kernel/linux.git/tools/perf/util/annotate-data.c, branch v7.1-rc5

perf annotate-data: Use DWARF location ranges to preserve reg state

2026-03-19T21:42:29+00:00

When a function call occurs, caller-saved registers are typically invalidated since the callee may clobber them. However, DWARF debug info provides location ranges that indicate exactly where a variable is valid in a register. Track the DWARF location range end address in type_state_reg and use it to determine if a caller-saved register should be preserved across a call. If the current call address is within the DWARF-specified lifetime of the variable, keep the register state valid instead of invalidating it. This improves type annotation for code where the compiler knows a register value survives across calls (e.g., when the callee is known not to clobber certain registers or when the value is reloaded after the call at the same logical location). Changes: - Add `end` and `has_range` fields to die_var_type to capture DWARF location range information - Add `lifetime_active` and `lifetime_end` fields to type_state_reg - Check location lifetime before invalidating caller-saved registers Signed-off-by: Zecheng Li Signed-off-by: Namhyung Kim

perf annotate-data: Handle global variable access with const register

2026-03-19T21:42:29+00:00

When a register holds a constant value (TSR_KIND_CONST) and is used with a negative offset, treat it as a potential global variable access instead of falling through to CFA (frame) handling. This fixes cases like array indexing with computed offsets: movzbl -0x7d72725a(%rax), %eax # array[%rax] Where %rax contains a computed index and the negative offset points to a global array. Previously this fell through to the CFA path which doesn't handle global variables, resulting in "no type information". The fix redirects such accesses to check_kernel which calls get_global_var_type() to resolve the type from the global variable cache. This is only done for kernel DSOs since the pattern relies on kernel-specific global variable resolution. We could also treat registers with integer types to the global variable path, but this requires more changes. Signed-off-by: Zecheng Li Signed-off-by: Namhyung Kim

perf annotate-data: Collect global variables without name

2026-03-19T21:42:29+00:00

Previously, global_var__collect() required get_global_var_info() to succeed (i.e., the variable must have a symbol name) before caching a global variable. This prevented variables that exist in DWARF but lack symbol table coverage from being cached. Remove the symbol table requirement since DW_OP_addr already provides the variable's address directly from DWARF. The symbol table lookup is now optional to obtain the variable name when available. Also remove the var_offset != 0 check, which was intended to skip variables where the access address doesn't match the symbol start. The symbol table lookup is now optional and I found removing this check has no effect on the annotation results for both kernel and userspace programs. Test results show improved annotation coverage especially for userspace programs with RIP-relative addressing instructions. Signed-off-by: Zecheng Li Signed-off-by: Namhyung Kim

perf annotate-data: Improve type comparison from different scopes

2026-03-19T21:42:29+00:00

When comparing types from different scopes, first compare their type offsets. A larger offset means the field belongs to an outer (enclosing) struct. This helps resolve cases where a pointer is found in an inner scope, but a struct containing that pointer exists in an outer scope. Previously, is_better_type would prefer the pointer type, but the struct type is actually more complete and should be chosen. Prefer types from outer scopes when is_better_type cannot determine a better type. This is a heuristic for the case `struct A { struct B; }` where A and B have the same size but I think in most cases A is in the outer scope and should be preferred. Signed-off-by: Zecheng Li Signed-off-by: Zecheng Li Signed-off-by: Namhyung Kim

perf dwarf-aux: Skip check_variable for variable lookup

2026-03-19T21:42:29+00:00

Both die_find_variable_by_reg and die_find_variable_by_addr call match_var_offset which already performs sufficient checking and type matching. The additional check_variable call is redundant, and its need_pointer logic is only a heuristic. Since DWARF encodes accurate type information, which match_var_offset verifies, skipping check_variable improves both coverage and accuracy. Return the matched type from die_find_variable_by_reg and die_find_variable_by_addr via the existing `type` field in find_var_data, removing the need for check_variable in find_data_type_die. Signed-off-by: Zecheng Li Signed-off-by: Zecheng Li Signed-off-by: Namhyung Kim

perf dwarf-aux: Add die_get_pointer_type to get pointer types

2026-03-19T21:42:29+00:00

When a variable type is wrapped in typedef/qualifiers, callers may need to first resolve it to the underlying DW_TAG_pointer_type or DW_TAG_array_type. A simple tag check is not enough and directly calling __die_get_real_type() can stop at the pointer type (e.g. typedef -> pointer) instead of the pointee type. Add die_get_pointer_type() helper that follows typedef/qualifier chains and returns the underlying pointer DIE. Use it in annotate-data.c so pointer checks and dereference work correctly for typedef'd pointers. Signed-off-by: Zecheng Li Signed-off-by: Namhyung Kim

perf disasm: Rework the string arch__is to use the ELF machine

2026-01-23T19:58:38+00:00

Add new arch__is_x86 and arch__is_powerpc functions that avoid string comparisons and use the ELF machine. Remove arch__is() that is no longer used. Reviewed-by: James Clark Signed-off-by: Ian Rogers Cc: Aditya Bodkhe Cc: Adrian Hunter Cc: Albert Ou Cc: Alexander Shishkin Cc: Alexandre Ghiti Cc: Athira Rajeev Cc: Bill Wendling Cc: Dr. David Alan Gilbert Cc: Guo Ren Cc: Howard Chu Cc: Ingo Molnar Cc: Jiri Olsa Cc: John Garry Cc: Julia Lawall Cc: Justin Stitt Cc: Krzysztof Łopatowski Cc: Leo Yan Cc: Namhyung Kim Cc: Nathan Chancellor Cc: Nick Desaulniers Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Sergei Trofimovich Cc: Shimin Guo Cc: Suchit Karunakaran Cc: Thomas Falcon Cc: Tianyou Li Cc: Will Deacon Cc: Zecheng Li Signed-off-by: Arnaldo Carvalho de Melo

perf disasm: Constify use of 'struct arch'

2026-01-23T19:58:38+00:00

The 'struct arch' holds variables that are read but not written, except during some initialization. Change most uses to be for a "const struct arch *" version to capture this immutability. Reviewed-by: James Clark Signed-off-by: Ian Rogers Cc: Aditya Bodkhe Cc: Adrian Hunter Cc: Albert Ou Cc: Alexander Shishkin Cc: Alexandre Ghiti Cc: Athira Rajeev Cc: Bill Wendling Cc: Dr. David Alan Gilbert Cc: Guo Ren Cc: Howard Chu Cc: Ingo Molnar Cc: Jiri Olsa Cc: John Garry Cc: Julia Lawall Cc: Justin Stitt Cc: Krzysztof Łopatowski Cc: Leo Yan Cc: Namhyung Kim Cc: Nathan Chancellor Cc: Nick Desaulniers Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Sergei Trofimovich Cc: Shimin Guo Cc: Suchit Karunakaran Cc: Thomas Falcon Cc: Tianyou Li Cc: Will Deacon Cc: Zecheng Li Signed-off-by: Arnaldo Carvalho de Melo

perf auxtrace: Remove errno.h from auxtrace.h and fix transitive dependencies

2025-11-14T07:03:11+00:00

errno.h isn't used in auxtrace.h so remove it and fix build failures caused by transitive dependencies through auxtrace.h on errno.h. Signed-off-by: Ian Rogers Reviewed-by: James Clark Signed-off-by: Namhyung Kim

perf annotate: Save pointer offset in stack state

2025-10-21T13:02:49+00:00

The tracked pointer offset was not being preserved in the stack state, which could lead to incorrect type analysis. This change adds a ptr_offset field to the type_state_stack struct and passes it to set_stack_state and findnew_stack_state to ensure the offset is preserved after the pointer is loaded from a stack location. It improves the type annotation coverage and quality. Signed-off-by: Zecheng Li Signed-off-by: Namhyung Kim