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.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:
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
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