Commit 2bc3cf57 authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
Browse files

perf annotate-data: Improve debug message with location info 



To verify it found the correct variable, let's add the location
expression to the debug message.

  $ perf --debug type-profile annotate --data-type
  ...
  -----------------------------------------------------------
  find data type for 0xaf0(reg15) at schedule+0xeb
  CU for kernel/sched/core.c (die:0x1180523)
  frame base: cfa=0 fbreg=6
  found "rq" in scope=3/4 (die: 0x11b6a00) type_offset=0xaf0
   variable location: reg15
   type='struct rq' size=0xfc0 (die:0x11892e2)
  -----------------------------------------------------------
  find data type for 0x7bc(reg3) at tcp_get_info+0x62
  CU for net/ipv4/tcp.c (die:0x7b5f516)
  frame base: cfa=0 fbreg=6
  offset: 1980 is bigger than size: 760
  check variable "sk" failed (die: 0x7b92b2c)
   variable location: reg3
   type='struct sock' size=0x2f8 (die:0x7b63c3a)
  -----------------------------------------------------------
  ...

The first case is fine.  It looked up a data type in r15 with offset of
0xaf0 at schedule+0xeb.  It found the CU die and the frame base info and
the variable "rq" was found in the scope 3/4.  Its location is the r15
register and the type size is 0xfc0 which includes 0xaf0.

But the second case is not good.  It looked up a data type in rbx (reg3)
with offset 0x7bc.  It found a CU and the frame base which is good so
far.  And it also found a variable "sk" but the access offset is bigger
than the type size (1980 vs. 760 or 0x7bc vs. 0x2f8).  The variable has
the right location (reg3) but I need to figure out why it accesses
beyond what it's supposed to.

Signed-off-by: default avatarNamhyung 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: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240412183310.2518474-2-namhyung@kernel.org


[ Fix the build on 32-bit by casting Dwarf_Word to (long) in pr_debug_location() ]
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 988052f4

tools/perf/util/annotate-data.c

+82 −17
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ static void pr_debug_type_name(Dwarf_Die *die, enum type_state_kind kind) 
{

	struct strbuf sb;

	char *str;

	Dwarf_Word size = 0;



	if (!debug_type_profile && verbose < 3)

		return;
@@ -72,13 +73,67 @@ static void pr_debug_type_name(Dwarf_Die *die, enum type_state_kind kind) 
		break;

	}



	dwarf_aggregate_size(die, &size);



	strbuf_init(&sb, 32);

	die_get_typename_from_type(die, &sb);

	str = strbuf_detach(&sb, NULL);

	pr_info(" type=%s (die:%lx)\n", str, (long)dwarf_dieoffset(die));

	pr_info(" type='%s' size=%#lx (die:%#lx)\n",

		str, (long)size, (long)dwarf_dieoffset(die));

	free(str);

}



static void pr_debug_location(Dwarf_Die *die, u64 pc, int reg)

{

	ptrdiff_t off = 0;

	Dwarf_Attribute attr;

	Dwarf_Addr base, start, end;

	Dwarf_Op *ops;

	size_t nops;



	if (!debug_type_profile && verbose < 3)

		return;



	if (dwarf_attr(die, DW_AT_location, &attr) == NULL)

		return;



	while ((off = dwarf_getlocations(&attr, off, &base, &start, &end, &ops, &nops)) > 0) {

		if (reg != DWARF_REG_PC && end < pc)

			continue;

		if (reg != DWARF_REG_PC && start > pc)

			break;



		pr_info(" variable location: ");

		switch (ops->atom) {

		case DW_OP_reg0 ...DW_OP_reg31:

			pr_info("reg%d\n", ops->atom - DW_OP_reg0);

			break;

		case DW_OP_breg0 ...DW_OP_breg31:

			pr_info("base=reg%d, offset=%#lx\n",

				ops->atom - DW_OP_breg0, (long)ops->number);

			break;

		case DW_OP_regx:

			pr_info("reg%ld\n", (long)ops->number);

			break;

		case DW_OP_bregx:

			pr_info("base=reg%ld, offset=%#lx\n",

				(long)ops->number, (long)ops->number2);

			break;

		case DW_OP_fbreg:

			pr_info("use frame base, offset=%#lx\n", (long)ops->number);

			break;

		case DW_OP_addr:

			pr_info("address=%#lx\n", (long)ops->number);

			break;

		default:

			pr_info("unknown: code=%#x, number=%#lx\n",

				ops->atom, (long)ops->number);

			break;

		}

		break;

	}

}



/*

 * Type information in a register, valid when @ok is true.

 * The @caller_saved registers are invalidated after a function call.
@@ -1404,7 +1459,7 @@ static int find_data_type_block(struct data_loc_info *dloc, int reg, 
		found = find_data_type_insn(dloc, reg, &basic_blocks, var_types,

					    cu_die, type_die);

		if (found > 0) {

			pr_debug_dtp("found by insn track: %#x(reg%d) type-offset=%#x",

			pr_debug_dtp("found by insn track: %#x(reg%d) type-offset=%#x\n",

				     dloc->op->offset, reg, dloc->type_offset);

			pr_debug_type_name(type_die, TSR_KIND_TYPE);

			ret = 0;
@@ -1440,16 +1495,16 @@ static int find_data_type_die(struct data_loc_info *dloc, Dwarf_Die *type_die) 
	char buf[64];



	if (dloc->op->multi_regs)

		snprintf(buf, sizeof(buf), " or reg%d", dloc->op->reg2);

		snprintf(buf, sizeof(buf), "reg%d, reg%d", dloc->op->reg1, dloc->op->reg2);

	else if (dloc->op->reg1 == DWARF_REG_PC)

		snprintf(buf, sizeof(buf), " (PC)");

		snprintf(buf, sizeof(buf), "PC");

	else

		buf[0] = '\0';

		snprintf(buf, sizeof(buf), "reg%d", dloc->op->reg1);



	pr_debug_dtp("-----------------------------------------------------------\n");

	pr_debug_dtp("%s [%"PRIx64"] for reg%d%s offset=%#x in %s\n",

		     __func__, dloc->ip - dloc->ms->sym->start,

		     dloc->op->reg1, buf, dloc->op->offset, dloc->ms->sym->name);

	pr_debug_dtp("find data type for %#x(%s) at %s+%#"PRIx64"\n",

		     dloc->op->offset, buf, dloc->ms->sym->name,

		     dloc->ip - dloc->ms->sym->start);



	/*

	 * IP is a relative instruction address from the start of the map, as
@@ -1468,14 +1523,15 @@ static int find_data_type_die(struct data_loc_info *dloc, Dwarf_Die *type_die) 
	reg = loc->reg1;

	offset = loc->offset;



	pr_debug_dtp("CU die offset: %#lx\n", (long)dwarf_dieoffset(&cu_die));

	pr_debug_dtp("CU for %s (die:%#lx)\n",

		     dwarf_diename(&cu_die), (long)dwarf_dieoffset(&cu_die));



	if (reg == DWARF_REG_PC) {

		if (get_global_var_type(&cu_die, dloc, dloc->ip, dloc->var_addr,

					&offset, type_die)) {

			dloc->type_offset = offset;



			pr_debug_dtp("found PC-rel by addr=%#"PRIx64" offset=%#x",

			pr_debug_dtp("found by addr=%#"PRIx64" type_offset=%#x\n",

				     dloc->var_addr, offset);

			pr_debug_type_name(type_die, TSR_KIND_TYPE);

			ret = 0;
@@ -1537,13 +1593,22 @@ static int find_data_type_die(struct data_loc_info *dloc, Dwarf_Die *type_die) 
			pr_debug_dtp("found \"%s\" in scope=%d/%d (die: %#lx) ",

				     dwarf_diename(&var_die), i+1, nr_scopes,

				     (long)dwarf_dieoffset(&scopes[i]));

			if (reg == DWARF_REG_PC)

				pr_debug_dtp("%#x(PC) offset=%#x", loc->offset, offset);

			else if (reg == DWARF_REG_FB || is_fbreg)

				pr_debug_dtp("%#x(reg%d) stack fb_offset=%#x offset=%#x",

					     loc->offset, reg, fb_offset, offset);

			else

				pr_debug_dtp("%#x(reg%d)", loc->offset, reg);

			if (reg == DWARF_REG_PC) {

				pr_debug_dtp("addr=%#"PRIx64" type_offset=%#x\n",

					     dloc->var_addr, offset);

			} else if (reg == DWARF_REG_FB || is_fbreg) {

				pr_debug_dtp("stack_offset=%#x type_offset=%#x\n",

					     fb_offset, offset);

			} else {

				pr_debug_dtp("type_offset=%#x\n", offset);

			}

			pr_debug_location(&var_die, pc, reg);

			pr_debug_type_name(type_die, TSR_KIND_TYPE);

		} else {

			pr_debug_dtp("check variable \"%s\" failed (die: %#lx)\n",

				     dwarf_diename(&var_die),

				     (long)dwarf_dieoffset(&var_die));

			pr_debug_location(&var_die, pc, reg);

			pr_debug_type_name(type_die, TSR_KIND_TYPE);

		}

		dloc->type_offset = offset;