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 --- lib/crypto/mpi/mpi-bit.c | 177 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 177 insertions(+) create mode 100644 lib/crypto/mpi/mpi-bit.c (limited to 'lib/crypto/mpi/mpi-bit.c') diff --git a/lib/crypto/mpi/mpi-bit.c b/lib/crypto/mpi/mpi-bit.c new file mode 100644 index 000000000..b3d0e7ddb --- /dev/null +++ b/lib/crypto/mpi/mpi-bit.c @@ -0,0 +1,177 @@ +/* mpi-bit.c - MPI bit level functions + * Copyright (C) 1998, 1999 Free Software Foundation, Inc. + * + * This file is part of GnuPG. + * + * GnuPG 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. + * + * GnuPG is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA + */ + +#include + +#include "mpi-internal.h" +#include "longlong.h" + +#define A_LIMB_1 ((mpi_limb_t) 1) + +/**************** + * Sometimes we have MSL (most significant limbs) which are 0; + * this is for some reasons not good, so this function removes them. + */ +void mpi_normalize(MPI a) +{ + for (; a->nlimbs && !a->d[a->nlimbs - 1]; a->nlimbs--) + ; +} + +/**************** + * Return the number of bits in A. + */ +unsigned mpi_get_nbits(MPI a) +{ + unsigned n; + + mpi_normalize(a); + + if (a->nlimbs) { + mpi_limb_t alimb = a->d[a->nlimbs - 1]; + if (alimb) + n = count_leading_zeros(alimb); + else + n = BITS_PER_MPI_LIMB; + n = BITS_PER_MPI_LIMB - n + (a->nlimbs - 1) * BITS_PER_MPI_LIMB; + } else + n = 0; + return n; +} +EXPORT_SYMBOL_GPL(mpi_get_nbits); + +/**************** + * Test whether bit N is set. + */ +int mpi_test_bit(MPI a, unsigned int n) +{ + unsigned int limbno, bitno; + mpi_limb_t limb; + + limbno = n / BITS_PER_MPI_LIMB; + bitno = n % BITS_PER_MPI_LIMB; + + if (limbno >= a->nlimbs) + return 0; /* too far left: this is a 0 */ + limb = a->d[limbno]; + return (limb & (A_LIMB_1 << bitno)) ? 1 : 0; +} +EXPORT_SYMBOL_GPL(mpi_test_bit); + +/**************** + * Set bit N of A. + */ +int mpi_set_bit(MPI a, unsigned int n) +{ + unsigned int i, limbno, bitno; + int err; + + limbno = n / BITS_PER_MPI_LIMB; + bitno = n % BITS_PER_MPI_LIMB; + + if (limbno >= a->nlimbs) { + for (i = a->nlimbs; i < a->alloced; i++) + a->d[i] = 0; + err = mpi_resize(a, limbno+1); + if (err) + return err; + a->nlimbs = limbno+1; + } + a->d[limbno] |= (A_LIMB_1<= x->nlimbs) { + x->nlimbs = 0; + return 0; + } + + if (nlimbs) { + for (i = 0; i < x->nlimbs - nlimbs; i++) + x->d[i] = x->d[i+nlimbs]; + x->d[i] = 0; + x->nlimbs -= nlimbs; + } + if (x->nlimbs && nbits) + mpihelp_rshift(x->d, x->d, x->nlimbs, nbits); + } else if (nlimbs) { + /* Copy and shift by more or equal bits than in a limb. */ + xsize = a->nlimbs; + x->sign = a->sign; + err = RESIZE_IF_NEEDED(x, xsize); + if (err) + return err; + x->nlimbs = xsize; + for (i = 0; i < a->nlimbs; i++) + x->d[i] = a->d[i]; + x->nlimbs = i; + + if (nlimbs >= x->nlimbs) { + x->nlimbs = 0; + return 0; + } + + for (i = 0; i < x->nlimbs - nlimbs; i++) + x->d[i] = x->d[i+nlimbs]; + x->d[i] = 0; + x->nlimbs -= nlimbs; + + if (x->nlimbs && nbits) + mpihelp_rshift(x->d, x->d, x->nlimbs, nbits); + } else { + /* Copy and shift by less than bits in a limb. */ + xsize = a->nlimbs; + x->sign = a->sign; + err = RESIZE_IF_NEEDED(x, xsize); + if (err) + return err; + x->nlimbs = xsize; + + if (xsize) { + if (nbits) + mpihelp_rshift(x->d, a->d, x->nlimbs, nbits); + else { + /* The rshift helper function is not specified for + * NBITS==0, thus we do a plain copy here. + */ + for (i = 0; i < x->nlimbs; i++) + x->d[i] = a->d[i]; + } + } + } + MPN_NORMALIZE(x->d, x->nlimbs); + + return 0; +} +EXPORT_SYMBOL_GPL(mpi_rshift); -- cgit v1.3.1