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Fix rustc
>= nightly-2021-03-05 builds (i.e. LLVM 12)
#135
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Relevant relocation from #define R_AARCH64_ADR_GOT_PAGE 311 /* P-page-rel. GOT off. ADRP 32:12. */ I took a look at the logs for the CI failure and was wondering if there's a way to grab artifacts from the build run. I couldn't find a way |
There is currently no way that I am aware of, because we do not upload them (the reason is that, when I tried a couple months ago, it turned out it failed from time to time, it was not reliable). |
This was due to Possibly also related to rust-lang/rust#83335. |
rustc
>= nightly-2021-03-05 builds (i.e. LLVM 12)
Definitely looks related, we set relocation-model: static in our targets,
so if that's not being respected with LLVM 12, that'd definitely do it.
…On Mon, Mar 22, 2021 at 8:38 PM Miguel Ojeda ***@***.***> wrote:
This was due to rustc's upgrade to LLVM 12 (rust-lang/rust#81451
<rust-lang/rust#81451>) starting in nightly
2021-03-05.
Possibly also related to rust-lang/rust#83335
<rust-lang/rust#83335>.
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Yeah, I tried setting |
LLVM issue: https://bugs.llvm.org/show_bug.cgi?id=49693 |
PR on the Rust side: rust-lang/rust#83592 |
The fix has been merged 🎊 -- I will try the new nightly tomorrow and update accordingly. |
No more unsupported relocations since nightly 2021-04-07. However, |
Rustfmt has been present since 2021-04-13: https://rust-lang.github.io/rustup-components-history/ |
Set dso_local for more items Related to rust-lang#83592. (cc `@nagisa)` Noticed that on x86_64 with `relocation-model: static` `R_X86_64_GOTPCREL` relocations were still generated in some cases. (related: Rust-for-Linux/linux#135; Rust-for-Linux needs these fixes to successfully build) First time doing anything with LLVM so not sure whether this is correct but the following are some of the things I've tried to convince myself. ## C equivalent Example from clang which also sets `dso_local` in these cases: `clang-12 -fno-PIC -S -emit-llvm test.c` ```C extern int A; int* a() { return &A; } int B; int* b() { return &B; } ``` ``` ; ModuleID = 'test.c' source_filename = "test.c" target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128" target triple = "x86_64-unknown-linux-gnu" `@A` = external dso_local global i32, align 4 `@B` = dso_local global i32 0, align 4 ; Function Attrs: noinline nounwind optnone uwtable define dso_local i32* `@a()` #0 { ret i32* `@A` } ; Function Attrs: noinline nounwind optnone uwtable define dso_local i32* `@b()` #0 { ret i32* `@B` } attributes #0 = { noinline nounwind optnone uwtable "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" } !llvm.module.flags = !{!0} !llvm.ident = !{!1} !0 = !{i32 1, !"wchar_size", i32 4} !1 = !{!"clang version 12.0.0 (https://github.com/llvm/llvm-project/ b978a93)"} ``` `clang-12 -fno-PIC -c test.c` `objdump test.o -r`: ``` test.o: file format elf64-x86-64 RELOCATION RECORDS FOR [.text]: OFFSET TYPE VALUE 0000000000000006 R_X86_64_64 A 0000000000000016 R_X86_64_64 B RELOCATION RECORDS FOR [.eh_frame]: OFFSET TYPE VALUE 0000000000000020 R_X86_64_PC32 .text 0000000000000040 R_X86_64_PC32 .text+0x0000000000000010 ``` ## Comparison to pre-LLVM 12 output `rustc --emit=obj,llvm-ir --target=x86_64-unknown-none-linuxkernel --crate-type rlib test.rs` ```Rust #![feature(no_core, lang_items)] #![no_core] #[lang="sized"] trait Sized {} #[lang="sync"] trait Sync {} #[lang = "drop_in_place"] pub unsafe fn drop_in_place<T: ?Sized>(_: *mut T) {} impl Sync for i32 {} pub static STATIC: i32 = 32; extern { pub static EXT_STATIC: i32; } pub fn a() -> &'static i32 { &STATIC } pub fn b() -> &'static i32 { unsafe {&EXT_STATIC} } ``` `objdump test.o -r` nightly-2021-02-20 (rustc target is `x86_64-linux-kernel`): ``` RELOCATION RECORDS FOR [.text._ZN4test1a17h1024ba65f3424175E]: OFFSET TYPE VALUE 0000000000000007 R_X86_64_32S _ZN4test6STATIC17h3adc41a83746c9ffE RELOCATION RECORDS FOR [.text._ZN4test1b17h86a6a80c1190ac8dE]: OFFSET TYPE VALUE 0000000000000007 R_X86_64_32S EXT_STATIC ``` nightly-2021-05-10: ``` RELOCATION RECORDS FOR [.text._ZN4test1a17he846f03bf37b2d20E]: OFFSET TYPE VALUE 0000000000000007 R_X86_64_GOTPCREL _ZN4test6STATIC17h5a059515bf3d4968E-0x0000000000000004 RELOCATION RECORDS FOR [.text._ZN4test1b17h7e0f7f80fbd91125E]: OFFSET TYPE VALUE 0000000000000007 R_X86_64_GOTPCREL EXT_STATIC-0x0000000000000004 ``` This PR: ``` RELOCATION RECORDS FOR [.text._ZN4test1a17he846f03bf37b2d20E]: OFFSET TYPE VALUE 0000000000000007 R_X86_64_32S _ZN4test6STATIC17h5a059515bf3d4968E RELOCATION RECORDS FOR [.text._ZN4test1b17h7e0f7f80fbd91125E]: OFFSET TYPE VALUE 0000000000000007 R_X86_64_32S EXT_STATIC ```
syzkaller report: kernel BUG at net/core/skbuff.c:3452! invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.7.0-rc4-00009-gbee0e7762ad2-dirty #135 RIP: 0010:skb_copy_and_csum_bits (net/core/skbuff.c:3452) Call Trace: icmp_glue_bits (net/ipv4/icmp.c:357) __ip_append_data.isra.0 (net/ipv4/ip_output.c:1165) ip_append_data (net/ipv4/ip_output.c:1362 net/ipv4/ip_output.c:1341) icmp_push_reply (net/ipv4/icmp.c:370) __icmp_send (./include/net/route.h:252 net/ipv4/icmp.c:772) ip_fragment.constprop.0 (./include/linux/skbuff.h:1234 net/ipv4/ip_output.c:592 net/ipv4/ip_output.c:577) __ip_finish_output (net/ipv4/ip_output.c:311 net/ipv4/ip_output.c:295) ip_output (net/ipv4/ip_output.c:427) __ip_queue_xmit (net/ipv4/ip_output.c:535) __tcp_transmit_skb (net/ipv4/tcp_output.c:1462) __tcp_retransmit_skb (net/ipv4/tcp_output.c:3387) tcp_retransmit_skb (net/ipv4/tcp_output.c:3404) tcp_retransmit_timer (net/ipv4/tcp_timer.c:604) tcp_write_timer (./include/linux/spinlock.h:391 net/ipv4/tcp_timer.c:716) The panic issue was trigered by tcp simultaneous initiation. The initiation process is as follows: TCP A TCP B 1. CLOSED CLOSED 2. SYN-SENT --> <SEQ=100><CTL=SYN> ... 3. SYN-RECEIVED <-- <SEQ=300><CTL=SYN> <-- SYN-SENT 4. ... <SEQ=100><CTL=SYN> --> SYN-RECEIVED 5. SYN-RECEIVED --> <SEQ=100><ACK=301><CTL=SYN,ACK> ... // TCP B: not send challenge ack for ack limit or packet loss // TCP A: close tcp_close tcp_send_fin if (!tskb && tcp_under_memory_pressure(sk)) tskb = skb_rb_last(&sk->tcp_rtx_queue); //pick SYN_ACK packet TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; // set FIN flag 6. FIN_WAIT_1 --> <SEQ=100><ACK=301><END_SEQ=102><CTL=SYN,FIN,ACK> ... // TCP B: send challenge ack to SYN_FIN_ACK 7. ... <SEQ=301><ACK=101><CTL=ACK> <-- SYN-RECEIVED //challenge ack // TCP A: <SND.UNA=101> 8. FIN_WAIT_1 --> <SEQ=101><ACK=301><END_SEQ=102><CTL=SYN,FIN,ACK> ... // retransmit panic __tcp_retransmit_skb //skb->len=0 tcp_trim_head len = tp->snd_una - TCP_SKB_CB(skb)->seq // len=101-100 __pskb_trim_head skb->data_len -= len // skb->len=-1, wrap around ... ... ip_fragment icmp_glue_bits //BUG_ON If we use tcp_trim_head() to remove acked SYN from packet that contains data or other flags, skb->len will be incorrectly decremented. We can remove SYN flag that has been acked from rtx_queue earlier than tcp_trim_head(), which can fix the problem mentioned above. Fixes: 1da177e ("Linux-2.6.12-rc2") Co-developed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> Link: https://lore.kernel.org/r/20231210020200.1539875-1-dongchenchen2@huawei.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
https://github.com/Rust-for-Linux/linux/pull/134/checks?check_run_id=2161428668
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