kernel.git/tools/perf/util/dwarf-aux.h, branch master

perf dwarf-aux: Better variable collection for insn tracking

2025-09-19T15:14:30Z

Utilizes the previous is_breg_access_indirect function to determine if the register + offset stores the variable itself or the struct it points to, save the information in die_var_type.is_reg_var_addr. Since we are storing the real types in the stack state, we need to do a type dereference when is_reg_var_addr is set to false for stack/frame registers. For other gp registers, skip the variable when the register is a pointer to the type. If we want to accept these variables, we might also utilize is_reg_var_addr in a different way, we need to mark that register as a pointer to the type. Reviewed-by: Namhyung Kim Signed-off-by: Zecheng Li Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Mark Rutland Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: Xu Liu Signed-off-by: Arnaldo Carvalho de Melo

perf libdw: Remove unnecessary defines

2024-10-18T17:17:40Z

As HAVE_DWARF_GETLOCATIONS_SUPPORT and HAVE_DWARF_CFI_SUPPORT always match HAVE_DWARF_SUPPORT remove the macros and use HAVE_DWARF_SUPPORT. If building the file is guarded by CONFIG_DWARF then remove all ifs. Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Anup Patel Cc: Yang Jihong Cc: Palmer Dabbelt Cc: David S. Miller Cc: Albert Ou Cc: Shenlin Liang Cc: Nick Terrell Cc: Guilherme Amadio Cc: Steinar H. Gunderson Cc: Changbin Du Cc: Alexander Lobakin Cc: Przemek Kitszel Cc: Huacai Chen Cc: Guo Ren Cc: Masahiro Yamada Cc: Masami Hiramatsu (Google) Cc: Will Deacon Cc: James Clark Cc: Mike Leach Cc: Chen Pei Cc: Leo Yan Cc: Oliver Upton Cc: Aditya Gupta Cc: Kajol Jain Cc: Athira Rajeev Cc: linux-arm-kernel@lists.infradead.org Cc: linux-riscv@lists.infradead.org Cc: Bibo Mao Cc: John Garry Cc: Atish Patra Cc: Dima Kogan Cc: Paul Walmsley Cc: Dr. David Alan Gilbert Cc: linux-csky@vger.kernel.org Link: https://lore.kernel.org/r/20241017001354.56973-10-irogers@google.com Signed-off-by: Namhyung Kim

perf dwarf-aux: Fix build with !HAVE_DWARF_GETLOCATIONS_SUPPORT

2024-10-02T21:21:49Z

The linked fixes commit added an #include "dwarf-aux.h" to disasm.h which gets picked up in a lot of places. Without HAVE_DWARF_GETLOCATIONS_SUPPORT the stubs return an errno, so include errno.h to fix the following build error: In file included from util/disasm.h:8, from util/annotate.h:16, from builtin-top.c:23: util/dwarf-aux.h: In function 'die_get_var_range': util/dwarf-aux.h:183:10: error: 'ENOTSUP' undeclared (first use in this function) 183 | return -ENOTSUP; | ^~~~~~~ Fixes: 782959ac248ac3cb ("perf annotate: Add "update_insn_state" callback function to handle arch specific instruction tracking") Signed-off-by: James Clark Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Athira Rajeev Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kajol Jain Cc: Kan Liang Cc: Mark Rutland Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20241001123625.1063153-1-james.clark@linaro.org Signed-off-by: Arnaldo Carvalho de Melo

perf annotate-data: Show typedef names properly

2024-08-08T12:36:52Z

The die_get_typename() would resolve typedef and get to the original type. But sometimes the original type is a struct without name and it makes the output confusing and hard to read. This is a diff of perf report -s type before and after the change. New types such as atomic{,64}_t and sigset_t appeared and the portion of unnamed struct was reduced. Also u32, u64 and size_t were splitted from the base types. --- b 2024-08-01 17:02:34.307809952 -0700 +++ a 2024-08-07 14:17:05.245853999 -0700 - 2.40% long unsigned int + 2.26% long unsigned int - 1.56% unsigned int + 1.27% unsigned int - 0.98% struct - 0.79% long long unsigned int + 0.58% long long unsigned int + 0.36% struct + 0.27% atomic64_t + 0.22% u32 + 0.21% u64 + 0.19% atomic_t + 0.13% size_t - 0.08% struct seqcount_spinlock + 0.08% seqcount_spinlock_t + 0.08% sigset_t + 0.08% __poll_t Let's use the typedef name directly and the resolved to get the size of the type. Committer testing: root@x1:~# diff -u before after | head -30 --- before 2024-08-08 09:35:13.917325041 -0300 +++ after 2024-08-08 09:37:35.312257905 -0300 @@ -10,25 +10,27 @@ # ........ ......... # 79.40% (unknown) - 2.28% union 1.96% (stack operation) - 1.24% struct + 1.87% pthread_mutex_t 0.99% u32[] - 0.92% unsigned int 0.77% struct task_struct + 0.75% U32 0.75% struct pcpu_hot 0.63% struct qspinlock + 0.61% atomic_t 0.59% struct list_head - 0.58% int 0.53% struct cfs_rq 0.51% BYTE* - 0.48% unsigned char + 0.48% BYTE 0.48% long unsigned int 0.46% struct rq 0.41% struct worker 0.41% struct memcg_vmstats_percpu + 0.41% pthread_cond_t 0.37% _Bool + 0.36% int root@x1:~# Signed-off-by: Namhyung Kim Tested-by: Arnaldo Carvalho de Melo Cc: Adrian Hunter Cc: Athira Rajeev Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Masami Hiramatsu Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20240807223129.1738004-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf dwarf-aux: Add die_collect_global_vars()

2024-05-02T13:45:30Z

This function is to search all global variables in the CU. We want to have the list of global variables at once and match them later. Signed-off-by: Namhyung Kim Cc: Adrian Hunter Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Masami Hiramatsu Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20240502060011.1838090-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf dwarf-aux: Add die_find_func_rettype()

2024-03-21T13:41:28Z

The die_find_func_rettype() is to find a debug entry for the given function name and sets the type information of the return value. By convention, it'd return the pointer to the type die (should be the same as the given mem_die argument) if found, or NULL otherwise. Signed-off-by: Namhyung Kim Cc: Adrian Hunter Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Linus Torvalds Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: Stephane Eranian Link: https://lore.kernel.org/r/20240319055115.4063940-5-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf dwarf-aux: Handle type transfer for memory access

2024-03-21T13:41:28Z

We want to track type states as instructions are executed. Each instruction can access compound types like struct or union and load/ store its members to a different location. The die_deref_ptr_type() is to find a type of memory access with a pointer variable. If it points to a compound type like struct, the target memory is a member in the struct. The access will happen with an offset indicating which member it refers. Let's follow the DWARF info to figure out the type of the pointer target. For example, say we have the following code. struct foo { int a; int b; }; struct foo *p = malloc(sizeof(*p)); p->b = 0; The last pointer access should produce x86 asm like below: mov 0x0, 4(%rbx) And we know %rbx register has a pointer to struct foo. Then offset 4 should return the debug info of member 'b'. Also variables of compound types can be accessed directly without a pointer. The die_get_member_type() is to handle a such case. Signed-off-by: Namhyung Kim Acked-by: Masami Hiramatsu Cc: Adrian Hunter Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Link: https://lore.kernel.org/r/20240319055115.4063940-4-namhyung@kernel.org [ Check if die_get_real_type() returned NULL ] Signed-off-by: Arnaldo Carvalho de Melo

perf dwarf-aux: Add die_collect_vars()

2024-03-21T13:41:28Z

The die_collect_vars() is to find all variable information in the scope including function parameters. The struct die_var_type is to save the type of the variable with the location (reg and offset) as well as where it's defined in the code (addr). Signed-off-by: Namhyung Kim Acked-by: Masami Hiramatsu Cc: Adrian Hunter Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Link: https://lore.kernel.org/r/20240319055115.4063940-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf dwarf-aux: Remove unused pc argument

2024-03-21T13:41:28Z

It's not used, let's get rid of it. Signed-off-by: Namhyung Kim Reviewed-by: Arnaldo Carvalho de Melo Cc: Adrian Hunter Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Linus Torvalds Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: Stephane Eranian Link: https://lore.kernel.org/r/20240319055115.4063940-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf annotate-data: Support stack variables

2024-01-22T20:08:20Z

Local variables are allocated in the stack and the location list should look like base register(s) and an offset. Extend the die_find_variable_by_reg() to handle the following expressions * DW_OP_breg{0..31} * DW_OP_bregx * DW_OP_fbreg Ususally DWARF subprogram entries have frame base information and use it to locate stack variable like below: <2><43d1575>: Abbrev Number: 62 (DW_TAG_variable) <43d1576> DW_AT_location : 2 byte block: 91 7c (DW_OP_fbreg: -4) <--- here <43d1579> DW_AT_name : (indirect string, offset: 0x2c00c9): i <43d157d> DW_AT_decl_file : 1 <43d157e> DW_AT_decl_line : 78 <43d157f> DW_AT_type : <0x43d19d7> I found some differences on saving the frame base between gcc and clang. The gcc uses the CFA to get the base so it needs to check the current frame's CFI info. In this case, stack offset needs to be adjusted from the start of the CFA. <1><1bb8d>: Abbrev Number: 102 (DW_TAG_subprogram) <1bb8e> DW_AT_name : (indirect string, offset: 0x74d41): kernel_init <1bb92> DW_AT_decl_file : 2 <1bb92> DW_AT_decl_line : 1440 <1bb94> DW_AT_decl_column : 18 <1bb95> DW_AT_prototyped : 1 <1bb95> DW_AT_type : <0xcc> <1bb99> DW_AT_low_pc : 0xffffffff81bab9e0 <1bba1> DW_AT_high_pc : 0x1b2 <1bba9> DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa) <------ here <1bbab> DW_AT_call_all_calls: 1 <1bbab> DW_AT_sibling : <0x1bf5a> While clang sets it to a register directly and it can check the register and offset in the instruction directly. <1><43d1542>: Abbrev Number: 60 (DW_TAG_subprogram) <43d1543> DW_AT_low_pc : 0xffffffff816a7c60 <43d154b> DW_AT_high_pc : 0x98 <43d154f> DW_AT_frame_base : 1 byte block: 56 (DW_OP_reg6 (rbp)) <---------- here <43d1551> DW_AT_GNU_all_call_sites: 1 <43d1551> DW_AT_name : (indirect string, offset: 0x3bce91): foo <43d1555> DW_AT_decl_file : 1 <43d1556> DW_AT_decl_line : 75 <43d1557> DW_AT_prototyped : 1 <43d1557> DW_AT_type : <0x43c7332> <43d155b> DW_AT_external : 1 Also it needs to update the offset after finding the type like global variables since the offset was from the frame base. Factor out match_var_offset() to check global and local variables in the same way. The type stats are improved too: Annotate data type stats: total 294, ok 160 (54.4%), bad 134 (45.6%) ----------------------------------------------------------- 30 : no_sym 32 : no_mem_ops 51 : no_var 14 : no_typeinfo 7 : bad_offset Reviewed-by: Ian Rogers Cc: Stephane Eranian Cc: Masami Hiramatsu Link: https://lore.kernel.org/r/20240117062657.985479-9-namhyung@kernel.org Signed-off-by: Namhyung Kim