perf annotate-data: Implement instruction tracking
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>
This commit is contained in:
Namhyung Kim
Arnaldo Carvalho de Melo
parent
cffb7910af
commit
eb8a55e01d
@ -430,6 +430,7 @@ static void print_annotate_data_stat(struct annotated_data_stat *s)
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PRINT_STAT(no_typeinfo);
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PRINT_STAT(invalid_size);
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PRINT_STAT(bad_offset);
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PRINT_STAT(insn_track);
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printf("\n");
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#undef PRINT_STAT
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@ -89,15 +89,7 @@ static bool has_reg_type(struct type_state *state, int reg)
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return (unsigned)reg < ARRAY_SIZE(state->regs);
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}
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/* These declarations will be remove once they are changed to static */
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void init_type_state(struct type_state *state, struct arch *arch __maybe_unused);
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void exit_type_state(struct type_state *state);
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void update_var_state(struct type_state *state, struct data_loc_info *dloc,
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u64 addr, u64 insn_offset, struct die_var_type *var_types);
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void update_insn_state(struct type_state *state, struct data_loc_info *dloc,
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Dwarf_Die *cu_die, struct disasm_line *dl);
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void init_type_state(struct type_state *state, struct arch *arch)
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static void init_type_state(struct type_state *state, struct arch *arch)
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{
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memset(state, 0, sizeof(*state));
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INIT_LIST_HEAD(&state->stack_vars);
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@ -116,7 +108,7 @@ void init_type_state(struct type_state *state, struct arch *arch)
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}
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}
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void exit_type_state(struct type_state *state)
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static void exit_type_state(struct type_state *state)
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{
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struct type_state_stack *stack, *tmp;
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@ -457,8 +449,8 @@ static bool get_global_var_type(Dwarf_Die *cu_die, struct data_loc_info *dloc,
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* This function fills the @state table using @var_types info. Each variable
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* is used only at the given location and updates an entry in the table.
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*/
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void update_var_state(struct type_state *state, struct data_loc_info *dloc,
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u64 addr, u64 insn_offset, struct die_var_type *var_types)
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static void update_var_state(struct type_state *state, struct data_loc_info *dloc,
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u64 addr, u64 insn_offset, struct die_var_type *var_types)
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{
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Dwarf_Die mem_die;
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struct die_var_type *var;
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@ -716,13 +708,207 @@ retry:
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* Note that ops->reg2 is only available when both mem_ref and multi_regs
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* are true.
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*/
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void update_insn_state(struct type_state *state, struct data_loc_info *dloc,
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Dwarf_Die *cu_die, struct disasm_line *dl)
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static void update_insn_state(struct type_state *state, struct data_loc_info *dloc,
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Dwarf_Die *cu_die, struct disasm_line *dl)
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{
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if (arch__is(dloc->arch, "x86"))
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update_insn_state_x86(state, dloc, cu_die, dl);
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}
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/*
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* Prepend this_blocks (from the outer scope) to full_blocks, removing
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* duplicate disasm line.
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*/
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static void prepend_basic_blocks(struct list_head *this_blocks,
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struct list_head *full_blocks)
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{
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struct annotated_basic_block *first_bb, *last_bb;
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last_bb = list_last_entry(this_blocks, typeof(*last_bb), list);
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first_bb = list_first_entry(full_blocks, typeof(*first_bb), list);
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if (list_empty(full_blocks))
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goto out;
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/* Last insn in this_blocks should be same as first insn in full_blocks */
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if (last_bb->end != first_bb->begin) {
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pr_debug("prepend basic blocks: mismatched disasm line %"PRIx64" -> %"PRIx64"\n",
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last_bb->end->al.offset, first_bb->begin->al.offset);
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goto out;
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}
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/* Is the basic block have only one disasm_line? */
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if (last_bb->begin == last_bb->end) {
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list_del(&last_bb->list);
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free(last_bb);
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goto out;
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}
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/* Point to the insn before the last when adding this block to full_blocks */
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last_bb->end = list_prev_entry(last_bb->end, al.node);
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out:
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list_splice(this_blocks, full_blocks);
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}
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static void delete_basic_blocks(struct list_head *basic_blocks)
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{
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struct annotated_basic_block *bb, *tmp;
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list_for_each_entry_safe(bb, tmp, basic_blocks, list) {
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list_del(&bb->list);
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free(bb);
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}
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}
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/* Make sure all variables have a valid start address */
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static void fixup_var_address(struct die_var_type *var_types, u64 addr)
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{
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while (var_types) {
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/*
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* Some variables have no address range meaning it's always
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* available in the whole scope. Let's adjust the start
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* address to the start of the scope.
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*/
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if (var_types->addr == 0)
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var_types->addr = addr;
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var_types = var_types->next;
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}
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}
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static void delete_var_types(struct die_var_type *var_types)
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{
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while (var_types) {
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struct die_var_type *next = var_types->next;
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free(var_types);
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var_types = next;
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}
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}
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/* It's at the target address, check if it has a matching type */
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static bool find_matching_type(struct type_state *state __maybe_unused,
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struct data_loc_info *dloc __maybe_unused,
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int reg __maybe_unused,
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Dwarf_Die *type_die __maybe_unused)
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{
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/* TODO */
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return false;
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}
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/* Iterate instructions in basic blocks and update type table */
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static bool find_data_type_insn(struct data_loc_info *dloc, int reg,
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struct list_head *basic_blocks,
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struct die_var_type *var_types,
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Dwarf_Die *cu_die, Dwarf_Die *type_die)
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{
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struct type_state state;
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struct symbol *sym = dloc->ms->sym;
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struct annotation *notes = symbol__annotation(sym);
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struct annotated_basic_block *bb;
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bool found = false;
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init_type_state(&state, dloc->arch);
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list_for_each_entry(bb, basic_blocks, list) {
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struct disasm_line *dl = bb->begin;
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pr_debug_dtp("bb: [%"PRIx64" - %"PRIx64"]\n",
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bb->begin->al.offset, bb->end->al.offset);
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list_for_each_entry_from(dl, ¬es->src->source, al.node) {
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u64 this_ip = sym->start + dl->al.offset;
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u64 addr = map__rip_2objdump(dloc->ms->map, this_ip);
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/* Update variable type at this address */
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update_var_state(&state, dloc, addr, dl->al.offset, var_types);
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if (this_ip == dloc->ip) {
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found = find_matching_type(&state, dloc, reg,
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type_die);
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goto out;
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}
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/* Update type table after processing the instruction */
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update_insn_state(&state, dloc, cu_die, dl);
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if (dl == bb->end)
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break;
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}
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}
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out:
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exit_type_state(&state);
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return found;
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}
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/*
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* Construct a list of basic blocks for each scope with variables and try to find
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* the data type by updating a type state table through instructions.
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*/
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static int find_data_type_block(struct data_loc_info *dloc, int reg,
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Dwarf_Die *cu_die, Dwarf_Die *scopes,
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int nr_scopes, Dwarf_Die *type_die)
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{
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LIST_HEAD(basic_blocks);
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struct die_var_type *var_types = NULL;
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u64 src_ip, dst_ip, prev_dst_ip;
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int ret = -1;
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/* TODO: other architecture support */
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if (!arch__is(dloc->arch, "x86"))
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return -1;
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prev_dst_ip = dst_ip = dloc->ip;
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for (int i = nr_scopes - 1; i >= 0; i--) {
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Dwarf_Addr base, start, end;
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LIST_HEAD(this_blocks);
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if (dwarf_ranges(&scopes[i], 0, &base, &start, &end) < 0)
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break;
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pr_debug_dtp("scope: [%d/%d] (die:%lx)\n",
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i + 1, nr_scopes, (long)dwarf_dieoffset(&scopes[i]));
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src_ip = map__objdump_2rip(dloc->ms->map, start);
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again:
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/* Get basic blocks for this scope */
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if (annotate_get_basic_blocks(dloc->ms->sym, src_ip, dst_ip,
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&this_blocks) < 0) {
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/* Try previous block if they are not connected */
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if (prev_dst_ip != dst_ip) {
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dst_ip = prev_dst_ip;
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goto again;
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}
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pr_debug_dtp("cannot find a basic block from %"PRIx64" to %"PRIx64"\n",
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src_ip - dloc->ms->sym->start,
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dst_ip - dloc->ms->sym->start);
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continue;
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}
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prepend_basic_blocks(&this_blocks, &basic_blocks);
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/* Get variable info for this scope and add to var_types list */
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die_collect_vars(&scopes[i], &var_types);
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fixup_var_address(var_types, start);
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/* Find from start of this scope to the target instruction */
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if (find_data_type_insn(dloc, reg, &basic_blocks, var_types,
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cu_die, type_die)) {
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ret = 0;
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break;
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}
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/* Go up to the next scope and find blocks to the start */
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prev_dst_ip = dst_ip;
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dst_ip = src_ip;
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}
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delete_basic_blocks(&basic_blocks);
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delete_var_types(var_types);
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return ret;
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}
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/* The result will be saved in @type_die */
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static int find_data_type_die(struct data_loc_info *dloc, Dwarf_Die *type_die)
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{
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@ -847,6 +1033,15 @@ retry:
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goto out;
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}
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if (reg != DWARF_REG_PC) {
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ret = find_data_type_block(dloc, reg, &cu_die, scopes,
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nr_scopes, type_die);
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if (ret == 0) {
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ann_data_stat.insn_track++;
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goto out;
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}
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}
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if (loc->multi_regs && reg == loc->reg1 && loc->reg1 != loc->reg2) {
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reg = loc->reg2;
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goto retry;
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@ -135,6 +135,7 @@ struct annotated_data_stat {
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int no_typeinfo;
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int invalid_size;
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int bad_offset;
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int insn_track;
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};
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extern struct annotated_data_stat ann_data_stat;
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