remove external __syscall function and last remaining users

the weak version of __syscall_cp_c was using a tail call to __syscall
to avoid duplicating the 6-argument syscall code inline in small
static-linked programs, but now that __syscall no longer exists, the
inline expansion is no longer duplication.

the syscall.h machinery suppported up to 7 syscall arguments, only via
an external __syscall function, but we presently have no syscall call
points that actually make use of that many, and the kernel only
defines 7-argument calling conventions for arm, powerpc (32-bit), and
sh. if it turns out we need them in the future, they can easily be
added.

src/internal/aarch64/syscall.s

-.global __syscall
-.hidden __syscall
-.type __syscall,%function
-__syscall:
-	uxtw x8,w0
-	mov x0,x1
-	mov x1,x2
-	mov x2,x3
-	mov x3,x4
-	mov x4,x5
-	mov x5,x6
-	mov x6,x7
-	svc 0
-	ret

src/internal/arm/syscall.s

-.syntax unified
-.global __syscall
-.hidden __syscall
-.type __syscall,%function
-__syscall:
-	mov ip,sp
-	stmfd sp!,{r4,r5,r6,r7}
-	mov r7,r0
-	mov r0,r1
-	mov r1,r2
-	mov r2,r3
-	ldmfd ip,{r3,r4,r5,r6}
-	svc 0
-	ldmfd sp!,{r4,r5,r6,r7}
-	bx lr

src/internal/i386/syscall.s

-.global __syscall
-.hidden __syscall
-.type __syscall,@function
-__syscall:
-	push %ebx
-	push %esi
-	push %edi
-	push %ebp
-	mov 20(%esp),%eax
-	mov 24(%esp),%ebx
-	mov 28(%esp),%ecx
-	mov 32(%esp),%edx
-	mov 36(%esp),%esi
-	mov 40(%esp),%edi
-	mov 44(%esp),%ebp
-	call *%gs:16
-	pop %ebp
-	pop %edi
-	pop %esi
-	pop %ebx
-	ret

src/internal/m68k/syscall.s

-.global __syscall
-.hidden __syscall
-.type __syscall,%function
-__syscall:
-	movem.l %d2-%d5,-(%sp)
-	movem.l 20(%sp),%d0-%d5/%a0
-	trap #0
-	movem.l (%sp)+,%d2-%d5
-	rts

src/internal/microblaze/syscall.s

-.global __syscall
-.hidden __syscall
-.type   __syscall,@function
-__syscall:
-	addi    r12, r5, 0              # Save the system call number
-	add     r5, r6, r0              # Shift the arguments, arg1
-	add     r6, r7, r0              # arg2
-	add     r7, r8, r0              # arg3
-	add     r8, r9, r0              # arg4
-	add     r9, r10, r0             # arg5
-	lwi     r10, r1, 28             # Get arg6.
-	brki    r14, 0x8                # syscall
-	rtsd    r15, 8
-	nop

src/internal/mips/syscall.s

-.set    noreorder
-
-.global __syscall
-.hidden __syscall
-.type   __syscall,@function
-__syscall:
-	move    $2, $4
-	move    $4, $5
-	move    $5, $6
-	move    $6, $7
-	lw      $7, 16($sp)
-	lw      $8, 20($sp)
-	lw      $9, 24($sp)
-	lw      $10,28($sp)
-	subu    $sp, $sp, 32
-	sw      $8, 16($sp)
-	sw      $9, 20($sp)
-	sw      $10,24($sp)
-	sw      $2 ,28($sp)
-	lw      $2, 28($sp)
-	syscall
-	beq     $7, $0, 1f
-	addu    $sp, $sp, 32
-	subu    $2, $0, $2
-1:	jr      $ra
-	nop

src/internal/mips64/syscall.s

-.set	noreorder
-.global	__syscall
-.hidden	__syscall
-.type	__syscall,@function
-__syscall:
-	move	$2, $4
-	move	$4, $5
-	move	$5, $6
-	move	$6, $7
-	move	$7, $8
-	move	$8, $9
-	move	$9, $10
-	move	$10, $11
-	syscall
-	beq	$7, $0, 1f
-	nop
-	dsubu	$2, $0, $2
-1:	jr	$ra
-	nop

src/internal/mipsn32/syscall.s

-.set	noreorder
-.global	__syscall
-.hidden	__syscall
-.type	__syscall,@function
-__syscall:
-	move	$2, $4
-	move	$4, $5
-	move	$5, $6
-	move	$6, $7
-	move	$7, $8
-	move	$8, $9
-	move	$9, $10
-	move	$10, $11
-	syscall
-	beq	$7, $0, 1f
-	nop
-	subu	$2, $0, $2
-1:	jr	$ra
-	nop

src/internal/or1k/syscall.s

-.global __syscall
-.hidden __syscall
-.type   __syscall,@function
-__syscall:
-	l.ori	r11, r3, 0
-	l.lwz	r3, 0(r1)
-	l.lwz	r4, 4(r1)
-	l.lwz	r5, 8(r1)
-	l.lwz	r6, 12(r1)
-	l.lwz	r7, 16(r1)
-	l.lwz	r8, 20(r1)
-	l.sys	1
-	l.jr	r9
-	 l.nop

src/internal/powerpc/syscall.s

-	.global __syscall
-	.hidden __syscall
-	.type   __syscall,@function
-__syscall:
-	mr      0, 3                  # Save the system call number
-	mr      3, 4                  # Shift the arguments: arg1
-	mr      4, 5                  # arg2
-	mr      5, 6                  # arg3
-	mr      6, 7                  # arg4
-	mr      7, 8                  # arg5
-	mr      8, 9                  # arg6
-	sc
-	bnslr+ # return if not summary overflow
-	#else error:
-	# return negated value.
-	neg 3, 3
-	blr
-	.end    __syscall
-	.size   __syscall, .-__syscall

src/internal/powerpc64/syscall.s

-	.global __syscall
-	.hidden __syscall
-	.type   __syscall,@function
-__syscall:
-	mr      0, 3                  # Save the system call number
-	mr      3, 4                  # Shift the arguments: arg1
-	mr      4, 5                  # arg2
-	mr      5, 6                  # arg3
-	mr      6, 7                  # arg4
-	mr      7, 8                  # arg5
-	mr      8, 9                  # arg6
-	sc
-	bnslr+       # return if not summary overflow
-	neg     3, 3 # otherwise error: return negated value.
-	blr
-	.end    __syscall
-	.size   __syscall, .-__syscall

src/internal/s390x/syscall.s

-.global __syscall
-.hidden __syscall
-.type   __syscall, %function
-__syscall:
-	stg %r7, 56(%r15)
-	lgr %r1, %r2
-	lgr %r2, %r3
-	lgr %r3, %r4
-	lgr %r4, %r5
-	lgr %r5, %r6
-	lg  %r6, 160(%r15)
-	lg  %r7, 168(%r15)
-	svc 0
-	lg  %r7, 56(%r15)
-	br  %r14

src/internal/sh/syscall.s

-.global __syscall
-.hidden __syscall
-.type   __syscall, @function
-__syscall:
-	! The kernel syscall entry point documents that the trap number indicates
-	! the number of arguments being passed, but it then ignores that information.
-	! Since we do not actually know how many arguments are being passed, we will
-	! say there are six, since that is the maximum we support here.
-	mov r4, r3
-	mov r5, r4
-	mov r6, r5
-	mov r7, r6
-	mov.l @r15, r7
-	mov.l @(4,r15), r0
-	mov.l @(8,r15), r1
-	trapa #31
-	or r0, r0
-	or r0, r0
-	or r0, r0
-	or r0, r0
-	or r0, r0
-	rts
-	 nop

src/internal/syscall.h

@@ -22,27 +22,16 @@
 typedef long syscall_arg_t;
 #endif
 
-hidden long __syscall_ret(unsigned long), __syscall(syscall_arg_t, ...),
+hidden long __syscall_ret(unsigned long),
 	__syscall_cp(syscall_arg_t, syscall_arg_t, syscall_arg_t, syscall_arg_t,
 	             syscall_arg_t, syscall_arg_t, syscall_arg_t);
 
-#ifdef SYSCALL_NO_INLINE
-#define __syscall0(n) (__syscall)(n)
-#define __syscall1(n,a) (__syscall)(n,__scc(a))
-#define __syscall2(n,a,b) (__syscall)(n,__scc(a),__scc(b))
-#define __syscall3(n,a,b,c) (__syscall)(n,__scc(a),__scc(b),__scc(c))
-#define __syscall4(n,a,b,c,d) (__syscall)(n,__scc(a),__scc(b),__scc(c),__scc(d))
-#define __syscall5(n,a,b,c,d,e) (__syscall)(n,__scc(a),__scc(b),__scc(c),__scc(d),__scc(e))
-#define __syscall6(n,a,b,c,d,e,f) (__syscall)(n,__scc(a),__scc(b),__scc(c),__scc(d),__scc(e),__scc(f))
-#else
 #define __syscall1(n,a) __syscall1(n,__scc(a))
 #define __syscall2(n,a,b) __syscall2(n,__scc(a),__scc(b))
 #define __syscall3(n,a,b,c) __syscall3(n,__scc(a),__scc(b),__scc(c))
 #define __syscall4(n,a,b,c,d) __syscall4(n,__scc(a),__scc(b),__scc(c),__scc(d))
 #define __syscall5(n,a,b,c,d,e) __syscall5(n,__scc(a),__scc(b),__scc(c),__scc(d),__scc(e))
 #define __syscall6(n,a,b,c,d,e,f) __syscall6(n,__scc(a),__scc(b),__scc(c),__scc(d),__scc(e),__scc(f))
-#endif
-#define __syscall7(n,a,b,c,d,e,f,g) (__syscall)(n,__scc(a),__scc(b),__scc(c),__scc(d),__scc(e),__scc(f),__scc(g))
 
 #define __SYSCALL_NARGS_X(a,b,c,d,e,f,g,h,n,...) n
 #define __SYSCALL_NARGS(...) __SYSCALL_NARGS_X(__VA_ARGS__,7,6,5,4,3,2,1,0,)

src/internal/x32/syscall.s

-.global __syscall
-.hidden __syscall
-.type __syscall,@function
-__syscall:
-	movq %rdi,%rax
-	movq %rsi,%rdi
-	movq %rdx,%rsi
-	movq %rcx,%rdx
-	movq %r8,%r10
-	movq %r9,%r8
-	movq 8(%rsp),%r9
-	syscall
-	ret

src/internal/x86_64/syscall.s

-.global __syscall
-.hidden __syscall
-.type __syscall,@function
-__syscall:
-	movq %rdi,%rax
-	movq %rsi,%rdi
-	movq %rdx,%rsi
-	movq %rcx,%rdx
-	movq %r8,%r10
-	movq %r9,%r8
-	movq 8(%rsp),%r9
-	syscall
-	ret

src/thread/__syscall_cp.c

@@ -7,7 +7,7 @@ static long sccp(syscall_arg_t nr,
                  syscall_arg_t u, syscall_arg_t v, syscall_arg_t w,
                  syscall_arg_t x, syscall_arg_t y, syscall_arg_t z)
 {
-	return (__syscall)(nr, u, v, w, x, y, z);
+	return __syscall(nr, u, v, w, x, y, z);
 }
 
 weak_alias(sccp, __syscall_cp_c);