kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

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 <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 230 insertions, 0 deletions

diff --git a/crypto/ecrdsa_defs.h b/crypto/ecrdsa_defs.h
new file mode 100644
index 000000000..1c2c2449e
--- /dev/null
+++ b/crypto/ecrdsa_defs.h
@@ -0,0 +1,230 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Definitions of EC-RDSA Curve Parameters
+ *
+ * Copyright (c) 2019 Vitaly Chikunov <vt@altlinux.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ */
+
+#ifndef _CRYTO_ECRDSA_DEFS_H
+#define _CRYTO_ECRDSA_DEFS_H
+
+#include <crypto/internal/ecc.h>
+
+#define ECRDSA_MAX_SIG_SIZE (2 * 512 / 8)
+#define ECRDSA_MAX_DIGITS (512 / 64)
+
+/*
+ * EC-RDSA uses its own set of curves.
+ *
+ * cp256{a,b,c} curves first defined for GOST R 34.10-2001 in RFC 4357 (as
+ * 256-bit {A,B,C}-ParamSet), but inherited for GOST R 34.10-2012 and
+ * proposed for use in R 50.1.114-2016 and RFC 7836 as the 256-bit curves.
+ */
+/* OID_gostCPSignA 1.2.643.2.2.35.1 */
+static u64 cp256a_g_x[] = {
+	0x0000000000000001ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull, };
+static u64 cp256a_g_y[] = {
+	0x22ACC99C9E9F1E14ull, 0x35294F2DDF23E3B1ull,
+	0x27DF505A453F2B76ull, 0x8D91E471E0989CDAull, };
+static u64 cp256a_p[] = { /* p = 2^256 - 617 */
+	0xFFFFFFFFFFFFFD97ull, 0xFFFFFFFFFFFFFFFFull,
+	0xFFFFFFFFFFFFFFFFull, 0xFFFFFFFFFFFFFFFFull };
+static u64 cp256a_n[] = {
+	0x45841B09B761B893ull, 0x6C611070995AD100ull,
+	0xFFFFFFFFFFFFFFFFull, 0xFFFFFFFFFFFFFFFFull };
+static u64 cp256a_a[] = { /* a = p - 3 */
+	0xFFFFFFFFFFFFFD94ull, 0xFFFFFFFFFFFFFFFFull,
+	0xFFFFFFFFFFFFFFFFull, 0xFFFFFFFFFFFFFFFFull };
+static u64 cp256a_b[] = {
+	0x00000000000000a6ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull };
+
+static struct ecc_curve gost_cp256a = {
+	.name = "cp256a",
+	.nbits = 256,
+	.g = {
+		.x = cp256a_g_x,
+		.y = cp256a_g_y,
+		.ndigits = 256 / 64,
+	},
+	.p = cp256a_p,
+	.n = cp256a_n,
+	.a = cp256a_a,
+	.b = cp256a_b
+};
+
+/* OID_gostCPSignB 1.2.643.2.2.35.2 */
+static u64 cp256b_g_x[] = {
+	0x0000000000000001ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull, };
+static u64 cp256b_g_y[] = {
+	0x744BF8D717717EFCull, 0xC545C9858D03ECFBull,
+	0xB83D1C3EB2C070E5ull, 0x3FA8124359F96680ull, };
+static u64 cp256b_p[] = { /* p = 2^255 + 3225 */
+	0x0000000000000C99ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x8000000000000000ull, };
+static u64 cp256b_n[] = {
+	0xE497161BCC8A198Full, 0x5F700CFFF1A624E5ull,
+	0x0000000000000001ull, 0x8000000000000000ull, };
+static u64 cp256b_a[] = { /* a = p - 3 */
+	0x0000000000000C96ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x8000000000000000ull, };
+static u64 cp256b_b[] = {
+	0x2F49D4CE7E1BBC8Bull, 0xE979259373FF2B18ull,
+	0x66A7D3C25C3DF80Aull, 0x3E1AF419A269A5F8ull, };
+
+static struct ecc_curve gost_cp256b = {
+	.name = "cp256b",
+	.nbits = 256,
+	.g = {
+		.x = cp256b_g_x,
+		.y = cp256b_g_y,
+		.ndigits = 256 / 64,
+	},
+	.p = cp256b_p,
+	.n = cp256b_n,
+	.a = cp256b_a,
+	.b = cp256b_b
+};
+
+/* OID_gostCPSignC 1.2.643.2.2.35.3 */
+static u64 cp256c_g_x[] = {
+	0x0000000000000000ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull, };
+static u64 cp256c_g_y[] = {
+	0x366E550DFDB3BB67ull, 0x4D4DC440D4641A8Full,
+	0x3CBF3783CD08C0EEull, 0x41ECE55743711A8Cull, };
+static u64 cp256c_p[] = {
+	0x7998F7B9022D759Bull, 0xCF846E86789051D3ull,
+	0xAB1EC85E6B41C8AAull, 0x9B9F605F5A858107ull,
+	/* pre-computed value for Barrett's reduction */
+	0xedc283cdd217b5a2ull, 0xbac48fc06398ae59ull,
+	0x405384d55f9f3b73ull, 0xa51f176161f1d734ull,
+	0x0000000000000001ull, };
+static u64 cp256c_n[] = {
+	0xF02F3A6598980BB9ull, 0x582CA3511EDDFB74ull,
+	0xAB1EC85E6B41C8AAull, 0x9B9F605F5A858107ull, };
+static u64 cp256c_a[] = { /* a = p - 3 */
+	0x7998F7B9022D7598ull, 0xCF846E86789051D3ull,
+	0xAB1EC85E6B41C8AAull, 0x9B9F605F5A858107ull, };
+static u64 cp256c_b[] = {
+	0x000000000000805aull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull, };
+
+static struct ecc_curve gost_cp256c = {
+	.name = "cp256c",
+	.nbits = 256,
+	.g = {
+		.x = cp256c_g_x,
+		.y = cp256c_g_y,
+		.ndigits = 256 / 64,
+	},
+	.p = cp256c_p,
+	.n = cp256c_n,
+	.a = cp256c_a,
+	.b = cp256c_b
+};
+
+/* tc512{a,b} curves first recommended in 2013 and then standardized in
+ * R 50.1.114-2016 and RFC 7836 for use with GOST R 34.10-2012 (as TC26
+ * 512-bit ParamSet{A,B}).
+ */
+/* OID_gostTC26Sign512A 1.2.643.7.1.2.1.2.1 */
+static u64 tc512a_g_x[] = {
+	0x0000000000000003ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull, };
+static u64 tc512a_g_y[] = {
+	0x89A589CB5215F2A4ull, 0x8028FE5FC235F5B8ull,
+	0x3D75E6A50E3A41E9ull, 0xDF1626BE4FD036E9ull,
+	0x778064FDCBEFA921ull, 0xCE5E1C93ACF1ABC1ull,
+	0xA61B8816E25450E6ull, 0x7503CFE87A836AE3ull, };
+static u64 tc512a_p[] = { /* p = 2^512 - 569 */
+	0xFFFFFFFFFFFFFDC7ull, 0xFFFFFFFFFFFFFFFFull,
+	0xFFFFFFFFFFFFFFFFull, 0xFFFFFFFFFFFFFFFFull,
+	0xFFFFFFFFFFFFFFFFull, 0xFFFFFFFFFFFFFFFFull,
+	0xFFFFFFFFFFFFFFFFull, 0xFFFFFFFFFFFFFFFFull, };
+static u64 tc512a_n[] = {
+	0xCACDB1411F10B275ull, 0x9B4B38ABFAD2B85Dull,
+	0x6FF22B8D4E056060ull, 0x27E69532F48D8911ull,
+	0xFFFFFFFFFFFFFFFFull, 0xFFFFFFFFFFFFFFFFull,
+	0xFFFFFFFFFFFFFFFFull, 0xFFFFFFFFFFFFFFFFull, };
+static u64 tc512a_a[] = { /* a = p - 3 */
+	0xFFFFFFFFFFFFFDC4ull, 0xFFFFFFFFFFFFFFFFull,
+	0xFFFFFFFFFFFFFFFFull, 0xFFFFFFFFFFFFFFFFull,
+	0xFFFFFFFFFFFFFFFFull, 0xFFFFFFFFFFFFFFFFull,
+	0xFFFFFFFFFFFFFFFFull, 0xFFFFFFFFFFFFFFFFull, };
+static u64 tc512a_b[] = {
+	0x503190785A71C760ull, 0x862EF9D4EBEE4761ull,
+	0x4CB4574010DA90DDull, 0xEE3CB090F30D2761ull,
+	0x79BD081CFD0B6265ull, 0x34B82574761CB0E8ull,
+	0xC1BD0B2B6667F1DAull, 0xE8C2505DEDFC86DDull, };
+
+static struct ecc_curve gost_tc512a = {
+	.name = "tc512a",
+	.nbits = 512,
+	.g = {
+		.x = tc512a_g_x,
+		.y = tc512a_g_y,
+		.ndigits = 512 / 64,
+	},
+	.p = tc512a_p,
+	.n = tc512a_n,
+	.a = tc512a_a,
+	.b = tc512a_b
+};
+
+/* OID_gostTC26Sign512B 1.2.643.7.1.2.1.2.2 */
+static u64 tc512b_g_x[] = {
+	0x0000000000000002ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull, };
+static u64 tc512b_g_y[] = {
+	0x7E21340780FE41BDull, 0x28041055F94CEEECull,
+	0x152CBCAAF8C03988ull, 0xDCB228FD1EDF4A39ull,
+	0xBE6DD9E6C8EC7335ull, 0x3C123B697578C213ull,
+	0x2C071E3647A8940Full, 0x1A8F7EDA389B094Cull, };
+static u64 tc512b_p[] = { /* p = 2^511 + 111 */
+	0x000000000000006Full, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x8000000000000000ull, };
+static u64 tc512b_n[] = {
+	0xC6346C54374F25BDull, 0x8B996712101BEA0Eull,
+	0xACFDB77BD9D40CFAull, 0x49A1EC142565A545ull,
+	0x0000000000000001ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x8000000000000000ull, };
+static u64 tc512b_a[] = { /* a = p - 3 */
+	0x000000000000006Cull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x0000000000000000ull,
+	0x0000000000000000ull, 0x8000000000000000ull, };
+static u64 tc512b_b[] = {
+	0xFB8CCBC7C5140116ull, 0x50F78BEE1FA3106Eull,
+	0x7F8B276FAD1AB69Cull, 0x3E965D2DB1416D21ull,
+	0xBF85DC806C4B289Full, 0xB97C7D614AF138BCull,
+	0x7E3E06CF6F5E2517ull, 0x687D1B459DC84145ull, };
+
+static struct ecc_curve gost_tc512b = {
+	.name = "tc512b",
+	.nbits = 512,
+	.g = {
+		.x = tc512b_g_x,
+		.y = tc512b_g_y,
+		.ndigits = 512 / 64,
+	},
+	.p = tc512b_p,
+	.n = tc512b_n,
+	.a = tc512b_a,
+	.b = tc512b_b
+};
+
+#endif