runtime: fix vet complaints for all freebsd, netbsd, openbsd

Working toward making the tree vet-safe instead of having
so many exceptions in cmd/vet/all/whitelist.

This CL makes "go vet -unsafeptr=false runtime" happy for these GOOSes,
while keeping "GO_BUILDER_NAME=misc-vetall go tool dist test" happy too.

For #31916.

Change-Id: I63c4805bdd44b301072da66c77086940e2a2765e
Reviewed-on: https://go-review.googlesource.com/c/go/+/176105
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/vet/all/whitelist/freebsd_386.txt

-// freebsd/386-specific vet whitelist. See readme.txt for details.
-
-runtime/sys_freebsd_386.s: [386] thr_start: unknown variable mm
-runtime/sys_freebsd_386.s: [386] sigtramp: unknown variable signo
-runtime/sys_freebsd_386.s: [386] sigtramp: unknown variable info
-runtime/sys_freebsd_386.s: [386] sigtramp: unknown variable context
-runtime/sys_freebsd_386.s: [386] sigtramp: unknown variable context
-runtime/sys_freebsd_386.s: [386] i386_set_ldt: function i386_set_ldt missing Go declaration

src/cmd/vet/all/whitelist/netbsd_386.txt

-// netbsd/386-specific vet whitelist. See readme.txt for details.
-
-runtime/sys_netbsd_386.s: [386] sigreturn_tramp: use of 140(SP) points beyond argument frame
-runtime/sys_netbsd_386.s: [386] sigreturn_tramp: use of 4(SP) points beyond argument frame
-runtime/sys_netbsd_386.s: [386] sigreturn_tramp: use of 4(SP) points beyond argument frame
-runtime/sys_netbsd_386.s: [386] sigtramp: unknown variable signo
-runtime/sys_netbsd_386.s: [386] sigtramp: unknown variable info
-runtime/sys_netbsd_386.s: [386] sigtramp: unknown variable context
-

src/cmd/vet/all/whitelist/netbsd_arm64.txt

-runtime/sys_netbsd_ARCHSUFF.s: [GOARCH] sigreturn_tramp: function sigreturn_tramp missing Go declaration

src/cmd/vet/all/whitelist/openbsd_386.txt

-// openbsd/386-specific vet whitelist. See readme.txt for details.
-
-runtime/sys_openbsd_386.s: [386] sigtramp: unknown variable signo
-runtime/sys_openbsd_386.s: [386] sigtramp: unknown variable info
-runtime/sys_openbsd_386.s: [386] sigtramp: unknown variable context

src/runtime/sys_freebsd_386.s

@@ -22,8 +22,10 @@ TEXT runtime·thr_new(SB),NOSPLIT,$-4
 	MOVL	AX, ret+8(FP)
 	RET
 
+// Called by OS using C ABI.
 TEXT runtime·thr_start(SB),NOSPLIT,$0
-	MOVL	mm+0(FP), AX
+	NOP	SP	// tell vet SP changed - stop checking offsets
+	MOVL	4(SP), AX // m
 	MOVL	m_g0(AX), BX
 	LEAL	m_tls(AX), BP
 	MOVL	m_id(AX), DI
@@ -234,17 +236,19 @@ TEXT runtime·sigfwd(SB),NOSPLIT,$12-16
 	MOVL	AX, SP
 	RET
 
+// Called by OS using C ABI.
 TEXT runtime·sigtramp(SB),NOSPLIT,$12
-	MOVL	signo+0(FP), BX
+	NOP	SP	// tell vet SP changed - stop checking offsets
+	MOVL	16(SP), BX	// signo
 	MOVL	BX, 0(SP)
-	MOVL	info+4(FP), BX
+	MOVL	20(SP), BX // info
 	MOVL	BX, 4(SP)
-	MOVL	context+8(FP), BX
+	MOVL	24(SP), BX // context
 	MOVL	BX, 8(SP)
 	CALL	runtime·sigtrampgo(SB)
 
 	// call sigreturn
-	MOVL	context+8(FP), AX
+	MOVL	24(SP), AX	// context
 	MOVL	$0, 0(SP)	// syscall gap
 	MOVL	AX, 4(SP)
 	MOVL	$417, AX	// sigreturn(ucontext)
@@ -319,7 +323,7 @@ TEXT runtime·setldt(SB),NOSPLIT,$32
 	MOVL	$0xffffffff, 0(SP)	// auto-allocate entry and return in AX
 	MOVL	AX, 4(SP)
 	MOVL	$1, 8(SP)
-	CALL	runtime·i386_set_ldt(SB)
+	CALL	i386_set_ldt<>(SB)
 
 	// compute segment selector - (entry*8+7)
 	SHLL	$3, AX
@@ -327,7 +331,7 @@ TEXT runtime·setldt(SB),NOSPLIT,$32
 	MOVW	AX, GS
 	RET
 
-TEXT runtime·i386_set_ldt(SB),NOSPLIT,$16
+TEXT i386_set_ldt<>(SB),NOSPLIT,$16
 	LEAL	args+0(FP), AX	// 0(FP) == 4(SP) before SP got moved
 	MOVL	$0, 0(SP)	// syscall gap
 	MOVL	$1, 4(SP)

src/runtime/sys_netbsd_386.s

@@ -236,7 +236,7 @@ TEXT runtime·sigprocmask(SB),NOSPLIT,$-4
 	MOVL	$0xf1, 0xf1		// crash
 	RET
 
-TEXT runtime·sigreturn_tramp(SB),NOSPLIT,$0
+TEXT sigreturn_tramp<>(SB),NOSPLIT,$0
 	LEAL	140(SP), AX		// Load address of ucontext
 	MOVL	AX, 4(SP)
 	MOVL	$SYS_setcontext, AX
@@ -252,7 +252,7 @@ TEXT runtime·sigaction(SB),NOSPLIT,$24
 	MOVSL				// arg 1 - sig
 	MOVSL				// arg 2 - act
 	MOVSL				// arg 3 - oact
-	LEAL	runtime·sigreturn_tramp(SB), AX
+	LEAL	sigreturn_tramp<>(SB), AX
 	STOSL				// arg 4 - tramp
 	MOVL	$2, AX
 	STOSL				// arg 5 - vers
@@ -279,7 +279,9 @@ TEXT runtime·sigfwd(SB),NOSPLIT,$12-16
 	MOVL	AX, SP
 	RET
 
+// Called by OS using C ABI.
 TEXT runtime·sigtramp(SB),NOSPLIT,$28
+	NOP	SP	// tell vet SP changed - stop checking offsets
 	// Save callee-saved C registers, since the caller may be a C signal handler.
 	MOVL	BX, bx-4(SP)
 	MOVL	BP, bp-8(SP)
@@ -288,11 +290,11 @@ TEXT runtime·sigtramp(SB),NOSPLIT,$28
 	// We don't save mxcsr or the x87 control word because sigtrampgo doesn't
 	// modify them.
 
-	MOVL	signo+0(FP), BX
+	MOVL	32(SP), BX // signo
 	MOVL	BX, 0(SP)
-	MOVL	info+4(FP), BX
+	MOVL	36(SP), BX // info
 	MOVL	BX, 4(SP)
-	MOVL	context+8(FP), BX
+	MOVL	40(SP), BX // context
 	MOVL	BX, 8(SP)
 	CALL	runtime·sigtrampgo(SB)
 

src/runtime/sys_netbsd_amd64.s

@@ -258,7 +258,7 @@ TEXT runtime·sigprocmask(SB),NOSPLIT,$0
 	MOVL	$0xf1, 0xf1		// crash
 	RET
 
-TEXT runtime·sigreturn_tramp(SB),NOSPLIT,$-8
+TEXT sigreturn_tramp<>(SB),NOSPLIT,$-8
 	MOVQ	R15, DI			// Load address of ucontext
 	MOVQ	$SYS_setcontext, AX
 	SYSCALL
@@ -271,7 +271,7 @@ TEXT runtime·sigaction(SB),NOSPLIT,$-8
 	MOVQ	new+8(FP), SI		// arg 2 - nsa
 	MOVQ	old+16(FP), DX		// arg 3 - osa
 					// arg 4 - tramp
-	LEAQ	runtime·sigreturn_tramp(SB), R10
+	LEAQ	sigreturn_tramp<>(SB), R10
 	MOVQ	$2, R8			// arg 5 - vers
 	MOVL	$SYS___sigaction_sigtramp, AX
 	SYSCALL

src/runtime/sys_netbsd_arm.s

@@ -240,7 +240,7 @@ TEXT runtime·sigprocmask(SB),NOSPLIT,$0
 	MOVW.CS R8, (R8)
 	RET
 
-TEXT runtime·sigreturn_tramp(SB),NOSPLIT|NOFRAME,$0
+TEXT sigreturn_tramp<>(SB),NOSPLIT|NOFRAME,$0
 	// on entry, SP points to siginfo, we add sizeof(ucontext)
 	// to SP to get a pointer to ucontext.
 	ADD $0x80, R13, R0 // 0x80 == sizeof(UcontextT)
@@ -254,7 +254,7 @@ TEXT runtime·sigaction(SB),NOSPLIT,$4
 	MOVW sig+0(FP), R0	// arg 1 - signum
 	MOVW new+4(FP), R1	// arg 2 - nsa
 	MOVW old+8(FP), R2	// arg 3 - osa
-	MOVW $runtime·sigreturn_tramp(SB), R3	// arg 4 - tramp
+	MOVW $sigreturn_tramp<>(SB), R3	// arg 4 - tramp
 	MOVW $2, R4	// arg 5 - vers
 	MOVW R4, 4(R13)
 	ADD $4, R13	// pass arg 5 on stack

src/runtime/sys_netbsd_arm64.s

@@ -249,7 +249,7 @@ fail:
 	MOVD	$0, R0
 	MOVD	R0, (R0)		// crash
 
-TEXT runtime·sigreturn_tramp(SB),NOSPLIT,$-8
+TEXT sigreturn_tramp<>(SB),NOSPLIT,$-8
 	MOVD	g, R0
 	SVC	$SYS_setcontext
 	MOVD	$0x4242, R0		// Something failed, return magic number
@@ -260,7 +260,7 @@ TEXT runtime·sigaction(SB),NOSPLIT,$-8
 	MOVD	new+8(FP), R1		// arg 2 - nsa
 	MOVD	old+16(FP), R2		// arg 3 - osa
 					// arg 4 - tramp
-	MOVD	$runtime·sigreturn_tramp(SB), R3
+	MOVD	$sigreturn_tramp<>(SB), R3
 	MOVW	$2, R4			// arg 5 - vers
 	SVC	$SYS___sigaction_sigtramp
 	BCS	fail

src/runtime/sys_openbsd_386.s

@@ -218,7 +218,9 @@ TEXT runtime·sigfwd(SB),NOSPLIT,$12-16
 	MOVL	AX, SP
 	RET
 
+// Called by OS using C ABI.
 TEXT runtime·sigtramp(SB),NOSPLIT,$28
+	NOP	SP	// tell vet SP changed - stop checking offsets
 	// Save callee-saved C registers, since the caller may be a C signal handler.
 	MOVL	BX, bx-4(SP)
 	MOVL	BP, bp-8(SP)
@@ -227,11 +229,11 @@ TEXT runtime·sigtramp(SB),NOSPLIT,$28
 	// We don't save mxcsr or the x87 control word because sigtrampgo doesn't
 	// modify them.
 
-	MOVL	signo+0(FP), BX
+	MOVL	32(SP), BX // signo
 	MOVL	BX, 0(SP)
-	MOVL	info+4(FP), BX
+	MOVL	36(SP), BX // info
 	MOVL	BX, 4(SP)
-	MOVL	context+8(FP), BX
+	MOVL	40(SP), BX // context
 	MOVL	BX, 8(SP)
 	CALL	runtime·sigtrampgo(SB)