[RFC v2 06/23] kvm: Adapt assembly for PIE support
From: Thomas Garnier <hidden>
Date: 2017-08-10 17:25:58
Also in:
kvm, linux-arch, linux-crypto, xen-devel
Subsystem:
kernel virtual machine for x86 (kvm/x86), kvm paravirt (kvm/paravirt), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
Change the assembly code to use only relative references of symbols for the kernel to be PIE compatible. The new __ASM_GET_PTR_PRE 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 <redacted> --- arch/x86/include/asm/kvm_host.h | 6 ++++-- arch/x86/kernel/kvm.c | 6 ++++-- arch/x86/kvm/svm.c | 4 ++-- 3 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 7cbaab523f22..276e288da25e 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h@@ -1352,9 +1352,11 @@ 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) "%%" _ASM_AX " \n\t" \ + __ASM_GET_PTR_PRE(666b) "%%" _ASM_AX "\n\t" \ + "xchg %%" _ASM_AX ", (%%" _ASM_SP ") \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 d04e30e3c0ff..cb83745185f2 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c@@ -620,8 +620,10 @@ 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 4d4743361f1e..6e611f9f6163 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c@@ -554,12 +554,12 @@ 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)
--
2.14.0.434.g98096fd7a8-goog
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