diff mbox series

[RFC,16/28] x86/entry_64: Use RIP-relative addressing

Message ID 20240925150059.3955569-46-ardb+git@google.com (mailing list archive)
State RFC, archived
Headers show
Series x86: Rely on toolchain for relocatable code | expand

Commit Message

Ard Biesheuvel Sept. 25, 2024, 3:01 p.m. UTC 
From: Ard Biesheuvel <ardb@kernel.org>

Fix up a couple of occurrences in the x86_64 entry code where we take
the absolute address of a symbol while we could use RIP-relative
addressing just the same. This avoids relocation fixups at boot for
these quantities.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/x86/entry/calling.h  |  9 +++++----
 arch/x86/entry/entry_64.S | 12 +++++++-----
 2 files changed, 12 insertions(+), 9 deletions(-)
diff mbox series

Patch

diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h
index ea81770629ee..099da5aaf929 100644
--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -375,8 +375,8 @@  For 32-bit we have the following conventions - kernel is built with
 .endm
 
 .macro SAVE_AND_SET_GSBASE scratch_reg:req save_reg:req
+	GET_PERCPU_BASE \scratch_reg \save_reg
 	rdgsbase \save_reg
-	GET_PERCPU_BASE \scratch_reg
 	wrgsbase \scratch_reg
 .endm
 
@@ -412,15 +412,16 @@  For 32-bit we have the following conventions - kernel is built with
  * Thus the kernel would consume a guest's TSC_AUX if an NMI arrives
  * while running KVM's run loop.
  */
-.macro GET_PERCPU_BASE reg:req
+.macro GET_PERCPU_BASE reg:req scratch:req
 	LOAD_CPU_AND_NODE_SEG_LIMIT \reg
 	andq	$VDSO_CPUNODE_MASK, \reg
-	movq	__per_cpu_offset(, \reg, 8), \reg
+	leaq	__per_cpu_offset(%rip), \scratch
+	movq	(\scratch, \reg, 8), \reg
 .endm
 
 #else
 
-.macro GET_PERCPU_BASE reg:req
+.macro GET_PERCPU_BASE reg:req scratch:req
 	movq	pcpu_unit_offsets(%rip), \reg
 .endm
 
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 1b5be07f8669..6509e12b6329 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1038,7 +1038,8 @@  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
 
 	/*
@@ -1250,10 +1251,10 @@  SYM_CODE_START(asm_exc_nmi)
 	 * 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:
@@ -1307,7 +1308,8 @@  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
@@ -1346,7 +1348,7 @@  first_nmi:
 	addq	$8, (%rsp)	/* Fix up RSP */
 	pushfq			/* RFLAGS */
 	pushq	$__KERNEL_CS	/* CS */
-	pushq	$1f		/* RIP */
+	pushq	1f@GOTPCREL(%rip) /* RIP */
 	iretq			/* continues at repeat_nmi below */
 	UNWIND_HINT_IRET_REGS
 1: