On Wed, Jan 13, 2021 at 12:55 PM Nathan Chancellor <natechancellor@xxxxxxxxx> wrote: > > However, I see an issue with actually using the data: > > $ sudo -s > # mount -t debugfs none /sys/kernel/debug > # cp -a /sys/kernel/debug/pgo/profraw vmlinux.profraw > # chown nathan:nathan vmlinux.profraw > # exit > $ tc-build/build/llvm/stage1/bin/llvm-profdata merge --output=vmlinux.profdata vmlinux.profraw > warning: vmlinux.profraw: Invalid instrumentation profile data (bad magic) > error: No profiles could be merged. > > Am I holding it wrong? :) Note, this is virtualized, I do not have any > "real" x86 hardware that I can afford to test on right now. Same. I think the magic calculation in this patch may differ from upstream llvm: https://github.com/llvm/llvm-project/blob/49142991a685bd427d7e877c29c77371dfb7634c/llvm/include/llvm/ProfileData/SampleProf.h#L96-L101 vs this patch: + * Note: These internal LLVM definitions must match the compiler version. + * See llvm/include/llvm/ProfileData/InstrProfData.inc in LLVM's source code. + */ + +#ifdef CONFIG_64BIT + #define LLVM_PRF_MAGIC \ + ((u64)255 << 56 | \ + (u64)'l' << 48 | \ + (u64)'p' << 40 | \ + (u64)'r' << 32 | \ + (u64)'o' << 24 | \ + (u64)'f' << 16 | \ + (u64)'r' << 8 | \ + (u64)129) +#else + #define LLVM_PRF_MAGIC \ + ((u64)255 << 56 | \ + (u64)'l' << 48 | \ + (u64)'p' << 40 | \ + (u64)'r' << 32 | \ + (u64)'o' << 24 | \ + (u64)'f' << 16 | \ + (u64)'R' << 8 | \ + (u64)129) +#endif -- Thanks, ~Nick Desaulniers
