When CONFIG_PRINTK_CALLER is set, struct printk_log contains an additional member caller_id. This affects the offset of the log text. Account for this by using the type information from gdb to determine all the offsets instead of using hardcoded values. This fixes following error: (gdb) lx-dmesg Python Exception <class 'ValueError'> embedded null character: Error occurred in Python command: embedded null character The read_u* utility functions now take an offset argument to make them easier to use.
Unified · Split
| @@ -16,6 +16,8 @@ import sys · 15 unmodified lines | ||
| 16 | 16 | |
| 17 | 17 | from linux import utils |
| 18 | 18 | |
| 19 | +printk_log_type = utils.CachedType("struct printk_log") | |
| 20 | + | |
| 19 | 21 | |
| 20 | 22 | class LxDmesg(gdb.Command): |
| 21 | 23 | """Print Linux kernel log buffer.""" |
| @@ -42,9 +44,14 @@ class LxDmesg(gdb.Command): · 20 unmodified lines | ||
| 42 | 44 | b = utils.read_memoryview(inf, log_buf_addr, log_next_idx) |
| 43 | 45 | log_buf = a.tobytes() + b.tobytes() |
| 44 | 46 | |
| 47 | + length_offset = printk_log_type.get_type()['len'].bitpos // 8 | |
| 48 | + text_len_offset = printk_log_type.get_type()['text_len'].bitpos // 8 | |
| 49 | + time_stamp_offset = printk_log_type.get_type()['ts_nsec'].bitpos // 8 | |
| 50 | + text_offset = printk_log_type.get_type().sizeof | |
| 51 | + | |
| 45 | 52 | pos = 0 |
| 46 | 53 | while pos < log_buf.__len__(): |
| 47 | − length = utils.read_u16(log_buf[pos + 8:pos + 10]) | |
| 54 | + length = utils.read_u16(log_buf, pos + length_offset) | |
| 48 | 55 | if length == 0: |
| 49 | 56 | if log_buf_2nd_half == -1: |
| 50 | 57 | gdb.write("Corrupted log buffer!\n") |
| @@ -52,10 +59,11 @@ class LxDmesg(gdb.Command): · 1 unmodified line | ||
| 52 | 59 | pos = log_buf_2nd_half |
| 53 | 60 | continue |
| 54 | 61 | |
| 55 | − text_len = utils.read_u16(log_buf[pos + 10:pos + 12]) | |
| 56 | − text = log_buf[pos + 16:pos + 16 + text_len].decode( | |
| 62 | + text_len = utils.read_u16(log_buf, pos + text_len_offset) | |
| 63 | + text_start = pos + text_offset | |
| 64 | + text = log_buf[text_start:text_start + text_len].decode( | |
| 57 | 65 | encoding='utf8', errors='replace') |
| 58 | − time_stamp = utils.read_u64(log_buf[pos:pos + 8]) | |
| 66 | + time_stamp = utils.read_u64(log_buf, pos + time_stamp_offset) | |
| 59 | 67 | |
| 60 | 68 | for line in text.splitlines(): |
| 61 | 69 | msg = u"[{time:12.6f}] {line}\n".format( |
| @@ -92,15 +92,16 @@ def read_memoryview(inf, start, length): · 91 unmodified lines | ||
| 92 | 92 | return memoryview(inf.read_memory(start, length)) |
| 93 | 93 | |
| 94 | 94 | |
| 95 | −def read_u16(buffer): | |
| 95 | +def read_u16(buffer, offset): | |
| 96 | + buffer_val = buffer[offset:offset + 2] | |
| 96 | 97 | value = [0, 0] |
| 97 | 98 | |
| 98 | − if type(buffer[0]) is str: | |
| 99 | − value[0] = ord(buffer[0]) | |
| 100 | − value[1] = ord(buffer[1]) | |
| 99 | + if type(buffer_val[0]) is str: | |
| 100 | + value[0] = ord(buffer_val[0]) | |
| 101 | + value[1] = ord(buffer_val[1]) | |
| 101 | 102 | else: |
| 102 | − value[0] = buffer[0] | |
| 103 | − value[1] = buffer[1] | |
| 103 | + value[0] = buffer_val[0] | |
| 104 | + value[1] = buffer_val[1] | |
| 104 | 105 | |
| 105 | 106 | if get_target_endianness() == LITTLE_ENDIAN: |
| 106 | 107 | return value[0] + (value[1] << 8) |
| @@ -108,18 +109,18 @@ def read_u16(buffer): · 1 unmodified line | ||
| 108 | 109 | return value[1] + (value[0] << 8) |
| 109 | 110 | |
| 110 | 111 | |
| 111 | −def read_u32(buffer): | |
| 112 | +def read_u32(buffer, offset): | |
| 112 | 113 | if get_target_endianness() == LITTLE_ENDIAN: |
| 113 | − return read_u16(buffer[0:2]) + (read_u16(buffer[2:4]) << 16) | |
| 114 | + return read_u16(buffer, offset) + (read_u16(buffer, offset + 2) << 16) | |
| 114 | 115 | else: |
| 115 | − return read_u16(buffer[2:4]) + (read_u16(buffer[0:2]) << 16) | |
| 116 | + return read_u16(buffer, offset + 2) + (read_u16(buffer, offset) << 16) | |
| 116 | 117 | |
| 117 | 118 | |
| 118 | −def read_u64(buffer): | |
| 119 | +def read_u64(buffer, offset): | |
| 119 | 120 | if get_target_endianness() == LITTLE_ENDIAN: |
| 120 | − return read_u32(buffer[0:4]) + (read_u32(buffer[4:8]) << 32) | |
| 121 | + return read_u32(buffer, offset) + (read_u32(buffer, offset + 4) << 32) | |
| 121 | 122 | else: |
| 122 | − return read_u32(buffer[4:8]) + (read_u32(buffer[0:4]) << 32) | |
| 123 | + return read_u32(buffer, offset + 4) + (read_u32(buffer, offset) << 32) | |
| 123 | 124 | |
| 124 | 125 | |
| 125 | 126 | target_arch = None |