add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/scripts/gdb/linux/dmesg.py
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@@ -16,6 +16,13 @@
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 from linux import utils
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+printk_info_type = utils.CachedType("struct printk_info")
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+prb_data_blk_lpos_type = utils.CachedType("struct prb_data_blk_lpos")
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+prb_desc_type = utils.CachedType("struct prb_desc")
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+prb_desc_ring_type = utils.CachedType("struct prb_desc_ring")
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+prb_data_ring_type = utils.CachedType("struct prb_data_ring")
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+printk_ringbuffer_type = utils.CachedType("struct printk_ringbuffer")
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+atomic_long_type = utils.CachedType("atomic_long_t")
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 class LxDmesg(gdb.Command):
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     """Print Linux kernel log buffer."""
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@@ -24,38 +31,110 @@
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         super(LxDmesg, self).__init__("lx-dmesg", gdb.COMMAND_DATA)
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     def invoke(self, arg, from_tty):
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-        log_buf_addr = int(str(gdb.parse_and_eval(
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-            "(void *)'printk.c'::log_buf")).split()[0], 16)
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-        log_first_idx = int(gdb.parse_and_eval("'printk.c'::log_first_idx"))
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-        log_next_idx = int(gdb.parse_and_eval("'printk.c'::log_next_idx"))
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-        log_buf_len = int(gdb.parse_and_eval("'printk.c'::log_buf_len"))
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-
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         inf = gdb.inferiors()[0]
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-        start = log_buf_addr + log_first_idx
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-        if log_first_idx < log_next_idx:
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-            log_buf_2nd_half = -1
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-            length = log_next_idx - log_first_idx
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-            log_buf = utils.read_memoryview(inf, start, length).tobytes()
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-        else:
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-            log_buf_2nd_half = log_buf_len - log_first_idx
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-            a = utils.read_memoryview(inf, start, log_buf_2nd_half)
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-            b = utils.read_memoryview(inf, log_buf_addr, log_next_idx)
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-            log_buf = a.tobytes() + b.tobytes()
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-        pos = 0
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-        while pos < log_buf.__len__():
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-            length = utils.read_u16(log_buf[pos + 8:pos + 10])
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-            if length == 0:
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-                if log_buf_2nd_half == -1:
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-                    gdb.write("Corrupted log buffer!\n")
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+        # read in prb structure
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+        prb_addr = int(str(gdb.parse_and_eval("(void *)'printk.c'::prb")).split()[0], 16)
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+        sz = printk_ringbuffer_type.get_type().sizeof
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+        prb = utils.read_memoryview(inf, prb_addr, sz).tobytes()
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+
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+        # read in descriptor ring structure
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+        off = printk_ringbuffer_type.get_type()['desc_ring'].bitpos // 8
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+        addr = prb_addr + off
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+        sz = prb_desc_ring_type.get_type().sizeof
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+        desc_ring = utils.read_memoryview(inf, addr, sz).tobytes()
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+
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+        # read in descriptor array
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+        off = prb_desc_ring_type.get_type()['count_bits'].bitpos // 8
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+        desc_ring_count = 1 << utils.read_u32(desc_ring, off)
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+        desc_sz = prb_desc_type.get_type().sizeof
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+        off = prb_desc_ring_type.get_type()['descs'].bitpos // 8
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+        addr = utils.read_ulong(desc_ring, off)
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+        descs = utils.read_memoryview(inf, addr, desc_sz * desc_ring_count).tobytes()
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+
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+        # read in info array
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+        info_sz = printk_info_type.get_type().sizeof
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+        off = prb_desc_ring_type.get_type()['infos'].bitpos // 8
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+        addr = utils.read_ulong(desc_ring, off)
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+        infos = utils.read_memoryview(inf, addr, info_sz * desc_ring_count).tobytes()
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+
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+        # read in text data ring structure
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+        off = printk_ringbuffer_type.get_type()['text_data_ring'].bitpos // 8
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+        addr = prb_addr + off
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+        sz = prb_data_ring_type.get_type().sizeof
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+        text_data_ring = utils.read_memoryview(inf, addr, sz).tobytes()
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+
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+        # read in text data
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+        off = prb_data_ring_type.get_type()['size_bits'].bitpos // 8
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+        text_data_sz = 1 << utils.read_u32(text_data_ring, off)
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+        off = prb_data_ring_type.get_type()['data'].bitpos // 8
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+        addr = utils.read_ulong(text_data_ring, off)
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+        text_data = utils.read_memoryview(inf, addr, text_data_sz).tobytes()
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+
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+        counter_off = atomic_long_type.get_type()['counter'].bitpos // 8
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+
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+        sv_off = prb_desc_type.get_type()['state_var'].bitpos // 8
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+
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+        off = prb_desc_type.get_type()['text_blk_lpos'].bitpos // 8
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+        begin_off = off + (prb_data_blk_lpos_type.get_type()['begin'].bitpos // 8)
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+        next_off = off + (prb_data_blk_lpos_type.get_type()['next'].bitpos // 8)
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+
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+        ts_off = printk_info_type.get_type()['ts_nsec'].bitpos // 8
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+        len_off = printk_info_type.get_type()['text_len'].bitpos // 8
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+
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+        # definitions from kernel/printk/printk_ringbuffer.h
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+        desc_committed = 1
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+        desc_finalized = 2
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+        desc_sv_bits = utils.get_long_type().sizeof * 8
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+        desc_flags_shift = desc_sv_bits - 2
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+        desc_flags_mask = 3 << desc_flags_shift
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+        desc_id_mask = ~desc_flags_mask
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+
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+        # read in tail and head descriptor ids
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+        off = prb_desc_ring_type.get_type()['tail_id'].bitpos // 8
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+        tail_id = utils.read_u64(desc_ring, off + counter_off)
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+        off = prb_desc_ring_type.get_type()['head_id'].bitpos // 8
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+        head_id = utils.read_u64(desc_ring, off + counter_off)
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+
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+        did = tail_id
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+        while True:
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+            ind = did % desc_ring_count
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+            desc_off = desc_sz * ind
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+            info_off = info_sz * ind
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+
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+            # skip non-committed record
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+            state = 3 & (utils.read_u64(descs, desc_off + sv_off +
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+                                        counter_off) >> desc_flags_shift)
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+            if state != desc_committed and state != desc_finalized:
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+                if did == head_id:
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                     break
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-                pos = log_buf_2nd_half
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+                did = (did + 1) & desc_id_mask
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                 continue
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-            text_len = utils.read_u16(log_buf[pos + 10:pos + 12])
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-            text = log_buf[pos + 16:pos + 16 + text_len].decode(
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-                encoding='utf8', errors='replace')
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-            time_stamp = utils.read_u64(log_buf[pos:pos + 8])
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+            begin = utils.read_ulong(descs, desc_off + begin_off) % text_data_sz
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+            end = utils.read_ulong(descs, desc_off + next_off) % text_data_sz
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+
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+            # handle data-less record
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+            if begin & 1 == 1:
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+                text = ""
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+            else:
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+                # handle wrapping data block
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+                if begin > end:
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+                    begin = 0
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+
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+                # skip over descriptor id
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+                text_start = begin + utils.get_long_type().sizeof
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+
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+                text_len = utils.read_u16(infos, info_off + len_off)
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+
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+                # handle truncated message
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+                if end - text_start < text_len:
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+                    text_len = end - text_start
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+
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+                text = text_data[text_start:text_start + text_len].decode(
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+                    encoding='utf8', errors='replace')
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+
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+            time_stamp = utils.read_u64(infos, info_off + ts_off)
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             for line in text.splitlines():
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                 msg = u"[{time:12.6f}] {line}\n".format(
..
..
@@ -67,7 +146,9 @@
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                     msg = msg.encode(encoding='utf8', errors='replace')
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                 gdb.write(msg)
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-            pos += length
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+            if did == head_id:
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+                break
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+            did = (did + 1) & desc_id_mask
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 LxDmesg()