ref: b1481c67d3e7709020bdb3a107602ab6ac80624f
dir: /lib/sys/syscall+freebsd-x64.s/
.globl sys$syscall
sys$syscall:
/*
hack: We load 6 args regardless of
how many we actually have. This may
load junk values, but if the syscall
doesn't use them, it's going to be
harmless.
*/
movq %rdi,%rax
/* 8(%rsp): hidden type arg */
movq 16(%rsp),%rdi
movq 24(%rsp),%rsi
movq 32(%rsp),%rdx
movq 40(%rsp),%r10
movq 48(%rsp),%r8
movq 56(%rsp),%r9
syscall
jae .success
negq %rax
.success:
ret