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  1. 28 Aug, 2024 30 commits
  3. 26 Aug, 2024 1 commit
  5. 22 Aug, 2024 6 commits
    • Arnaldo Carvalho de Melo's avatar
      perf python: Disable -Wno-cast-function-type-mismatch if present on clang · 00dc5146
      Arnaldo Carvalho de Melo authored 
      The -Wcast-function-type-mismatch option was introduced in clang 19 and
its enabled by default, since we use -Werror, and python bindings do
casts that are valid but trips this warning, disable it if present.

Closes: https://lore.kernel.org/all/CA+icZUXoJ6BS3GMhJHV3aZWyb5Cz2haFneX0C5pUMUUhG-UVKQ@mail.gmail.comReported-by: default avatarSedat Dilek <sedat.dilek@gmail.com>
Tested-by: default avatarSedat Dilek <sedat.dilek@gmail.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org # To allow building with the upcoming clang 19
Link: https://lore.kernel.org/lkml/CA+icZUVtHn8X1Tb_Y__c-WswsO0K8U9uy3r2MzKXwTA5THtL7w@mail.gmail.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      00dc5146
    • Arnaldo Carvalho de Melo's avatar
      perf python: Allow checking for the existence of warning options in clang · b8116230
      Arnaldo Carvalho de Melo authored 
      We'll need to check if an warning option introduced in clang 19 is
available on the clang version being used, so cover the error message
emitted when testing for a -W option.
Tested-by: default avatarSedat Dilek <sedat.dilek@gmail.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/lkml/CA+icZUVtHn8X1Tb_Y__c-WswsO0K8U9uy3r2MzKXwTA5THtL7w@mail.gmail.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      b8116230
    • Namhyung Kim's avatar
      perf annotate-data: Copy back variable types after move · 1cfd01eb
      Namhyung Kim authored 
      In some cases, compilers don't set the location expression in DWARF
precisely.  For instance, it may assign a variable to a register after
copying it from a different register.  Then it should use the register
for the new type but still uses the old register.  This makes hard to
track the type information properly.

This is an example I found in __tcp_transmit_skb().  The first argument
(sk) of this function is a pointer to sock and there's a variable (tp)
for tcp_sock.

  static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
  				int clone_it, gfp_t gfp_mask, u32 rcv_nxt)
  {
  	...
  	struct tcp_sock *tp;

  	BUG_ON(!skb || !tcp_skb_pcount(skb));
  	tp = tcp_sk(sk);
  	prior_wstamp = tp->tcp_wstamp_ns;
  	tp->tcp_wstamp_ns = max(tp->tcp_wstamp_ns, tp->tcp_clock_cache);
  	...

So it basically calls tcp_sk(sk) to get the tcp_sock pointer from sk.
But it turned out to be the same value because tcp_sock embeds sock as
the first member.  The sk is located in reg5 (RDI) and tp is in reg3
(RBX).  The offset of tcp_wstamp_ns is 0x748 and tcp_clock_cache is
0x750.  So you need to use RBX (reg3) to access the fields in the
tcp_sock.  But the code used RDI (reg5) as it has the same value.

  $ pahole --hex -C tcp_sock vmlinux | grep -e 748 -e 750
	u64                tcp_wstamp_ns;        /* 0x748   0x8 */
	u64                tcp_clock_cache;      /* 0x750   0x8 */

And this is the disassembly of the part of the function.

  <__tcp_transmit_skb>:
  ...
  44:  mov    %rdi, %rbx
  47:  mov    0x748(%rdi), %rsi
  4e:  mov    0x750(%rdi), %rax
  55:  cmp    %rax, %rsi

Because compiler put the debug info to RBX, it only knows RDI is a
pointer to sock and accessing those two fields resulted in error
due to offset being beyond the type size.

  -----------------------------------------------------------
  find data type for 0x748(reg5) at __tcp_transmit_skb+0x63
  CU for net/ipv4/tcp_output.c (die:0x817f543)
  frame base: cfa=0 fbreg=6
  scope: [1/1] (die:81aac3e)
  bb: [0 - 30]
  var [0] -0x98(stack) type='struct tcp_out_options' size=0x28 (die:0x81af3df)
  var [5] reg8 type='unsigned int' size=0x4 (die:0x8180ed6)
  var [5] reg2 type='unsigned int' size=0x4 (die:0x8180ed6)
  var [5] reg1 type='int' size=0x4 (die:0x818059e)
  var [5] reg4 type='struct sk_buff*' size=0x8 (die:0x8181360)
  var [5] reg5 type='struct sock*' size=0x8 (die:0x8181a0c)                   <<<--- the first argument ('sk' at %RDI)
  mov [19] reg8 -> -0xa8(stack) type='unsigned int' size=0x4 (die:0x8180ed6)
  mov [20] stack canary -> reg0
  mov [29] reg0 -> -0x30(stack) stack canary
  bb: [36 - 3e]
  mov [36] reg4 -> reg15 type='struct sk_buff*' size=0x8 (die:0x8181360)
  bb: [44 - 63]
  mov [44] reg5 -> reg3 type='struct sock*' size=0x8 (die:0x8181a0c)          <<<--- calling tcp_sk()
  var [47] reg3 type='struct tcp_sock*' size=0x8 (die:0x819eead)              <<<--- new variable ('tp' at %RBX)
  var [4e] reg4 type='unsigned long long' size=0x8 (die:0x8180edd)
  mov [58] reg4 -> -0xc0(stack) type='unsigned long long' size=0x8 (die:0x8180edd)
  chk [63] reg5 offset=0x748 ok=1 kind=1 (struct sock*) : offset bigger than size    <<<--- access with old variable
  final result: offset bigger than size

While it's a fault in the compiler, we could work around this issue by
using the type of new variable when it's copied directly.  So I've added
copied_from field in the register state to track those direct register
to register copies.  After that new register gets a new type and the old
register still has the same type, it'll update (copy it back) the type
of the old register.

For example, if we can update type of reg5 at __tcp_transmit_skb+0x47,
we can find the target type of the instruction at 0x63 like below:

  -----------------------------------------------------------
  find data type for 0x748(reg5) at __tcp_transmit_skb+0x63
  ...
  bb: [44 - 63]
  mov [44] reg5 -> reg3 type='struct sock*' size=0x8 (die:0x8181a0c)
  var [47] reg3 type='struct tcp_sock*' size=0x8 (die:0x819eead)
  var [47] copyback reg5 type='struct tcp_sock*' size=0x8 (die:0x819eead)     <<<--- here
  mov [47] 0x748(reg5) -> reg4 type='unsigned long long' size=0x8 (die:0x8180edd)
  mov [4e] 0x750(reg5) -> reg0 type='unsigned long long' size=0x8 (die:0x8180edd)
  mov [58] reg4 -> -0xc0(stack) type='unsigned long long' size=0x8 (die:0x8180edd)
  chk [63] reg5 offset=0x748 ok=1 kind=1 (struct tcp_sock*) : Good!           <<<--- new type
  found by insn track: 0x748(reg5) type-offset=0x748
  final result:  type='struct tcp_sock' size=0xa98 (die:0x819eeb2)
Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240821232628.353177-5-namhyung@kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      1cfd01eb
    • Namhyung Kim's avatar
      perf annotate-data: Update stack slot for the store · 895891da
      Namhyung Kim authored 
      When checking the match variable at the target instruction, it might not
have any information if it's a first write to a stack slot.  In this
case it could spill a register value into the stack so the type info is
in the source operand.

But currently it's hard to get the operand from the checking function.
Let's process the instruction and retry to get the type info from the
stack if there's no information already.

This is an example of __tcp_transmit_skb().  The instructions are

  <__tcp_transmit_skb>:
   0: nopl   0x0(%rax, %rax, 1)
   5: push   %rbp
   6: mov    %rsp, %rbp
   9: push   %r15
   b: push   %r14
   d: push   %r13
   f: push   %r12
  11: push   %rbx
  12: sub    $0x98, %rsp
  19: mov    %r8d, -0xa8(%rbp)
  ...

It cannot find any variable at -0xa8(%rbp) at this point.
  -----------------------------------------------------------
  find data type for -0xa8(reg6) at __tcp_transmit_skb+0x19
  CU for net/ipv4/tcp_output.c (die:0x817f543)
  frame base: cfa=0 fbreg=6
  scope: [1/1] (die:81aac3e)
  bb: [0 - 19]
  var [0] -0x98(stack) type='struct tcp_out_options' size=0x28 (die:0x81af3df)
  var [5] reg8 type='unsigned int' size=0x4 (die:0x8180ed6)
  var [5] reg2 type='unsigned int' size=0x4 (die:0x8180ed6)
  var [5] reg1 type='int' size=0x4 (die:0x818059e)
  var [5] reg4 type='struct sk_buff*' size=0x8 (die:0x8181360)
  var [5] reg5 type='struct sock*' size=0x8 (die:0x8181a0c)
  chk [19] reg6 offset=-0xa8 ok=0 kind=0 fbreg : no type information
  no type information

And it was able to find the type after processing the 'mov' instruction.
  -----------------------------------------------------------
  find data type for -0xa8(reg6) at __tcp_transmit_skb+0x19
  CU for net/ipv4/tcp_output.c (die:0x817f543)
  frame base: cfa=0 fbreg=6
  scope: [1/1] (die:81aac3e)
  bb: [0 - 19]
  var [0] -0x98(stack) type='struct tcp_out_options' size=0x28 (die:0x81af3df)
  var [5] reg8 type='unsigned int' size=0x4 (die:0x8180ed6)
  var [5] reg2 type='unsigned int' size=0x4 (die:0x8180ed6)
  var [5] reg1 type='int' size=0x4 (die:0x818059e)
  var [5] reg4 type='struct sk_buff*' size=0x8 (die:0x8181360)
  var [5] reg5 type='struct sock*' size=0x8 (die:0x8181a0c)
  chk [19] reg6 offset=-0xa8 ok=0 kind=0 fbreg : retry                    <<<--- here
  mov [19] reg8 -> -0xa8(stack) type='unsigned int' size=0x4 (die:0x8180ed6)
  chk [19] reg6 offset=-0xa8 ok=0 kind=0 fbreg : Good!
  found by insn track: -0xa8(reg6) type-offset=0
  final result:  type='unsigned int' size=0x4 (die:0x8180ed6)
Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240821232628.353177-4-namhyung@kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      895891da
    • Namhyung Kim's avatar
      perf annotate-data: Update debug messages · a0d57c60
      Namhyung Kim authored 
      In check_matching_type(), it'd be easier to display the typename in
question if it's available.

For example, check out the line starts with 'chk'.
  -----------------------------------------------------------
  find data type for 0x10(reg0) at cpuacct_charge+0x13
  CU for kernel/sched/build_utility.c (die:0x137ee0b)
  frame base: cfa=1 fbreg=7
  scope: [3/3] (die:13d9632)
  bb: [c - 13]
  var [c] reg5 type='struct task_struct*' size=0x8 (die:0x1381230)
  mov [c] 0xdf8(reg5) -> reg0 type='struct css_set*' size=0x8 (die:0x1385c56)
  chk [13] reg0 offset=0x10 ok=1 kind=1 (struct css_set*) : Good!         <<<--- here
  found by insn track: 0x10(reg0) type-offset=0x10
  final result:  type='struct css_set' size=0x250 (die:0x1385b0e)

Another example:
  -----------------------------------------------------------
  find data type for 0x8(reg0) at menu_select+0x279
  CU for drivers/cpuidle/governors/menu.c (die:0x7b0fe79)
  frame base: cfa=1 fbreg=7
  scope: [2/2] (die:7b11010)
  bb: [273 - 277]
  bb: [279 - 279]
  chk [279] reg0 offset=0x8 ok=0 kind=0 cfa : no type information
  scope: [1/2] (die:7b10cbc)
  bb: [0 - 64]
  ...
  mov [26a] imm=0xffffffff -> reg15
  bb: [273 - 277]
  bb: [279 - 279]
  chk [279] reg0 offset=0x8 ok=1 kind=1 (long long unsigned int) : no/void pointer    <<<--- here
  final result: no/void pointer

Also change some places to print negative offsets properly.

Before:
  -----------------------------------------------------------
  find data type for 0xffffff40(reg6) at __tcp_transmit_skb+0x58

After:
  -----------------------------------------------------------
  find data type for -0xc0(reg6) at __tcp_transmit_skb+0x58
Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240821232628.353177-3-namhyung@kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      a0d57c60
    • Namhyung Kim's avatar
      perf dwarf-aux: Handle bitfield members from pointer access · a11b4222
      Namhyung Kim authored 
      The __die_find_member_offset_cb() missed to handle bitfield members
which don't have DW_AT_data_member_location.  Like in adding member
types in __add_member_cb() it should fallback to check the bit offset
when it resolves the member type for an offset.

Fixes: 437683a9 ("perf dwarf-aux: Handle type transfer for memory access")
Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240821232628.353177-2-namhyung@kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      a11b4222
  7. 21 Aug, 2024 3 commits
    • Namhyung Kim's avatar
      perf annotate-data: Add 'typecln' sort key · fd45d52e
      Namhyung Kim authored 
      Sometimes it's useful to organize member fields in cache-line boundary.

The 'typecln' sort key is short for type-cacheline and to show samples
in each cacheline.  The cacheline size is fixed to 64 for now, but it
can read the actual size once it saves the value from sysfs.

For example, you maybe want to which cacheline in a target is hot or
cold.  The following shows members in the cfs_rq's first cache line.

  $ perf report -s type,typecln,typeoff -H
  ...
  -    2.67%        struct cfs_rq
     +    1.23%        struct cfs_rq: cache-line 2
     +    0.57%        struct cfs_rq: cache-line 4
     +    0.46%        struct cfs_rq: cache-line 6
     -    0.41%        struct cfs_rq: cache-line 0
             0.39%        struct cfs_rq +0x14 (h_nr_running)
             0.02%        struct cfs_rq +0x38 (tasks_timeline.rb_leftmost)
  ...

Committer testing:

  # root@number:~# perf report -s type,typecln,typeoff -H --stdio
  # Total Lost Samples: 0
  #
  # Samples: 5K of event 'cpu_atom/mem-loads,ldlat=5/P'
  # Event count (approx.): 312251
  #
  #       Overhead  Data Type / Data Type Cacheline / Data Type Offset
  # ..............  ..................................................
  #
  <SNIP>
       0.07%        struct sigaction
          0.05%        struct sigaction: cache-line 1
             0.02%        struct sigaction +0x58 (sa_mask)
             0.02%        struct sigaction +0x78 (sa_mask)
          0.03%        struct sigaction: cache-line 0
             0.02%        struct sigaction +0x38 (sa_mask)
             0.01%        struct sigaction +0x8 (sa_mask)
  <SNIP>
Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240819233603.54941-2-namhyung@kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      fd45d52e
    • Namhyung Kim's avatar
      perf annotate-data: Show offset and size in hex · 7a5c2170
      Namhyung Kim authored 
      It'd be better to have them in hex to check cacheline alignment.

 Percent     offset       size  field
  100.00          0      0x1c0  struct cfs_rq    {
    0.00          0       0x10      struct load_weight  load {
    0.00          0        0x8          long unsigned int       weight;
    0.00        0x8        0x4          u32     inv_weight;
                                    };
    0.00       0x10        0x4      unsigned int        nr_running;
   14.56       0x14        0x4      unsigned int        h_nr_running;
    0.00       0x18        0x4      unsigned int        idle_nr_running;
    0.00       0x1c        0x4      unsigned int        idle_h_nr_running;
  ...

Committer notes:

Justification from Namhyung when asked about why it would be "better":

Cache line sizes are power of 2 so it'd be natural to use hex and
check whether an offset is in the same boundary.  Also 'perf annotate'
shows instruction offsets in hex.

>
> Maybe this should be selectable?

I can add an option and/or a config if you want.
Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240819233603.54941-1-namhyung@kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      7a5c2170
    • Yang Ruibin's avatar
      perf bpf: Remove redundant check that map is NULL · ce66d7c7
      Yang Ruibin authored 
      The check that map is NULL is already done in the bpf_map__fd(map) and
returns an errno, which does not run further checks.

In addition, even if the check for map is run, the return is a pointer,
which is not consistent with the err_number returned by bpf_map__fd(map).
Signed-off-by: default avatarYang Ruibin <11162571@vivo.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: opensource.kernel@vivo.com
Link: https://lore.kernel.org/r/20240821101500.4568-1-11162571@vivo.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      ce66d7c7
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