Revert "syscall: define Syscall6 in terms of RawSyscall6 on linux"

This reverts CL 388478. Parent CL 388477 breaks cmd/go
TestScript/cover_pkgall_runtime.

For #51087.
For #52472.

Change-Id: Id5d5a4e138792cf130ecdcc6b996c8102d142a7e
Reviewed-on: https://go-review.googlesource.com/c/go/+/401635
Run-TryBot: Michael Pratt <mpratt@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

10 files changed, 242 insertions, 10 deletions

diff --git a/src/syscall/asm_linux_386.s b/src/syscall/asm_linux_386.s
index e86a859f4e..ae0047b6fb 100644
--- a/src/syscall/asm_linux_386.s
+++ b/src/syscall/asm_linux_386.s
@@ -13,6 +13,32 @@
 // instead of the glibc-specific "CALL 0x10(GS)".
 #define INVOKE_SYSCALL	INT	$0x80
 
+// func Syscall6(trap uintptr, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr);
+TEXT ·Syscall6(SB),NOSPLIT,$0-40
+	CALL	runtime·entersyscall(SB)
+	MOVL	trap+0(FP), AX	// syscall entry
+	MOVL	a1+4(FP), BX
+	MOVL	a2+8(FP), CX
+	MOVL	a3+12(FP), DX
+	MOVL	a4+16(FP), SI
+	MOVL	a5+20(FP), DI
+	MOVL	a6+24(FP), BP
+	INVOKE_SYSCALL
+	CMPL	AX, $0xfffff001
+	JLS	ok6
+	MOVL	$-1, r1+28(FP)
+	MOVL	$0, r2+32(FP)
+	NEGL	AX
+	MOVL	AX, err+36(FP)
+	CALL	runtime·exitsyscall(SB)
+	RET
+ok6:
+	MOVL	AX, r1+28(FP)
+	MOVL	DX, r2+32(FP)
+	MOVL	$0, err+36(FP)
+	CALL	runtime·exitsyscall(SB)
+	RET
+
 // func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
 TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-16
 	MOVL	trap+0(FP), AX	// syscall entry
diff --git a/src/syscall/asm_linux_amd64.s b/src/syscall/asm_linux_amd64.s
index 3206a45d5d..ea939b39f0 100644
--- a/src/syscall/asm_linux_amd64.s
+++ b/src/syscall/asm_linux_amd64.s
@@ -11,6 +11,32 @@
 
 #define SYS_gettimeofday 96
 
+// func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr)
+TEXT ·Syscall6(SB),NOSPLIT,$0-80
+	CALL	runtime·entersyscall<ABIInternal>(SB)
+	MOVQ	a1+8(FP), DI
+	MOVQ	a2+16(FP), SI
+	MOVQ	a3+24(FP), DX
+	MOVQ	a4+32(FP), R10
+	MOVQ	a5+40(FP), R8
+	MOVQ	a6+48(FP), R9
+	MOVQ	trap+0(FP), AX	// syscall entry
+	SYSCALL
+	CMPQ	AX, $0xfffffffffffff001
+	JLS	ok6
+	MOVQ	$-1, r1+56(FP)
+	MOVQ	$0, r2+64(FP)
+	NEGQ	AX
+	MOVQ	AX, err+72(FP)
+	CALL	runtime·exitsyscall<ABIInternal>(SB)
+	RET
+ok6:
+	MOVQ	AX, r1+56(FP)
+	MOVQ	DX, r2+64(FP)
+	MOVQ	$0, err+72(FP)
+	CALL	runtime·exitsyscall<ABIInternal>(SB)
+	RET
+
 // func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
 TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
 	MOVQ	a1+8(FP), DI
diff --git a/src/syscall/asm_linux_arm.s b/src/syscall/asm_linux_arm.s
index 3252220562..6f9a612fa1 100644
--- a/src/syscall/asm_linux_arm.s
+++ b/src/syscall/asm_linux_arm.s
@@ -9,6 +9,37 @@
 // System calls for arm, Linux
 //
 
+// func Syscall6(trap uintptr, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr);
+// Actually Syscall5 but the rest of the code expects it to be named Syscall6.
+TEXT ·Syscall6(SB),NOSPLIT,$0-40
+	BL	runtime·entersyscall(SB)
+	MOVW	trap+0(FP), R7	// syscall entry
+	MOVW	a1+4(FP), R0
+	MOVW	a2+8(FP), R1
+	MOVW	a3+12(FP), R2
+	MOVW	a4+16(FP), R3
+	MOVW	a5+20(FP), R4
+	MOVW	a6+24(FP), R5
+	SWI	$0
+	MOVW	$0xfffff001, R6
+	CMP	R6, R0
+	BLS	ok6
+	MOVW	$-1, R1
+	MOVW	R1, r1+28(FP)
+	MOVW	$0, R2
+	MOVW	R2, r2+32(FP)
+	RSB	$0, R0, R0
+	MOVW	R0, err+36(FP)
+	BL	runtime·exitsyscall(SB)
+	RET
+ok6:
+	MOVW	R0, r1+28(FP)
+	MOVW	R1, r2+32(FP)
+	MOVW	$0, R0
+	MOVW	R0, err+36(FP)
+	BL	runtime·exitsyscall(SB)
+	RET
+
 #define SYS__LLSEEK 140  /* from zsysnum_linux_arm.go */
 // func seek(fd int, offset int64, whence int) (newoffset int64, errno int)
 // Implemented in assembly to avoid allocation when
diff --git a/src/syscall/asm_linux_arm64.s b/src/syscall/asm_linux_arm64.s
index be78ac8ac4..c9d28d301a 100644
--- a/src/syscall/asm_linux_arm64.s
+++ b/src/syscall/asm_linux_arm64.s
@@ -4,6 +4,32 @@
 
 #include "textflag.h"
 
+TEXT ·Syscall6(SB),NOSPLIT,$0-80
+	BL	runtime·entersyscall<ABIInternal>(SB)
+	MOVD	a1+8(FP), R0
+	MOVD	a2+16(FP), R1
+	MOVD	a3+24(FP), R2
+	MOVD	a4+32(FP), R3
+	MOVD	a5+40(FP), R4
+	MOVD	a6+48(FP), R5
+	MOVD	trap+0(FP), R8	// syscall entry
+	SVC
+	CMN	$4095, R0
+	BCC	ok
+	MOVD	$-1, R4
+	MOVD	R4, r1+56(FP)	// r1
+	MOVD	ZR, r2+64(FP)	// r2
+	NEG	R0, R0
+	MOVD	R0, err+72(FP)	// errno
+	BL	runtime·exitsyscall<ABIInternal>(SB)
+	RET
+ok:
+	MOVD	R0, r1+56(FP)	// r1
+	MOVD	R1, r2+64(FP)	// r2
+	MOVD	ZR, err+72(FP)	// errno
+	BL	runtime·exitsyscall<ABIInternal>(SB)
+	RET
+
 // func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
 TEXT ·rawVforkSyscall(SB),NOSPLIT,$0-32
 	MOVD	a1+8(FP), R0
diff --git a/src/syscall/asm_linux_mips64x.s b/src/syscall/asm_linux_mips64x.s
index fadf1939e0..994d7779fb 100644
--- a/src/syscall/asm_linux_mips64x.s
+++ b/src/syscall/asm_linux_mips64x.s
@@ -10,6 +10,30 @@
 // System calls for mips64, Linux
 //
 
+TEXT ·Syscall6(SB),NOSPLIT,$0-80
+	JAL	runtime·entersyscall(SB)
+	MOVV	a1+8(FP), R4
+	MOVV	a2+16(FP), R5
+	MOVV	a3+24(FP), R6
+	MOVV	a4+32(FP), R7
+	MOVV	a5+40(FP), R8
+	MOVV	a6+48(FP), R9
+	MOVV	trap+0(FP), R2	// syscall entry
+	SYSCALL
+	BEQ	R7, ok6
+	MOVV	$-1, R1
+	MOVV	R1, r1+56(FP)	// r1
+	MOVV	R0, r2+64(FP)	// r2
+	MOVV	R2, err+72(FP)	// errno
+	JAL	runtime·exitsyscall(SB)
+	RET
+ok6:
+	MOVV	R2, r1+56(FP)	// r1
+	MOVV	R3, r2+64(FP)	// r2
+	MOVV	R0, err+72(FP)	// errno
+	JAL	runtime·exitsyscall(SB)
+	RET
+
 // func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
 TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
 	MOVV	a1+8(FP), R4
diff --git a/src/syscall/asm_linux_mipsx.s b/src/syscall/asm_linux_mipsx.s
index b8cae96b1a..8c45861d64 100644
--- a/src/syscall/asm_linux_mipsx.s
+++ b/src/syscall/asm_linux_mipsx.s
@@ -11,6 +11,36 @@
 // System calls for mips, Linux
 //
 
+// func Syscall6(trap trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr);
+// 5th and 6th arg go at sp+16, sp+20.
+// Note that frame size of 20 means that 24 bytes gets reserved on stack.
+TEXT ·Syscall6(SB),NOSPLIT,$20-40
+	NO_LOCAL_POINTERS
+	JAL	runtime·entersyscall(SB)
+	MOVW	a1+4(FP), R4
+	MOVW	a2+8(FP), R5
+	MOVW	a3+12(FP), R6
+	MOVW	a4+16(FP), R7
+	MOVW	a5+20(FP), R8
+	MOVW	a6+24(FP), R9
+	MOVW	R8, 16(R29)
+	MOVW	R9, 20(R29)
+	MOVW	trap+0(FP), R2	// syscall entry
+	SYSCALL
+	BEQ	R7, ok6
+	MOVW	$-1, R1
+	MOVW	R1, r1+28(FP)	// r1
+	MOVW	R0, r2+32(FP)	// r2
+	MOVW	R2, err+36(FP)	// errno
+	JAL	runtime·exitsyscall(SB)
+	RET
+ok6:
+	MOVW	R2, r1+28(FP)	// r1
+	MOVW	R3, r2+32(FP)	// r2
+	MOVW	R0, err+36(FP)	// errno
+	JAL	runtime·exitsyscall(SB)
+	RET
+
 // func Syscall9(trap trap, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2, err uintptr);
 // Actually Syscall8 but the rest of the code expects it to be named Syscall9.
 TEXT ·Syscall9(SB),NOSPLIT,$28-52
diff --git a/src/syscall/asm_linux_ppc64x.s b/src/syscall/asm_linux_ppc64x.s
index 89cc1c2b0b..d60e472226 100644
--- a/src/syscall/asm_linux_ppc64x.s
+++ b/src/syscall/asm_linux_ppc64x.s
@@ -10,6 +10,30 @@
 // System calls for ppc64, Linux
 //
 
+TEXT ·Syscall6(SB),NOSPLIT,$0-80
+	BL	runtime·entersyscall<ABIInternal>(SB)
+	MOVD	a1+8(FP), R3
+	MOVD	a2+16(FP), R4
+	MOVD	a3+24(FP), R5
+	MOVD	a4+32(FP), R6
+	MOVD	a5+40(FP), R7
+	MOVD	a6+48(FP), R8
+	MOVD	trap+0(FP), R9	// syscall entry
+	SYSCALL R9
+	BVC	ok6
+	MOVD	$-1, R4
+	MOVD	R4, r1+56(FP)	// r1
+	MOVD	R0, r2+64(FP)	// r2
+	MOVD	R3, err+72(FP)	// errno
+	BL	runtime·exitsyscall<ABIInternal>(SB)
+	RET
+ok6:
+	MOVD	R3, r1+56(FP)	// r1
+	MOVD	R0, r2+64(FP)	// r2
+	MOVD	R0, err+72(FP)	// errno
+	BL	runtime·exitsyscall<ABIInternal>(SB)
+	RET
+
 // func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
 TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
 	MOVD	a1+8(FP), R3
diff --git a/src/syscall/asm_linux_riscv64.s b/src/syscall/asm_linux_riscv64.s
index 0fc1f73581..60b5cdbc1c 100644
--- a/src/syscall/asm_linux_riscv64.s
+++ b/src/syscall/asm_linux_riscv64.s
@@ -8,6 +8,33 @@
 // System calls for riscv64, Linux
 //
 
+// func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr)
+TEXT ·Syscall6(SB),NOSPLIT,$0-80
+	CALL	runtime·entersyscall(SB)
+	MOV	a1+8(FP), A0
+	MOV	a2+16(FP), A1
+	MOV	a3+24(FP), A2
+	MOV	a4+32(FP), A3
+	MOV	a5+40(FP), A4
+	MOV	a6+48(FP), A5
+	MOV	trap+0(FP), A7	// syscall entry
+	ECALL
+	MOV	$-4096, T0
+	BLTU	T0, A0, err
+	MOV	A0, r1+56(FP)	// r1
+	MOV	A1, r2+64(FP)	// r2
+	MOV	ZERO, err+72(FP)	// errno
+	CALL	runtime·exitsyscall(SB)
+	RET
+err:
+	MOV	$-1, T0
+	MOV	T0, r1+56(FP)	// r1
+	MOV	ZERO, r2+64(FP)	// r2
+	SUB	A0, ZERO, A0
+	MOV	A0, err+72(FP)	// errno
+	CALL	runtime·exitsyscall(SB)
+	RET
+
 // func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
 TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
 	MOV	a1+8(FP), A0
diff --git a/src/syscall/asm_linux_s390x.s b/src/syscall/asm_linux_s390x.s
index c3631c1261..14dabd85c2 100644
--- a/src/syscall/asm_linux_s390x.s
+++ b/src/syscall/asm_linux_s390x.s
@@ -8,6 +8,32 @@
 // System calls for s390x, Linux
 //
 
+// func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr)
+TEXT ·Syscall6(SB),NOSPLIT,$0-80
+	BL	runtime·entersyscall(SB)
+	MOVD	a1+8(FP), R2
+	MOVD	a2+16(FP), R3
+	MOVD	a3+24(FP), R4
+	MOVD	a4+32(FP), R5
+	MOVD	a5+40(FP), R6
+	MOVD	a6+48(FP), R7
+	MOVD	trap+0(FP), R1	// syscall entry
+	SYSCALL
+	MOVD	$0xfffffffffffff001, R8
+	CMPUBLT	R2, R8, ok6
+	MOVD	$-1, r1+56(FP)
+	MOVD	$0, r2+64(FP)
+	NEG	R2, R2
+	MOVD	R2, err+72(FP)	// errno
+	BL	runtime·exitsyscall(SB)
+	RET
+ok6:
+	MOVD	R2, r1+56(FP)
+	MOVD	R3, r2+64(FP)
+	MOVD	$0, err+72(FP)	// errno
+	BL	runtime·exitsyscall(SB)
+	RET
+
 // func rawVforkSyscall(trap, a1 uintptr) (r1, err uintptr)
 TEXT ·rawVforkSyscall(SB),NOSPLIT|NOFRAME,$0-32
 	MOVD	$0, R2
diff --git a/src/syscall/syscall_linux.go b/src/syscall/syscall_linux.go
index a796d17066..57e4769731 100644
--- a/src/syscall/syscall_linux.go
+++ b/src/syscall/syscall_linux.go
@@ -16,6 +16,8 @@ import (
 	"unsafe"
 )
 
+func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
+
 // N.B. RawSyscall6 is provided via linkname by runtime/internal/syscall.
 //
 // Errno is uintptr and thus compatible with the runtime/internal/syscall
@@ -66,16 +68,6 @@ func Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno) {
 	return
 }
 
-//go:uintptrkeepalive
-//go:nosplit
-//go:linkname Syscall6
-func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno) {
-	runtime_entersyscall()
-	r1, r2, err = RawSyscall6(trap, a1, a2, a3, a4, a5, a6)
-	runtime_exitsyscall()
-	return
-}
-
 func rawSyscallNoError(trap, a1, a2, a3 uintptr) (r1, r2 uintptr)
 
 /*