From f284304dd62aadea65deb3ca5aaf1f16a03e8931 Mon Sep 17 00:00:00 2001
From: Patrick Lipka <patrick.lipka@codasip.com>
Date: Mon, 18 Aug 2025 16:48:33 +0200
Subject: [PATCH] add symbol lookup

---
 src/rvprof_symbols.c | 94 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)

diff --git a/src/rvprof_symbols.c b/src/rvprof_symbols.c
index d130a4d..d166897 100644
--- a/src/rvprof_symbols.c
+++ b/src/rvprof_symbols.c
@@ -232,4 +232,98 @@ static int parse_elf_symbols(const char* filepath){
     }
 
     return 0;
+}
+
+// symbol lookup
+const char* rvprof_symbols_lookup(void* addr){
+    if (!g_rvprof.symbols_loaded || g_rvprof.symbols.size == 0){
+        snprintf(g_tmp_func_name, sizeof(g_tmp_func_name), "func_%p", addr);
+        return g_tmp_func_name;
+    }
+
+    uintptr_t target_addr = (uintptr_t)addr;
+
+    // try to calculate base address offset using known symbols
+    if (!g_base_address_calculated && g_rvprof.symbols.size > 0){
+        // use our own profiling functions as reference points since we know their addresses
+        for (int i = 0; i < g_rvprof.symbols.size; i++){
+            symbol_entry_t* sym = &g_rvprof.symbols.data[i];
+            
+            // use rvprof functions as reference points
+            if (strcmp(sym->name, "__cyg_profile_func_enter") == 0){
+                calculate_base_address_offset((void*)__cyg_profile_func_enter, sym->addr);
+                break;
+            } else if (strcmp(sym->name, "rvprof_init") == 0){
+                calculate_base_address_offset((void*)rvprof_init, sym->addr);
+                break;
+            }
+        }
+        
+        // if we still haven't calculated it, try to infer from the lookup addresses
+        if (!g_base_address_calculated && g_rvprof.symbols.size > 0){
+            // find the closest symbol and use it to estimate base offset
+            uintptr_t highest_elf_addr = 0;
+            for (int i = 0; i < g_rvprof.symbols.size; i++) {
+                if (g_rvprof.symbols.data[i].addr > highest_elf_addr) {
+                    highest_elf_addr = g_rvprof.symbols.data[i].addr;
+                }
+            }
+            
+            // if the target address is much higher than any ELF address, calculate offset
+            if (target_addr > highest_elf_addr && (target_addr - highest_elf_addr) > 0x100000){
+                // estimate base offset
+                uintptr_t estimated_offset = target_addr - highest_elf_addr;
+                // round down to page boundary (typically 4KB)
+                g_base_address_offset = (estimated_offset & ~0xFFF);
+                g_base_address_calculated = 1;
+            }
+        }
+    }
+
+    // adjust target address by base offset
+    uintptr_t adjusted_addr = target_addr;
+    if (g_base_address_calculated && g_base_address_offset > 0){
+        adjusted_addr = target_addr - g_base_address_offset;
+    }
+    
+    // binary search for closest symbol
+    int left = 0;
+    int right = g_rvprof.symbols.size - 1;
+    int best_match = -1;
+    
+    while (left <= right){
+        int mid = (left + right) / 2;
+        
+        if (g_rvprof.symbols.data[mid].addr <= adjusted_addr){
+            best_match = mid;
+            left = mid + 1;
+        } else {
+            right = mid - 1;
+        }
+    }
+
+    // match?
+    if (best_match >= 0) {
+        symbol_entry_t* sym = &g_rvprof.symbols.data[best_match];
+        
+        // if symbol has size info, check if address is within range
+        if (sym->size > 0) {
+            if (adjusted_addr >= sym->addr && adjusted_addr < sym->addr + sym->size){
+                strncpy(g_temp_func_name, sym->name, sizeof(g_temp_func_name) - 1);
+                g_temp_func_name[sizeof(g_temp_func_name) - 1] = '\0';
+                return g_temp_func_name;
+            }
+        } else {
+            // no size info, use 64 KB heuristic: must be within reasonable range
+            if (adjusted_addr >= sym->addr && (adjusted_addr - sym->addr) < 0x10000){ 
+                strncpy(g_temp_func_name, sym->name, sizeof(g_temp_func_name) - 1);
+                g_temp_func_name[sizeof(g_temp_func_name) - 1] = '\0';
+                return g_temp_func_name;
+            }
+        }
+    }
+    
+    // fallback to addresses if we cannot resolve symbols
+    snprintf(g_temp_func_name, sizeof(g_temp_func_name), "func_%p", addr);
+    return g_temp_func_name;
 }
\ No newline at end of file