[PATCH RFC 04/43] x86/entry/64: Adapt assembly for PIE support

[Hou Wenlong]

From: Thomas Garnier <thgarnie@xxxxxxxxxxxx>

From: Thomas Garnier <thgarnie@xxxxxxxxxxxx>

Change the assembly code to use only relative references of symbols for
the kernel to be PIE compatible.

Signed-off-by: Thomas Garnier <thgarnie@xxxxxxxxxxxx>
Signed-off-by: Hou Wenlong <houwenlong.hwl@xxxxxxxxxxxx>
Cc: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
---
 arch/x86/entry/entry_64.S | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 21dca946955e..6f2297ebb15f 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1089,7 +1089,8 @@ SYM_CODE_START(error_entry)
 	movl	%ecx, %eax			/* zero extend */
 	cmpq	%rax, RIP+8(%rsp)
 	je	.Lbstep_iret
-	cmpq	$.Lgs_change, RIP+8(%rsp)
+	leaq	.Lgs_change(%rip), %rcx
+	cmpq	%rcx, RIP+8(%rsp)
 	jne	.Lerror_entry_done_lfence
 
 	/*
@@ -1302,10 +1303,10 @@ SYM_CODE_START(asm_exc_nmi)
 	 * resume the outer NMI.
 	 */
 
-	movq	$repeat_nmi, %rdx
+	leaq	repeat_nmi(%rip), %rdx
 	cmpq	8(%rsp), %rdx
 	ja	1f
-	movq	$end_repeat_nmi, %rdx
+	leaq	end_repeat_nmi(%rip), %rdx
 	cmpq	8(%rsp), %rdx
 	ja	nested_nmi_out
 1:
@@ -1359,7 +1360,8 @@ nested_nmi:
 	pushq	%rdx
 	pushfq
 	pushq	$__KERNEL_CS
-	pushq	$repeat_nmi
+	leaq	repeat_nmi(%rip), %rdx
+	pushq	%rdx
 
 	/* Put stack back */
 	addq	$(6*8), %rsp
@@ -1398,7 +1400,11 @@ first_nmi:
 	addq	$8, (%rsp)	/* Fix up RSP */
 	pushfq			/* RFLAGS */
 	pushq	$__KERNEL_CS	/* CS */
-	pushq	$1f		/* RIP */
+	pushq	$0		/* Space for RIP */
+	pushq	%rdx		/* Save RDX */
+	leaq	1f(%rip), %rdx	/* Put the address of 1f label into RDX */
+	movq	%rdx, 8(%rsp)   /* Store it in RIP field */
+	popq	%rdx		/* Restore RDX */
 	iretq			/* continues at repeat_nmi below */
 	UNWIND_HINT_IRET_REGS
 1:
-- 
2.31.1