ref: 488d30c090a2316c851e6d6d25c0c7c7540cb3a4
dir: /libstd/syscall+plan9-x64.s/
/* Ugly: Kernel is caller-save, Myrddin is callee-save. We need to preserve registers before entering the kernel. However, we also need SP to point to the start of the arguments. Luckily, the kernel doesn't touch our stack, and we have 256 bytes of gap if we get a note. */ TEXT sys$syscall+0(SB),1,$0 MOVQ BX,-16(SP) MOVQ CX,-24(SP) MOVQ DX,-32(SP) MOVQ SI,-40(SP) MOVQ DI,-48(SP) MOVQ BP,-56(SP) MOVQ R8,-64(SP) MOVQ R9,-72(SP) MOVQ R10,-80(SP) MOVQ R11,-88(SP) MOVQ R12,-104(SP) MOVQ R13,-112(SP) MOVQ R14,-120(SP) MOVQ R15,-128(SP) MOVQ 8(SP),RARG ADDQ $8,SP SYSCALL SUBQ $8,SP MOVQ -16(SP),BX MOVQ -24(SP),CX MOVQ -32(SP),DX MOVQ -40(SP),SI MOVQ -48(SP),DI MOVQ -56(SP),BP MOVQ -64(SP),R8 MOVQ -72(SP),R9 MOVQ -80(SP),R10 MOVQ -88(SP),R11 MOVQ -104(SP),R12 MOVQ -112(SP),R13 MOVQ -120(SP),R14 MOVQ -128(SP),R15 RET