mirror of
https://github.com/Fishwaldo/Star64_linux.git
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Merge branch 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (40 commits) tracing: Separate raw syscall from syscall tracer ring-buffer-benchmark: Add parameters to set produce/consumer priorities tracing, function tracer: Clean up strstrip() usage ring-buffer benchmark: Run producer/consumer threads at nice +19 tracing: Remove the stale include/trace/power.h tracing: Only print objcopy version warning once from recordmcount tracing: Prevent build warning: 'ftrace_graph_buf' defined but not used ring-buffer: Move access to commit_page up into function used tracing: do not disable interrupts for trace_clock_local ring-buffer: Add multiple iterations between benchmark timestamps kprobes: Sanitize struct kretprobe_instance allocations tracing: Fix to use __always_unused attribute compiler: Introduce __always_unused tracing: Exit with error if a weak function is used in recordmcount.pl tracing: Move conditional into update_funcs() in recordmcount.pl tracing: Add regex for weak functions in recordmcount.pl tracing: Move mcount section search to front of loop in recordmcount.pl tracing: Fix objcopy revision check in recordmcount.pl tracing: Check absolute path of input file in recordmcount.pl tracing: Correct the check for number of arguments in recordmcount.pl ...
This commit is contained in:
Linus Torvalds
commit
96fa2b508d
28 changed files with 856 additions and 518 deletions
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@ -6,77 +6,93 @@
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# all the offsets to the calls to mcount.
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#
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#
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# What we want to end up with is a section in vmlinux called
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# __mcount_loc that contains a list of pointers to all the
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# call sites in the kernel that call mcount. Later on boot up, the kernel
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# will read this list, save the locations and turn them into nops.
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# When tracing or profiling is later enabled, these locations will then
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# be converted back to pointers to some function.
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# What we want to end up with this is that each object file will have a
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# section called __mcount_loc that will hold the list of pointers to mcount
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# callers. After final linking, the vmlinux will have within .init.data the
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# list of all callers to mcount between __start_mcount_loc and __stop_mcount_loc.
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# Later on boot up, the kernel will read this list, save the locations and turn
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# them into nops. When tracing or profiling is later enabled, these locations
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# will then be converted back to pointers to some function.
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#
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# This is no easy feat. This script is called just after the original
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# object is compiled and before it is linked.
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#
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# The references to the call sites are offsets from the section of text
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# that the call site is in. Hence, all functions in a section that
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# has a call site to mcount, will have the offset from the beginning of
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# the section and not the beginning of the function.
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# When parse this object file using 'objdump', the references to the call
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# sites are offsets from the section that the call site is in. Hence, all
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# functions in a section that has a call site to mcount, will have the
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# offset from the beginning of the section and not the beginning of the
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# function.
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#
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# But where this section will reside finally in vmlinx is undetermined at
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# this point. So we can't use this kind of offsets to record the final
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# address of this call site.
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#
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# The trick is to change the call offset referring the start of a section to
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# referring a function symbol in this section. During the link step, 'ld' will
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# compute the final address according to the information we record.
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#
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# The trick is to find a way to record the beginning of the section.
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# The way we do this is to look at the first function in the section
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# which will also be the location of that section after final link.
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# e.g.
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#
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# .section ".sched.text", "ax"
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# .globl my_func
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# my_func:
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# [...]
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# call mcount (offset: 0x5)
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# func1:
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# [...]
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# call mcount (offset: 0x10)
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# [...]
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# ret
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# other_func:
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# .globl fun2
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# func2: (offset: 0x20)
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# [...]
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# call mcount (offset: 0x1b)
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# [...]
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# ret
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# func3:
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# [...]
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# call mcount (offset: 0x30)
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# [...]
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#
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# Both relocation offsets for the mcounts in the above example will be
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# offset from .sched.text. If we make another file called tmp.s with:
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# offset from .sched.text. If we choose global symbol func2 as a reference and
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# make another file called tmp.s with the new offsets:
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#
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# .section __mcount_loc
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# .quad my_func + 0x5
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# .quad my_func + 0x1b
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# .quad func2 - 0x10
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# .quad func2 + 0x10
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#
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# We can then compile this tmp.s into tmp.o, and link it to the original
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# We can then compile this tmp.s into tmp.o, and link it back to the original
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# object.
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#
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# But this gets hard if my_func is not globl (a static function).
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# In such a case we have:
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# In our algorithm, we will choose the first global function we meet in this
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# section as the reference. But this gets hard if there is no global functions
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# in this section. In such a case we have to select a local one. E.g. func1:
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#
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# .section ".sched.text", "ax"
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# my_func:
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# func1:
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# [...]
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# call mcount (offset: 0x5)
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# call mcount (offset: 0x10)
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# [...]
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# ret
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# other_func:
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# func2:
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# [...]
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# call mcount (offset: 0x1b)
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# call mcount (offset: 0x20)
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# [...]
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# .section "other.section"
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#
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# If we make the tmp.s the same as above, when we link together with
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# the original object, we will end up with two symbols for my_func:
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# the original object, we will end up with two symbols for func1:
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# one local, one global. After final compile, we will end up with
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# an undefined reference to my_func.
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# an undefined reference to func1 or a wrong reference to another global
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# func1 in other files.
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#
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# Since local objects can reference local variables, we need to find
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# a way to make tmp.o reference the local objects of the original object
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# file after it is linked together. To do this, we convert the my_func
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# file after it is linked together. To do this, we convert func1
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# into a global symbol before linking tmp.o. Then after we link tmp.o
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# we will only have a single symbol for my_func that is global.
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# We can convert my_func back into a local symbol and we are done.
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# we will only have a single symbol for func1 that is global.
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# We can convert func1 back into a local symbol and we are done.
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#
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# Here are the steps we take:
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#
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# 1) Record all the local symbols by using 'nm'
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# 1) Record all the local and weak symbols by using 'nm'
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# 2) Use objdump to find all the call site offsets and sections for
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# mcount.
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# 3) Compile the list into its own object.
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@ -86,10 +102,8 @@
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# 6) Link together this new object with the list object.
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# 7) Convert the local functions back to local symbols and rename
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# the result as the original object.
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# End.
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# 8) Link the object with the list object.
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# 9) Move the result back to the original object.
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# End.
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#
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use strict;
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@ -99,7 +113,7 @@ $P =~ s@.*/@@g;
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my $V = '0.1';
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if ($#ARGV < 7) {
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if ($#ARGV != 10) {
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print "usage: $P arch bits objdump objcopy cc ld nm rm mv is_module inputfile\n";
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print "version: $V\n";
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exit(1);
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@ -109,7 +123,7 @@ my ($arch, $bits, $objdump, $objcopy, $cc,
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$ld, $nm, $rm, $mv, $is_module, $inputfile) = @ARGV;
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# This file refers to mcount and shouldn't be ftraced, so lets' ignore it
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if ($inputfile eq "kernel/trace/ftrace.o") {
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if ($inputfile =~ m,kernel/trace/ftrace\.o$,) {
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exit(0);
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}
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@ -119,6 +133,7 @@ my %text_sections = (
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".sched.text" => 1,
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".spinlock.text" => 1,
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".irqentry.text" => 1,
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".text.unlikely" => 1,
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);
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$objdump = "objdump" if ((length $objdump) == 0);
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@ -137,13 +152,47 @@ my %weak; # List of weak functions
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my %convert; # List of local functions used that needs conversion
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my $type;
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my $nm_regex; # Find the local functions (return function)
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my $local_regex; # Match a local function (return function)
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my $weak_regex; # Match a weak function (return function)
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my $section_regex; # Find the start of a section
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my $function_regex; # Find the name of a function
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# (return offset and func name)
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my $mcount_regex; # Find the call site to mcount (return offset)
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my $alignment; # The .align value to use for $mcount_section
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my $section_type; # Section header plus possible alignment command
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my $can_use_local = 0; # If we can use local function references
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# Shut up recordmcount if user has older objcopy
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my $quiet_recordmcount = ".tmp_quiet_recordmcount";
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my $print_warning = 1;
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$print_warning = 0 if ( -f $quiet_recordmcount);
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##
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# check_objcopy - whether objcopy supports --globalize-symbols
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#
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# --globalize-symbols came out in 2.17, we must test the version
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# of objcopy, and if it is less than 2.17, then we can not
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# record local functions.
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sub check_objcopy
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{
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open (IN, "$objcopy --version |") or die "error running $objcopy";
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while (<IN>) {
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if (/objcopy.*\s(\d+)\.(\d+)/) {
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$can_use_local = 1 if ($1 > 2 || ($1 == 2 && $2 >= 17));
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last;
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}
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}
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close (IN);
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if (!$can_use_local && $print_warning) {
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print STDERR "WARNING: could not find objcopy version or version " .
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"is less than 2.17.\n" .
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"\tLocal function references are disabled.\n";
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open (QUIET, ">$quiet_recordmcount");
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printf QUIET "Disables the warning from recordmcount.pl\n";
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close QUIET;
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}
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}
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if ($arch eq "x86") {
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if ($bits == 64) {
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@ -157,7 +206,8 @@ if ($arch eq "x86") {
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# We base the defaults off of i386, the other archs may
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# feel free to change them in the below if statements.
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#
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$nm_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\S+)";
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$local_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\S+)";
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$weak_regex = "^[0-9a-fA-F]+\\s+([wW])\\s+(\\S+)";
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$section_regex = "Disassembly of section\\s+(\\S+):";
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$function_regex = "^([0-9a-fA-F]+)\\s+<(.*?)>:";
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$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\smcount\$";
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@ -206,7 +256,7 @@ if ($arch eq "x86_64") {
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$cc .= " -m32";
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} elsif ($arch eq "powerpc") {
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$nm_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\.?\\S+)";
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$local_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\.?\\S+)";
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$function_regex = "^([0-9a-fA-F]+)\\s+<(\\.?.*?)>:";
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$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s\\.?_mcount\$";
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@ -278,44 +328,17 @@ if ($filename =~ m,^(.*)(\.\S),) {
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my $mcount_s = $dirname . "/.tmp_mc_" . $prefix . ".s";
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my $mcount_o = $dirname . "/.tmp_mc_" . $prefix . ".o";
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#
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# --globalize-symbols came out in 2.17, we must test the version
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# of objcopy, and if it is less than 2.17, then we can not
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# record local functions.
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my $use_locals = 01;
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my $local_warn_once = 0;
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my $found_version = 0;
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open (IN, "$objcopy --version |") || die "error running $objcopy";
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while (<IN>) {
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if (/objcopy.*\s(\d+)\.(\d+)/) {
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my $major = $1;
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my $minor = $2;
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$found_version = 1;
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if ($major < 2 ||
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($major == 2 && $minor < 17)) {
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$use_locals = 0;
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}
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last;
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}
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}
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close (IN);
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if (!$found_version) {
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print STDERR "WARNING: could not find objcopy version.\n" .
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"\tDisabling local function references.\n";
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}
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check_objcopy();
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#
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# Step 1: find all the local (static functions) and weak symbols.
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# 't' is local, 'w/W' is weak (we never use a weak function)
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# 't' is local, 'w/W' is weak
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#
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open (IN, "$nm $inputfile|") || die "error running $nm";
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while (<IN>) {
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if (/$nm_regex/) {
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if (/$local_regex/) {
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$locals{$1} = 1;
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} elsif (/^[0-9a-fA-F]+\s+([wW])\s+(\S+)/) {
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} elsif (/$weak_regex/) {
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$weak{$2} = $1;
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}
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}
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@ -333,26 +356,20 @@ my $offset = 0; # offset of ref_func to section beginning
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#
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sub update_funcs
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{
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return if ($#offsets < 0);
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return unless ($ref_func and @offsets);
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defined($ref_func) || die "No function to reference";
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# A section only had a weak function, to represent it.
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# Unfortunately, a weak function may be overwritten by another
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# function of the same name, making all these offsets incorrect.
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# To be safe, we simply print a warning and bail.
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# Sanity check on weak function. A weak function may be overwritten by
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# another function of the same name, making all these offsets incorrect.
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if (defined $weak{$ref_func}) {
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print STDERR
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"$inputfile: WARNING: referencing weak function" .
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die "$inputfile: ERROR: referencing weak function" .
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" $ref_func for mcount\n";
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return;
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}
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# is this function static? If so, note this fact.
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if (defined $locals{$ref_func}) {
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# only use locals if objcopy supports globalize-symbols
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if (!$use_locals) {
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if (!$can_use_local) {
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return;
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}
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$convert{$ref_func} = 1;
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@ -378,9 +395,27 @@ open(IN, "$objdump -hdr $inputfile|") || die "error running $objdump";
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my $text;
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# read headers first
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my $read_headers = 1;
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while (<IN>) {
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if ($read_headers && /$mcount_section/) {
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#
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# Somehow the make process can execute this script on an
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# object twice. If it does, we would duplicate the mcount
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# section and it will cause the function tracer self test
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# to fail. Check if the mcount section exists, and if it does,
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# warn and exit.
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#
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print STDERR "ERROR: $mcount_section already in $inputfile\n" .
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"\tThis may be an indication that your build is corrupted.\n" .
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"\tDelete $inputfile and try again. If the same object file\n" .
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"\tstill causes an issue, then disable CONFIG_DYNAMIC_FTRACE.\n";
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exit(-1);
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}
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# is it a section?
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if (/$section_regex/) {
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$read_headers = 0;
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@ -392,7 +427,7 @@ while (<IN>) {
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$read_function = 0;
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}
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# print out any recorded offsets
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update_funcs() if (defined($ref_func));
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update_funcs();
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# reset all markers and arrays
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$text_found = 0;
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@ -421,21 +456,7 @@ while (<IN>) {
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$offset = hex $1;
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}
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}
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} elsif ($read_headers && /$mcount_section/) {
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#
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# Somehow the make process can execute this script on an
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# object twice. If it does, we would duplicate the mcount
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# section and it will cause the function tracer self test
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# to fail. Check if the mcount section exists, and if it does,
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# warn and exit.
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#
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print STDERR "ERROR: $mcount_section already in $inputfile\n" .
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"\tThis may be an indication that your build is corrupted.\n" .
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"\tDelete $inputfile and try again. If the same object file\n" .
|
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"\tstill causes an issue, then disable CONFIG_DYNAMIC_FTRACE.\n";
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exit(-1);
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}
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# is this a call site to mcount? If so, record it to print later
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if ($text_found && /$mcount_regex/) {
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$offsets[$#offsets + 1] = hex $1;
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@ -443,7 +464,7 @@ while (<IN>) {
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}
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# dump out anymore offsets that may have been found
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update_funcs() if (defined($ref_func));
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update_funcs();
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# If we did not find any mcount callers, we are done (do nothing).
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if (!$opened) {
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||||
|
|
|
|||
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