From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- include/net/ip6_checksum.h | 85 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 85 insertions(+) create mode 100644 include/net/ip6_checksum.h (limited to 'include/net/ip6_checksum.h') diff --git a/include/net/ip6_checksum.h b/include/net/ip6_checksum.h new file mode 100644 index 000000000..6677b3cc3 --- /dev/null +++ b/include/net/ip6_checksum.h @@ -0,0 +1,85 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * INET An implementation of the TCP/IP protocol suite for the LINUX + * operating system. INET is implemented using the BSD Socket + * interface as the means of communication with the user level. + * + * Checksumming functions for IPv6 + * + * Authors: Jorge Cwik, + * Arnt Gulbrandsen, + * Borrows very liberally from tcp.c and ip.c, see those + * files for more names. + */ + +/* + * Fixes: + * + * Ralf Baechle : generic ipv6 checksum + * + */ + +#ifndef _CHECKSUM_IPV6_H +#define _CHECKSUM_IPV6_H + +#include +#include +#include +#include +#include +#include +#include + +#ifndef _HAVE_ARCH_IPV6_CSUM +__sum16 csum_ipv6_magic(const struct in6_addr *saddr, + const struct in6_addr *daddr, + __u32 len, __u8 proto, __wsum csum); +#endif + +static inline __wsum ip6_compute_pseudo(struct sk_buff *skb, int proto) +{ + return ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr, + &ipv6_hdr(skb)->daddr, + skb->len, proto, 0)); +} + +static __inline__ __sum16 tcp_v6_check(int len, + const struct in6_addr *saddr, + const struct in6_addr *daddr, + __wsum base) +{ + return csum_ipv6_magic(saddr, daddr, len, IPPROTO_TCP, base); +} + +static inline void __tcp_v6_send_check(struct sk_buff *skb, + const struct in6_addr *saddr, + const struct in6_addr *daddr) +{ + struct tcphdr *th = tcp_hdr(skb); + + th->check = ~tcp_v6_check(skb->len, saddr, daddr, 0); + skb->csum_start = skb_transport_header(skb) - skb->head; + skb->csum_offset = offsetof(struct tcphdr, check); +} + +static inline void tcp_v6_gso_csum_prep(struct sk_buff *skb) +{ + struct ipv6hdr *ipv6h = ipv6_hdr(skb); + struct tcphdr *th = tcp_hdr(skb); + + ipv6h->payload_len = 0; + th->check = ~tcp_v6_check(0, &ipv6h->saddr, &ipv6h->daddr, 0); +} + +static inline __sum16 udp_v6_check(int len, + const struct in6_addr *saddr, + const struct in6_addr *daddr, + __wsum base) +{ + return csum_ipv6_magic(saddr, daddr, len, IPPROTO_UDP, base); +} + +void udp6_set_csum(bool nocheck, struct sk_buff *skb, + const struct in6_addr *saddr, + const struct in6_addr *daddr, int len); +#endif -- cgit v1.3.1