| 28,14 → 28,14 |
|---|
| |
| .text |
| |
| /** Syscall wrapper. |
| /** Syscall wrapper - INT $0x30 version. |
| * |
| * Mind the order of arguments. First two arguments and the syscall number go to |
| * scratch registers. An optimized version of this wrapper for fewer arguments |
| * could benefit from this and not save unused registers on the stack. |
| */ |
| .global __syscall |
| __syscall: |
| .global __syscall_int |
| __syscall_int: |
| pushl %ebx |
| pushl %esi |
| pushl %edi |
| 53,3 → 53,38 |
|---|
| popl %esi |
| popl %ebx |
| ret |
| |
| |
| /** Syscall wrapper - SYSENTER version. |
| * |
| * This is an optimized version of syscall for four or less arguments. Note |
| * that EBP and EDI are used to remember user stack address and the return |
| * address. The kernel part doesn't save DS, ES and FS so the handler restores |
| * these to the selector immediately following CS (it must be the flat data |
| * segment, otherwise the SYSENTER wouldn't work in the first place). |
| */ |
| .global __syscall_sysenter |
| __syscall_sysenter: |
| pushl %ebx |
| pushl %esi |
| pushl %edi |
| pushl %ebp |
| mov %esp, %ebp |
| lea ra, %edi |
| movl 20(%esp), %edx # First argument. |
| movl 24(%esp), %ecx # Second argument. |
| movl 28(%esp), %ebx # Third argument. |
| movl 32(%esp), %esi # Fourth argument. |
| movl 44(%esp), %eax # Syscall number. |
| sysenter |
| ra: |
| movw %cs, %cx |
| addw $8, %cx |
| movw %cx, %ds |
| movw %cx, %es |
| movw %cx, %fs |
| popl %ebp |
| popl %edi |
| popl %esi |
| popl %ebx |
| ret |