In Makefile.config for unwinding the name dwarf implies either
libunwind or libdw. Make it clearer that HAVE_DWARF_SUPPORT is really
just defined when libdw is present by renaming to HAVE_LIBDW_SUPPORT.
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Leo Yan <leo.yan@arm.com>
Cc: Anup Patel <anup@brainfault.org>
Cc: Yang Jihong <yangjihong@bytedance.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Shenlin Liang <liangshenlin@eswincomputing.com>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Guilherme Amadio <amadio@gentoo.org>
Cc: Steinar H. Gunderson <sesse@google.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: James Clark <james.clark@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Chen Pei <cp0613@linux.alibaba.com>
Cc: Leo Yan <leo.yan@linux.dev>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Aditya Gupta <adityag@linux.ibm.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-riscv@lists.infradead.org
Cc: Bibo Mao <maobibo@loongson.cn>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Atish Patra <atishp@rivosinc.com>
Cc: Dima Kogan <dima@secretsauce.net>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Dr. David Alan Gilbert <linux@treblig.org>
Cc: linux-csky@vger.kernel.org
Link: https://lore.kernel.org/r/20241017001354.56973-11-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
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: Namhyung 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.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
In find_data_type(), it creates and deletes a debug info whenver it
tries to find data type for a sample. This is inefficient and it most
likely accesses the same binary again and again.
Let's add a single entry cache the debug info structure for the last DSO.
Depending on sample data, it usually gives me 2~3x (and sometimes more)
speed ups.
Note that this will introduce a little difference in the output due to
the order of checking stack operations. It used to check the stack ops
before checking the availability of debug info but I moved it after the
symbol check. So it'll report stack operations in DSOs without debug
info as unknown. But I think it's ok and better to have the checking
near the caching logic.
Committer testing:
root@x1:~# perf mem record -a sleep 5s
root@x1:~# perf evlist
cpu_atom/mem-loads,ldlat=30/P
cpu_atom/mem-stores/P
dummy:u
root@x1:~# diff -u before after
--- before 2024-08-08 09:33:53.880780784 -0300
+++ after 2024-08-08 09:35:13.917325041 -0300
@@ -81,8 +81,8 @@
# Overhead Data Type
# ........ .........
#
- 55.43% (unknown)
- 11.61% (stack operation)
+ 55.56% (unknown)
+ 11.48% (stack operation)
4.93% struct pcpu_hot
3.26% unsigned int
2.48% struct
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo 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/20240805234648.1453689-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
TYPE_STATE_MAX_REGS is arch-dependent. Currently this is defined to be
16.
While checking if reg is valid using has_reg_type, max value is checked
using TYPE_STATE_MAX_REGS value.
Define this conditionally for powerpc.
Reviewed-by: Kajol Jain <kjain@linux.ibm.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Tested-by: Kajol Jain <kjain@linux.ibm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Akanksha J N <akanksha@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Disha Goel <disgoel@linux.vnet.ibm.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Link: https://lore.kernel.org/lkml/20240718084358.72242-4-atrajeev@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Add "update_insn_state" callback to "struct arch" to handle instruction
tracking. Currently updating instruction state is handled by static
function "update_insn_state_x86" which is defined in "annotate-data.c".
Make this as a callback for specific arch and move to archs specific
file "arch/x86/annotate/instructions.c" . This will help to add helper
function for other platforms in file:
"arch/<platform>/annotate/instructions.c" and make changes/updates
easier.
Define callback "update_insn_state" as part of "struct arch", also make
some of the debug functions non-static so that it can be referenced from
other places.
Reviewed-by: Kajol Jain <kjain@linux.ibm.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Tested-by: Kajol Jain <kjain@linux.ibm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Akanksha J N <akanksha@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Disha Goel <disgoel@linux.vnet.ibm.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Link: https://lore.kernel.org/lkml/20240718084358.72242-3-atrajeev@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Data type profiling uses instruction tracking by checking each
instruction and updating the register type state in some data
structures.
This is useful to find the data type in cases when the register state
gets transferred from one reg to another.
Example, in x86, "mov" instruction and in powerpc, "mr" instruction.
Currently these structures are defined in annotate-data.c and
instruction tracking is implemented only for x86.
Move these data structures to "annotate-data.h" header file so that
other arch implementations can use it in arch specific files as well.
Reviewed-by: Kajol Jain <kjain@linux.ibm.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Tested-by: Kajol Jain <kjain@linux.ibm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Akanksha J N <akanksha@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Disha Goel <disgoel@linux.vnet.ibm.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Link: https://lore.kernel.org/lkml/20240718084358.72242-2-atrajeev@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Support data type profiling output on TUI.
Testing from Arnaldo:
First make sure that the debug information for your workload binaries
in embedded in them by building it with '-g' or install the debuginfo
packages, since our workload is 'find':
root@number:~# type find
find is hashed (/usr/bin/find)
root@number:~# rpm -qf /usr/bin/find
findutils-4.9.0-5.fc39.x86_64
root@number:~# dnf debuginfo-install findutils
<SNIP>
root@number:~#
Then collect some data:
root@number:~# echo 1 > /proc/sys/vm/drop_caches
root@number:~# perf mem record find / > /dev/null
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.331 MB perf.data (3982 samples) ]
root@number:~#
Finally do data-type annotation with the following command, that will
default, as 'perf report' to the --tui mode, with lines colored to
highlight the hotspots, etc.
root@number:~# perf annotate --data-type
Annotate type: 'struct predicate' (58 samples)
Percent Offset Size Field
100.00 0 312 struct predicate {
0.00 0 8 PRED_FUNC pred_func;
0.00 8 8 char* p_name;
0.00 16 4 enum predicate_type p_type;
0.00 20 4 enum predicate_precedence p_prec;
0.00 24 1 _Bool side_effects;
0.00 25 1 _Bool no_default_print;
0.00 26 1 _Bool need_stat;
0.00 27 1 _Bool need_type;
0.00 28 1 _Bool need_inum;
0.00 32 4 enum EvaluationCost p_cost;
0.00 36 4 float est_success_rate;
0.00 40 1 _Bool literal_control_chars;
0.00 41 1 _Bool artificial;
0.00 48 8 char* arg_text;
<SNIP>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.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/20240411033256.2099646-5-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
And move the related code into util/annotate-data.c file.
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.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/20240411033256.2099646-4-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
They are often searched by many different places. Let's add a cache
for them to reduce the duplicate DWARF access.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20240319055115.4063940-23-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When the stack protector is enabled, compiler would generate code to
check stack overflow with a special value called 'stack carary' at
runtime. On x86_64, GCC hard-codes the stack canary as %gs:40.
While there's a definition of fixed_percpu_data in asm/processor.h,
it seems that the header is not included everywhere and many places
it cannot find the type info. As it's in the well-known location (at
%gs:40), let's add a pseudo stack canary type to handle it specially.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20240319055115.4063940-22-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
If it failed to find a variable for the location directly, it might be
due to a missing variable in the source code. For example, accessing
pointer variables in a chain can result in the case like below:
struct foo *foo = ...;
int i = foo->bar->baz;
The DWARF debug information is created for each variable so it'd have
one for 'foo'. But there's no variable for 'foo->bar' and then it
cannot know the type of 'bar' and 'baz'.
The above source code can be compiled to the follow x86 instructions:
mov 0x8(%rax), %rcx
mov 0x4(%rcx), %rdx <=== PMU sample
mov %rdx, -4(%rbp)
Let's say 'foo' is located in the %rax and it has a pointer to struct
foo. But perf sample is captured in the second instruction and there
is no variable or type info for the %rcx.
It'd be great if compiler could generate debug info for %rcx, but we
should handle it on our side. So this patch implements the logic to
iterate instructions and update the type table for each location.
As it already collected a list of scopes including the target
instruction, we can use it to construct the type table smartly.
+---------------- scope[0] subprogram
|
| +-------------- scope[1] lexical_block
| |
| | +------------ scope[2] inlined_subroutine
| | |
| | | +---------- scope[3] inlined_subroutine
| | | |
| | | | +-------- scope[4] lexical_block
| | | | |
| | | | | *** target instruction
...
Image the target instruction has 5 scopes, each scope will have its own
variables and parameters. Then it can start with the innermost scope
(4). So it'd search the shortest path from the start of scope[4] to
the target address and build a list of basic blocks. Then it iterates
the basic blocks with the variables in the scope and update the table.
If it finds a type at the target instruction, then returns it.
Otherwise, it moves to the upper scope[3]. Now it'd search the shortest
path from the start of scope[3] to the start of scope[4]. Then connect
it to the existing basic block list. Then it'd iterate the blocks with
variables for both scopes. It can repeat this until it finds a type at
the target instruction or reaches to the top scope[0].
As the basic blocks contain the shortest path, it won't worry about
branches and can update the table simply.
The final check will be done by find_matching_type() in the next patch.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20240319055115.4063940-15-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Accessing global variable is common when it tracks execution later.
Factor out the common code into a function for later use.
It adds thread and cpumode to struct data_loc_info to find (global)
symbols if needed. Also remove var_name as it's retrieved in the
helper function.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20240319055115.4063940-12-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The update_insn_state() function is to update the type state table after
processing each instruction. For now, it handles MOV (on x86) insn
to transfer type info from the source location to the target.
The location can be a register or a stack slot. Check carefully when
memory reference happens and fetch the type correctly. It basically
ignores write to a memory since it doesn't change the type info. One
exception is writes to (new) stack slots for register spilling.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20240319055115.4063940-11-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The find_data_type() needs many information to describe the location of
the data. Add the new 'struct data_loc_info' to pass those information at
once.
No functional changes intended.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20240319055115.4063940-7-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Global variables are accessed using PC-relative address so it needs to
be handled separately. The PC-rel addressing is detected by using
DWARF_REG_PC. On x86, %rip register would be used.
The address can be calculated using the ip and offset in the
instruction. But it should start from the next instruction so add
calculate_pcrel_addr() to do it properly.
But global variables defined in a different file would only have a
declaration which doesn't include a location list. So it first tries
to get the type info using the address, and then looks up the variable
declarations using name. The name of global variables should be get
from the symbol table. The declaration would have the type info.
So extend find_var_type() to take both address and name for global
variables.
The stat is now looks like:
Annotate data type stats:
total 294, ok 153 (52.0%), bad 141 (48.0%)
-----------------------------------------------------------
30 : no_sym
32 : no_mem_ops
61 : no_var
10 : no_typeinfo
8 : bad_offset
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20240117062657.985479-7-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
A typical function prologue and epilogue include multiple stack
operations to save and restore the current value of registers.
On x86, it looks like below:
push r15
push r14
push r13
push r12
...
pop r12
pop r13
pop r14
pop r15
ret
As these all touches the stack memory region, chances are high that they
appear in a memory profile data. But these are not used for any real
purpose yet so it'd return no types.
One of my profile type shows that non neglible portion of data came from
the stack operations. It also seems GCC generates more stack operations
than clang.
Annotate Instruction stats
total 264, ok 169 (64.0%), bad 95 (36.0%)
Name : Good Bad
-----------------------------------------------------------
movq : 49 27
movl : 24 9
popq : 0 19 <-- here
cmpl : 17 2
addq : 14 1
cmpq : 12 2
cmpxchgl : 3 7
Instead of dealing them as unknown, let's create a seperate pseudo type
to represent those stack operations separately.
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20240117062657.985479-5-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
On x86, instructions for array access often looks like below.
mov 0x1234(%rax,%rbx,8), %rcx
Usually the first register holds the type information and the second one
has the index. And the current code only looks up a variable for the
first register. But it's possible to be in the other way around so it
needs to check the second register if the first one failed.
The stat changed like this.
Annotate data type stats:
total 294, ok 148 (50.3%), bad 146 (49.7%)
-----------------------------------------------------------
30 : no_sym
32 : no_mem_ops
66 : no_var
10 : no_typeinfo
8 : bad_offset
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20240117062657.985479-4-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
The --type-stat option is to be used with --data-type and to print
detailed failure reasons for the data type annotation.
$ perf annotate --data-type --type-stat
Annotate data type stats:
total 294, ok 116 (39.5%), bad 178 (60.5%)
-----------------------------------------------------------
30 : no_sym
40 : no_insn_ops
33 : no_mem_ops
63 : no_var
4 : no_typeinfo
8 : bad_offset
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: linux-toolchains@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Link: https://lore.kernel.org/r/20231213001323.718046-17-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The annotated_data_type__update_samples() to get histogram for data type
access.
It'll be called by perf annotate to show which fields in the data type
are accessed frequently.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: linux-toolchains@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Link: https://lore.kernel.org/r/20231213001323.718046-12-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Add child member field if the current type is a composite type like a
struct or union. The member fields are linked in the children list and
do the same recursively if the child itself is a composite type.
Add 'self' member to the annotated_data_type to handle the members in
the same way.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: linux-toolchains@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Link: https://lore.kernel.org/r/20231213001323.718046-11-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
To aggregate accesses to the same data type, add 'data_types' tree in
DSO to maintain data types and find it by name and size.
It might have different data types that happen to have the same name,
so it also compares the size of the type.
Even if it doesn't 100% guarantee, it reduces the possibility of
mis-handling of such conflicts.
And I don't think it's common to have different types with the same
name.
Committer notes:
Very few cases on the Linux kernel, but there are some different types
with the same name, unsure if there is a debug mode in libbpf dedup that
warns about such cases, but there are provisions in pahole for that,
see:
"emit: Notice type shadowing, i.e. multiple types with the same name (enum, struct, union, etc)"
https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?id=4f332dbfd02072e4f410db7bdcda8d6e3422974b
$ pahole --compile > vmlinux.h
$ rm -f a ; make a
cc a.c -o a
$ grep __[0-9] vmlinux.h
union irte__1 {
struct map_info__1;
struct map_info__1 {
struct map_info__1 * next; /* 0 8 */
$
drivers/iommu/amd/amd_iommu_types.h 'union irte'
include/linux/dmar.h 'struct irte'
include/linux/device-mapper.h:
union map_info {
void *ptr;
};
include/linux/mtd/map.h:
struct map_info {
const char *name;
unsigned long size;
resource_size_t phys;
<SNIP>
kernel/events/uprobes.c:
struct map_info {
struct map_info *next;
struct mm_struct *mm;
unsigned long vaddr;
};
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: linux-toolchains@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Link: https://lore.kernel.org/r/20231213001323.718046-5-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The find_data_type() is to get a data type from the memory access at the
given address (IP) using a register and an offset.
It requires DWARF debug info in the DSO and searches the list of
variables and function parameters in the scope.
In a pseudo code, it does basically the following:
find_data_type(dso, ip, reg, offset)
{
pc = map__rip_2objdump(ip);
CU = dwarf_addrdie(dso->dwarf, pc);
scopes = die_get_scopes(CU, pc);
for_each_scope(S, scopes) {
V = die_find_variable_by_reg(S, pc, reg);
if (V && V.type == pointer_type) {
T = die_get_real_type(V);
if (offset < T.size)
return T;
}
}
return NULL;
}
Committer notes:
The 'size' variable in check_variable() is 64-bit, so use PRIu64 and
inttypes.h to debug it.
Ditto at find_data_type_die().
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: linux-toolchains@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Link: https://lore.kernel.org/r/20231213001323.718046-4-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
