ref: dfed30d87b4f9dbae24b16ddd32ea0be69a5d602
dir: /lib/sys/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 R11,-16(SP) MOVQ R12,-24(SP) MOVQ R13,-32(SP) MOVQ R14,-40(SP) MOVQ R15,-48(SP) MOVQ BP,-56(SP) MOVQ 8(SP),RARG ADDQ $8,SP MOVQ DI, RARG SYSCALL SUBQ $8,SP MOVQ -16(SP),R11 MOVQ -24(SP),R12 MOVQ -32(SP),R13 MOVQ -40(SP),R14 MOVQ -48(SP),R15 MOVQ -56(SP),BP RET