WIP COMPACTTTT

javierhonduco · Feb 5, 2023 · c31c0f7 · c31c0f7
1 parent 049abbd
commit c31c0f7
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Showing 3 changed files with 5 additions and 4 deletions.
diff --git a/bpf/cpu/cpu.bpf.c b/bpf/cpu/cpu.bpf.c
@@ -615,7 +615,7 @@ int walk_user_stacktrace_impl(struct bpf_perf_event_data *ctx) {
     }
 
     // add first
-    u64 found_pc = unwind_table->rows[table_idx].pc + first_pc;
+    u64 found_pc = first_pc + unwind_table->rows[table_idx].pc;
     u8 found_cfa_type = unwind_table->rows[table_idx].cfa_type;
     u8 found_rbp_type = unwind_table->rows[table_idx].rbp_type;
     s16 found_cfa_offset = unwind_table->rows[table_idx].cfa_offset;

diff --git a/pkg/profiler/cpu/maps.go b/pkg/profiler/cpu/maps.go
@@ -1082,7 +1082,7 @@ func (m *bpfMaps) setUnwindTableForMapping(pid int, mapping *unwind.ExecutableMa
 			// ====================== Write unwind table =====================
 			for _, row := range currentChunk {
 				leRow := row
-				leRow.SetPc(leRow.Pc() - firstPc)
+				leRow.AdjustPc(firstPc)
 				if err := m.writeUnwindTableRow(m.unwindInfoBuf, leRow); err != nil {
 					return fmt.Errorf("writing unwind table row: %w", err)
 				}

diff --git a/pkg/stack/unwind/compact_unwind_table.go b/pkg/stack/unwind/compact_unwind_table.go
@@ -49,8 +49,9 @@ type CompactUnwindTableRow struct {
 	rbpOffset         int16
 }
 
-func (cutr *CompactUnwindTableRow) SetPc(pc uint64) {
-	cutr.pc = pc
+func (cutr *CompactUnwindTableRow) AdjustPc(offset uint64) {
+	cutr.pc -= offset
+	// assert that it fits in 32 bits
 }
 
 func (cutr *CompactUnwindTableRow) Pc() uint64 {