+.hidden __sysinfo
+
+# The calling convention for __vsyscall has the syscall number
+# and 5 args arriving as: eax, edx, ecx, edi, esi, 4(%esp).
+# This ensures that the inline asm in the C code never has to touch
+# ebx or ebp (which are unavailable in PIC and frame-pointer-using
+# code, respectively), and optimizes for size/simplicity in the caller.
+
+.global __vsyscall
+.type __vsyscall,@function
+__vsyscall:
+ push %edi
+ push %ebx
+ mov %edx,%ebx
+ mov %edi,%edx
+ mov 12(%esp),%edi
+ push %eax
+ call 1f
+2: mov %ebx,%edx
+ pop %ebx
+ pop %ebx
+ pop %edi
+ ret
+
+1: mov (%esp),%eax
+ add $[__sysinfo-2b],%eax
+ mov (%eax),%eax
+ test %eax,%eax
+ jz 1f
+ push %eax
+ mov 8(%esp),%eax
+ ret # tail call to kernel vsyscall entry
+1: mov 4(%esp),%eax
+ int $128
+ ret
+
+# The __vsyscall6 entry point is used only for 6-argument syscalls.
+# Instead of passing the 5th argument on the stack, a pointer to the
+# 5th and 6th arguments is passed. This is ugly, but there are no
+# register constraints the inline asm could use that would make it
+# possible to pass two arguments on the stack.
+
+.global __vsyscall6
+.type __vsyscall6,@function
+__vsyscall6:
+ push %ebp
+ push %eax
+ mov 12(%esp), %ebp
+ mov (%ebp), %eax
+ mov 4(%ebp), %ebp
+ push %eax
+ mov 4(%esp),%eax
+ call __vsyscall
+ pop %ebp
+ pop %ebp
+ pop %ebp
+ ret
+
.global __syscall
+.type __syscall,@function
__syscall:
- pushl %ebx
- pushl %esi
- pushl %edi
- pushl %ebp
- movl 20(%esp),%eax
- movl 24(%esp),%ebx
- movl 28(%esp),%ecx
- movl 32(%esp),%edx
- movl 36(%esp),%esi
- movl 40(%esp),%edi
- movl 44(%esp),%ebp
- int $128
- popl %ebp
- popl %edi
- popl %esi
- popl %ebx
+ lea 24(%esp),%eax
+ push %esi
+ push %edi
+ push %eax
+ mov 16(%esp),%eax
+ mov 20(%esp),%edx
+ mov 24(%esp),%ecx
+ mov 28(%esp),%edi
+ mov 32(%esp),%esi
+ call __vsyscall6
+ pop %edi
+ pop %edi
+ pop %esi
ret