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/* sclow.S: Low level special syscall handling.
 *          Basically these are cases where we can completely
 *          handle the system call without saving any state
 *          because we know that the process will not sleep.
 *
 * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
 */

#include <asm/cprefix.h>
#include <asm/ptrace.h>
#include <asm/errno.h>
#include <asm/winmacro.h>
#include <asm/psr.h>

#define CC_AND_RETT  \
        set     PSR_C, %l4; \
        andn    %l0, %l4, %l4; \
        wr      %l4, 0x0, %psr; \
        nop; nop; nop; \
        jmp     %l2; \
        rett    %l2 + 4;

#define SC_AND_RETT  \
        set     PSR_C, %l4; \
        or      %l0, %l4, %l4; \
        wr      %l4, 0x0, %psr; \
        nop; nop; nop; \
        jmp     %l2; \
        rett    %l2 + 4;

#define LABEL(func)  CONCAT(func, _low)

        .globl  LABEL(sunosnop)
LABEL(sunosnop):
        CC_AND_RETT

        .globl  LABEL(sunosgetpid)
LABEL(sunosgetpid):
        LOAD_CURRENT(l4, l5)
        ld      [%l4 + 108], %i0
        ld      [%l4 + 256], %l5
        ld      [%l5 + 108], %i1
        CC_AND_RETT

        .globl  LABEL(sunosgetuid)
LABEL(sunosgetuid):
        LOAD_CURRENT(l4, l5)
        lduh    [%l4 + 280], %i0
        lduh    [%l4 + 282], %i1
        CC_AND_RETT

        .globl  LABEL(sunosgetgid)
LABEL(sunosgetgid):
        LOAD_CURRENT(l4, l5)
        lduh    [%l4 + 288], %i0
        lduh    [%l4 + 290], %i1
        CC_AND_RETT

        .globl  LABEL(sunosmctl)
LABEL(sunosmctl):
        mov     0, %i0
        CC_AND_RETT

        .globl  LABEL(sunosgdtsize)
LABEL(sunosgdtsize):    
        mov     256, %i0
        CC_AND_RETT

        .globl  LABEL(sunossblock)
LABEL(sunossblock):
        LOAD_CURRENT(l4, l5)
        set     -65793, %l5
        and     %i0, %l5, %l5
        ld      [%l4 + TASK_BLOCKED], %i0
        or      %i0, %l5, %l5
        st      %l5, [%l4 + TASK_BLOCKED]
        CC_AND_RETT

        .globl  LABEL(sunossmask)
LABEL(sunossmask):
        LOAD_CURRENT(l4, l5)
        set     -65793, %l5
        and     %i0, %l5, %l5
        ld      [%l4 + TASK_BLOCKED], %i0
        st      %l5, [%l4 + TASK_BLOCKED]
        CC_AND_RETT

        .globl  LABEL(getpagesize)
LABEL(getpagesize):
        set     4096, %i0
        CC_AND_RETT

        .globl  LABEL(umask)
LABEL(umask):
        LOAD_CURRENT(l4, l5)
        ld      [%l4 + 1560], %l5
        and     %i0, 511, %l4
        lduh    [%l5 + 4], %i0
        sth     %l4, [%l5 + 4]
        CC_AND_RETT

        .globl  LABEL(write)
LABEL(write):
        cmp     %i0, 255                /* fd >= NR_OPEN */
        bgu,a   write_error_return
         mov    EBADF, %i0

        LOAD_CURRENT(l4, l5)
        ld      [%l4 + 1564], %l5
        sll     %i0, 2, %l6
        add     %l5, %l6, %l5
        ld      [%l5 + 36], %l6
        cmp     %l6, 0                  /* !(file=current->files->fd[fd]) */
        be,a    write_error_return
         mov    EBADF, %i0      

        ld      [%l6 + 36], %l5
        cmp     %l5, 0                  /* !(inode=file->f_inode) */
        be,a    write_error_return
         mov    EBADF, %i0

        lduh    [%l6], %l5              /* !(file->f_mode & 2) */
        andcc   %l5, 2, %g0
        be,a    write_error_return
         mov    EBADF, %i0

        ld      [%l6 + 40], %l5
        cmp     %l5, 0                  /* !file->f_op */
        be,a    write_error_return
         mov    EINVAL, %i0

        ld      [%l5 + 8], %l5          /* !file->f_op->write */
        cmp     %l5, 0
        be,a    write_error_return
         mov    EINVAL, %i0

        cmp     %i2, 0                  /* count == 0 */
        bne     1f
         nop

        mov     0, %i0
        CC_AND_RETT

1:
        /* See if we can do the optimization... */
        ld      [%l6 + 36], %l5
        lduh    [%l5 + 16], %l5
        srl     %l5, 8, %l6
        cmp     %l6, 1                  /* MEM_MAJOR */
        bne,a   write_is_too_hard
         sethi  %hi(C_LABEL(quick_sys_write)), %l7

        and     %l5, 0xff, %l5
        cmp     %l5, 3                  /* NULL_MINOR */
        bne,a   write_is_too_hard
         sethi  %hi(C_LABEL(quick_sys_write)), %l7

        /* We only optimize for the /dev/null case currently,
         * however to stay POSIX4 compliant we must check the
         * validity of the passed buffer.  Blowlaris2.x does not
         * do this and is therefore not POSIX4 compliant!
         * If you are going to optimize for benchmarks, fine,
         * but to break behavior of a system call in the process
         * is complete brain damage...
         */

        /* XXX write verify_area thingy for full POSIX conformance! XXX */

        mov     %i2, %i0
        CC_AND_RETT

write_is_too_hard:
        b       syscall_is_too_hard
         or     %l7, %lo(C_LABEL(quick_sys_write)), %l7

write_error_return:
        SC_AND_RETT

        /* XXX sys_nice() XXX */
        /* XXX sys_setpriority() XXX */
        /* XXX sys_getpriority() XXX */
        /* XXX sys_setregid() XXX */
        /* XXX sys_setgid() XXX */
        /* XXX sys_setreuid() XXX */
        /* XXX sys_setuid() XXX */
        /* XXX sys_setfsuid() XXX */
        /* XXX sys_setfsgid() XXX */
        /* XXX sys_setpgid() XXX */
        /* XXX sys_getpgid() XXX */
        /* XXX sys_setsid() XXX */
        /* XXX sys_getsid() XXX */