From: Antonio Borneo antonio.borneo@foss.st.com
[ Upstream commit e3c8d33e0d62175c31ca7ab7ab01b18f0b6318d3 ]
The type atomic_long_t can have size 4 or 8 bytes, depending on CONFIG_64BIT; it's only content, the field 'counter', is either an int or a s64 value.
Current code incorrectly uses the fixed size utils.read_u64() to read the field 'counter' inside atomic_long_t.
On 32 bits architectures reading the last element 'tail_id' of the struct prb_desc_ring: struct prb_desc_ring { ... atomic_long_t tail_id; }; causes the utils.read_u64() to access outside the boundary of the struct and the gdb command 'lx-dmesg' exits with error: Python Exception <class 'IndexError'>: index out of range Error occurred in Python: index out of range
Query the really used atomic_long_t counter type size.
Link: https://lore.kernel.org/r/20220617143758.137307-1-antonio.borneo@foss.st.com Fixes: e60768311af8 ("scripts/gdb: update for lockless printk ringbuffer") Signed-off-by: Antonio Borneo antonio.borneo@foss.st.com [pmladek@suse.com: Query the really used atomic_long_t counter type size] Tested-by: Antonio Borneo antonio.borneo@foss.st.com Reviewed-by: John Ogness john.ogness@linutronix.de Signed-off-by: Petr Mladek pmladek@suse.com Link: https://lore.kernel.org/r/20220719122831.19890-1-pmladek@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- scripts/gdb/linux/dmesg.py | 9 +++------ scripts/gdb/linux/utils.py | 14 ++++++++++++-- 2 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/scripts/gdb/linux/dmesg.py b/scripts/gdb/linux/dmesg.py index d5983cf3db7d..c771831eb077 100644 --- a/scripts/gdb/linux/dmesg.py +++ b/scripts/gdb/linux/dmesg.py @@ -22,7 +22,6 @@ prb_desc_type = utils.CachedType("struct prb_desc") prb_desc_ring_type = utils.CachedType("struct prb_desc_ring") prb_data_ring_type = utils.CachedType("struct prb_data_ring") printk_ringbuffer_type = utils.CachedType("struct printk_ringbuffer") -atomic_long_type = utils.CachedType("atomic_long_t")
class LxDmesg(gdb.Command): """Print Linux kernel log buffer.""" @@ -68,8 +67,6 @@ class LxDmesg(gdb.Command): off = prb_data_ring_type.get_type()['data'].bitpos // 8 text_data_addr = utils.read_ulong(text_data_ring, off)
- counter_off = atomic_long_type.get_type()['counter'].bitpos // 8 - sv_off = prb_desc_type.get_type()['state_var'].bitpos // 8
off = prb_desc_type.get_type()['text_blk_lpos'].bitpos // 8 @@ -89,9 +86,9 @@ class LxDmesg(gdb.Command):
# read in tail and head descriptor ids off = prb_desc_ring_type.get_type()['tail_id'].bitpos // 8 - tail_id = utils.read_u64(desc_ring, off + counter_off) + tail_id = utils.read_atomic_long(desc_ring, off) off = prb_desc_ring_type.get_type()['head_id'].bitpos // 8 - head_id = utils.read_u64(desc_ring, off + counter_off) + head_id = utils.read_atomic_long(desc_ring, off)
did = tail_id while True: @@ -102,7 +99,7 @@ class LxDmesg(gdb.Command): desc = utils.read_memoryview(inf, desc_addr + desc_off, desc_sz).tobytes()
# skip non-committed record - state = 3 & (utils.read_u64(desc, sv_off + counter_off) >> desc_flags_shift) + state = 3 & (utils.read_atomic_long(desc, sv_off) >> desc_flags_shift) if state != desc_committed and state != desc_finalized: if did == head_id: break diff --git a/scripts/gdb/linux/utils.py b/scripts/gdb/linux/utils.py index ff7c1799d588..1553f68716cc 100644 --- a/scripts/gdb/linux/utils.py +++ b/scripts/gdb/linux/utils.py @@ -35,13 +35,12 @@ class CachedType:
long_type = CachedType("long") - +atomic_long_type = CachedType("atomic_long_t")
def get_long_type(): global long_type return long_type.get_type()
- def offset_of(typeobj, field): element = gdb.Value(0).cast(typeobj) return int(str(element[field].address).split()[0], 16) @@ -129,6 +128,17 @@ def read_ulong(buffer, offset): else: return read_u32(buffer, offset)
+atomic_long_counter_offset = atomic_long_type.get_type()['counter'].bitpos +atomic_long_counter_sizeof = atomic_long_type.get_type()['counter'].type.sizeof + +def read_atomic_long(buffer, offset): + global atomic_long_counter_offset + global atomic_long_counter_sizeof + + if atomic_long_counter_sizeof == 8: + return read_u64(buffer, offset + atomic_long_counter_offset) + else: + return read_u32(buffer, offset + atomic_long_counter_offset)
target_arch = None