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26 | # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
26 | # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
27 | # |
27 | # |
28 | 28 | ||
29 | .text |
29 | .text |
30 | 30 | ||
31 | /** Syscall wrapper. |
31 | /** Syscall wrapper - INT $0x30 version. |
32 | * |
32 | * |
33 | * Mind the order of arguments. First two arguments and the syscall number go to |
33 | * Mind the order of arguments. First two arguments and the syscall number go to |
34 | * scratch registers. An optimized version of this wrapper for fewer arguments |
34 | * scratch registers. An optimized version of this wrapper for fewer arguments |
35 | * could benefit from this and not save unused registers on the stack. |
35 | * could benefit from this and not save unused registers on the stack. |
36 | */ |
36 | */ |
37 | .global __syscall |
37 | .global __syscall_int |
38 | __syscall: |
38 | __syscall_int: |
39 | pushl %ebx |
39 | pushl %ebx |
40 | pushl %esi |
40 | pushl %esi |
41 | pushl %edi |
41 | pushl %edi |
42 | pushl %ebp |
42 | pushl %ebp |
43 | movl 20(%esp), %edx # First argument. |
43 | movl 20(%esp), %edx # First argument. |
Line 51... | Line 51... | ||
51 | popl %ebp |
51 | popl %ebp |
52 | popl %edi |
52 | popl %edi |
53 | popl %esi |
53 | popl %esi |
54 | popl %ebx |
54 | popl %ebx |
55 | ret |
55 | ret |
- | 56 | ||
- | 57 | ||
- | 58 | /** Syscall wrapper - SYSENTER version. |
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- | 59 | * |
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- | 60 | * This is an optimized version of syscall for four or less arguments. Note |
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- | 61 | * that EBP and EDI are used to remember user stack address and the return |
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- | 62 | * address. The kernel part doesn't save DS, ES and FS so the handler restores |
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- | 63 | * these to the selector immediately following CS (it must be the flat data |
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- | 64 | * segment, otherwise the SYSENTER wouldn't work in the first place). |
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- | 65 | */ |
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- | 66 | .global __syscall_sysenter |
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- | 67 | __syscall_sysenter: |
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- | 68 | pushl %ebx |
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- | 69 | pushl %esi |
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- | 70 | pushl %edi |
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- | 71 | pushl %ebp |
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- | 72 | mov %esp, %ebp |
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- | 73 | lea ra, %edi |
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- | 74 | movl 20(%esp), %edx # First argument. |
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- | 75 | movl 24(%esp), %ecx # Second argument. |
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- | 76 | movl 28(%esp), %ebx # Third argument. |
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- | 77 | movl 32(%esp), %esi # Fourth argument. |
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- | 78 | movl 44(%esp), %eax # Syscall number. |
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- | 79 | sysenter |
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- | 80 | ra: |
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- | 81 | movw %cs, %cx |
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- | 82 | addw $8, %cx |
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- | 83 | movw %cx, %ds |
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- | 84 | movw %cx, %es |
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- | 85 | movw %cx, %fs |
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- | 86 | popl %ebp |
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- | 87 | popl %edi |
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- | 88 | popl %esi |
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- | 89 | popl %ebx |
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- | 90 | ret |