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

perf dwarf-aux: Fix __die_find_scope_cb() for namespaces

2025-09-19T15:14:30Z

Currently __die_find_scope_cb() goes to check siblings when the DIE doesn't include the given PC. However namespaces don't have a PC and could contain children that have that PC. When we encounter a namespace, we should check both its children and siblings. 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 Link: https://lore.kernel.org/r/20250825195817.226560-1-zecheng@google.com Signed-off-by: Arnaldo Carvalho de Melo

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 dwarf-aux: More accurate variable type match for breg

2025-09-19T15:14:29Z

Introduces the function is_breg_access_indirect to determine whether a memory access involving a DW_OP_breg* operation refers to the variable's value directly or requires dereferencing the variable's type as a pointer based on the DWARF expression. Previously, all breg based accesses were assumed to directly access the variable's value (is_pointer = false). The is_breg_access_indirect function handles three cases: 1. Base register + offset only: (e.g., DW_OP_breg7 RSP+88) The calculated address is the location of the variable. The access is direct, so no type dereference is needed. Returns false. 2. Base register + offset, followed by other operations ending in DW_OP_stack_value, including DW_OP_deref: (e.g., DW_OP_breg*, DW_OP_deref, DW_OP_stack_value) The DWARF expression computes the variable's value, but that value requires a dereference. The memory access is fetching that value, so no type dereference is needed. Returns false. 3. Base register + offset, followed only by DW_OP_stack_value: (e.g., DW_OP_breg13 R13+256, DW_OP_stack_value) This indicates the value at the base + offset is the variable's value. Since this value is being used as an address in the memory access, the variable's type is treated as a pointer and requires a type dereference. Returns true. The is_pointer argument passed to match_var_offset is now set by is_breg_access_indirect for breg accesses. There are more complex expressions that includes multiple operations and may require additional handling, such as DW_OP_deref without a DW_OP_stack_value, or including multiple base registers. They are less common in the Linux kernel dwarf and are skipped in check_allowed_ops. 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 Link: https://lore.kernel.org/r/CAJUgMyK2wTiEZB__dtgCELmaNGFWhG1j0g9rv_C=cLD6Zq4_5w@mail.gmail.com Signed-off-by: Arnaldo Carvalho de Melo

perf dwarf-aux: Use signed variable types in match_var_offset

2025-09-03T18:45:50Z

match_var_offset() compares address offsets to determine if an access falls within a variable's bounds. The offsets involved for those relative to base registers from DW_OP_breg can be negative. The current implementation uses unsigned types (u64) for these offsets, which rejects almost all negative values. Change the signature of match_var_offset() to use signed types (s64). This ensures correct behavior when addr_offset or addr_type are negative. 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 Link: https://lore.kernel.org/r/20250825195412.223077-2-zecheng@google.com 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: Handle bitfield members from pointer access

2024-08-22T15:32:18Z

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: 437683a9941891c1 ("perf dwarf-aux: Handle type transfer for memory access") Signed-off-by: Namhyung Kim Cc: Adrian Hunter Cc: Athira Rajeev Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20240821232628.353177-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf annotate-data: Fix off-by-one in location range check

2024-08-19T14:35:56Z

The location list will have entries with half-open addressing like [start, end) which means it doesn't include the end address. So it should skip entries at the end address and match to the next entry. An example location list looks like this (from readelf -wo): 00237876 ffffffff8110d32b (base address) 0023787f v000000000000000 v000000000000002 views at 00237868 for: ffffffff8110d32b ffffffff8110d4eb (DW_OP_reg3 (rbx)) <<<--- 1 00237885 v000000000000002 v000000000000000 views at 0023786a for: ffffffff8110d4eb ffffffff8110d50b (DW_OP_reg14 (r14)) <<<--- 2 0023788c v000000000000000 v000000000000001 views at 0023786c for: ffffffff8110d50b ffffffff8110d7c4 (DW_OP_reg3 (rbx)) 00237893 v000000000000000 v000000000000000 views at 0023786e for: ffffffff8110d806 ffffffff8110d854 (DW_OP_reg3 (rbx)) 0023789a v000000000000000 v000000000000000 views at 00237870 for: ffffffff8110d876 ffffffff8110d88e (DW_OP_reg3 (rbx)) The first entry at 0023787f has [8110d32b, 8110d4eb) (omitting the ffffffff at the beginning), and the second one has [8110d4eb, 8110d50b). Fixes: 2bc3cf575a162a2c ("perf annotate-data: Improve debug message with location info") Reviewed-by: Masami Hiramatsu Signed-off-by: Namhyung Kim Cc: Adrian Hunter Cc: Athira Rajeev Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20240816235840.2754937-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf dwarf-aux: Check allowed location expressions when collecting variables

2024-08-19T14:34:07Z

It missed to call check_allowed_ops() in __die_collect_vars_cb() so it can take variables with complex location expression incorrectly. For example, I found some variable has this expression. 015d8df8 ffffffff81aacfb3 (base address) 015d8e01 v000000000000004 v000000000000000 views at 015d8df2 for: ffffffff81aacfb3 ffffffff81aacfd2 (DW_OP_fbreg: -176; DW_OP_deref; DW_OP_plus_uconst: 332; DW_OP_deref_size: 4; DW_OP_lit1; DW_OP_shra; DW_OP_const1u: 64; DW_OP_minus; DW_OP_stack_value) 015d8e14 v000000000000000 v000000000000000 views at 015d8df4 for: ffffffff81aacfd2 ffffffff81aacfd7 (DW_OP_reg3 (rbx)) 015d8e19 v000000000000000 v000000000000000 views at 015d8df6 for: ffffffff81aacfd7 ffffffff81aad020 (DW_OP_fbreg: -176; DW_OP_deref; DW_OP_plus_uconst: 332; DW_OP_deref_size: 4; DW_OP_lit1; DW_OP_shra; DW_OP_const1u: 64; DW_OP_minus; DW_OP_stack_value) 015d8e2c It looks like '((int *)(-176(%rbp) + 332) >> 1) - 64' but the current code thought it's just -176(%rbp) and processed the variable incorrectly. It should reject such a complex expression if check_allowed_ops() doesn't like it. :) Fixes: 932dcc2c39aedf54 ("perf dwarf-aux: Add die_collect_vars()") Signed-off-by: Namhyung Kim Acked-by: Masami Hiramatsu Cc: Adrian Hunter Cc: Athira Rajeev Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20240816235840.2754937-2-namhyung@kernel.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: Fix build with HAVE_DWARF_CFI_SUPPORT

2024-05-09T21:19:27Z

check_allowed_ops() is used from both HAVE_DWARF_GETLOCATIONS_SUPPORT and HAVE_DWARF_CFI_SUPPORT sections, so move it into the right place so that it's available when either are defined. This shows up when doing a static cross compile for arm64: $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- LDFLAGS="-static" \ EXTRA_PERFLIBS="-lexpat" util/dwarf-aux.c:1723:6: error: implicit declaration of function 'check_allowed_ops' Fixes: 55442cc2f22d0727 ("perf dwarf-aux: Check allowed DWARF Ops") Reviewed-by: Ian Rogers Signed-off-by: James Clark Acked-by: Masami Hiramatsu Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ingo Molnar Cc: Jiri Olsa Cc: Leo Yan Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20240508141458.439017-1-james.clark@arm.com Signed-off-by: Arnaldo Carvalho de Melo