embedded_debugger_mcp/rtt/
elf_parser.rs

1//! ELF symbol parsing for RTT control block detection
2//! Based on probe-rs implementation analysis
3
4use crate::error::{DebugError, Result};
5use std::path::Path;
6use tracing::{debug, info, warn};
7
8/// RTT symbol name as defined by SEGGER RTT implementation
9const RTT_SYMBOL_NAME: &str = "_SEGGER_RTT";
10
11/// Extract RTT control block address from ELF symbol table
12/// This is the primary method used by probe-rs for RTT detection
13pub fn get_rtt_symbol_from_elf(elf_path: &Path) -> Result<u64> {
14    debug!("Parsing ELF file for RTT symbol: {}", elf_path.display());
15    
16    // Read ELF file
17    let elf_data = std::fs::read(elf_path).map_err(|e| {
18        DebugError::RttError(format!("Failed to read ELF file {}: {}", elf_path.display(), e))
19    })?;
20    
21    // Parse ELF structure
22    let elf = goblin::elf::Elf::parse(&elf_data).map_err(|e| {
23        DebugError::RttError(format!("Failed to parse ELF file {}: {}", elf_path.display(), e))
24    })?;
25    
26    info!("ELF file parsed successfully, searching for {} symbol", RTT_SYMBOL_NAME);
27    debug!("ELF info - entry: 0x{:08X}, symbols: {}", elf.entry, elf.syms.len());
28    
29    // Search for _SEGGER_RTT symbol in symbol table
30    for sym in elf.syms.iter() {
31        if let Some(name) = elf.strtab.get_at(sym.st_name) {
32            debug!("Found symbol: {} at 0x{:08X}", name, sym.st_value);
33            
34            if name == RTT_SYMBOL_NAME {
35                let rtt_address = sym.st_value;
36                info!("✅ Found {} symbol at address 0x{:08X}", RTT_SYMBOL_NAME, rtt_address);
37                
38                // Validate address is reasonable (should be in RAM)
39                if is_valid_rtt_address(rtt_address) {
40                    return Ok(rtt_address);
41                } else {
42                    warn!("RTT symbol address 0x{:08X} appears invalid (not in typical RAM range)", rtt_address);
43                    return Err(DebugError::RttError(format!(
44                        "RTT symbol found at invalid address 0x{:08X} (expected in RAM range 0x20000000-0x2FFFFFFF)", 
45                        rtt_address
46                    )));
47                }
48            }
49        }
50    }
51    
52    // Symbol not found
53    debug!("RTT symbol search completed, {} not found in {} symbols", RTT_SYMBOL_NAME, elf.syms.len());
54    Err(DebugError::RttError(format!(
55        "{} symbol not found in ELF file {}. Firmware may not have RTT enabled or symbols may be stripped.", 
56        RTT_SYMBOL_NAME, 
57        elf_path.display()
58    )))
59}
60
61/// Validate that RTT address is in a reasonable memory range
62/// RTT control blocks are typically placed in RAM
63fn is_valid_rtt_address(address: u64) -> bool {
64    // Common ARM Cortex-M RAM ranges
65    // STM32G4: 0x20000000 - 0x2000A000 (SRAM1 + SRAM2)
66    // But allow broader range for different MCUs
67    const RAM_START: u64 = 0x20000000;
68    const RAM_END: u64 = 0x2FFFFFFF;
69    
70    address >= RAM_START && address <= RAM_END
71}
72
73/// Get comprehensive ELF information for debugging
74pub fn get_elf_debug_info(elf_path: &Path) -> Result<ElfDebugInfo> {
75    let elf_data = std::fs::read(elf_path).map_err(|e| {
76        DebugError::RttError(format!("Failed to read ELF file: {}", e))
77    })?;
78    
79    let elf = goblin::elf::Elf::parse(&elf_data).map_err(|e| {
80        DebugError::RttError(format!("Failed to parse ELF file: {}", e))
81    })?;
82    
83    let mut debug_symbols = Vec::new();
84    for sym in elf.syms.iter() {
85        if let Some(name) = elf.strtab.get_at(sym.st_name) {
86            if name.contains("RTT") || name.contains("rtt") {
87                debug_symbols.push(SymbolInfo {
88                    name: name.to_string(),
89                    address: sym.st_value,
90                    size: sym.st_size,
91                });
92            }
93        }
94    }
95    
96    Ok(ElfDebugInfo {
97        entry_point: elf.entry,
98        symbol_count: elf.syms.len(),
99        has_debug_info: !elf.section_headers.is_empty(),
100        rtt_related_symbols: debug_symbols,
101    })
102}
103
104#[derive(Debug)]
105pub struct ElfDebugInfo {
106    pub entry_point: u64,
107    pub symbol_count: usize,
108    pub has_debug_info: bool,
109    pub rtt_related_symbols: Vec<SymbolInfo>,
110}
111
112#[derive(Debug)]
113pub struct SymbolInfo {
114    pub name: String,
115    pub address: u64,
116    pub size: u64,
117}
118
119#[cfg(test)]
120mod tests {
121    use super::*;
122    
123    #[test]
124    fn test_valid_rtt_address() {
125        // Valid STM32G4 RAM addresses
126        assert!(is_valid_rtt_address(0x20000000)); // Start of SRAM1
127        assert!(is_valid_rtt_address(0x20008000)); // Start of SRAM2
128        assert!(is_valid_rtt_address(0x2000A000)); // End of SRAM2
129        
130        // Invalid addresses
131        assert!(!is_valid_rtt_address(0x08000000)); // Flash
132        assert!(!is_valid_rtt_address(0x00000000)); // Null
133        assert!(!is_valid_rtt_address(0x40000000)); // Peripherals
134    }
135}
embedded_debugger_mcp/rtt/elf_parser.rs

embedded_debugger_mcp/rtt/
elf_parser.rs
