kernel_5.10 no rt

hc

2023-12-11 6778948f9de86c3cfaf36725a7c87dcff9ba247f

 kernel/arch/x86/platform/efi/efi_stub_32.S
..
..
@@ -7,118 +7,54 @@
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  */
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 #include <linux/linkage.h>
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+#include <linux/init.h>
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+#include <asm/asm-offsets.h>
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 #include <asm/page_types.h>
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13
 
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-/*
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- * efi_call_phys(void *, ...) is a function with variable parameters.
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- * All the callers of this function assure that all the parameters are 4-bytes.
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- */
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+	__INIT
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+SYM_FUNC_START(efi_call_svam)
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+	push	%ebp
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+	movl	%esp, %ebp
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+	push	%ebx
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-/*
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- * In gcc calling convention, EBX, ESP, EBP, ESI and EDI are all callee save.
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- * So we'd better save all of them at the beginning of this function and restore
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- * at the end no matter how many we use, because we can not assure EFI runtime
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- * service functions will comply with gcc calling convention, too.
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- */
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-
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-.text
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-ENTRY(efi_call_phys)
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-	/*
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-	 * 0. The function can only be called in Linux kernel. So CS has been
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-	 * set to 0x0010, DS and SS have been set to 0x0018. In EFI, I found
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-	 * the values of these registers are the same. And, the corresponding
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-	 * GDT entries are identical. So I will do nothing about segment reg
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-	 * and GDT, but change GDT base register in prolog and epilog.
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-	 */
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+	push	16(%esp)
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+	push	16(%esp)
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+	push	%ecx
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+	push	%edx
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+	movl	%eax, %ebx		// &systab_phys->runtime
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25
 
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 	/*
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-	 * 1. Now I am running with EIP = <physical address> + PAGE_OFFSET.
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-	 * But to make it smoothly switch from virtual mode to flat mode.
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-	 * The mapping of lower virtual memory has been created in prolog and
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-	 * epilog.
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+	 * Switch to the flat mapped alias of this routine, by jumping to the
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+	 * address of label '1' after subtracting PAGE_OFFSET from it.
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 	 */
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 	movl	$1f, %edx
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 	subl	$__PAGE_OFFSET, %edx
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 	jmp	*%edx
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 1:
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-	/*
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-	 * 2. Now on the top of stack is the return
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-	 * address in the caller of efi_call_phys(), then parameter 1,
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-	 * parameter 2, ..., param n. To make things easy, we save the return
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-	 * address of efi_call_phys in a global variable.
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-	 */
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-	popl	%edx
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-	movl	%edx, saved_return_addr
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-	/* get the function pointer into ECX*/
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-	popl	%ecx
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-	movl	%ecx, efi_rt_function_ptr
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-	movl	$2f, %edx
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-	subl	$__PAGE_OFFSET, %edx
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-	pushl	%edx
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-
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-	/*
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-	 * 3. Clear PG bit in %CR0.
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-	 */
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+	/* disable paging */
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 	movl	%cr0, %edx
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 	andl	$0x7fffffff, %edx
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 	movl	%edx, %cr0
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-	jmp	1f
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-1:
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39
 
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-	/*
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-	 * 4. Adjust stack pointer.
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-	 */
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+	/* convert the stack pointer to a flat mapped address */
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 	subl	$__PAGE_OFFSET, %esp
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42
 
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-	/*
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-	 * 5. Call the physical function.
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-	 */
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-	jmp	*%ecx
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+	/* call the EFI routine */
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+	movl	(%eax), %eax
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+	call	*EFI_svam(%eax)
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46
 
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-2:
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-	/*
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-	 * 6. After EFI runtime service returns, control will return to
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-	 * following instruction. We'd better readjust stack pointer first.
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-	 */
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-	addl	$__PAGE_OFFSET, %esp
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+	/* grab the virtually remapped EFI runtime services table pointer */
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+	movl	(%ebx), %ecx
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+	movl	36(%esp), %edx		// &efi.runtime
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+	movl	%ecx, (%edx)
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-	/*
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-	 * 7. Restore PG bit
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-	 */
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+	/* re-enable paging */
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 	movl	%cr0, %edx
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 	orl	$0x80000000, %edx
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 	movl	%edx, %cr0
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-	jmp	1f
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-1:
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-	/*
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-	 * 8. Now restore the virtual mode from flat mode by
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-	 * adding EIP with PAGE_OFFSET.
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-	 */
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-	movl	$1f, %edx
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-	jmp	*%edx
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-1:
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-	/*
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-	 * 9. Balance the stack. And because EAX contain the return value,
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-	 * we'd better not clobber it.
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-	 */
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-	leal	efi_rt_function_ptr, %edx
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-	movl	(%edx), %ecx
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-	pushl	%ecx
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-
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-	/*
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-	 * 10. Push the saved return address onto the stack and return.
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-	 */
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-	leal	saved_return_addr, %edx
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-	movl	(%edx), %ecx
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-	pushl	%ecx
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-	ret
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-ENDPROC(efi_call_phys)
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-.previous
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-
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-.data
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-saved_return_addr:
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-	.long 0
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-efi_rt_function_ptr:
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-	.long 0
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+	movl	16(%esp), %ebx
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+	leave
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+	RET
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+SYM_FUNC_END(efi_call_svam)