Messages in this thread | | | Date | Tue, 15 Oct 2019 01:33:06 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v2] arm64: lse: fix LSE atomics with LLVM's integrated assembler |
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On Tue, Oct 08, 2019 at 02:27:30PM -0700, Sami Tolvanen wrote: > Unlike gcc, clang considers each inline assembly block to be independent > and therefore, when using the integrated assembler for inline assembly, > any preambles that enable features must be repeated in each block. > > This change defines __LSE_PREAMBLE and adds it to each inline assembly > block that has LSE instructions, which allows them to be compiled also > with clang's assembler. > > Link: https://github.com/ClangBuiltLinux/linux/issues/671 > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > --- > v2: > - Add a preamble to inline assembly blocks that use LSE instead > of allowing the compiler to emit LSE instructions everywhere. > > --- > arch/arm64/include/asm/atomic_lse.h | 19 +++++++++++++++++++ > arch/arm64/include/asm/lse.h | 6 +++--- > 2 files changed, 22 insertions(+), 3 deletions(-)
One thing I've always wanted from binutils is the ability to pass a flag to the assembler which means that it accepts all of the instructions that it knows about for a given major architecture (a bit like the '-cpu max' option to qemu). Even better would be the ability to supply a file at build time specifying the encodings, so that we could ship that with the kernel and avoid some of the mess we have in places like sysreg.h were we end up fighting against the assembler when trying to define new system register accessors.
The latter suggestion is a bit "pie in the sky", but do you think there is any scope for the former with clang?
Will
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