diff options
Diffstat (limited to 'arch/x86/boot/compressed/efi_stub_32.S')
| -rw-r--r-- | arch/x86/boot/compressed/efi_stub_32.S | 87 |
1 files changed, 0 insertions, 87 deletions
diff --git a/arch/x86/boot/compressed/efi_stub_32.S b/arch/x86/boot/compressed/efi_stub_32.S deleted file mode 100644 index ed6c351d34ed..000000000000 --- a/arch/x86/boot/compressed/efi_stub_32.S +++ /dev/null @@ -1,87 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -/* - * EFI call stub for IA32. - * - * This stub allows us to make EFI calls in physical mode with interrupts - * turned off. Note that this implementation is different from the one in - * arch/x86/platform/efi/efi_stub_32.S because we're _already_ in physical - * mode at this point. - */ - -#include <linux/linkage.h> -#include <asm/page_types.h> - -/* - * efi_call_phys(void *, ...) is a function with variable parameters. - * All the callers of this function assure that all the parameters are 4-bytes. - */ - -/* - * In gcc calling convention, EBX, ESP, EBP, ESI and EDI are all callee save. - * So we'd better save all of them at the beginning of this function and restore - * at the end no matter how many we use, because we can not assure EFI runtime - * service functions will comply with gcc calling convention, too. - */ - -.text -SYM_FUNC_START(efi_call_phys) - /* - * 0. The function can only be called in Linux kernel. So CS has been - * set to 0x0010, DS and SS have been set to 0x0018. In EFI, I found - * the values of these registers are the same. And, the corresponding - * GDT entries are identical. So I will do nothing about segment reg - * and GDT, but change GDT base register in prelog and epilog. - */ - - /* - * 1. Because we haven't been relocated by this point we need to - * use relative addressing. - */ - call 1f -1: popl %edx - subl $1b, %edx - - /* - * 2. Now on the top of stack is the return - * address in the caller of efi_call_phys(), then parameter 1, - * parameter 2, ..., param n. To make things easy, we save the return - * address of efi_call_phys in a global variable. - */ - popl %ecx - movl %ecx, saved_return_addr(%edx) - /* get the function pointer into ECX*/ - popl %ecx - movl %ecx, efi_rt_function_ptr(%edx) - - /* - * 3. Call the physical function. - */ - call *%ecx - - /* - * 4. Balance the stack. And because EAX contain the return value, - * we'd better not clobber it. We need to calculate our address - * again because %ecx and %edx are not preserved across EFI function - * calls. - */ - call 1f -1: popl %edx - subl $1b, %edx - - movl efi_rt_function_ptr(%edx), %ecx - pushl %ecx - - /* - * 10. Push the saved return address onto the stack and return. - */ - movl saved_return_addr(%edx), %ecx - pushl %ecx - ret -SYM_FUNC_END(efi_call_phys) -.previous - -.data -saved_return_addr: - .long 0 -efi_rt_function_ptr: - .long 0 |