call_o32.s

linux 内核源代码

/*
 *	arch/mips/dec/prom/call_o32.S
 *
 *	O32 interface for the 64 (or N32) ABI.
 *
 *	Copyright (C) 2002  Maciej W. Rozycki
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 */

#include <asm/asm.h>
#include <asm/regdef.h>

/* Maximum number of arguments supported.  Must be even!  */
#define O32_ARGC	32
/* Number of static registers we save.  */
#define O32_STATC	11
/* Frame size for both of the above.  */
#define O32_FRAMESZ	(4 * O32_ARGC + SZREG * O32_STATC)

		.text

/*
 * O32 function call dispatcher, for interfacing 32-bit ROM routines.
 *
 * The standard 64 (N32) calling sequence is supported, with a0
 * holding a function pointer, a1-a7 -- its first seven arguments
 * and the stack -- remaining ones (up to O32_ARGC, including a1-a7).
 * Static registers, gp and fp are preserved, v0 holds a result.
 * This code relies on the called o32 function for sp and ra
 * restoration and thus both this dispatcher and the current stack
 * have to be placed in a KSEGx (or KUSEG) address space.  Any
 * pointers passed have to point to addresses within one of these
 * spaces as well.
 */
NESTED(call_o32, O32_FRAMESZ, ra)
		REG_SUBU	sp,O32_FRAMESZ

		REG_S		ra,O32_FRAMESZ-1*SZREG(sp)
		REG_S		fp,O32_FRAMESZ-2*SZREG(sp)
		REG_S		gp,O32_FRAMESZ-3*SZREG(sp)
		REG_S		s7,O32_FRAMESZ-4*SZREG(sp)
		REG_S		s6,O32_FRAMESZ-5*SZREG(sp)
		REG_S		s5,O32_FRAMESZ-6*SZREG(sp)
		REG_S		s4,O32_FRAMESZ-7*SZREG(sp)
		REG_S		s3,O32_FRAMESZ-8*SZREG(sp)
		REG_S		s2,O32_FRAMESZ-9*SZREG(sp)
		REG_S		s1,O32_FRAMESZ-10*SZREG(sp)
		REG_S		s0,O32_FRAMESZ-11*SZREG(sp)

		move		jp,a0

		sll		a0,a1,zero
		sll		a1,a2,zero
		sll		a2,a3,zero
		sll		a3,a4,zero
		sw		a5,0x10(sp)
		sw		a6,0x14(sp)
		sw		a7,0x18(sp)

		PTR_LA		t0,O32_FRAMESZ(sp)
		PTR_LA		t1,0x1c(sp)
		li		t2,O32_ARGC-7
1:
		lw		t3,(t0)
		REG_ADDU	t0,SZREG
		sw		t3,(t1)
		REG_SUBU	t2,1
		REG_ADDU	t1,4
		bnez		t2,1b

		jalr		jp

		REG_L		s0,O32_FRAMESZ-11*SZREG(sp)
		REG_L		s1,O32_FRAMESZ-10*SZREG(sp)
		REG_L		s2,O32_FRAMESZ-9*SZREG(sp)
		REG_L		s3,O32_FRAMESZ-8*SZREG(sp)
		REG_L		s4,O32_FRAMESZ-7*SZREG(sp)
		REG_L		s5,O32_FRAMESZ-6*SZREG(sp)
		REG_L		s6,O32_FRAMESZ-5*SZREG(sp)
		REG_L		s7,O32_FRAMESZ-4*SZREG(sp)
		REG_L		gp,O32_FRAMESZ-3*SZREG(sp)
		REG_L		fp,O32_FRAMESZ-2*SZREG(sp)
		REG_L		ra,O32_FRAMESZ-1*SZREG(sp)

		REG_ADDU	sp,O32_FRAMESZ
		jr		ra
END(call_o32)