Christian Weisgerber: > Because amd64 should suffer from the same problem: > > fr->cpu_opts.the_dct36 = dct36_avx; > ... > fr->cpu_opts.the_dct36 = dct36_x86_64; > > dct36_avx and dct36_x86_64 are assembly routines that lack the > endbr64 landing pad. And yet, on my IBT-enabled amd64 laptop, > mpg123 plays just fine with both the avx and x86_64 decoders.
I have examined the generated assembly on the calling side. There is no "jmp *%r11" or such. Instead, calling the function pointer goes through __llvm_retpoline_r11: 0000000000000000 <__llvm_retpoline_r11>: 0: e8 0b 00 00 00 callq 10 <__llvm_retpoline_r11+0x10> 5: f3 90 pause 7: 0f ae e8 lfence %eax a: e9 f6 ff ff ff jmpq 5 <__llvm_retpoline_r11+0x5> f: cc int3 10: 4c 89 1c 24 mov %r11,(%rsp) 14: c3 retq 15: 0f ae e8 lfence %eax -- Christian "naddy" Weisgerber na...@mips.inka.de
