From: Namhyung Kim <namhyung@kernel.org>
Date: Tue, 19 Mar 2024 05:51:10 +0000 (-0700)
Subject: perf annotate-data: Track instructions with a this-cpu variable
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=ad62edbfc55b23347539c8c6fff9a70de17c4b95;p=linux.git

perf annotate-data: Track instructions with a this-cpu variable

Like global variables, this per-cpu variables should be tracked
correctly.  Factor our get_global_var_type() to handle both global
and per-cpu (for this cpu) variables in the same manner.

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/20240319055115.4063940-19-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---

diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c
index d57622ddd5d31..48fea0c716ef9 100644
--- a/tools/perf/util/annotate-data.c
+++ b/tools/perf/util/annotate-data.c
@@ -553,12 +553,41 @@ static void update_insn_state_x86(struct type_state *state,
 			fbreg = -1;
 	}
 
-	/* Case 1. register to register transfers */
+	/* Case 1. register to register or segment:offset to register transfers */
 	if (!src->mem_ref && !dst->mem_ref) {
 		if (!has_reg_type(state, dst->reg1))
 			return;
 
 		tsr = &state->regs[dst->reg1];
+		if (map__dso(dloc->ms->map)->kernel &&
+		    src->segment == INSN_SEG_X86_GS && src->imm) {
+			u64 ip = dloc->ms->sym->start + dl->al.offset;
+			u64 var_addr;
+			int offset;
+
+			/*
+			 * In kernel, %gs points to a per-cpu region for the
+			 * current CPU.  Access with a constant offset should
+			 * be treated as a global variable access.
+			 */
+			var_addr = src->offset;
+
+			if (!get_global_var_type(cu_die, dloc, ip, var_addr,
+						 &offset, &type_die) ||
+			    !die_get_member_type(&type_die, offset, &type_die)) {
+				tsr->ok = false;
+				return;
+			}
+
+			tsr->type = type_die;
+			tsr->ok = true;
+
+			pr_debug_dtp("mov [%x] this-cpu addr=%#"PRIx64" -> reg%d",
+				     insn_offset, var_addr, dst->reg1);
+			pr_debug_type_name(&tsr->type);
+			return;
+		}
+
 		if (!has_reg_type(state, src->reg1) ||
 		    !state->regs[src->reg1].ok) {
 			tsr->ok = false;