1 | #
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2 | # Copyright (C) 2001-2004 Jakub Jermar
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3 | # All rights reserved.
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4 | #
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5 | # Redistribution and use in source and binary forms, with or without
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6 | # modification, are permitted provided that the following conditions
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7 | # are met:
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8 | #
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9 | # - Redistributions of source code must retain the above copyright
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10 | # notice, this list of conditions and the following disclaimer.
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11 | # - Redistributions in binary form must reproduce the above copyright
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12 | # notice, this list of conditions and the following disclaimer in the
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13 | # documentation and/or other materials provided with the distribution.
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14 | # - The name of the author may not be used to endorse or promote products
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15 | # derived from this software without specific prior written permission.
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16 | #
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17 | # THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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18 | # IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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19 | # OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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20 | # IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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21 | # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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22 | # NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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23 | # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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24 | # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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25 | # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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26 | # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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27 | #
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28 |
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29 | .text
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30 |
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31 | .global context_save
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32 | .global context_restore
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33 |
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34 | #
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35 | # save context of this CPU
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36 | context_save:
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37 | push %ebx
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38 |
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39 | movl 4(%esp),%eax # the caller's return %eip
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40 | movl 8(%esp),%ebx # address of the kernel_context variable to save context to
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41 | movl %eax,4(%ebx) # %eip -> ctx->pc
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42 | movl %esp,(%ebx) # %esp -> ctx->sp
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43 |
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44 | movl %ebx,%eax
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45 | pop %ebx
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46 |
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47 | movl %ebx,8(%eax)
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48 | movl %ecx,12(%eax)
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49 | movl %edx,16(%eax)
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50 | movl %esi,20(%eax)
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51 | movl %edi,24(%eax)
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52 | movl %ebp,28(%eax)
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53 |
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54 | xorl %eax,%eax # context_save returns 1
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55 | incl %eax
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56 | ret
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57 |
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58 | #
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59 | # restore saved context on this CPU
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60 | context_restore:
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61 | movl 4(%esp),%eax # address of the kernel_context variable to restore context from
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62 | movl (%eax),%esp # ctx->sp -> %esp
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63 | addl $4,%esp # this is for the pop we don't do
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64 |
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65 | movl 8(%eax),%ebx
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66 | movl 12(%eax),%ecx
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67 | movl 16(%eax),%edx
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68 | movl 20(%eax),%esi
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69 | movl 24(%eax),%edi
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70 | movl 28(%eax),%ebp
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71 |
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72 | movl 4(%eax),%eax
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73 | movl %eax,(%esp) # ctx->pc -> saver's return %eip
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74 | xorl %eax,%eax # context_restore returns 0
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75 | ret
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