linux.git/tools/perf/util/disasm.c, branch v6.12

perf annotate: LLVM-based disassembler

2024-09-03T13:39:20+00:00

Support using LLVM as a disassembler method, allowing helperless
annotation in non-distro builds. (It is also much faster than
using libbfd or bfd objdump on binaries with a lot of debug
information.)

This is nearly identical to the output of llvm-objdump; there are
some very rare whitespace differences, some minor changes to demangling
(since we use perf's regular demangling and not LLVM's own) and
the occasional case where llvm-objdump makes a different choice
when multiple symbols share the same address.

It should work across all of LLVM's supported architectures, although
I've only tested 64-bit x86, and finding the right triple from perf's
idea of machine architecture can sometimes be a bit tricky. Ideally, we
should have some way of finding the triplet just from the file itself.

Committer notes:

Address this on 32-bit systems by using PRIu64 from inttypes.h

     3    17.58 almalinux:9-i386              : FAIL gcc version 11.4.1 20231218 (Red Hat 11.4.1-3) (GCC)
      util/llvm-c-helpers.cpp: In function ‘char* make_symbol_relative_string(dso*, const char*, u64, u64)’:
      util/llvm-c-helpers.cpp:150:52: error: format ‘%lx’ expects argument of type ‘long unsigned int’, but argument 5 has type ‘u64’ {aka
  +‘long long unsigned int’} [-Werror=format=]
        150 |                 snprintf(buf, sizeof(buf), "%s+0x%lx",
            |                                                  ~~^
            |                                                    |
            |                                                    long unsigned int
            |                                                  %llx
        151 |                          demangled ? demangled : sym_name, addr - base_addr);
            |                                                            ~~~~~~~~~~~~~~~~
            |                                                                 |
            |                                                                 u64 {aka long long unsigned int}
      cc1plus: all warnings being treated as errors

Signed-off-by: Steinar H. Gunderson 
Cc: Ian Rogers 
Link: https://lore.kernel.org/r/20240803152008.2818485-3-sesse@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate: Split out read_symbol()

2024-09-03T13:15:55+00:00

The Capstone disassembler code has a useful code snippet to read the
bytes for a given code symbol into memory. Split it out into its own
function, so that the LLVM disassembler can use it in the next patch.

Signed-off-by: Steinar H. Gunderson 
Cc: Ian Rogers 
Link: https://lore.kernel.org/r/20240803152008.2818485-2-sesse@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate: Display the branch counter histogram

2024-08-14T13:20:40+00:00

Display the branch counter histogram in the annotation view.

Press 'B' to display the branch counter's abbreviation list as well.

  Samples: 1M of events 'anon group { branch-instructions:ppp, branch-misses }',
  4000 Hz, Event count (approx.):
  f3  /home/sdp/test/tchain_edit [Percent: local period]
  Percent       │ IPC Cycle       Branch Counter (Average IPC: 1.39, IPC Coverage: 29.4%)
                │                                     0000000000401755 :
    0.00   0.00 │                                       endbr64
                │                                       push    %rbp
                │                                       mov     %rsp,%rbp
                │                                       movl    $0x0,-0x4(%rbp)
    0.00   0.00 │1.33     3          |A   |-   |      ↓ jmp     25
   11.03  11.03 │                                 11:   mov     -0x4(%rbp),%eax
                │                                       and     $0x1,%eax
                │                                       test    %eax,%eax
   17.13  17.13 │2.41     1          |A   |-   |      ↓ je      21
                │                                       addl    $0x1,-0x4(%rbp)
   21.84  21.84 │2.22     2          |AA  |-   |      ↓ jmp     25
   17.13  17.13 │                                 21:   addl    $0x1,-0x4(%rbp)
   21.84  21.84 │                                 25:   cmpl    $0x270f,-0x4(%rbp)
   11.03  11.03 │0.61     3          |A   |-   |      ↑ jle     11
                │                                       nop
                │                                       pop     %rbp
    0.00   0.00 │0.24    20          |AA  |B   |      ← ret

Originally-by: Tinghao Zhang 
Reviewed-by: Andi Kleen 
Signed-off-by: Kan Liang 
Acked-by: Namhyung Kim 
Cc: Adrian Hunter 
Cc: Ian Rogers 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Link: https://lore.kernel.org/r/20240813160208.2493643-8-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf disasm: Fix memory leak for locked operations

2024-08-14T12:35:18+00:00

lock__parse() calls disasm_line__parse() passing
&ops->locked.ins.name that will use strdup() to populate it.

Ensure ops->locked.ins.name is freed in lock__delete().

Found with address/leak sanitizer.

Signed-off-by: Ian Rogers 
Acked-by: Namhyung Kim 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Athira Rajeev 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: Kajol Jain 
Cc: Kan Liang 
Cc: Mark Rutland 
Cc: Peter Zijlstra 
Cc: Thomas Richter 
Link: https://lore.kernel.org/r/20240813040613.882075-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate: Set al->data_nr using the notes->src->nr_events

2024-08-05T19:13:18+00:00

This is a preparation to support skipping empty events.

Signed-off-by: Namhyung Kim 
Cc: Adrian Hunter 
Cc: Ian Rogers 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: Kan Liang 
Cc: Peter Zijlstra 
Link: https://lore.kernel.org/r/20240803211332.1107222-5-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf bpf: Move BPF disassembly routines to separate file to avoid clash with capstone bpf headers

2024-08-01T21:54:19+00:00

There is a clash of the libbpf and capstone libraries, that ends up
with:

  In file included from /usr/include/capstone/capstone.h:325,
                   from util/disasm.c:1513:
  /usr/include/capstone/bpf.h:94:14: error: ‘bpf_insn’ defined as wrong kind of tag
     94 | typedef enum bpf_insn {

So far we're just trying to avoid this by not having both headers
included in the same .c or .h file, do it one more time by moving the
BPF diassembly routines from util/disasm.c to util/disasm_bpf.c.

This is only being hit when building with BUILD_NONDISTRO=1, i.e.
building with binutils-devel, that isn't the in the default build due to
a licencing clash. We need to reimplement what is now isolated in
util/disasm_bpf.c using some other library to have BPF annotation
feature that now only is available with BUILD_NONDISTRO=1.

Fixes: 6d17edc113de1e21 ("perf annotate: Use libcapstone to disassemble")
Cc: Adrian Hunter 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Kan Liang 
Cc: Namhyung Kim 
Link: https://lore.kernel.org/lkml/ZqpUSKPxMwaQKORr@x1
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate: Set instruction name to be used with insn-stat when using raw instruction

2024-07-31T19:12:59+00:00

Since the "ins.name" is not set while using raw instruction,
'perf annotate' with insn-stat gives wrong data:

Result from "./perf annotate --data-type --insn-stat":

  Annotate Instruction stats
  total 615, ok 419 (68.1%), bad 196 (31.9%)

    Name      :  Good   Bad
    -----------------------------------------------------------
              :   419   196

This patch sets "dl->ins.name" in arch specific function
"check_ppc_insn" while initialising "struct disasm_line".

Also update "ins_find" function to pass "struct disasm_line" as a
parameter so as to set its name field in arch specific call.

With the patch changes:

  Annotate Instruction stats
  total 609, ok 446 (73.2%), bad 163 (26.8%)

  Name/opcode         :  Good   Bad
  -----------------------------------------------------------
  58                  :   323    80
  32                  :    49    43
  34                  :    33    11
  OP_31_XOP_LDX       :     8    20
  40                  :    23     0
  OP_31_XOP_LWARX     :     5     1
  OP_31_XOP_LWZX      :     2     3
  OP_31_XOP_LDARX     :     3     0
  33                  :     0     2
  OP_31_XOP_LBZX      :     0     1
  OP_31_XOP_LWAX      :     0     1
  OP_31_XOP_LHZX      :     0     1

Reviewed-by: Kajol Jain 
Reviewed-by: Namhyung Kim 
Signed-off-by: Athira Rajeev 
Tested-by: Kajol Jain 
Cc: Adrian Hunter 
Cc: Akanksha J N 
Cc: Christophe Leroy 
Cc: Disha Goel 
Cc: Hari Bathini 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Madhavan Srinivasan 
Cc: Segher Boessenkool 
Link: https://lore.kernel.org/lkml/20240718084358.72242-16-atrajeev@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate: Add support to use libcapstone in powerpc

2024-07-31T19:12:59+00:00

Now perf uses the capstone library to disassemble the instructions in
x86. capstone is used (if available) for perf annotate to speed up.

Currently it only supports x86 architecture.

This patch includes changes to enable this in powerpc.

For now, only for data type sort keys, this method is used and only
binary code (raw instruction) is read. This is because powerpc approach
to understand instructions and reg fields uses raw instruction.

The "cs_disasm" is currently not enabled. While attempting to do
cs_disasm, observation is that some of the instructions were not
identified (ex: extswsli, maddld) and it had to fallback to use objdump.

Hence enabling "cs_disasm" is added in comment section as a TODO for
powerpc.

Reviewed-by: Kajol Jain 
Reviewed-by: Namhyung Kim 
Signed-off-by: Athira Rajeev 
Tested-by: Kajol Jain 
Cc: Adrian Hunter 
Cc: Akanksha J N 
Cc: Christophe Leroy 
Cc: Disha Goel 
Cc: Hari Bathini 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Madhavan Srinivasan 
Cc: Segher Boessenkool 
Link: https://lore.kernel.org/lkml/20240718084358.72242-15-atrajeev@linux.vnet.ibm.com
[ Use dso__nsinfo(dso) as required to match EXTRA_CFLAGS=-DREFCNT_CHECKING=1 build expectations ]
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate: Use capstone_init and remove open_capstone_handle from disasm.c

2024-07-31T19:12:59+00:00

capstone_init is made availbale for all archs to use and updated to
enable support for CS_ARCH_PPC as well. Patch removes
open_capstone_handle and uses capstone_init in all the places.

Committer notes:

Avoid including capstone/capstone.h from print_insn.h to not break the
build in builtin-script.c due to the namespace clash with libbpf:

  /usr/include/capstone/bpf.h:94:14: error: 'bpf_insn' defined as wrong kind of tag

Reviewed-by: Kajol Jain 
Reviewed-by: Namhyung Kim 
Signed-off-by: Athira Rajeev 
Tested-by: Kajol Jain 
Cc: Adrian Hunter 
Cc: Akanksha J N 
Cc: Christophe Leroy 
Cc: Disha Goel 
Cc: Hari Bathini 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Madhavan Srinivasan 
Cc: Segher Boessenkool 
Link: https://lore.kernel.org/lkml/20240718084358.72242-14-atrajeev@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo

perf annotate: Update instruction tracking for powerpc

2024-07-31T19:12:59+00:00

Add instruction tracking function "update_insn_state_powerpc" for
powerpc. Example sequence in powerpc:

  ld      r10,264(r3)
  mr      r31,r3
  <
  ld      r9,312(r31)

Consider ithe sample is pointing to: "ld r9,312(r31)".

Here the memory reference is hit at "312(r31)" where 312 is the offset
and r31 is the source register.

Previous instruction sequence shows that register state of r3 is moved
to r31.

So to identify the data type for r31 access, the previous instruction
("mr") needs to be tracked and the state type entry has to be updated.

Current instruction tracking support in perf tools infrastructure is
specific to x86. Patch adds this support for powerpc as well.

Reviewed-by: Kajol Jain 
Reviewed-by: Namhyung Kim 
Signed-off-by: Athira Rajeev 
Tested-by: Kajol Jain 
Cc: Adrian Hunter 
Cc: Akanksha J N 
Cc: Christophe Leroy 
Cc: Disha Goel 
Cc: Hari Bathini 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Madhavan Srinivasan 
Cc: Segher Boessenkool 
Link: https://lore.kernel.org/lkml/20240718084358.72242-12-atrajeev@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo