[v3,19/27] kvm: Adapt assembly for PIE support

Commit Message

Thomas Garnier May 23, 2018, 7:54 p.m. UTC

Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible. The new __ASM_MOVABS macro is used to
get the address of a symbol on both 32 and 64-bit with PIE support.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <[e-mail]>
---
 arch/x86/include/asm/kvm_host.h | 8 ++++++--
 arch/x86/kernel/kvm.c           | 6 ++++--
 arch/x86/kvm/svm.c              | 4 ++--
 3 files changed, 12 insertions(+), 6 deletions(-)

Patch

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b27de80f5870..312a398465e8 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1389,9 +1389,13 @@  asmlinkage void kvm_spurious_fault(void);
 	".pushsection .fixup, \"ax\" \n" \
 	"667: \n\t" \
 	cleanup_insn "\n\t"		      \
-	"cmpb $0, kvm_rebooting \n\t"	      \
+	"cmpb $0, kvm_rebooting" __ASM_SEL(,(%%rip)) " \n\t" \
 	"jne 668b \n\t"      		      \
-	__ASM_SIZE(push) " $666b \n\t"	      \
+	__ASM_SIZE(push) "$0 \n\t"		\
+	__ASM_SIZE(push) "%%" _ASM_AX " \n\t"		\
+	_ASM_MOVABS " $666b, %%" _ASM_AX "\n\t"	\
+	_ASM_MOV " %%" _ASM_AX ", " __ASM_SEL(4,8) "(%%" _ASM_SP ") \n\t" \
+	__ASM_SIZE(pop) "%%" _ASM_AX " \n\t"		\
 	"call kvm_spurious_fault \n\t"	      \
 	".popsection \n\t" \
 	_ASM_EXTABLE(666b, 667b)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 7867417cfaff..394c00f21f05 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -726,8 +726,10 @@  asm(
 ".global __raw_callee_save___kvm_vcpu_is_preempted;"
 ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
 "__raw_callee_save___kvm_vcpu_is_preempted:"
-"movq	__per_cpu_offset(,%rdi,8), %rax;"
-"cmpb	$0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
+"leaq	__per_cpu_offset(%rip), %rax;"
+"movq	(%rax,%rdi,8), %rax;"
+"addq	" __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rip), %rax;"
+"cmpb	$0, (%rax);"
 "setne	%al;"
 "ret;"
 ".popsection");
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 220e5a89465a..2b0b25be5236 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -701,12 +701,12 @@  static u32 svm_msrpm_offset(u32 msr)
 
 static inline void clgi(void)
 {
-	asm volatile (__ex(SVM_CLGI));
+	asm volatile (__ex(SVM_CLGI) : :);
 }
 
 static inline void stgi(void)
 {
-	asm volatile (__ex(SVM_STGI));
+	asm volatile (__ex(SVM_STGI) : :);
 }
 
 static inline void invlpga(unsigned long addr, u32 asid)