1*4882a593Smuzhiyun/* SPDX-License-Identifier: GPL-2.0-only */ 2*4882a593Smuzhiyun/* 3*4882a593Smuzhiyun * thunks_32.S - assembly helpers for mixed-bitness code 4*4882a593Smuzhiyun * Copyright (c) 2015 Denys Vlasenko 5*4882a593Smuzhiyun * 6*4882a593Smuzhiyun * These are little helpers that make it easier to switch bitness on 7*4882a593Smuzhiyun * the fly. 8*4882a593Smuzhiyun */ 9*4882a593Smuzhiyun 10*4882a593Smuzhiyun .text 11*4882a593Smuzhiyun .code32 12*4882a593Smuzhiyun 13*4882a593Smuzhiyun .global call64_from_32 14*4882a593Smuzhiyun .type call32_from_64, @function 15*4882a593Smuzhiyun 16*4882a593Smuzhiyun // 4(%esp): function to call 17*4882a593Smuzhiyuncall64_from_32: 18*4882a593Smuzhiyun // Fetch function address 19*4882a593Smuzhiyun mov 4(%esp), %eax 20*4882a593Smuzhiyun 21*4882a593Smuzhiyun // Save registers which are callee-clobbered by 64-bit ABI 22*4882a593Smuzhiyun push %ecx 23*4882a593Smuzhiyun push %edx 24*4882a593Smuzhiyun push %esi 25*4882a593Smuzhiyun push %edi 26*4882a593Smuzhiyun 27*4882a593Smuzhiyun // Switch to long mode 28*4882a593Smuzhiyun jmp $0x33,$1f 29*4882a593Smuzhiyun1: .code64 30*4882a593Smuzhiyun 31*4882a593Smuzhiyun // Call the function 32*4882a593Smuzhiyun call *%rax 33*4882a593Smuzhiyun 34*4882a593Smuzhiyun // Switch to compatibility mode 35*4882a593Smuzhiyun push $0x23 /* USER32_CS */ 36*4882a593Smuzhiyun .code32; push $1f; .code64 /* hack: can't have X86_64_32S relocation in 32-bit ELF */ 37*4882a593Smuzhiyun lretq 38*4882a593Smuzhiyun1: .code32 39*4882a593Smuzhiyun 40*4882a593Smuzhiyun pop %edi 41*4882a593Smuzhiyun pop %esi 42*4882a593Smuzhiyun pop %edx 43*4882a593Smuzhiyun pop %ecx 44*4882a593Smuzhiyun 45*4882a593Smuzhiyun ret 46*4882a593Smuzhiyun 47*4882a593Smuzhiyun.size call64_from_32, .-call64_from_32 48