From: Conor Dooley <conor@kernel.org> To: Nathan Chancellor <nathan@kernel.org> Cc: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, conor.dooley@microchip.com, ndesaulniers@google.com, trix@redhat.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, patches@lists.linux.dev, stable@vger.kernel.org Subject: Re: [PATCH] riscv: Handle zicsr/zifencei issues between clang and binutils Date: Tue, 14 Mar 2023 17:08:09 +0000 [thread overview] Message-ID: <75037eb4-7be4-4182-a377-18343491c7da@spud> (raw) In-Reply-To: <20230313-riscv-zicsr-zifencei-fiasco-v1-1-dd1b7840a551@kernel.org> [-- Attachment #1: Type: text/plain, Size: 4506 bytes --] Hey Nathan, On Mon, Mar 13, 2023 at 04:00:23PM -0700, Nathan Chancellor wrote: > There are two related issues that appear in certain combinations with > clang and GNU binutils. > > The first occurs when a version of clang that supports zicsr or zifencei > via '-march=' [1] (i.e, >= 17.x) is used in combination with a version > of GNU binutils that do not recognize zicsr and zifencei in the > '-march=' value (i.e., < 2.36): > > riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_c2p0_zicsr2p0_zifencei2p0: Invalid or unknown z ISA extension: 'zifencei' > riscv64-linux-gnu-ld: failed to merge target specific data of file fs/efivarfs/file.o > riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_c2p0_zicsr2p0_zifencei2p0: Invalid or unknown z ISA extension: 'zifencei' > riscv64-linux-gnu-ld: failed to merge target specific data of file fs/efivarfs/super.o > > The second occurs when a version of clang that does not support zicsr or > zifencei via '-march=' (i.e., <= 16.x) is used in combination with a > version of GNU as that defaults to a newer ISA base spec, which requires > specifying zicsr and zifencei in the '-march=' value explicitly (i.e, >= > 2.38): > > ../arch/riscv/kernel/kexec_relocate.S: Assembler messages: > ../arch/riscv/kernel/kexec_relocate.S:147: Error: unrecognized opcode `fence.i', extension `zifencei' required > clang-12: error: assembler command failed with exit code 1 (use -v to see invocation) > > This is the same issue addressed by commit 6df2a016c0c8 ("riscv: fix > build with binutils 2.38") (see [2] for additional information) but > older versions of clang miss out on it because the cc-option check > fails: > > clang-12: error: invalid arch name 'rv64imac_zicsr_zifencei', unsupported standard user-level extension 'zicsr' > clang-12: error: invalid arch name 'rv64imac_zicsr_zifencei', unsupported standard user-level extension 'zicsr' > > To resolve the first issue, only attempt to add zicsr and zifencei to > the march string when using the GNU assembler 2.38 or newer, which is > when the default ISA spec was updated, requiring these extensions to be > specified explicitly. LLVM implements an older version of the base > specification for all currently released versions, so these instructions > are available as part of the 'i' extension. If LLVM's implementation is > updated in the future, a CONFIG_AS_IS_LLVM condition can be added to > CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI. > > To resolve the second issue, use version 2.2 of the base ISA spec when > using an older version of clang that does not support zicsr or zifencei > via '-march=', as that is the spec version most compatible with the one > clang/LLVM implements and avoids the need to specify zicsr and zifencei > explicitly due to still being a part of 'i'. > > [1]: https://github.com/llvm/llvm-project/commit/22e199e6afb1263c943c0c0d4498694e15bf8a16 > [2]: https://lore.kernel.org/ZAxT7T9Xy1Fo3d5W@aurel32.net/ > > Cc: stable@vger.kernel.org > Link: https://github.com/ClangBuiltLinux/linux/issues/1808 > Co-developed-by: Conor Dooley <conor.dooley@microchip.com> > Signed-off-by: Conor Dooley <conor.dooley@microchip.com> TBH, barely identifiable as having much to do with my V1 anymore, so could easily have dropped those. Either way, thanks for sorting this out while I've been sick :) Acked-by: Conor Dooley <conor.dooley@microchip.com> > Signed-off-by: Nathan Chancellor <nathan@kernel.org> > --- > This is essentially a v3 of Conor's v1 and v2 but since I am sending the > patch after finding a separate but related issue, I left it at v1: > > - v1: https://lore.kernel.org/20230223220546.52879-1-conor@kernel.org/ > - v2: https://lore.kernel.org/20230308220842.1231003-1-conor@kernel.org/ > > I have built allmodconfig with the following toolchain combinations to > confirm this problem is resolved: > > - clang 12/17 + GNU as and ld 2.35/2.39 > - clang 12/17 with the integrated assembler + GNU ld 2.35/2.39 > - clang 12/17 with the integrated assembler + ld.lld > > There are a couple of other incompatibilities between clang-17 and GNU > binutils that I had to patch to get allmodconfig to build successfully > but those are less likely to be hit in practice because the full LLVM > stack can be used with LLVM versions 13.x and newer. > I will follow up > with separate issues and patches. Cool, I'll "look forward" to those... Thanks, Conor. [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 228 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Conor Dooley <conor@kernel.org> To: Nathan Chancellor <nathan@kernel.org> Cc: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, conor.dooley@microchip.com, ndesaulniers@google.com, trix@redhat.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, patches@lists.linux.dev, stable@vger.kernel.org Subject: Re: [PATCH] riscv: Handle zicsr/zifencei issues between clang and binutils Date: Tue, 14 Mar 2023 17:08:09 +0000 [thread overview] Message-ID: <75037eb4-7be4-4182-a377-18343491c7da@spud> (raw) In-Reply-To: <20230313-riscv-zicsr-zifencei-fiasco-v1-1-dd1b7840a551@kernel.org> [-- Attachment #1.1: Type: text/plain, Size: 4506 bytes --] Hey Nathan, On Mon, Mar 13, 2023 at 04:00:23PM -0700, Nathan Chancellor wrote: > There are two related issues that appear in certain combinations with > clang and GNU binutils. > > The first occurs when a version of clang that supports zicsr or zifencei > via '-march=' [1] (i.e, >= 17.x) is used in combination with a version > of GNU binutils that do not recognize zicsr and zifencei in the > '-march=' value (i.e., < 2.36): > > riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_c2p0_zicsr2p0_zifencei2p0: Invalid or unknown z ISA extension: 'zifencei' > riscv64-linux-gnu-ld: failed to merge target specific data of file fs/efivarfs/file.o > riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_c2p0_zicsr2p0_zifencei2p0: Invalid or unknown z ISA extension: 'zifencei' > riscv64-linux-gnu-ld: failed to merge target specific data of file fs/efivarfs/super.o > > The second occurs when a version of clang that does not support zicsr or > zifencei via '-march=' (i.e., <= 16.x) is used in combination with a > version of GNU as that defaults to a newer ISA base spec, which requires > specifying zicsr and zifencei in the '-march=' value explicitly (i.e, >= > 2.38): > > ../arch/riscv/kernel/kexec_relocate.S: Assembler messages: > ../arch/riscv/kernel/kexec_relocate.S:147: Error: unrecognized opcode `fence.i', extension `zifencei' required > clang-12: error: assembler command failed with exit code 1 (use -v to see invocation) > > This is the same issue addressed by commit 6df2a016c0c8 ("riscv: fix > build with binutils 2.38") (see [2] for additional information) but > older versions of clang miss out on it because the cc-option check > fails: > > clang-12: error: invalid arch name 'rv64imac_zicsr_zifencei', unsupported standard user-level extension 'zicsr' > clang-12: error: invalid arch name 'rv64imac_zicsr_zifencei', unsupported standard user-level extension 'zicsr' > > To resolve the first issue, only attempt to add zicsr and zifencei to > the march string when using the GNU assembler 2.38 or newer, which is > when the default ISA spec was updated, requiring these extensions to be > specified explicitly. LLVM implements an older version of the base > specification for all currently released versions, so these instructions > are available as part of the 'i' extension. If LLVM's implementation is > updated in the future, a CONFIG_AS_IS_LLVM condition can be added to > CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI. > > To resolve the second issue, use version 2.2 of the base ISA spec when > using an older version of clang that does not support zicsr or zifencei > via '-march=', as that is the spec version most compatible with the one > clang/LLVM implements and avoids the need to specify zicsr and zifencei > explicitly due to still being a part of 'i'. > > [1]: https://github.com/llvm/llvm-project/commit/22e199e6afb1263c943c0c0d4498694e15bf8a16 > [2]: https://lore.kernel.org/ZAxT7T9Xy1Fo3d5W@aurel32.net/ > > Cc: stable@vger.kernel.org > Link: https://github.com/ClangBuiltLinux/linux/issues/1808 > Co-developed-by: Conor Dooley <conor.dooley@microchip.com> > Signed-off-by: Conor Dooley <conor.dooley@microchip.com> TBH, barely identifiable as having much to do with my V1 anymore, so could easily have dropped those. Either way, thanks for sorting this out while I've been sick :) Acked-by: Conor Dooley <conor.dooley@microchip.com> > Signed-off-by: Nathan Chancellor <nathan@kernel.org> > --- > This is essentially a v3 of Conor's v1 and v2 but since I am sending the > patch after finding a separate but related issue, I left it at v1: > > - v1: https://lore.kernel.org/20230223220546.52879-1-conor@kernel.org/ > - v2: https://lore.kernel.org/20230308220842.1231003-1-conor@kernel.org/ > > I have built allmodconfig with the following toolchain combinations to > confirm this problem is resolved: > > - clang 12/17 + GNU as and ld 2.35/2.39 > - clang 12/17 with the integrated assembler + GNU ld 2.35/2.39 > - clang 12/17 with the integrated assembler + ld.lld > > There are a couple of other incompatibilities between clang-17 and GNU > binutils that I had to patch to get allmodconfig to build successfully > but those are less likely to be hit in practice because the full LLVM > stack can be used with LLVM versions 13.x and newer. > I will follow up > with separate issues and patches. Cool, I'll "look forward" to those... Thanks, Conor. [-- Attachment #1.2: signature.asc --] [-- Type: application/pgp-signature, Size: 228 bytes --] [-- Attachment #2: Type: text/plain, Size: 161 bytes --] _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2023-03-14 17:08 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-03-13 23:00 [PATCH] riscv: Handle zicsr/zifencei issues between clang and binutils Nathan Chancellor 2023-03-13 23:00 ` Nathan Chancellor 2023-03-14 17:08 ` Conor Dooley [this message] 2023-03-14 17:08 ` Conor Dooley 2023-03-23 20:48 ` Palmer Dabbelt 2023-03-23 20:48 ` Palmer Dabbelt 2023-03-23 20:49 ` Palmer Dabbelt 2023-03-23 20:49 ` Palmer Dabbelt 2023-03-23 20:55 ` b4 send (was Re: [PATCH] riscv: Handle zicsr/zifencei issues between clang and binutils) Conor Dooley 2023-03-23 20:55 ` Conor Dooley 2023-03-23 21:00 ` [PATCH] riscv: Handle zicsr/zifencei issues between clang and binutils patchwork-bot+linux-riscv 2023-03-23 21:00 ` patchwork-bot+linux-riscv
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