Commit 4449c904 authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
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perf annotate-data: Handle direct global variable access 



Like per-cpu base offset array, sometimes it accesses the global
variable directly using the offset.  Allow this type of instructions as
long as it finds a global variable for the address.

  movslq  %edi, %rcx
  mov     -0x7dc94ae0(,%rcx,8), %rcx   <<<--- here

As %rcx has a valid type (i.e. array index) from the first instruction,
it will be checked by the first case in check_matching_type().  But as
it's not a pointer type, the match will fail.  But in this case, it
should check if it accesses the kernel global array variable.

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/20240502060011.1838090-4-namhyung@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent c1da8411

tools/perf/util/annotate-data.c

+15 −12
Original line number Diff line number Diff line
@@ -1256,14 +1256,19 @@ static int check_matching_type(struct type_state *state, 
	if (state->regs[reg].ok && state->regs[reg].kind == TSR_KIND_TYPE) {

		int tag = dwarf_tag(&state->regs[reg].type);



		pr_debug_dtp("\n");



		/*

		 * Normal registers should hold a pointer (or array) to

		 * dereference a memory location.

		 */

		if (tag != DW_TAG_pointer_type && tag != DW_TAG_array_type)

		if (tag != DW_TAG_pointer_type && tag != DW_TAG_array_type) {

			if (dloc->op->offset < 0 && reg != state->stack_reg)

				goto check_kernel;



			pr_debug_dtp("\n");

			return -1;

		}



		pr_debug_dtp("\n");



		/* Remove the pointer and get the target type */

		if (die_get_real_type(&state->regs[reg].type, type_die) == NULL)
@@ -1376,12 +1381,14 @@ static int check_matching_type(struct type_state *state, 
		return -1;

	}



	if (map__dso(dloc->ms->map)->kernel && arch__is(dloc->arch, "x86")) {

check_kernel:

	if (map__dso(dloc->ms->map)->kernel) {

		u64 addr;

		int offset;



		/* Direct this-cpu access like "%gs:0x34740" */

		if (dloc->op->segment == INSN_SEG_X86_GS && dloc->op->imm) {

		if (dloc->op->segment == INSN_SEG_X86_GS && dloc->op->imm &&

		    arch__is(dloc->arch, "x86")) {

			pr_debug_dtp(" this-cpu var\n");



			addr = dloc->op->offset;
@@ -1394,17 +1401,13 @@ static int check_matching_type(struct type_state *state, 
			return -1;

		}



		/* Access to per-cpu base like "-0x7dcf0500(,%rdx,8)" */

		/* Access to global variable like "-0x7dcf0500(,%rdx,8)" */

		if (dloc->op->offset < 0 && reg != state->stack_reg) {

			const char *var_name = NULL;



			addr = (s64) dloc->op->offset;



			if (get_global_var_info(dloc, addr, &var_name, &offset) &&

			    !strcmp(var_name, "__per_cpu_offset") && offset == 0 &&

			    get_global_var_type(cu_die, dloc, dloc->ip, addr,

			if (get_global_var_type(cu_die, dloc, dloc->ip, addr,

						&offset, type_die)) {

				pr_debug_dtp(" percpu base\n");

				pr_debug_dtp(" global var\n");



				dloc->type_offset = offset;

				return 1;