diff options
Diffstat (limited to 'arch/i386/kernel/efi_stub_32.S')
| -rw-r--r-- | arch/i386/kernel/efi_stub_32.S | 122 |
1 files changed, 0 insertions, 122 deletions
diff --git a/arch/i386/kernel/efi_stub_32.S b/arch/i386/kernel/efi_stub_32.S deleted file mode 100644 index ef00bb7..0000000 --- a/arch/i386/kernel/efi_stub_32.S +++ /dev/null @@ -1,122 +0,0 @@ -/* - * EFI call stub for IA32. - * - * This stub allows us to make EFI calls in physical mode with interrupts - * turned off. - */ - -#include <linux/linkage.h> -#include <asm/page.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 -ENTRY(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. Now I am running with EIP = <physical address> + PAGE_OFFSET. - * But to make it smoothly switch from virtual mode to flat mode. - * The mapping of lower virtual memory has been created in prelog and - * epilog. - */ - movl $1f, %edx - subl $__PAGE_OFFSET, %edx - jmp *%edx -1: - - /* - * 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 %edx - movl %edx, saved_return_addr - /* get the function pointer into ECX*/ - popl %ecx - movl %ecx, efi_rt_function_ptr - movl $2f, %edx - subl $__PAGE_OFFSET, %edx - pushl %edx - - /* - * 3. Clear PG bit in %CR0. - */ - movl %cr0, %edx - andl $0x7fffffff, %edx - movl %edx, %cr0 - jmp 1f -1: - - /* - * 4. Adjust stack pointer. - */ - subl $__PAGE_OFFSET, %esp - - /* - * 5. Call the physical function. - */ - jmp *%ecx - -2: - /* - * 6. After EFI runtime service returns, control will return to - * following instruction. We'd better readjust stack pointer first. - */ - addl $__PAGE_OFFSET, %esp - - /* - * 7. Restore PG bit - */ - movl %cr0, %edx - orl $0x80000000, %edx - movl %edx, %cr0 - jmp 1f -1: - /* - * 8. Now restore the virtual mode from flat mode by - * adding EIP with PAGE_OFFSET. - */ - movl $1f, %edx - jmp *%edx -1: - - /* - * 9. Balance the stack. And because EAX contain the return value, - * we'd better not clobber it. - */ - leal efi_rt_function_ptr, %edx - movl (%edx), %ecx - pushl %ecx - - /* - * 10. Push the saved return address onto the stack and return. - */ - leal saved_return_addr, %edx - movl (%edx), %ecx - pushl %ecx - ret -.previous - -.data -saved_return_addr: - .long 0 -efi_rt_function_ptr: - .long 0 |