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Fix dead_code in rust KParamGuard. #448

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Fix dead_code in rust KParamGuard. #448

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@kloenk kloenk commented Jul 16, 2021

Noticed as part of #439 With disabled CONFIG_SYSFS

@kloenk kloenk added • lib Related to the `rust/` library. • misc Related to other topics (e.g. CI). labels Jul 16, 2021
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alex commented Jul 16, 2021

Would it make more sense to put it behind a #[cfg]?

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kloenk commented Jul 16, 2021

I don't think so. It makes the api the same, and so easier to handle. Just did not want a compiler warning

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bjorn3 commented Jul 16, 2021

Maybe put just the #[allow] behind a #[cfg]? Also why does that lint fire at all? The type is exported from the kernel crate, right?

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kloenk commented Jul 16, 2021

I think because the internal type that is note used without the cfg.

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kloenk commented Jul 17, 2021

I will remove the inner type, and replace it with a Zero Sized type. this has the advantage, that it is not creating a lint problem, but also the interface to the kernel crate stays the same with or without the CONFIG

@kloenk kloenk force-pushed the KParamGuard-dead_code branch 2 times, most recently from aaf5d63 to e632fe9 Compare July 18, 2021 09:26
bjorn3
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This makes the KParamGuard's generics arity different depending on config, making it impossible to use with Rust 2018 idiom enforced.

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kloenk commented Jul 19, 2021

@nbdd0121 does that mean it would be better to just add the allow dead_code if not CONFIG_SYSFS and be done with it?

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Either that or just touch it using let _ = .... As @bjorn3 mentioned a Drop impl for KParamGuard is desirable anyway so you can just touch unused fields in drop.

@kloenk kloenk force-pushed the KParamGuard-dead_code branch from e632fe9 to 4b191e1 Compare July 23, 2021 12:12
@kloenk kloenk requested a review from bjorn3 July 23, 2021 12:13
bjorn3
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@kloenk kloenk force-pushed the KParamGuard-dead_code branch from 4b191e1 to 70720d8 Compare July 25, 2021 08:29
@kloenk kloenk requested a review from bjorn3 July 25, 2021 08:29
nbdd0121
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@kloenk kloenk force-pushed the KParamGuard-dead_code branch from 70720d8 to c8fcdcf Compare August 27, 2021 11:28
@kloenk kloenk requested a review from nbdd0121 November 25, 2021 08:06
ojeda
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@kloenk
Fix dead_code in rust KParamGuard.
6b55976 
Signed-off-by: Finn Behrens <me@kloenk.de>
@kloenk kloenk force-pushed the KParamGuard-dead_code branch from c8fcdcf to 6b55976 Compare January 27, 2022 12:11
@kloenk kloenk requested a review from ojeda January 27, 2022 12:11
ojeda pushed a commit that referenced this pull request Jun 11, 2024
@akpm00
vmalloc: check CONFIG_EXECMEM in is_vmalloc_or_module_addr()
0105eaa 
After commit 2c9e5d4 ("bpf: remove CONFIG_BPF_JIT dependency on
CONFIG_MODULES of") CONFIG_BPF_JIT does not depend on CONFIG_MODULES any
more and bpf jit also uses the [MODULES_VADDR, MODULES_END] memory region.
But is_vmalloc_or_module_addr() still checks CONFIG_MODULES, which then
returns false for a bpf jit memory region when CONFIG_MODULES is not
defined.  It leads to the following kernel BUG:

[    1.567023] ------------[ cut here ]------------
[    1.567883] kernel BUG at mm/vmalloc.c:745!
[    1.568477] Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI
[    1.569367] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.9.0+ #448
[    1.570247] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014
[    1.570786] RIP: 0010:vmalloc_to_page+0x48/0x1ec
[    1.570786] Code: 0f 00 00 e8 eb 1a 05 00 b8 37 00 00 00 48 ba fe ff ff ff ff 1f 00 00 4c 03 25 76 49 c6 02 48 c1 e0 28 48 01 e8 48 39 d0 76 02 <0f> 0b 4c 89 e7 e8 bf 1a 05 00 49 8b 04 24 48 a9 9f ff ff ff 0f 84
[    1.570786] RSP: 0018:ffff888007787960 EFLAGS: 00010212
[    1.570786] RAX: 000036ffa0000000 RBX: 0000000000000640 RCX: ffffffff8147e93c
[    1.570786] RDX: 00001ffffffffffe RSI: dffffc0000000000 RDI: ffffffff840e32c8
[    1.570786] RBP: ffffffffa0000000 R08: 0000000000000000 R09: 0000000000000000
[    1.570786] R10: ffff888007787a88 R11: ffffffff8475d8e7 R12: ffffffff83e80ff8
[    1.570786] R13: 0000000000000640 R14: 0000000000000640 R15: 0000000000000640
[    1.570786] FS:  0000000000000000(0000) GS:ffff88806cc00000(0000) knlGS:0000000000000000
[    1.570786] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    1.570786] CR2: ffff888006a01000 CR3: 0000000003e80000 CR4: 0000000000350ef0
[    1.570786] Call Trace:
[    1.570786]  <TASK>
[    1.570786]  ? __die_body+0x1b/0x58
[    1.570786]  ? die+0x31/0x4b
[    1.570786]  ? do_trap+0x9d/0x138
[    1.570786]  ? vmalloc_to_page+0x48/0x1ec
[    1.570786]  ? do_error_trap+0xcd/0x102
[    1.570786]  ? vmalloc_to_page+0x48/0x1ec
[    1.570786]  ? vmalloc_to_page+0x48/0x1ec
[    1.570786]  ? handle_invalid_op+0x2f/0x38
[    1.570786]  ? vmalloc_to_page+0x48/0x1ec
[    1.570786]  ? exc_invalid_op+0x2b/0x41
[    1.570786]  ? asm_exc_invalid_op+0x16/0x20
[    1.570786]  ? vmalloc_to_page+0x26/0x1ec
[    1.570786]  ? vmalloc_to_page+0x48/0x1ec
[    1.570786]  __text_poke+0xb6/0x458
[    1.570786]  ? __pfx_text_poke_memcpy+0x10/0x10
[    1.570786]  ? __pfx___mutex_lock+0x10/0x10
[    1.570786]  ? __pfx___text_poke+0x10/0x10
[    1.570786]  ? __pfx_get_random_u32+0x10/0x10
[    1.570786]  ? srso_return_thunk+0x5/0x5f
[    1.570786]  text_poke_copy_locked+0x70/0x84
[    1.570786]  text_poke_copy+0x32/0x4f
[    1.570786]  bpf_arch_text_copy+0xf/0x27
[    1.570786]  bpf_jit_binary_pack_finalize+0x26/0x5a
[    1.570786]  bpf_int_jit_compile+0x576/0x8ad
[    1.570786]  ? __pfx_bpf_int_jit_compile+0x10/0x10
[    1.570786]  ? srso_return_thunk+0x5/0x5f
[    1.570786]  ? __kmalloc_node_track_caller+0x2b5/0x2e0
[    1.570786]  bpf_prog_select_runtime+0x7c/0x199
[    1.570786]  bpf_prepare_filter+0x1e9/0x25b
[    1.570786]  ? __pfx_bpf_prepare_filter+0x10/0x10
[    1.570786]  ? srso_return_thunk+0x5/0x5f
[    1.570786]  ? _find_next_bit+0x29/0x7e
[    1.570786]  bpf_prog_create+0xb8/0xe0
[    1.570786]  ptp_classifier_init+0x75/0xa1
[    1.570786]  ? __pfx_ptp_classifier_init+0x10/0x10
[    1.570786]  ? srso_return_thunk+0x5/0x5f
[    1.570786]  ? register_pernet_subsys+0x36/0x42
[    1.570786]  ? srso_return_thunk+0x5/0x5f
[    1.570786]  sock_init+0x99/0xa3
[    1.570786]  ? __pfx_sock_init+0x10/0x10
[    1.570786]  do_one_initcall+0x104/0x2c4
[    1.570786]  ? __pfx_do_one_initcall+0x10/0x10
[    1.570786]  ? parameq+0x25/0x2d
[    1.570786]  ? rcu_is_watching+0x1c/0x3c
[    1.570786]  ? trace_kmalloc+0x81/0xb2
[    1.570786]  ? srso_return_thunk+0x5/0x5f
[    1.570786]  ? __kmalloc+0x29c/0x2c7
[    1.570786]  ? srso_return_thunk+0x5/0x5f
[    1.570786]  do_initcalls+0xf9/0x123
[    1.570786]  kernel_init_freeable+0x24f/0x289
[    1.570786]  ? __pfx_kernel_init+0x10/0x10
[    1.570786]  kernel_init+0x19/0x13a
[    1.570786]  ret_from_fork+0x24/0x41
[    1.570786]  ? __pfx_kernel_init+0x10/0x10
[    1.570786]  ret_from_fork_asm+0x1a/0x30
[    1.570786]  </TASK>
[    1.570819] ---[ end trace 0000000000000000 ]---
[    1.571463] RIP: 0010:vmalloc_to_page+0x48/0x1ec
[    1.572111] Code: 0f 00 00 e8 eb 1a 05 00 b8 37 00 00 00 48 ba fe ff ff ff ff 1f 00 00 4c 03 25 76 49 c6 02 48 c1 e0 28 48 01 e8 48 39 d0 76 02 <0f> 0b 4c 89 e7 e8 bf 1a 05 00 49 8b 04 24 48 a9 9f ff ff ff 0f 84
[    1.574632] RSP: 0018:ffff888007787960 EFLAGS: 00010212
[    1.575129] RAX: 000036ffa0000000 RBX: 0000000000000640 RCX: ffffffff8147e93c
[    1.576097] RDX: 00001ffffffffffe RSI: dffffc0000000000 RDI: ffffffff840e32c8
[    1.577084] RBP: ffffffffa0000000 R08: 0000000000000000 R09: 0000000000000000
[    1.578077] R10: ffff888007787a88 R11: ffffffff8475d8e7 R12: ffffffff83e80ff8
[    1.578810] R13: 0000000000000640 R14: 0000000000000640 R15: 0000000000000640
[    1.579823] FS:  0000000000000000(0000) GS:ffff88806cc00000(0000) knlGS:0000000000000000
[    1.580992] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    1.581869] CR2: ffff888006a01000 CR3: 0000000003e80000 CR4: 0000000000350ef0
[    1.582800] Kernel panic - not syncing: Fatal exception
[    1.583765] ---[ end Kernel panic - not syncing: Fatal exception ]---

Fix this by checking CONFIG_EXECMEM instead.

Link: https://lkml.kernel.org/r/20240528160838.102223-1-xiyou.wangcong@gmail.com
Fixes: 2c9e5d4 ("bpf: remove CONFIG_BPF_JIT dependency on CONFIG_MODULES of")
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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@kloenk @alex @bjorn3 @nbdd0121 @ojeda