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authorAntonio Borneo <antonio.borneo@foss.st.com>2022-07-19 14:28:31 +0200
committerPetr Mladek <pmladek@suse.com>2022-07-21 15:32:52 +0200
commite3c8d33e0d62175c31ca7ab7ab01b18f0b6318d3 (patch)
tree6e2693311ac5b129dfaf3fb80b142d70498f2c81 /scripts/gdb
parentlib/test_printf.c: split write-beyond-buffer check in two (diff)
downloadlinux-e3c8d33e0d62175c31ca7ab7ab01b18f0b6318d3.tar.xz
linux-e3c8d33e0d62175c31ca7ab7ab01b18f0b6318d3.zip
scripts/gdb: fix 'lx-dmesg' on 32 bits arch
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
Diffstat (limited to 'scripts/gdb')
-rw-r--r--scripts/gdb/linux/dmesg.py9
-rw-r--r--scripts/gdb/linux/utils.py14
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