draft PR for gaining insight into what is needed for Go 1.17 calling conventions; DO NOT MERGE

kernel/asm_amd64.s

@@ -14,6 +14,23 @@ TEXT ·rt0(SB), NOSPLIT, $0-0
 	SUBQ $0x10, SP
 	MOVQ DI, 0(SP)
 	MOVQ SI, 8(SP)
+
+	// NOTE: the SSE instruction set must be initialized prior to invoking the
+	// first Go function, since any transition from asm -> Go will be handled by
+	// an autogenerated Go function wrapper for the given function (e.g.
+	// kernel.preinit<autogenerated>). The autogenerated function invokes
+	// `xorps %xmm15, %xmm15` which crashes the machine unless the FPU has been
+	// initialized.
+	CALL ·sseInit(SB)
+
+	// NOTE: the fs segment register must be set prior to invoking the first Go
+	// function, since any transition from asm -> Go will be handled by an
+	// autogenerated Go function wrapper for the given function (e.g.
+	// kernel.preinit<autogenerated>). The autogenerated function invokes
+	// `%fs:0xfffffffffffffff8,%r14` which crashes the machine unless the fs
+	// segment register has been set.
+	CALL ·initFakeFS(SB)
+
 	CALL ·preinit(SB)
 	INT  $3
 
@@ -27,6 +44,24 @@ TEXT ·go_entry(SB), NOSPLIT, $0
 	ADDQ  $8, SP
 	JMP   _rt0_amd64_linux(SB)
 
+// initFakeFS initializes a valid fake %fs segment register as required by the
+// <autogenerated> function wrappers of the Go 1.17 calling convention
+// (see icexin/eggos#100) when invoked before kernel.thread0Init.
+TEXT ·initFakeFS(SB), NOSPLIT, $0
+	// HACK: just use a memory pointer on the stack that we are unlikely to
+	// overwrite untill we run thread0Init, at which point, %fs will be set to
+	// its real value.
+	SUBQ $100000, SP        // TODO: figure out a better way to handle %fs, use a memory address that will never be used before by other instructions before thread0Init.
+
+	MOVL $0xc0000100, CX // _MSR_FS_BASE
+	MOVL SP, AX          // low, just to get a valid address to.
+	//ADDL $0x3, AX      // low, set lower 2 bits to prevent EIO error
+	MOVL $0x0, DX        // high
+	WRMSR
+
+	ADDQ  $100000, SP
+	RET
+
 // sseInit initializes the SSE instruction set.
 TEXT ·sseInit(SB), NOSPLIT, $0
 	MOVL CR0, AX

kernel/simd.go

@@ -20,7 +20,7 @@ func cpuid(fn, cx uint32) (eax, ebx, ecx, edx uint32)
 
 //go:nosplit
 func simdInit() {
-	sseInit()
+	//sseInit() // NOTE: invoked from asm (instead of Go) to support <autogenerated> function wrappers introduced in Go 1.17.
 
 	// init for avx
 	// first check avx function

kernel/trap.s

@@ -57,5 +57,13 @@ TEXT ·trapret(SB), NOSPLIT, $0
 
 	ADDQ $16, SP // skip trapno and errcode
 
+	ADDQ $8, SP // NOTE: skip return address of <autogenerated> function (added in Go 1.17).
+
+	// Dump of assembler code for function github.com/icexin/eggos/kernel.trapret<autogenerated>:
+	// => 0x00000000002bbf60 <+0>:   call   0x2b9e40 <github.com/icexin/eggos/kernel.trapret>
+	//    0x00000000002bbf65 <+5>:   xorps  %xmm15,%xmm15
+	//    0x00000000002bbf69 <+9>:   mov    %fs:0xfffffffffffffff8,%r14
+	//    0x00000000002bbf72 <+18>:  ret
+
 	IRETQ