: "Rafael J. Wysocki"
Cc: Russell King
Cc: Thomas Gleixner
Cc: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
29 Sep, 2016
1 commit
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be7635e7287e ("arch, ftrace: for KASAN put hard/soft IRQ entries into
separate sections") added .softirqentry.text section, but it was not added
to recordmcount. So functions in the section are untracable. Add the
section to scripts/recordmcount.c and scripts/recordmcount.pl.Fixes: be7635e7287e ("arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections")
Link: http://lkml.kernel.org/r/1474902626-73468-1-git-send-email-dvyukov@google.com
Signed-off-by: Dmitry Vyukov
Acked-by: Steve Rostedt
Cc: [4.6+]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
13 Jan, 2016
1 commit
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If a text section starts out with a data blob before the first
function start label, disassembly parsing doing in recordmcount.pl
gets confused on powerpc, leading to creation of corrupted module
objects.This was not a problem so far since the compiler would never create
such text sections. However, this has changed with a recent change
in GCC 6 to support distances of > 2GB between a function and its
assoicated TOC in the ELFv2 ABI, exposing this problem.There is already code in recordmcount.pl to handle such data blobs
on the sparc64 platform. This patch uses the same method to handle
those on powerpc as well.Cc: stable@vger.kernel.org
Acked-by: Steven Rostedt
Signed-off-by: Ulrich Weigand
Signed-off-by: Michael Ellerman
12 Feb, 2015
1 commit
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Pull s390 updates from Martin Schwidefsky:
- The remaining patches for the z13 machine support: kernel build
option for z13, the cache synonym avoidance, SMT support,
compare-and-delay for spinloops and the CES5S crypto adapater.- The ftrace support for function tracing with the gcc hotpatch option.
This touches common code Makefiles, Steven is ok with the changes.- The hypfs file system gets an extension to access diagnose 0x0c data
in user space for performance analysis for Linux running under z/VM.- The iucv hvc console gets wildcard spport for the user id filtering.
- The cacheinfo code is converted to use the generic infrastructure.
- Cleanup and bug fixes.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (42 commits)
s390/process: free vx save area when releasing tasks
s390/hypfs: Eliminate hypfs interval
s390/hypfs: Add diagnose 0c support
s390/cacheinfo: don't use smp_processor_id() in preemptible context
s390/zcrypt: fixed domain scanning problem (again)
s390/smp: increase maximum value of NR_CPUS to 512
s390/jump label: use different nop instruction
s390/jump label: add sanity checks
s390/mm: correct missing space when reporting user process faults
s390/dasd: cleanup profiling
s390/dasd: add locking for global_profile access
s390/ftrace: hotpatch support for function tracing
ftrace: let notrace function attribute disable hotpatching if necessary
ftrace: allow architectures to specify ftrace compile options
s390: reintroduce diag 44 calls for cpu_relax()
s390/zcrypt: Add support for new crypto express (CEX5S) adapter.
s390/zcrypt: Number of supported ap domains is not retrievable.
s390/spinlock: add compare-and-delay to lock wait loops
s390/tape: remove redundant if statement
s390/hvc_iucv: add simple wildcard matches to the iucv allow filter
...
29 Jan, 2015
1 commit
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Make use of gcc's hotpatch support to generate better code for ftrace
function tracing.
The generated code now contains only a six byte nop in each function
prologue instead of a 24 byte code block which will be runtime patched to
support function tracing.
With the new code generation the runtime overhead for supporting function
tracing is close to zero, while the original code did show a significant
performance impact.Acked-by: Steven Rostedt
Signed-off-by: Heiko Carstens
Signed-off-by: Martin Schwidefsky
20 Jan, 2015
1 commit
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Compiling SH with gcc-4.8 fails due to the -m32 option not being
supported.From http://buildd.debian-ports.org/status/fetch.php?pkg=linux&arch=sh4&ver=3.16.7-ckt4-1&stamp=1421425783
CC init/main.o
gcc-4.8: error: unrecognized command line option '-m32'
ld: cannot find init/.tmp_mc_main.o: No such file or directory
objcopy: 'init/.tmp_mx_main.o': No such file
rm: cannot remove 'init/.tmp_mx_main.o': No such file or directory
rm: cannot remove 'init/.tmp_mc_main.o': No such file or directoryLink: http://lkml.kernel.org/r/1421537778-29001-1-git-send-email-kernel@mkarcher.dialup.fu-berlin.de
Link: http://lkml.kernel.org/r/54BCBDD4.10102@physik.fu-berlin.deCc: stable@vger.kernel.org
Cc: Matt Fleming
Reported-by: John Paul Adrian Glaubitz
Signed-off-by: Michael Karcher
Signed-off-by: Steven Rostedt
27 Oct, 2014
1 commit
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If the function tracer is enabled, allow to set kprobes on the first
instruction of a function (which is the function trace caller):If no kprobe is set handling of enabling and disabling function tracing
of a function simply patches the first instruction. Either it is a nop
(right now it's an unconditional branch, which skips the mcount block),
or it's a branch to the ftrace_caller() function.If a kprobe is being placed on a function tracer calling instruction
we encode if we actually have a nop or branch in the remaining bytes
after the breakpoint instruction (illegal opcode).
This is possible, since the size of the instruction used for the nop
and branch is six bytes, while the size of the breakpoint is only
two bytes.
Therefore the first two bytes contain the illegal opcode and the last
four bytes contain either "0" for nop or "1" for branch. The kprobes
code will then execute/simulate the correct instruction.Instruction patching for kprobes and function tracer is always done
with stop_machine(). Therefore we don't have any races where an
instruction is patched concurrently on a different cpu.
Besides that also the program check handler which executes the function
trace caller instruction won't be executed concurrently to any
stop_machine() execution.This allows to keep full fault based kprobes handling which generates
correct pt_regs contents automatically.Signed-off-by: Heiko Carstens
Signed-off-by: Martin Schwidefsky
09 Oct, 2014
1 commit
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31 bit and 64 bit diverge more and more and it is rather painful
to keep both parts running.
To make things simpler just remove the 31 bit support which nobody
uses anyway.Signed-off-by: Heiko Carstens
Signed-off-by: Martin Schwidefsky
29 May, 2014
1 commit
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Recordmcount utility under scripts is run, after compiling each object,
to find out all the locations of calling _mcount() and put them into
specific seciton named __mcount_loc.
Then linker collects all such information into a table in the kernel image
(between __start_mcount_loc and __stop_mcount_loc) for later use by ftrace.This patch adds arm64 specific definitions to identify such locations.
There are two types of implementation, C and Perl. On arm64, only C version
is used to build the kernel now that CONFIG_HAVE_C_RECORDMCOUNT is on.
But Perl version is also maintained.This patch also contains a workaround just in case where a header file,
elf.h, on host machine doesn't have definitions of EM_AARCH64 nor
R_AARCH64_ABS64. Without them, compiling C version of recordmcount will
fail.Acked-by: Will Deacon
Signed-off-by: AKASHI Takahiro
Signed-off-by: Will Deacon
06 Dec, 2013
1 commit
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This matches the existing behavior in arch/tile/Makefile for defconfig.
Reported-by: fengguang.wu@intel.com
Acked-by: Steven Rostedt
Signed-off-by: Tony Lu
Signed-off-by: Chris Metcalf
06 Nov, 2013
1 commit
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With gcc 4.6.0 the -mfentry feature places the function profiling call
at the start of the function. When this is used, the call is to
__fentry__ and not mcount. This is required for Ksplice as the C
version of recordmcount doesn't insert section symbols for the
__mcount_loc section so we fall back to the perl version.Based on 48bb5dc6cd9d30fe0d594947563da1f8bd9abada (ftrace: Make
recordmcount.c handle __fentry__).
Link: http://lkml.kernel.org/r/1383648129-10724-1-git-send-email-jamie.iles@oracle.comSigned-off-by: Jamie Iles
Signed-off-by: Steven Rostedt
30 Aug, 2013
1 commit
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This commit adds support for static ftrace, graph function support,
and dynamic tracer support.Signed-off-by: Tony Lu
Signed-off-by: Chris Metcalf
17 May, 2011
3 commits
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Do the mcount offset adjustment in the recordmcount.pl/recordmcount.[ch]
at compile time and not in ftrace_call_adjust at run time.Signed-off-by: Martin Schwidefsky
Signed-off-by: Steven Rostedt -
Do the mcount offset adjustment in the recordmcount.pl/recordmcount.[ch]
at compile time and not in ftrace_call_adjust at run time.Signed-off-by: Martin Schwidefsky
Signed-off-by: Steven Rostedt -
The .kprobe.text section is safe to modify mcount to nop and tracing.
Add it to the whitelist in recordmcount.c and recordmcount.pl.Cc: John Reiser
Cc: Masami Hiramatsu
Link: http://lkml.kernel.org/r/20110421023737.743350547@goodmis.org
Signed-off-by: Steven Rostedt
10 Mar, 2011
1 commit
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The section .ref.text will not go away unexpectedly and is
safe to trace. Add it to the safe list of sections to allow
tracing.Signed-off-by: Steven Rostedt
02 Sep, 2010
2 commits
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Handle the different nop and call instructions for Thumb-2. Also, we
need to adjust the recorded mcount_loc addresses because they have the
lsb set.Cc: Catalin Marinas
Acked-by: Steven Rostedt [recordmcount.pl change]
Signed-off-by: Rabin Vincent
Signed-off-by: Russell King -
This adds mcount recording and updates dynamic ftrace for ARM to work
with the new ftrace dyamic tracing implementation. It also adds support
for the mcount format used by newer ARM compilers.With dynamic tracing, mcount() is implemented as a nop. Callsites are
patched on startup with nops, and dynamically patched to call to the
ftrace_caller() routine as needed.Acked-by: Steven Rostedt [recordmcount.pl change]
Signed-off-by: Rabin Vincent
Signed-off-by: Russell King
16 Aug, 2010
1 commit
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…t/rostedt/linux-2.6-trace into trace/tip/perf/urgent-4
Conflicts:
kernel/trace/trace_events.cSigned-off-by: Steven Rostedt <rostedt@goodmis.org>
12 Aug, 2010
1 commit
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The mcount call on Blackfin systems includes some stack manipulation
around the actual call site, so extend the build time perl script to
support this. This way we can avoid doing the calculation at runtime.Signed-off-by: Mike Frysinger
LKML-Reference:
Signed-off-by: Steven Rostedt
23 Jul, 2010
1 commit
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I found this issue in a locally patched 2.6.32.x, current kernels have
moved the offending code to an __init function which is skipped by
recordmcount.pl, so the bug is not currently being exercised.
However, I think the patch is still a good idea, to avoid future
problems if _mcount were to ever have its address taken in normal
code.This is what I originally saw:
Although arch/mips/kernel/ftrace.c is built without -pg, and thus
contains no calls to _mcount, it does use the address of _mcount
in ftrace_make_nop(). This was causing relocations to be emitted
for _mcount which recordmcount.pl erronously took to be _mcount
call sites. The result was that the text of ftrace_make_nop()
would be patched with garbage leading to a system crash.In non-module code, all _mcount call sites will have R_MIPS_26
relocations, so we restrict $mcount_regex to only match on these.Acked-by: Ralf Baechle
Acked-by: Wu Zhangjin
Signed-off-by: David Daney
LKML-Reference:
Cc: Li Hong
Cc: Ingo Molnar
Cc: Matt Fleming
Signed-off-by: Steven Rostedt
26 Feb, 2010
1 commit
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Conflicts:
scripts/recordmcount.plMerge reason: Merge up to v2.6.33.
Signed-off-by: Ingo Molnar
12 Jan, 2010
1 commit
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Let the arch argument be overruled by bits. Otherwise, building of
external modules against a i386 target on a x86-64 host (and likely vice
versa as well) fails unless ARCH=i386 is explicitly passed to make.Signed-off-by: Jan Kiszka
LKML-Reference:
Signed-off-by: Steven Rostedt
07 Jan, 2010
2 commits
-
Modified recordmcount.pl to use perl constructs that are still
understandable by C hackers that are not perl programmers.Signed-off-by: Wolfram Sang
LKML-Reference:
Signed-off-by: Steven Rostedt -
- move check for open file in front of the writing loop
- use perl-constructs to access the arraySigned-off-by: Wolfram Sang
LKML-Reference:
Signed-off-by: Steven Rostedt
17 Dec, 2009
2 commits
-
With dynamic function tracer, by default, _mcount is defined as an
"empty" function, it returns directly without any more action . When
enabling it in user-space, it will jump to a real tracing
function(ftrace_caller), and do the real job for us.Differ from the static function tracer, dynamic function tracer provides
two functions ftrace_make_call()/ftrace_make_nop() to enable/disable the
tracing of some indicated kernel functions(set_ftrace_filter).In the -v4 version, the implementation of this support is basically the same as
X86 version does: _mcount is implemented as an empty function and ftrace_caller
is implemented as a real tracing function respectively.But in this version, to support module tracing with the help of
-mlong-calls in arch/mips/Makefile:MODFLAGS += -mlong-calls.
The stuff becomes a little more complex. We need to cope with two
different type of calling to _mcount.For the kernel part, the calling to _mcount(result of "objdump -hdr
vmlinux"). is like this:108: 03e0082d move at,ra
10c: 0c000000 jal 0
10c: R_MIPS_26 _mcount
10c: R_MIPS_NONE *ABS*
10c: R_MIPS_NONE *ABS*
110: 00020021 nopFor the module with -mlong-calls, it looks like this:
c: 3c030000 lui v1,0x0
c: R_MIPS_HI16 _mcount
c: R_MIPS_NONE *ABS*
c: R_MIPS_NONE *ABS*
10: 64630000 daddiu v1,v1,0
10: R_MIPS_LO16 _mcount
10: R_MIPS_NONE *ABS*
10: R_MIPS_NONE *ABS*
14: 03e0082d move at,ra
18: 0060f809 jalr v1In the kernel version, there is only one "_mcount" string for every
kernel function, so, we just need to match this one in mcount_regex of
scripts/recordmcount.pl, but in the module version, we need to choose
one of the two to match. Herein, I choose the first one with
"R_MIPS_HI16 _mcount".and In the kernel verion, without module tracing support, we just need
to replace "jal _mcount" by "jal ftrace_caller" to do real tracing, and
filter the tracing of some kernel functions via replacing it by a nop
instruction.but as we have described before, the instruction "jal ftrace_caller" only left
32bit length for the address of ftrace_caller, it will fail when calling from
the module space. so, herein, we must replace something else.the basic idea is loading the address of ftrace_caller to v1 via changing these
two instructions:lui v1,0x0
addiu v1,v1,0If we want to enable the tracing, we need to replace the above instructions to:
lui v1, HI_16BIT_ftrace_caller
addiu v1, v1, LOW_16BIT_ftrace_callerIf we want to stop the tracing of the indicated kernel functions, we
just need to replace the "jalr v1" to a nop instruction. but we need to
replace two instructions and encode the above two instructions
oursevles.Is there a simpler solution? Yes! Here it is, in this version, we put _mcount
and ftrace_caller together, which means the address of _mcount and
ftrace_caller is the same:_mcount:
ftrace_caller:
j ftrace_stub
nop...(do real tracing here)...
ftrace_stub:
jr ra
move ra, atBy default, the kernel functions call _mcount, and then jump to ftrace_stub and
return. and when we want to do real tracing, we just need to remove that "j
ftrace_stub", and it will run through the two "nop" instructions and then do
the real tracing job.what about filtering job? we just need to do this:
lui v1, hi_16bit_of_mcount b 1f (0x10000004)
addiu v1, v1, low_16bit_of_mcount
move at, ra
jalr v1
nop
1f: (rec->ip + 12)In linux-mips64, there will be some local symbols, whose name are
prefixed by $L, which need to be filtered. thanks goes to Steven for
writing the mips64-specific function_regex.In a conclusion, with RISC, things becomes easier with such a "stupid"
trick, RISC is something like K.I.S.S, and also, there are lots of
"simple" tricks in the whole ftrace support, thanks goes to Steven and
the other folks for providing such a wonderful tracing framework!Signed-off-by: Wu Zhangjin
Cc: Nicholas Mc Guire
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: Frederic Weisbecker
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/675/
Acked-by: Steven Rostedt
Signed-off-by: Ralf Baechle -
MIPS and some other architectures need this argument to handle
big/little endian respectively.Signed-off-by: Wu Zhangjin
Cc: Nicholas Mc Guire
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin
Cc: Ingo Molnar
Cc: Thomas Gleixner
Cc: Frederic Weisbecker
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/674/
Acked-by: Steven Rostedt
Signed-off-by: Ralf Baechle
