From 4d8289494a37e19cd7f3beacea9c957ad3debad6 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Tue, 13 Oct 2009 16:33:54 -0400 Subject: tracing: Enable "__cold" functions Based on the commit: a586df06 "x86: Support __attribute__((__cold__)) in gcc 4.3" some of the functions goes to the ".text.unlikely" section. Looks like there's not many of them (I found printk, panic, __ssb_dma_not_implemented, fat_fs_error), but still worth to include I think. Signed-off-by: Jiri Olsa Cc: Frederic Weisbecker Signed-off-by: Steven Rostedt LKML-Reference: <20091013203426.175845614@goodmis.org> Signed-off-by: Ingo Molnar --- scripts/recordmcount.pl | 1 + 1 file changed, 1 insertion(+) (limited to 'scripts') diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl index 090d300d739..bfb8b2cdd92 100755 --- a/scripts/recordmcount.pl +++ b/scripts/recordmcount.pl @@ -119,6 +119,7 @@ my %text_sections = ( ".sched.text" => 1, ".spinlock.text" => 1, ".irqentry.text" => 1, + ".text.unlikely" => 1, ); $objdump = "objdump" if ((length $objdump) == 0); -- cgit v1.2.3 From d49f6aa76d24c60a52530474cb662e8ad9f09471 Mon Sep 17 00:00:00 2001 From: Li Hong Date: Wed, 28 Oct 2009 13:01:38 +0800 Subject: tracing: Amend documentation in recordmcount.pl to reflect implementation The documentation currently says we will use the first function in a section as a reference. The actual algorithm is: choose the first global function we meet as a reference. If there is none, choose the first local one. Change the documentation to be consistent with the code. Also add several other clarifications. Signed-off-by: Li Hong LKML-Reference: <20091028050138.GA30758@uhli> Signed-off-by: Steven Rostedt --- scripts/recordmcount.pl | 84 ++++++++++++++++++++++++++++--------------------- 1 file changed, 49 insertions(+), 35 deletions(-) (limited to 'scripts') diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl index bfb8b2cdd92..a569be72f3b 100755 --- a/scripts/recordmcount.pl +++ b/scripts/recordmcount.pl @@ -6,73 +6,89 @@ # all the offsets to the calls to mcount. # # -# What we want to end up with is a section in vmlinux called -# __mcount_loc that contains a list of pointers to all the -# call sites in the kernel that call mcount. Later on boot up, the kernel -# will read this list, save the locations and turn them into nops. -# When tracing or profiling is later enabled, these locations will then -# be converted back to pointers to some function. +# What we want to end up with this is that each object file will have a +# section called __mcount_loc that will hold the list of pointers to mcount +# callers. After final linking, the vmlinux will have within .init.data the +# list of all callers to mcount between __start_mcount_loc and __stop_mcount_loc. +# Later on boot up, the kernel will read this list, save the locations and turn +# them into nops. When tracing or profiling is later enabled, these locations +# will then be converted back to pointers to some function. # # This is no easy feat. This script is called just after the original # object is compiled and before it is linked. # -# The references to the call sites are offsets from the section of text -# that the call site is in. Hence, all functions in a section that -# has a call site to mcount, will have the offset from the beginning of -# the section and not the beginning of the function. +# When parse this object file using 'objdump', the references to the call +# sites are offsets from the section that the call site is in. Hence, all +# functions in a section that has a call site to mcount, will have the +# offset from the beginning of the section and not the beginning of the +# function. +# +# But where this section will reside finally in vmlinx is undetermined at +# this point. So we can't use this kind of offsets to record the final +# address of this call site. +# +# The trick is to change the call offset referring the start of a section to +# referring a function symbol in this section. During the link step, 'ld' will +# compute the final address according to the information we record. # -# The trick is to find a way to record the beginning of the section. -# The way we do this is to look at the first function in the section -# which will also be the location of that section after final link. # e.g. # # .section ".sched.text", "ax" -# .globl my_func -# my_func: # [...] -# call mcount (offset: 0x5) +# func1: +# [...] +# call mcount (offset: 0x10) +# [...] +# ret +# .globl fun2 +# func2: (offset: 0x20) +# [...] # [...] # ret -# other_func: +# func3: # [...] -# call mcount (offset: 0x1b) +# call mcount (offset: 0x30) # [...] # # Both relocation offsets for the mcounts in the above example will be -# offset from .sched.text. If we make another file called tmp.s with: +# offset from .sched.text. If we choose global symbol func2 as a reference and +# make another file called tmp.s with the new offsets: # # .section __mcount_loc -# .quad my_func + 0x5 -# .quad my_func + 0x1b +# .quad func2 - 0x10 +# .quad func2 + 0x10 # -# We can then compile this tmp.s into tmp.o, and link it to the original +# We can then compile this tmp.s into tmp.o, and link it back to the original # object. # -# But this gets hard if my_func is not globl (a static function). -# In such a case we have: +# In our algorithm, we will choose the first global function we meet in this +# section as the reference. But this gets hard if there is no global functions +# in this section. In such a case we have to select a local one. E.g. func1: # # .section ".sched.text", "ax" -# my_func: +# func1: # [...] -# call mcount (offset: 0x5) +# call mcount (offset: 0x10) # [...] # ret -# other_func: +# func2: # [...] -# call mcount (offset: 0x1b) +# call mcount (offset: 0x20) # [...] +# .section "other.section" # # If we make the tmp.s the same as above, when we link together with -# the original object, we will end up with two symbols for my_func: +# the original object, we will end up with two symbols for func1: # one local, one global. After final compile, we will end up with -# an undefined reference to my_func. +# an undefined reference to func1 or a wrong reference to another global +# func1 in other files. # # Since local objects can reference local variables, we need to find # a way to make tmp.o reference the local objects of the original object -# file after it is linked together. To do this, we convert the my_func +# file after it is linked together. To do this, we convert func1 # into a global symbol before linking tmp.o. Then after we link tmp.o -# we will only have a single symbol for my_func that is global. -# We can convert my_func back into a local symbol and we are done. +# we will only have a single symbol for func1 that is global. +# We can convert func1 back into a local symbol and we are done. # # Here are the steps we take: # @@ -86,10 +102,8 @@ # 6) Link together this new object with the list object. # 7) Convert the local functions back to local symbols and rename # the result as the original object. -# End. # 8) Link the object with the list object. # 9) Move the result back to the original object. -# End. # use strict; -- cgit v1.2.3 From e2d753fac5b3954a3b6001f98479f0435fe7c868 Mon Sep 17 00:00:00 2001 From: Li Hong Date: Tue, 27 Oct 2009 14:57:33 +0800 Subject: tracing: Correct the check for number of arguments in recordmcount.pl The number of arguments passed into recordmcount.pl is 10, but the code checks if only 7 are passed in. Signed-off-by: Li Hong LKML-Reference: <20091027065733.GB22032@uhli> Signed-off-by: Steven Rostedt --- scripts/recordmcount.pl | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts') diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl index a569be72f3b..a512af1514b 100755 --- a/scripts/recordmcount.pl +++ b/scripts/recordmcount.pl @@ -113,7 +113,7 @@ $P =~ s@.*/@@g; my $V = '0.1'; -if ($#ARGV < 7) { +if ($#ARGV != 10) { print "usage: $P arch bits objdump objcopy cc ld nm rm mv is_module inputfile\n"; print "version: $V\n"; exit(1); -- cgit v1.2.3 From bdd3b052c63b2c19a0118937f500985c01a19956 Mon Sep 17 00:00:00 2001 From: Li Hong Date: Wed, 28 Oct 2009 13:03:32 +0800 Subject: tracing: Check absolute path of input file in recordmcount.pl The ftrace.c file may reference the mcount function and this may interfere with the recordmcount.pl processing. To avoid this, the code does not process the kernel/trace/ftrace.o. But currently the check is against a relative path. This patch modifies the check to succeed if the path is an absolute path. Signed-off-by: Li Hong LKML-Reference: <20091028050332.GC30758@uhli> Signed-off-by: Steven Rostedt --- scripts/recordmcount.pl | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts') diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl index a512af1514b..b80e5d04416 100755 --- a/scripts/recordmcount.pl +++ b/scripts/recordmcount.pl @@ -123,7 +123,7 @@ my ($arch, $bits, $objdump, $objcopy, $cc, $ld, $nm, $rm, $mv, $is_module, $inputfile) = @ARGV; # This file refers to mcount and shouldn't be ftraced, so lets' ignore it -if ($inputfile eq "kernel/trace/ftrace.o") { +if ($inputfile =~ m,kernel/trace/ftrace\.o$,) { exit(0); } -- cgit v1.2.3 From 7b7edc27683e20624f4daf17c76041719184201c Mon Sep 17 00:00:00 2001 From: Li Hong Date: Wed, 28 Oct 2009 13:04:21 +0800 Subject: tracing: Fix objcopy revision check in recordmcount.pl The current logic to check objcopy's version is incorrect. This patch fixes the algorithm and disables the use of local functions as a reference if the objcopy version does not support static to global conversions. Also remove some usused variables. Signed-off-by: Li Hong LKML-Reference: <20091028050421.GD30758@uhli> Signed-off-by: Steven Rostedt --- scripts/recordmcount.pl | 56 ++++++++++++++++++++++++------------------------- 1 file changed, 27 insertions(+), 29 deletions(-) (limited to 'scripts') diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl index b80e5d04416..d6199fc4870 100755 --- a/scripts/recordmcount.pl +++ b/scripts/recordmcount.pl @@ -159,6 +159,31 @@ my $function_regex; # Find the name of a function my $mcount_regex; # Find the call site to mcount (return offset) my $alignment; # The .align value to use for $mcount_section my $section_type; # Section header plus possible alignment command +my $can_use_local = 0; # If we can use local function references + +## +# check_objcopy - whether objcopy supports --globalize-symbols +# +# --globalize-symbols came out in 2.17, we must test the version +# of objcopy, and if it is less than 2.17, then we can not +# record local functions. +sub check_objcopy +{ + open (IN, "$objcopy --version |") or die "error running $objcopy"; + while () { + if (/objcopy.*\s(\d+)\.(\d+)/) { + $can_use_local = 1 if ($1 > 2 || ($1 == 2 && $2 >= 17)); + last; + } + } + close (IN); + + if (!$can_use_local) { + print STDERR "WARNING: could not find objcopy version or version " . + "is less than 2.17.\n" . + "\tLocal function references is disabled.\n"; + } +} if ($arch eq "x86") { if ($bits == 64) { @@ -293,34 +318,7 @@ if ($filename =~ m,^(.*)(\.\S),) { my $mcount_s = $dirname . "/.tmp_mc_" . $prefix . ".s"; my $mcount_o = $dirname . "/.tmp_mc_" . $prefix . ".o"; -# -# --globalize-symbols came out in 2.17, we must test the version -# of objcopy, and if it is less than 2.17, then we can not -# record local functions. -my $use_locals = 01; -my $local_warn_once = 0; -my $found_version = 0; - -open (IN, "$objcopy --version |") || die "error running $objcopy"; -while () { - if (/objcopy.*\s(\d+)\.(\d+)/) { - my $major = $1; - my $minor = $2; - - $found_version = 1; - if ($major < 2 || - ($major == 2 && $minor < 17)) { - $use_locals = 0; - } - last; - } -} -close (IN); - -if (!$found_version) { - print STDERR "WARNING: could not find objcopy version.\n" . - "\tDisabling local function references.\n"; -} +check_objcopy(); # # Step 1: find all the local (static functions) and weak symbols. @@ -367,7 +365,7 @@ sub update_funcs if (defined $locals{$ref_func}) { # only use locals if objcopy supports globalize-symbols - if (!$use_locals) { + if (!$can_use_local) { return; } $convert{$ref_func} = 1; -- cgit v1.2.3 From db24c7dcf42f78629d89b34e5d5a98ed56ea2ff5 Mon Sep 17 00:00:00 2001 From: Li Hong Date: Wed, 28 Oct 2009 13:05:23 +0800 Subject: tracing: Move mcount section search to front of loop in recordmcount.pl Move the mcount section check to the beginning of the objdump read loop. This makes the code easier to follow since the search for the mcount section is performed first before the mcount callers are processed. Signed-off-by: Li Hong LKML-Reference: <20091028050523.GE30758@uhli> Signed-off-by: Steven Rostedt --- scripts/recordmcount.pl | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-) (limited to 'scripts') diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl index d6199fc4870..02c80552b07 100755 --- a/scripts/recordmcount.pl +++ b/scripts/recordmcount.pl @@ -391,9 +391,27 @@ open(IN, "$objdump -hdr $inputfile|") || die "error running $objdump"; my $text; + +# read headers first my $read_headers = 1; while () { + + if ($read_headers && /$mcount_section/) { + # + # Somehow the make process can execute this script on an + # object twice. If it does, we would duplicate the mcount + # section and it will cause the function tracer self test + # to fail. Check if the mcount section exists, and if it does, + # warn and exit. + # + print STDERR "ERROR: $mcount_section already in $inputfile\n" . + "\tThis may be an indication that your build is corrupted.\n" . + "\tDelete $inputfile and try again. If the same object file\n" . + "\tstill causes an issue, then disable CONFIG_DYNAMIC_FTRACE.\n"; + exit(-1); + } + # is it a section? if (/$section_regex/) { $read_headers = 0; @@ -434,21 +452,7 @@ while () { $offset = hex $1; } } - } elsif ($read_headers && /$mcount_section/) { - # - # Somehow the make process can execute this script on an - # object twice. If it does, we would duplicate the mcount - # section and it will cause the function tracer self test - # to fail. Check if the mcount section exists, and if it does, - # warn and exit. - # - print STDERR "ERROR: $mcount_section already in $inputfile\n" . - "\tThis may be an indication that your build is corrupted.\n" . - "\tDelete $inputfile and try again. If the same object file\n" . - "\tstill causes an issue, then disable CONFIG_DYNAMIC_FTRACE.\n"; - exit(-1); } - # is this a call site to mcount? If so, record it to print later if ($text_found && /$mcount_regex/) { $offsets[$#offsets + 1] = hex $1; -- cgit v1.2.3 From 306dcf47d28aaf9aedfafb17a602768584cfc0f2 Mon Sep 17 00:00:00 2001 From: Li Hong Date: Wed, 28 Oct 2009 13:06:19 +0800 Subject: tracing: Add regex for weak functions in recordmcount.pl Add a variable to contain the regex needed to find weak functions in the 'nm' output. This will allow other archs to easily override it. Also rename the regex variable $nm_regex to $local_regex to be more descriptive. Signed-off-by: Li Hong LKML-Reference: <20091028050619.GF30758@uhli> Signed-off-by: Steven Rostedt --- scripts/recordmcount.pl | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) (limited to 'scripts') diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl index 02c80552b07..7265a7dcac4 100755 --- a/scripts/recordmcount.pl +++ b/scripts/recordmcount.pl @@ -92,7 +92,7 @@ # # Here are the steps we take: # -# 1) Record all the local symbols by using 'nm' +# 1) Record all the local and weak symbols by using 'nm' # 2) Use objdump to find all the call site offsets and sections for # mcount. # 3) Compile the list into its own object. @@ -152,7 +152,8 @@ my %weak; # List of weak functions my %convert; # List of local functions used that needs conversion my $type; -my $nm_regex; # Find the local functions (return function) +my $local_regex; # Match a local function (return function) +my $weak_regex; # Match a weak function (return function) my $section_regex; # Find the start of a section my $function_regex; # Find the name of a function # (return offset and func name) @@ -197,7 +198,8 @@ if ($arch eq "x86") { # We base the defaults off of i386, the other archs may # feel free to change them in the below if statements. # -$nm_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\S+)"; +$local_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\S+)"; +$weak_regex = "^[0-9a-fA-F]+\\s+([wW])\\s+(\\S+)"; $section_regex = "Disassembly of section\\s+(\\S+):"; $function_regex = "^([0-9a-fA-F]+)\\s+<(.*?)>:"; $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\smcount\$"; @@ -246,7 +248,7 @@ if ($arch eq "x86_64") { $cc .= " -m32"; } elsif ($arch eq "powerpc") { - $nm_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\.?\\S+)"; + $local_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\.?\\S+)"; $function_regex = "^([0-9a-fA-F]+)\\s+<(\\.?.*?)>:"; $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s\\.?_mcount\$"; @@ -322,13 +324,13 @@ check_objcopy(); # # Step 1: find all the local (static functions) and weak symbols. -# 't' is local, 'w/W' is weak (we never use a weak function) +# 't' is local, 'w/W' is weak # open (IN, "$nm $inputfile|") || die "error running $nm"; while () { - if (/$nm_regex/) { + if (/$local_regex/) { $locals{$1} = 1; - } elsif (/^[0-9a-fA-F]+\s+([wW])\s+(\S+)/) { + } elsif (/$weak_regex/) { $weak{$2} = $1; } } -- cgit v1.2.3 From 6092858c60f168c1950f8ad73880d54271696ec5 Mon Sep 17 00:00:00 2001 From: Li Hong Date: Wed, 28 Oct 2009 13:07:03 +0800 Subject: tracing: Move conditional into update_funcs() in recordmcount.pl Move all the condition validations into the function update_funcs(). Also update_funcs should not die if $ref_func is undefined for there may be more than one valid section in an object file. Signed-off-by: Li Hong LKML-Reference: <20091028050703.GG30758@uhli> Signed-off-by: Steven Rostedt --- scripts/recordmcount.pl | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) (limited to 'scripts') diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl index 7265a7dcac4..884776a6e01 100755 --- a/scripts/recordmcount.pl +++ b/scripts/recordmcount.pl @@ -348,9 +348,7 @@ my $offset = 0; # offset of ref_func to section beginning # sub update_funcs { - return if ($#offsets < 0); - - defined($ref_func) || die "No function to reference"; + return unless ($ref_func and @offsets); # A section only had a weak function, to represent it. # Unfortunately, a weak function may be overwritten by another @@ -425,7 +423,7 @@ while () { $read_function = 0; } # print out any recorded offsets - update_funcs() if (defined($ref_func)); + update_funcs(); # reset all markers and arrays $text_found = 0; @@ -462,7 +460,7 @@ while () { } # dump out anymore offsets that may have been found -update_funcs() if (defined($ref_func)); +update_funcs(); # If we did not find any mcount callers, we are done (do nothing). if (!$opened) { -- cgit v1.2.3 From c4b8ac2c1aee1398b9378b8730bac56294b3410b Mon Sep 17 00:00:00 2001 From: Li Hong Date: Wed, 28 Oct 2009 13:07:43 +0800 Subject: tracing: Exit with error if a weak function is used in recordmcount.pl If a weak function is used as a relocation reference for mcount callers and that function is overridden, it will cause ftrace to fail at run time. The current code should prevent a weak function from being used, but if one is, the code should exit with an error to fail at compile time. Signed-off-by: Li Hong LKML-Reference: <20091028050743.GH30758@uhli> Signed-off-by: Steven Rostedt --- scripts/recordmcount.pl | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) (limited to 'scripts') diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl index 884776a6e01..a4e2435d482 100755 --- a/scripts/recordmcount.pl +++ b/scripts/recordmcount.pl @@ -350,15 +350,11 @@ sub update_funcs { return unless ($ref_func and @offsets); - # A section only had a weak function, to represent it. - # Unfortunately, a weak function may be overwritten by another - # function of the same name, making all these offsets incorrect. - # To be safe, we simply print a warning and bail. + # Sanity check on weak function. A weak function may be overwritten by + # another function of the same name, making all these offsets incorrect. if (defined $weak{$ref_func}) { - print STDERR - "$inputfile: WARNING: referencing weak function" . + die "$inputfile: ERROR: referencing weak function" . " $ref_func for mcount\n"; - return; } # is this function static? If so, note this fact. -- cgit v1.2.3 From 638adb0561264a3360a53e93def62288c85d8373 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 17 Nov 2009 10:48:25 -0500 Subject: tracing: Only print objcopy version warning once from recordmcount If the user has an older version of objcopy, that can not handle converting local symbols to global and vice versa, then some functions will not be part of the dynamic function tracer. The current code in recordmcount.pl will print a warning in this case. Unfortunately, there exists lots of files that may have this issue with older objcopys and this will cause a warning for every file compiled with this issue. This patch solves this overwhelming output by creating a .tmp_quiet_recordmcount file on the first instance the warning is encountered. The warning will not print if this file exists. The temp file is deleted at the beginning of the compile to ensure that the warning will happen once again on new compiles (because the issue is still present). Reported-by: Andrew Morton Cc: Sam Ravnborg Signed-off-by: Steven Rostedt --- scripts/recordmcount.pl | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'scripts') diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl index a4e2435d482..f0d14452632 100755 --- a/scripts/recordmcount.pl +++ b/scripts/recordmcount.pl @@ -162,6 +162,11 @@ my $alignment; # The .align value to use for $mcount_section my $section_type; # Section header plus possible alignment command my $can_use_local = 0; # If we can use local function references +# Shut up recordmcount if user has older objcopy +my $quiet_recordmcount = ".tmp_quiet_recordmcount"; +my $print_warning = 1; +$print_warning = 0 if ( -f $quiet_recordmcount); + ## # check_objcopy - whether objcopy supports --globalize-symbols # @@ -179,10 +184,13 @@ sub check_objcopy } close (IN); - if (!$can_use_local) { + if (!$can_use_local && $print_warning) { print STDERR "WARNING: could not find objcopy version or version " . "is less than 2.17.\n" . - "\tLocal function references is disabled.\n"; + "\tLocal function references are disabled.\n"; + open (QUIET, ">$quiet_recordmcount"); + printf QUIET "Disables the warning from recordmcount.pl\n"; + close QUIET; } } -- cgit v1.2.3