On 21/10/2024 11:07, Uros Bizjak wrote: > Cast pointer from percpu address space to generic (kernel) address > space in PERCPU_PTR() macro via unsigned long intermediate cast [1]. > This intermediate cast is also required to avoid build failure > when GCC's strict named address space checks for x86 targets [2] > are enabled. > > Found by GCC's named address space checks. > > [1] https://sparse.docs.kernel.org/en/latest/annotations.html#address-space-name > [2] https://gcc.gnu.org/onlinedocs/gcc/Named-Address-Spaces.html#x86-Named-Address-Spaces > > Signed-off-by: Uros Bizjak <ubizjak@xxxxxxxxx> > Cc: Dennis Zhou <dennis@xxxxxxxxxx> > Cc: Tejun Heo <tj@xxxxxxxxxx> > Cc: Christoph Lameter <cl@xxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- > include/linux/percpu-defs.h | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h > index e1cf7982424f..35842d1e3879 100644 > --- a/include/linux/percpu-defs.h > +++ b/include/linux/percpu-defs.h > @@ -221,7 +221,10 @@ do { \ > } while (0) > > #define PERCPU_PTR(__p) \ > - (typeof(*(__p)) __force __kernel *)(__p); > +({ \ > + unsigned long __pcpu_ptr = (__force unsigned long)(__p); \ > + (typeof(*(__p)) __force __kernel *)(__pcpu_ptr); \ > +}) > > #ifdef CONFIG_SMP > Hello Uros, We've encountered a kernel panic on boot [1] bisected to this patch. I believe the patch is fine and the issue is caused by a compiler bug. The panic reproduces when compiling the kernel with gcc 11.3.1, but does not reproduce with latest gcc/clang. I have a patch that workarounds the issue by ditching the intermediate variable and does the casting in a single line. Will that be enough to solve the sparse/build issues? Do you have anything else in mind? Thanks [1] [ 46.055628] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] SMP KASAN [ 46.057809] KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f] [ 46.059429] CPU: 0 UID: 0 PID: 547 Comm: iptables Not tainted 6.13.0-rc1_external_tested-master #1 [ 46.061243] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 [ 46.063453] RIP: 0010:nf_ct_netns_do_get+0x139/0x540 [ 46.064513] Code: 03 00 00 48 81 c4 88 00 00 00 5b 5d 41 5c 41 5d 41 5e 41 5f c3 4d 8d 75 08 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 27 03 00 00 41 8b 45 08 83 c0 [ 46.068081] RSP: 0018:ffff888116df75e8 EFLAGS: 00010207 [ 46.069186] RAX: dffffc0000000000 RBX: 1ffff11022dbeebe RCX: ffffffff839a2382 [ 46.070662] RDX: 0000000000000003 RSI: 0000000000000008 RDI: ffff88842ec46d10 [ 46.072086] RBP: 0000000000000002 R08: 0000000000000000 R09: fffffbfff0b0860c [ 46.073513] R10: ffff888116df75e8 R11: 0000000000000001 R12: ffffffff879d6a80 [ 46.075021] R13: 0000000000000016 R14: 000000000000001e R15: ffff888116df7908 [ 46.076447] FS: 00007fba01646740(0000) GS:ffff88842ec00000(0000) knlGS:0000000000000000 [ 46.078159] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 46.079353] CR2: 000055bd901800d8 CR3: 00000001205f0003 CR4: 0000000000172eb0 [ 46.080772] Call Trace: [ 46.081417] <TASK> [ 46.082014] ? die_addr+0x3d/0xa0 [ 46.082855] ? exc_general_protection+0x144/0x220 [ 46.083893] ? asm_exc_general_protection+0x22/0x30 [ 46.084934] ? __mutex_lock+0x2c2/0x1d70 [ 46.085859] ? nf_ct_netns_do_get+0x139/0x540 [ 46.086858] ? nf_ct_netns_do_get+0xb5/0x540 [ 46.087812] ? net_generic+0x1f0/0x1f0 [ 46.088663] ? __create_object+0x5e/0x80 [ 46.089559] xt_check_target+0x1f0/0x930 [ 46.090520] ? textify_hooks.constprop.0+0x110/0x110 [ 46.091581] ? pcpu_alloc_noprof+0x7cd/0xcf0 [ 46.092535] ? xt_find_target+0x148/0x1e0 [ 46.093434] find_check_entry.constprop.0+0x6c0/0x920 [ 46.094582] ? get_info+0x380/0x380 [ 46.095408] ? __virt_addr_valid+0x1df/0x3b0 [ 46.096363] ? kasan_quarantine_put+0xe3/0x200 [ 46.097341] ? kfree+0x13e/0x3d0 [ 46.098171] ? translate_table+0xaf5/0x1750 [ 46.099114] translate_table+0xbd8/0x1750 [ 46.100021] ? ipt_unregister_table_exit+0x30/0x30 [ 46.101047] ? __might_fault+0xbb/0x170 [ 46.101937] do_ipt_set_ctl+0x408/0x1340 [ 46.102856] ? nf_sockopt_find.constprop.0+0x17b/0x1f0 [ 46.103943] ? lock_downgrade+0x680/0x680 [ 46.104849] ? lockdep_hardirqs_on_prepare+0x284/0x400 [ 46.105973] ? ipt_register_table+0x440/0x440 [ 46.106978] ? bit_wait_timeout+0x160/0x160 [ 46.107916] nf_setsockopt+0x6f/0xd0 [ 46.108745] raw_setsockopt+0x7e/0x200 [ 46.109608] ? raw_bind+0x590/0x590 [ 46.110462] ? do_user_addr_fault+0x812/0xd20 [ 46.111425] do_sock_setsockopt+0x1e2/0x3f0 [ 46.112360] ? move_addr_to_user+0x90/0x90 [ 46.113279] ? lock_downgrade+0x680/0x680 [ 46.114225] __sys_setsockopt+0x9e/0x100 [ 46.115420] __x64_sys_setsockopt+0xb9/0x150 [ 46.116413] ? do_syscall_64+0x33/0x140 [ 46.117296] do_syscall_64+0x6d/0x140 [ 46.118194] entry_SYSCALL_64_after_hwframe+0x4b/0x53 [ 46.119289] RIP: 0033:0x7fba015134ce [ 46.120129] Code: 0f 1f 40 00 48 8b 15 59 69 0e 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b1 0f 1f 00 f3 0f 1e fa 49 89 ca b8 36 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 0a c3 66 0f 1f 84 00 00 00 00 00 48 8b 15 21 [ 46.123951] RSP: 002b:00007ffd9de6f388 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 [ 46.125530] RAX: ffffffffffffffda RBX: 000055bd9017f490 RCX: 00007fba015134ce [ 46.127088] RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000004 [ 46.128503] RBP: 0000000000000500 R08: 0000000000000560 R09: 0000000000000052 [ 46.129920] R10: 000055bd901800e0 R11: 0000000000000246 R12: 000055bd90180140 [ 46.131445] R13: 000055bd901800e0 R14: 000055bd9017f498 R15: 000055bd9017ff10 [ 46.133422] </TASK> [ 46.134351] Modules linked in: xt_MASQUERADE nf_conntrack_netlink nfnetlink xt_addrtype iptable_nat nf_nat br_netfilter rpcsec_gss_krb5 auth_rpcgss oid_registry overlay zram zsmalloc mlx4_ib mlx4_en mlx4_core rpcrdma rdma_ucm ib_uverbs ib_iser libiscsi scsi_transport_iscsi fuse ib_umad rdma_cm ib_ipoib iw_cm ib_cm ib_core [ 46.140665] ---[ end trace 0000000000000000 ]---
