ucbcmd/sbcp/sbcp.s

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

    .file   "sbcp.s"

#include <sys/asm_linkage.h>
#include <sys/link.h>
#include <sys/syscall.h>

#define PIC_SETUP(r)                        \
    mov %o7, %g1;                   \
9:  call    8f;                     \
    sethi   %hi(_GLOBAL_OFFSET_TABLE_ - (9b - .)), %r;  \
8:  or  %r, %lo(_GLOBAL_OFFSET_TABLE_ - (9b - .)), %r;  \
    add %r, %o7, %r;                    \
    mov %g1, %o7

#define FUNC(x) \
    .section    ".text"; \
    .align  4; \
    .type   x, #function; \
x:

#define ENOSYS  90      /* 4.x ENOSYS */

/* derived from <sys/exechdr.h>, which we can't include */
#define A_MAGIC 0x02    /* offset of a_magic field */
#define A_ENTRY 0x14    /* offset of a_entry field */
#define ZMAGIC  0413    /* magic number for demand paged executable */

    .global atexit, errno

!
!   _start - execution starts here (after the runtime linker runs)
!
!   The SPARC ABI defines our "environment" at this point, see page 3-34.
!   Register the exit handler, register the trap0 handler, find the
!   entry point, and jump to it.  We depend on the stack (argv, envp)
!   being compatible between 4.x and 5.x.  We also depend on the
!   runtime linker to set up ``environ''.
!

ENTRY_NP(_start)
    tst %g1         ! is there a handler to register?
    bz  1f          ! no
    nop
    mov %g1, %o0
    call    atexit          ! yes, register it with atexit()
    nop
1:

    !
    ! Aside from a value in %g1, there were no arguments explicitly
    ! passed to this routine, but we do know how our initial stack has
    ! been setup by the kernel.  The stack format is documented in:
    !   usr/src/cmd/sgs/rtld/sparc/boot.s
    !   usr/src/cmd/sgs/rtld/sparcv9/boot.s
    !
    ! Since we want to invoke the following c initalization routine:
    !   sbcp_init(int argc, char *argv[], char *envp[]))
    ! we need to troll through the stack to setup it's argument values.
    !
    save    %sp, -SA(MINFRAME + EB_MAX_SIZE32), %sp

    ldn [%fp + WINDOWSIZE + STACK_BIAS], %o0        ! get argc
    add %fp, + WINDOWSIZE + CPTRSIZE + STACK_BIAS, %o1  ! get argv

    add %o0, 1, %l0     ! add 1 to argc for last element of 0
    sll %l0, CPTRSHIFT, %l0 ! multiply argc by pointer size
    add %o1, %l0, %o2       !  and add to argv to get envp

    call    sbcp_init       ! Call our c initalization routine
    nop
    restore

    PIC_SETUP(g2)
    ld  [%g2+trap0], %g1
    ta  9

    ! jump to the main program's entry point

    sethi   %hi(0x2000), %o0
    lduh    [%o0 + A_MAGIC], %g1
    cmp     %g1, ZMAGIC     ! is it a ZMAGIC executable?
    be,a    1f          ! yes,
    ld      [%o0 + A_ENTRY], %o0    !   get entry point
1:                  ! else, assume entry point is 0x2000
    jmp %o0
    nop
    SET_SIZE(_start)

!
!   trap0 - glue between 4.x syscall trap and 5.x BCP routine
!
!   enter with:
!       %g1 syscall number
!       %g6 return address (after trap instruction)
!
!   We used to use %g7, but that conflicts with threading code
!   which uses %g7 as the curthread pointer.  That is why we
!   changed to using %g6 instead.
!
!   We use an extra window to save the %o registers we're entered
!   with (which the 4.x system call stubs depend on) and to allow
!   recursive traps (e.g., from a signal handler).
!

FUNC(trap0)
    save    %sp, -SA(MINFRAME), %sp
    tst %g1
    be  1f
    nop
    mov %i0, %o0
    mov %i1, %o1
    mov %i2, %o2
    mov %i3, %o3
    mov %i4, %o4
    mov %i5, %o5
    ba,a    2f
1:
    ! indir syscall
    mov %i0, %g1
    mov %i1, %o0
    mov %i2, %o1
    mov %i3, %o2
    mov %i4, %o3
    mov %i5, %o4
    ld  [%fp + MINFRAME], %o5
2:
    sll %g1, 4, %l1
    PIC_SETUP(l0)
    ld  [%l0+sysent], %l0
    add %l1, %l0, %l1
    jmp %l1         ! jump into branch table
    nop
    SET_SIZE(trap0)

FUNC(trap0rtn)
    cmp %o0, -1
    bne 1f
    addcc   %g0, %g0, %g0       ! psr &= ~C
    PIC_SETUP(o1)
    ld  [%o1+errno], %o1
    ld  [%o1], %o0
    subcc   %g0, 1, %g0     ! psr |= C
1:
    mov %o0, %i0
    restore
    jmp %g6
    nop
    SET_SIZE(trap0rtn)

!
!   nullsys
!
FUNC(nullsys)
    clr %o0
    b,a trap0rtn
    SET_SIZE(nullsys)

!
!   nosys
!
FUNC(nosys)
    set ENOSYS, %o1
    PIC_SETUP(g2)
    ld  [%g2+errno], %g2
    st  %o1, [%g2]
    set -1, %o0
    b,a trap0rtn
    SET_SIZE(nosys)

!
!   Have to #include the sysent table and stubs so that all
!   symbols referenced between here and there are "static"
!   to this module so the assembler can resolve them without
!   the linker needing to deal with them at run time.
!
#include "sysent.s"