scripts/gdb/slab: add slab support

Add 'lx-slabinfo' and 'lx-slabtrace' support.

This GDB scripts print slabinfo and slabtrace for user
to analyze slab memory usage.

Example output like below:
(gdb) lx-slabinfo
Pointer | name | active_objs | num_objs | objsize | objperslab | pagesperslab
------------------ | -------------------- | ------------ | ------------ | -------- | ----------- | -------------
0xffff0000c59df480 | p9_req_t | 0 | 0 | 280 | 29 | 2
0xffff0000c59df280 | isp1760_qh | 0 | 0 | 160 | 25 | 1
0xffff0000c59df080 | isp1760_qtd | 0 | 0 | 184 | 22 | 1
0xffff0000c59dee80 | isp1760_urb_listite | 0 | 0 | 136 | 30 | 1
0xffff0000c59dec80 | asd_sas_event | 0 | 0 | 256 | 32 | 2
0xffff0000c59dea80 | sas_task | 0 | 0 | 448 | 36 | 4
0xffff0000c59de880 | bio-120 | 18 | 21 | 384 | 21 | 2
0xffff0000c59de680 | io_kiocb | 0 | 0 | 448 | 36 | 4
0xffff0000c59de480 | bfq_io_cq | 0 | 0 | 1504 | 21 | 8
0xffff0000c59de280 | bfq_queue | 0 | 0 | 720 | 22 | 4
0xffff0000c59de080 | mqueue_inode_cache | 1 | 28 | 1152 | 28 | 8
0xffff0000c59dde80 | v9fs_inode_cache | 0 | 0 | 832 | 39 | 8
...

(gdb) lx-slabtrace --cache_name kmalloc-1k
63 <tty_register_device_attr+508> waste=16632/264 age=46856/46871/46888 pid=1 cpus=6,
0xffff800008720240 <__kmem_cache_alloc_node+236>: mov x22, x0
0xffff80000862a4fc <kmalloc_trace+64>: mov x21, x0
0xffff8000095d086c <tty_register_device_attr+508>: mov x19, x0
0xffff8000095d0f98 <tty_register_driver+704>: cmn x0, #0x1, lsl #12
0xffff80000c2677e8 <vty_init+620>: Cannot access memory at address 0xffff80000c2677e8
0xffff80000c265a10 <tty_init+276>: Cannot access memory at address 0xffff80000c265a10
0xffff80000c26d3c4 <chr_dev_init+204>: Cannot access memory at address 0xffff80000c26d3c4
0xffff8000080161d4 <do_one_initcall+176>: mov w21, w0
0xffff80000c1c1b58 <kernel_init_freeable+956>: Cannot access memory at address 0xffff80000c1c1b58
0xffff80000acf1334 <kernel_init+36>: bl 0xffff8000081ac040 <async_synchronize_full>
0xffff800008018d00 <ret_from_fork+16>: mrs x28, sp_el0

(gdb) lx-slabtrace --cache_name kmalloc-1k --free
428 <not-available> age=4294958600 pid=0 cpus=0,

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Kuan-Ying Lee <[e-mail]>
Cc: AngeloGioacchino Del Regno <[e-mail]>
Cc: Chinwen Chang <[e-mail]>
Cc: Matthias Brugger <[e-mail]>
Cc: Qun-Wei Lin <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

scripts/gdb/linux/constants.py.in

···
 #include <linux/of_fdt.h>
 #include <linux/page_ext.h>
 #include <linux/radix-tree.h>
+#include <linux/slab.h>
 #include <linux/threads.h>
 
 /* We need to stringify expanded macros so that they can be parsed */
···
     LX_GDBPARSED(PAGE_EXT_OWNER)
     LX_GDBPARSED(PAGE_EXT_OWNER_ALLOCATED)
 
+/* linux/slab.h */
+LX_GDBPARSED(SLAB_RED_ZONE)
+LX_GDBPARSED(SLAB_POISON)
+LX_GDBPARSED(SLAB_KMALLOC)
+LX_GDBPARSED(SLAB_HWCACHE_ALIGN)
+LX_GDBPARSED(SLAB_CACHE_DMA)
+LX_GDBPARSED(SLAB_CACHE_DMA32)
+LX_GDBPARSED(SLAB_STORE_USER)
+LX_GDBPARSED(SLAB_PANIC)
+
 /* Kernel Configs */
 LX_CONFIG(CONFIG_GENERIC_CLOCKEVENTS)
 LX_CONFIG(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST)
···
 LX_CONFIG(CONFIG_DEBUG_VIRTUAL)
 LX_CONFIG(CONFIG_STACKDEPOT)
 LX_CONFIG(CONFIG_PAGE_OWNER)
+LX_CONFIG(CONFIG_SLUB_DEBUG)
+LX_CONFIG(CONFIG_SLAB_FREELIST_HARDENED)

scripts/gdb/linux/slab.py

···
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (c) 2023 MediaTek Inc.
+#
+# Authors:
+#  Kuan-Ying Lee <[e-mail]>
+#
+
+import gdb
+import re
+import traceback
+from linux import lists, utils, stackdepot, constants, mm
+
+SLAB_RED_ZONE       = constants.LX_SLAB_RED_ZONE
+SLAB_POISON         = constants.LX_SLAB_POISON
+SLAB_KMALLOC        = constants.LX_SLAB_KMALLOC
+SLAB_HWCACHE_ALIGN  = constants.LX_SLAB_HWCACHE_ALIGN
+SLAB_CACHE_DMA      = constants.LX_SLAB_CACHE_DMA
+SLAB_CACHE_DMA32    = constants.LX_SLAB_CACHE_DMA32
+SLAB_STORE_USER     = constants.LX_SLAB_STORE_USER
+SLAB_PANIC          = constants.LX_SLAB_PANIC
+
+OO_SHIFT = 16
+OO_MASK = (1 << OO_SHIFT) - 1
+
+if constants.LX_CONFIG_SLUB_DEBUG:
+    slab_type = utils.CachedType("struct slab")
+    slab_ptr_type = slab_type.get_type().pointer()
+    kmem_cache_type = utils.CachedType("struct kmem_cache")
+    kmem_cache_ptr_type = kmem_cache_type.get_type().pointer()
+    freeptr_t = utils.CachedType("freeptr_t")
+    freeptr_t_ptr = freeptr_t.get_type().pointer()
+
+    track_type = gdb.lookup_type('struct track')
+    track_alloc = int(gdb.parse_and_eval('TRACK_ALLOC'))
+    track_free = int(gdb.parse_and_eval('TRACK_FREE'))
+
+def slab_folio(slab):
+    return slab.cast(gdb.lookup_type("struct folio").pointer())
+
+def slab_address(slab):
+    p_ops = mm.page_ops().ops
+    folio = slab_folio(slab)
+    return p_ops.folio_address(folio)
+
+def for_each_object(cache, addr, slab_objects):
+    p = addr
+    if cache['flags'] & SLAB_RED_ZONE:
+        p += int(cache['red_left_pad'])
+    while p < addr + (slab_objects * cache['size']):
+        yield p
+        p = p + int(cache['size'])
+
+def get_info_end(cache):
+    if (cache['offset'] >= cache['inuse']):
+        return cache['inuse'] + gdb.lookup_type("void").pointer().sizeof
+    else:
+        return cache['inuse']
+
+def get_orig_size(cache, obj):
+    if cache['flags'] & SLAB_STORE_USER and cache['flags'] & SLAB_KMALLOC:
+        p = mm.page_ops().ops.kasan_reset_tag(obj)
+        p += get_info_end(cache)
+        p += gdb.lookup_type('struct track').sizeof * 2
+        p = p.cast(utils.get_uint_type().pointer())
+        return p.dereference()
+    else:
+        return cache['object_size']
+
+def get_track(cache, object_pointer, alloc):
+    p = object_pointer + get_info_end(cache)
+    p += (alloc * track_type.sizeof)
+    return p
+
+def oo_objects(x):
+    return int(x['x']) & OO_MASK
+
+def oo_order(x):
+    return int(x['x']) >> OO_SHIFT
+
+def reciprocal_divide(a, R):
+    t = (a * int(R['m'])) >> 32
+    return (t + ((a - t) >> int(R['sh1']))) >> int(R['sh2'])
+
+def __obj_to_index(cache, addr, obj):
+    return reciprocal_divide(int(mm.page_ops().ops.kasan_reset_tag(obj)) - addr, cache['reciprocal_size'])
+
+def swab64(x):
+    result = (((x & 0x00000000000000ff) << 56) |   \
+    ((x & 0x000000000000ff00) << 40) |   \
+    ((x & 0x0000000000ff0000) << 24) |   \
+    ((x & 0x00000000ff000000) <<  8) |   \
+    ((x & 0x000000ff00000000) >>  8) |   \
+    ((x & 0x0000ff0000000000) >> 24) |   \
+    ((x & 0x00ff000000000000) >> 40) |   \
+    ((x & 0xff00000000000000) >> 56))
+    return result
+
+def freelist_ptr_decode(cache, ptr, ptr_addr):
+    if constants.LX_CONFIG_SLAB_FREELIST_HARDENED:
+        return ptr['v'] ^ cache['random'] ^ swab64(int(ptr_addr))
+    else:
+        return ptr['v']
+
+def get_freepointer(cache, obj):
+    obj = mm.page_ops().ops.kasan_reset_tag(obj)
+    ptr_addr = obj + cache['offset']
+    p = ptr_addr.cast(freeptr_t_ptr).dereference()
+    return freelist_ptr_decode(cache, p, ptr_addr)
+
+def loc_exist(loc_track, addr, handle, waste):
+    for loc in loc_track:
+        if loc['addr'] == addr and loc['handle'] == handle and loc['waste'] == waste:
+            return loc
+    return None
+
+def add_location(loc_track, cache, track, orig_size):
+    jiffies = gdb.parse_and_eval("jiffies_64")
+    age = jiffies - track['when']
+    handle = 0
+    waste = cache['object_size'] - int(orig_size)
+    pid = int(track['pid'])
+    cpuid = int(track['cpu'])
+    addr = track['addr']
+    if constants.LX_CONFIG_STACKDEPOT:
+        handle = track['handle']
+
+    loc = loc_exist(loc_track, addr, handle, waste)
+    if loc:
+        loc['count'] += 1
+        if track['when']:
+            loc['sum_time'] += age
+            loc['min_time'] = min(loc['min_time'], age)
+            loc['max_time'] = max(loc['max_time'], age)
+            loc['min_pid'] = min(loc['min_pid'], pid)
+            loc['max_pid'] = max(loc['max_pid'], pid)
+            loc['cpus'].add(cpuid)
+    else:
+        loc_track.append({
+            'count' : 1,
+            'addr' : addr,
+            'sum_time' : age,
+            'min_time' : age,
+            'max_time' : age,
+            'min_pid' : pid,
+            'max_pid' : pid,
+            'handle' : handle,
+            'waste' : waste,
+            'cpus' : {cpuid}
+            }
+        )
+
+def slabtrace(alloc, cache_name):
+
+    def __fill_map(obj_map, cache, slab):
+        p = slab['freelist']
+        addr = slab_address(slab)
+        while p != gdb.Value(0):
+            index = __obj_to_index(cache, addr, p)
+            obj_map[index] = True # free objects
+            p = get_freepointer(cache, p)
+
+    # process every slab page on the slab_list (partial and full list)
+    def process_slab(loc_track, slab_list, alloc, cache):
+        for slab in lists.list_for_each_entry(slab_list, slab_ptr_type, "slab_list"):
+            obj_map[:] = [False] * oo_objects(cache['oo'])
+            __fill_map(obj_map, cache, slab)
+            addr = slab_address(slab)
+            for object_pointer in for_each_object(cache, addr, slab['objects']):
+                if obj_map[__obj_to_index(cache, addr, object_pointer)] == True:
+                    continue
+                p = get_track(cache, object_pointer, alloc)
+                track = gdb.Value(p).cast(track_type.pointer())
+                if alloc == track_alloc:
+                    size = get_orig_size(cache, object_pointer)
+                else:
+                    size = cache['object_size']
+                add_location(loc_track, cache, track, size)
+                continue
+
+    slab_caches = gdb.parse_and_eval("slab_caches")
+    if mm.page_ops().ops.MAX_NUMNODES > 1:
+        nr_node_ids = int(gdb.parse_and_eval("nr_node_ids"))
+    else:
+        nr_node_ids = 1
+
+    target_cache = None
+    loc_track = []
+
+    for cache in lists.list_for_each_entry(slab_caches, kmem_cache_ptr_type, 'list'):
+        if cache['name'].string() == cache_name:
+            target_cache = cache
+            break
+
+    obj_map = [False] * oo_objects(target_cache['oo'])
+
+    if target_cache['flags'] & SLAB_STORE_USER:
+        for i in range(0, nr_node_ids):
+            cache_node = target_cache['node'][i]
+            if cache_node['nr_slabs']['counter'] == 0:
+                continue
+            process_slab(loc_track, cache_node['partial'], alloc, target_cache)
+            process_slab(loc_track, cache_node['full'], alloc, target_cache)
+    else:
+        raise gdb.GdbError("SLAB_STORE_USER is not set in %s" % target_cache['name'].string())
+
+    for loc in sorted(loc_track, key=lambda x:x['count'], reverse=True):
+        if loc['addr']:
+            addr = loc['addr'].cast(utils.get_ulong_type().pointer())
+            gdb.write("%d %s" % (loc['count'], str(addr).split(' ')[-1]))
+        else:
+            gdb.write("%d <not-available>" % loc['count'])
+
+        if loc['waste']:
+            gdb.write(" waste=%d/%d" % (loc['count'] * loc['waste'], loc['waste']))
+
+        if loc['sum_time'] != loc['min_time']:
+            gdb.write(" age=%d/%d/%d" % (loc['min_time'], loc['sum_time']/loc['count'], loc['max_time']))
+        else:
+            gdb.write(" age=%d" % loc['min_time'])
+
+        if loc['min_pid'] != loc['max_pid']:
+            gdb.write(" pid=%d-%d" % (loc['min_pid'], loc['max_pid']))
+        else:
+            gdb.write(" pid=%d" % loc['min_pid'])
+
+        if constants.LX_NR_CPUS > 1:
+            nr_cpu = gdb.parse_and_eval('__num_online_cpus')['counter']
+            if nr_cpu > 1:
+                gdb.write(" cpus=")
+                for i in loc['cpus']:
+                    gdb.write("%d," % i)
+        gdb.write("\n")
+        if constants.LX_CONFIG_STACKDEPOT:
+            if loc['handle']:
+                stackdepot.stack_depot_print(loc['handle'])
+        gdb.write("\n")
+
+def help():
+    t = """Usage: lx-slabtrace --cache_name [cache_name] [Options]
+    Options:
+        --alloc
+            print information of allocation trace of the allocated objects
+        --free
+            print information of freeing trace of the allocated objects
+    Example:
+        lx-slabtrace --cache_name kmalloc-1k --alloc
+        lx-slabtrace --cache_name kmalloc-1k --free\n"""
+    gdb.write("Unrecognized command\n")
+    raise gdb.GdbError(t)
+
+class LxSlabTrace(gdb.Command):
+    """Show specific cache slabtrace"""
+
+    def __init__(self):
+        super(LxSlabTrace, self).__init__("lx-slabtrace", gdb.COMMAND_DATA)
+
+    def invoke(self, arg, from_tty):
+        if not constants.LX_CONFIG_SLUB_DEBUG:
+            raise gdb.GdbError("CONFIG_SLUB_DEBUG is not enabled")
+
+        argv = gdb.string_to_argv(arg)
+        alloc = track_alloc # default show alloc_traces
+
+        if len(argv) == 3:
+            if argv[2] == '--alloc':
+                alloc = track_alloc
+            elif argv[2] == '--free':
+                alloc = track_free
+            else:
+                help()
+        if len(argv) >= 2 and argv[0] == '--cache_name':
+            slabtrace(alloc, argv[1])
+        else:
+            help()
+LxSlabTrace()
+
+def slabinfo():
+    nr_node_ids = None
+
+    if not constants.LX_CONFIG_SLUB_DEBUG:
+        raise gdb.GdbError("CONFIG_SLUB_DEBUG is not enabled")
+
+    def count_free(slab):
+        total_free = 0
+        for slab in lists.list_for_each_entry(slab, slab_ptr_type, 'slab_list'):
+            total_free += int(slab['objects'] - slab['inuse'])
+        return total_free
+
+    gdb.write("{:^18} | {:^20} | {:^12} | {:^12} | {:^8} | {:^11} | {:^13}\n".format('Pointer', 'name', 'active_objs', 'num_objs', 'objsize', 'objperslab', 'pagesperslab'))
+    gdb.write("{:-^18} | {:-^20} | {:-^12} | {:-^12} | {:-^8} | {:-^11} | {:-^13}\n".format('', '', '', '', '', '', ''))
+
+    slab_caches = gdb.parse_and_eval("slab_caches")
+    if mm.page_ops().ops.MAX_NUMNODES > 1:
+        nr_node_ids = int(gdb.parse_and_eval("nr_node_ids"))
+    else:
+        nr_node_ids = 1
+
+    for cache in lists.list_for_each_entry(slab_caches, kmem_cache_ptr_type, 'list'):
+        nr_objs = 0
+        nr_free = 0
+        nr_slabs = 0
+        for i in range(0, nr_node_ids):
+            cache_node = cache['node'][i]
+            try:
+                nr_slabs += cache_node['nr_slabs']['counter']
+                nr_objs = int(cache_node['total_objects']['counter'])
+                nr_free = count_free(cache_node['partial'])
+            except:
+                raise gdb.GdbError(traceback.format_exc())
+        active_objs = nr_objs - nr_free
+        num_objs = nr_objs
+        active_slabs = nr_slabs
+        objects_per_slab = oo_objects(cache['oo'])
+        cache_order = oo_order(cache['oo'])
+        gdb.write("{:18s} | {:20.19s} | {:12} | {:12} | {:8} | {:11} | {:13}\n".format(hex(cache), cache['name'].string(), str(active_objs), str(num_objs), str(cache['size']), str(objects_per_slab), str(1 << cache_order)))
+
+class LxSlabInfo(gdb.Command):
+    """Show slabinfo"""
+
+    def __init__(self):
+        super(LxSlabInfo, self).__init__("lx-slabinfo", gdb.COMMAND_DATA)
+
+    def invoke(self, arg, from_tty):
+        slabinfo()
+LxSlabInfo()

scripts/gdb/vmlinux-gdb.py

···
     import linux.mm
     import linux.stackdepot
     import linux.page_owner
+    import linux.slab