On Tue, Oct 22, 2024 at 01:31:24PM -0700, Raghavendra Rao Ananta wrote: > Hi Andrew, > > > > > With clang 18.1.8 (Fedora 18.1.8-1.fc40) I get a bunch of errors like > > these > > > > arm/fpu.c:281:3: error: instruction requires: fp-armv8 > > > > I used my cross-clang series[1] and configured with > > > > ./configure --arch=arm64 --cc=clang --cflags='--target=aarch64' > --cross-prefix=aarch64-linux-gnu- > > > > [1] > https://lore.kernel.org/all/20240911091406.134240-7-andrew.jones@xxxxxxxxx/ > > > > Thanks, > > drew > > I was able to reproduce the errors by pointing to a newer clang (20) and > applying your series. > I think we see the errors because llvm decided to disable loads and stores > on FP registers with "-mgeneral-regs-only" [1]. Explicitly adding > ".arch_extension fp" for the fp_reg_{read,write}() helped with the build: > > diff --git a/arm/fpu.c b/arm/fpu.c > index 6b0411d3..f44ed82a 100644 > --- a/arm/fpu.c > +++ b/arm/fpu.c > @@ -38,7 +38,8 @@ static inline bool arch_collect_entropy(uint64_t *random) > #define fpu_reg_read(val) \ > ({ \ > uint64_t *__val = (val); \ > - asm volatile("stp q0, q1, [%0], #32\n\t" \ > + asm volatile(".arch_extension fp\n" \ > + "stp q0, q1, [%0], #32\n\t" \ > "stp q2, q3, [%0], #32\n\t" \ > "stp q4, q5, [%0], #32\n\t" \ > "stp q6, q7, [%0], #32\n\t" \ > @@ -71,7 +72,8 @@ static inline bool arch_collect_entropy(uint64_t *random) > #define fpu_reg_write(val) \ > do { \ > uint64_t *__val = (val); \ > - asm volatile("ldp q0, q1, [%0], #32\n\t" \ > + asm volatile(".arch_extension fp\n" \ > + "ldp q0, q1, [%0], #32\n\t" \ > "ldp q2, q3, [%0], #32\n\t" \ > "ldp q4, q5, [%0], #32\n\t" \ > "ldp q6, q7, [%0], #32\n\t" \ > > If you are fine with this, I can push it as a separate patch in v2. The fix works for me too. Please post v2. Thanks, drew
