The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array
member[1][2], introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by this
change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Gustavo A. R. Silva <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lore.kernel.org/lkml/20200515172926.GA31976@embeddedor
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
For perf report on stripped binaries it is currently impossible to do
annotation. The annotation state is all tied to symbols, but there are
either no symbols, or symbols are not covering all the code.
We should support the annotation functionality even without symbols.
This patch fakes a symbol and the symbol name is the string of address.
After that, we just follow current annotation working flow.
For example,
1. perf report
Overhead Command Shared Object Symbol
20.67% div libc-2.27.so [.] __random_r
17.29% div libc-2.27.so [.] __random
10.59% div div [.] 0x0000000000000628
9.25% div div [.] 0x0000000000000612
6.11% div div [.] 0x0000000000000645
2. Select the line of "10.59% div div [.] 0x0000000000000628" and ENTER.
Annotate 0x0000000000000628
Zoom into div thread
Zoom into div DSO (use the 'k' hotkey to zoom directly into the kernel)
Browse map details
Run scripts for samples of symbol [0x0000000000000628]
Run scripts for all samples
Switch to another data file in PWD
Exit
3. Select the "Annotate 0x0000000000000628" and ENTER.
Percent│
│
│
│ Disassembly of section .text:
│
│ 0000000000000628 <.text+0x68>:
│ divsd %xmm4,%xmm0
│ divsd %xmm3,%xmm1
│ movsd (%rsp),%xmm2
│ addsd %xmm1,%xmm0
│ addsd %xmm2,%xmm0
│ movsd %xmm0,(%rsp)
Now we can see the dump of object starting from 0x628.
v5:
---
Remove the hotkey 'a' implementation from this patch. It
will be moved to a separate patch.
v4:
---
1. Support the hotkey 'a'. When we press 'a' on address,
now it supports the annotation.
2. Change the patch title from
"Support interactive annotation of code without symbols" to
"perf report: Support interactive annotation of code without symbols"
v3:
---
Keep just the ANNOTATION_DUMMY_LEN, and remove the
opts->annotate_dummy_len since it's the "maybe in future
we will provide" feature.
v2:
---
Fix a crash issue when annotating an address in "unknown" object.
The steps to reproduce this issue:
perf record -e cycles:u ls
perf report
75.29% ls ld-2.27.so [.] do_lookup_x
23.64% ls ld-2.27.so [.] __GI___tunables_init
1.04% ls [unknown] [k] 0xffffffff85c01210
0.03% ls ld-2.27.so [.] _start
When annotating 0xffffffff85c01210, the crash happens.
v2 adds checking for ms->map in add_annotate_opt(). If the object is
"unknown", ms->map is NULL.
Committer notes:
Renamed new_annotate_sym() to symbol__new_unresolved().
Use PRIx64 to fix this issue in some 32-bit arches:
ui/browsers/hists.c: In function 'symbol__new_unresolved':
ui/browsers/hists.c:2474:38: error: format '%lx' expects argument of type 'long unsigned int', but argument 5 has type 'u64' {aka 'long long unsigned int'} [-Werror=format=]
snprintf(name, sizeof(name), "%-#.*lx", BITS_PER_LONG / 4, addr);
~~~~~~^ ~~~~
%-#.*llx
Signed-off-by: Jin Yao <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Tested-by: Ravi Bangoria <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
We are allocating disasm_line object in annotation_line__new() instead
of disasm_line__new(). Similarly annotation_line__delete() is actually
freeing disasm_line object as well. This complexity is because of
privsize. But we don't need privsize anymore so get rid of privsize and
simplify disasm_line allocation and freeing code.
Signed-off-by: Ravi Bangoria <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Jin Yao <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Song Liu <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
perf annotate --show-total-period does not really show total period.
The reason is we have two separate variables for the same purpose.
One is in symbol_conf.show_total_period and another is
annotation_options.show_total_period.
We save command line option in symbol_conf.show_total_period but uses
annotation_option.show_total_period while rendering tui/stdio2 browser.
Though, we copy symbol_conf.show_total_period to
annotation__default_options.show_total_period but that is not really
effective as we don't use annotation__default_options once we copy
default options to dynamic variable annotate.opts in cmd_annotate().
Instead of all these complication, keep only one variable and use it all
over. symbol_conf.show_total_period is used by perf report/top as well.
So let's kill annotation_options.show_total_period.
On a side note, I've kept annotation_options.show_total_period
definition because it's still used by perf-config code. Follow up patch
to fix perf-config for annotate will remove
annotation_options.show_total_period.
Signed-off-by: Ravi Bangoria <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexey Budankov <[email protected]>
Cc: Changbin Du <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Jin Yao <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Taeung Song <[email protected]>
Cc: Thomas Richter <[email protected]>
Cc: Yisheng Xie <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
We are already passing things like:
symbol__annotate(ms->sym, ms->map, ...)
So shorten the signature of such functions to receive the 'map_symbol'
pointer.
This also paves the way to having the 'struct map_groups' pointer in the
'struct map_symbol' so that we can get rid of 'struct map'->groups.
Cc: Adrian Hunter <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Link: https://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
Starting with binutils 2.28, aarch64 objdump adds comments to the
disassembly output to show the alternative names of a condition code
[1].
It is assumed that commas in objdump comments could occur in other
arches now or in the future, so this fix is arch-independent.
The fix could have been done with arm64 specific jump__parse and
jump__scnprintf functions, but the jump__scnprintf instruction would
have to have its comment character be a literal, since the scnprintf
functions cannot receive a struct arch easily.
This inconvenience also applies to the generic jump__scnprintf, which is
why we add a raw_comment pointer to struct ins_operands, so the __parse
function assigns it to be re-used by its corresponding __scnprintf
function.
Example differences in 'perf annotate --stdio2' output on an aarch64
perf.data file:
BEFORE: → b.cs ffff200008133d1c <unwind_frame+0x18c> // b.hs, dffff7ecc47b
AFTER : ↓ b.cs 18c
BEFORE: → b.cc ffff200008d8d9cc <get_alloc_profile+0x31c> // b.lo, b.ul, dffff727295b
AFTER : ↓ b.cc 31c
The branch target labels 18c and 31c also now appear in the output:
BEFORE: add x26, x29, #0x80
AFTER : 18c: add x26, x29, #0x80
BEFORE: add x21, x21, #0x8
AFTER : 31c: add x21, x21, #0x8
The Fixes: tag below is added so stable branches will get the update; it
doesn't necessarily mean that commit was broken at the time, rather it
didn't withstand the aarch64 objdump update.
Tested no difference in output for sample x86_64, power arch perf.data files.
[1] https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=bb7eff5206e4795ac79c177a80fe9f4630aaf730
Signed-off-by: Kim Phillips <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ravi Bangoria <[email protected]>
Cc: Robin Murphy <[email protected]>
Cc: Taeung Song <[email protected]>
Cc: [email protected]
Fixes: b13bbeee5e ("perf annotate: Fix branch instruction with multiple operands")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
Add --percent-type option to set annotation percent type from following
choices:
global-period, local-period, global-hits, local-hits
Examples:
$ perf annotate --percent-type period-local --stdio | head -1
Percent | Source code ... es, percent: local period)
$ perf annotate --percent-type hits-local --stdio | head -1
Percent | Source code ... es, percent: local hits)
$ perf annotate --percent-type hits-global --stdio | head -1
Percent | Source code ... es, percent: global hits)
$ perf annotate --percent-type period-global --stdio | head -1
Percent | Source code ... es, percent: global period)
The local/global keywords set if the percentage is computed in the scope
of the function (local) or the whole data (global).
The period/hits keywords set the base the percentage is computed on -
the samples period or the number of samples (hits).
Signed-off-by: Jiri Olsa <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
Add new key bindings to toggle percent type/base in annotation UI browser:
'p' to switch between local and global percent type
'b' to switch between hits and perdio percent base
Add the following help messages to the UI browser '?' window:
...
p Toggle percent type [local/global]
b Toggle percent base [period/hits]
...
Signed-off-by: Jiri Olsa <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
[ Moved percent_type to be the last arg to sym_title(), its an arg to what is being formmated (buf, size) ]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
So we can hold multiple percent values for annotation line.
The first member of this array is current local hits percent value
(PERCENT_HITS_LOCAL index), so no functional change is expected.
Adding annotation_data__percent function to return requested percent
value from struct annotation_data.
Signed-off-by: Jiri Olsa <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
We have more current function tto get the title for annotation,
which is hists__scnprintf_title. They both have same output as
far as the annotation's header line goes.
They differ in counting of the nr_samples, hists__scnprintf_title
provides more accurate number based on the setup of the
symbol_conf.filter_relative variable.
Plus it also displays any uid/thread/dso/socket filters/zooms
if there are set any, which annotation__scnprintf_samples_period
does not.
Signed-off-by: Jiri Olsa <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
When we have multiple groups in an evlist, say:
$ perf stat -e '{cycles,instructions},{cache-references,cache-misses}' sleep 1
Performance counter stats for 'sleep 1':
343,134 cycles:u
249,292 instructions:u # 0.73 insn per cycle
15,556 cache-references:u
8,925 cache-misses:u # 57.373 % of all cache refs
1.000957550 seconds time elapsed
$
Then the perf_evsel instances for the two group leaders ("cycles" and
"cache-references") will have evsel->nr_members set to 2, while all the
evsel->evlist->nr_entries will be set to 4, so we can't use
evsel->evlist->nr_entries everywhere, as event groups need to be taken
into account.
But this probably requires us to audit at least the forced-group code,
where we want all of the events to be in a "group", to see them all in
the screen, one column for each, even knowing that they were not
necessarily scheduled to count at the same time by the kernel perf
subsystem.
Cc: Adrian Hunter <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Wang Nan <[email protected]>
Link: https://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
Currently perf has a feature to account cycles for LBRs
For example, on skylake:
perf record -b ...
perf report or perf annotate
And then browsing the annotate browser gives average cycle counts for
program blocks.
For some analysis it would be useful if we could know not only the
average cycles but also the min and max cycles.
This patch records the min and max cycles.
Signed-off-by: Jin Yao <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
[ Switch from max/min to min/max ]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
Because they all really check if we can access data structures/visual
constructs where a "jump" instruction targets code in the same function,
i.e. things like:
__pthread_mutex_lock /usr/lib64/libpthread-2.26.so
1.95 │ mov __pthread_force_elision,%ecx
│ ┌──test %ecx,%ecx
0.07 │ ├──je 60
│ │ test $0x300,%esi
│ │↓ jne 60
│ │ or $0x100,%esi
│ │ mov %esi,0x10(%rdi)
│ 42:│ mov %esi,%edx
│ │ lea 0x16(%r8),%rsi
│ │ mov %r8,%rdi
│ │ and $0x80,%edx
│ │ add $0x8,%rsp
│ │→ jmpq __lll_lock_elision
│ │ nop
0.29 │ 60:└─→and $0x80,%esi
0.07 │ mov $0x1,%edi
0.29 │ xor %eax,%eax
2.53 │ lock cmpxchg %edi,(%r8)
And not things like that "jmpq __lll_lock_elision", that instead should behave
like a "call" instruction and "jump" to the disassembly of "___lll_lock_elision".
Cc: Adrian Hunter <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Jin Yao <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Wang Nan <[email protected]>
Link: https://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
Things like this in _cpp_lex_token (gcc's cc1 program):
cpp_named_operator2name@@Base+0xa72
Point to a place that is after the cpp_named_operator2name boundaries,
i.e. in the ELF symbol table for cc1 cpp_named_operator2name is marked
as being 32-bytes long, but it in fact is much larger than that, so we
seem to need a symbols__find() routine that looks for >= current->start
and < next_symbol->start, possibly just for C++ objects?
For now lets just make some progress by marking jumps to outside the
current function as call like.
Actual navigation will come next, with further understanding of how the
symbol searching and disassembly should be done.
Cc: Adrian Hunter <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Jin Yao <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Wang Nan <[email protected]>
Link: https://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
Just like we have in the histograms browser used as the main screen for
'perf top --tui' and 'perf report --tui', to print the current
annotation to a file with a named composed by the symbol name and the
".annotation" suffix.
Here is one example of pressing 'A' on 'perf top' to live annotate a
kernel function and then press 'P' to dump that annotation, the
resulting file:
# cat _raw_spin_lock_irqsave.annotation
_raw_spin_lock_irqsave() /proc/kcore
Event: cycles:ppp
7.14 nop
21.43 push %rbx
7.14 pushfq
pop %rax
nop
mov %rax,%rbx
cli
nop
xor %eax,%eax
mov $0x1,%edx
64.29 lock cmpxchg %edx,(%rdi)
test %eax,%eax
↓ jne 2b
mov %rbx,%rax
pop %rbx
← retq
2b: mov %eax,%esi
→ callq queued_spin_lock_slowpath
mov %rbx,%rax
pop %rbx
← retq
#
Cc: Adrian Hunter <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Jin Yao <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Wang Nan <[email protected]>
Link: https://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
Gustavo A. R. Silva