| Message ID | 3aa0b464e9aba9609de4d4118e4be7526f6dbab9.1406177531.git.luto@amacapital.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Il 24/07/2014 06:57, Andy Lutomirski ha scritto: > It's considerably better than any of the alternatives on KVM. > > Rather than reinventing all of the cpu feature query code, this fixes > native_cpuid to work in PIC objects. > > I haven't combined it with boot/cpuflags.c's cpuid implementation: > including asm/processor.h from boot/cpuflags.c results in a flood of > unrelated errors, and fixing it might be messy. > > Reviewed-by: Kees Cook <keescook@chromium.org> > Signed-off-by: Andy Lutomirski <luto@amacapital.net> > --- > arch/x86/boot/compressed/aslr.c | 27 +++++++++++++++++++++++++++ > arch/x86/include/asm/processor.h | 21 ++++++++++++++++++--- > 2 files changed, 45 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c > index fc6091a..8583f0e 100644 > --- a/arch/x86/boot/compressed/aslr.c > +++ b/arch/x86/boot/compressed/aslr.c > @@ -5,6 +5,8 @@ > #include <asm/archrandom.h> > #include <asm/e820.h> > > +#include <uapi/asm/kvm_para.h> > + > #include <generated/compile.h> > #include <linux/module.h> > #include <linux/uts.h> > @@ -15,6 +17,22 @@ > static const char build_str[] = UTS_RELEASE " (" LINUX_COMPILE_BY "@" > LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION; > > +static bool kvm_para_has_feature(unsigned int feature) > +{ > + u32 kvm_base; > + u32 features; > + > + if (!has_cpuflag(X86_FEATURE_HYPERVISOR)) > + return false; > + > + kvm_base = hypervisor_cpuid_base("KVMKVMKVM\0\0\0", KVM_CPUID_FEATURES); > + if (!kvm_base) > + return false; > + > + features = cpuid_eax(kvm_base | KVM_CPUID_FEATURES); > + return features & (1UL << feature); > +} > + > #define I8254_PORT_CONTROL 0x43 > #define I8254_PORT_COUNTER0 0x40 > #define I8254_CMD_READBACK 0xC0 > @@ -81,6 +99,15 @@ static unsigned long get_random_long(void) > } > } > > + if (kvm_para_has_feature(KVM_FEATURE_GET_RNG_SEED)) { > + u64 seed; > + > + debug_putstr(" MSR_KVM_GET_RNG_SEED"); > + rdmsrl(MSR_KVM_GET_RNG_SEED, seed); > + random ^= (unsigned long)seed; > + use_i8254 = false; > + } > + > if (has_cpuflag(X86_FEATURE_TSC)) { > debug_putstr(" RDTSC"); > rdtscll(raw); > diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h > index a4ea023..6096f3c 100644 > --- a/arch/x86/include/asm/processor.h > +++ b/arch/x86/include/asm/processor.h > @@ -189,10 +189,25 @@ static inline int have_cpuid_p(void) > static inline void native_cpuid(unsigned int *eax, unsigned int *ebx, > unsigned int *ecx, unsigned int *edx) > { > - /* ecx is often an input as well as an output. */ > - asm volatile("cpuid" > + /* > + * This function can be used from the boot code, so it needs > + * to avoid using EBX in constraints in PIC mode. > + * > + * ecx is often an input as well as an output. > + */ > + asm volatile(".ifnc %%ebx,%1 ; .ifnc %%rbx,%1 \n\t" > + "movl %%ebx,%1 \n\t" > + ".endif ; .endif \n\t" > + "cpuid \n\t" > + ".ifnc %%ebx,%1 ; .ifnc %%rbx,%1 \n\t" > + "xchgl %%ebx,%1 \n\t" > + ".endif ; .endif" > : "=a" (*eax), > - "=b" (*ebx), > +#if defined(__i386__) && defined(__PIC__) > + "=r" (*ebx), /* gcc won't let us use ebx */ > +#else > + "=b" (*ebx), /* ebx is okay */ > +#endif > "=c" (*ecx), > "=d" (*edx) > : "0" (*eax), "2" (*ecx) > Acked-by: Paolo Bonzini <pbonzini@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c index fc6091a..8583f0e 100644 --- a/arch/x86/boot/compressed/aslr.c +++ b/arch/x86/boot/compressed/aslr.c @@ -5,6 +5,8 @@ #include <asm/archrandom.h> #include <asm/e820.h> +#include <uapi/asm/kvm_para.h> + #include <generated/compile.h> #include <linux/module.h> #include <linux/uts.h> @@ -15,6 +17,22 @@ static const char build_str[] = UTS_RELEASE " (" LINUX_COMPILE_BY "@" LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION; +static bool kvm_para_has_feature(unsigned int feature) +{ + u32 kvm_base; + u32 features; + + if (!has_cpuflag(X86_FEATURE_HYPERVISOR)) + return false; + + kvm_base = hypervisor_cpuid_base("KVMKVMKVM\0\0\0", KVM_CPUID_FEATURES); + if (!kvm_base) + return false; + + features = cpuid_eax(kvm_base | KVM_CPUID_FEATURES); + return features & (1UL << feature); +} + #define I8254_PORT_CONTROL 0x43 #define I8254_PORT_COUNTER0 0x40 #define I8254_CMD_READBACK 0xC0 @@ -81,6 +99,15 @@ static unsigned long get_random_long(void) } } + if (kvm_para_has_feature(KVM_FEATURE_GET_RNG_SEED)) { + u64 seed; + + debug_putstr(" MSR_KVM_GET_RNG_SEED"); + rdmsrl(MSR_KVM_GET_RNG_SEED, seed); + random ^= (unsigned long)seed; + use_i8254 = false; + } + if (has_cpuflag(X86_FEATURE_TSC)) { debug_putstr(" RDTSC"); rdtscll(raw); diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index a4ea023..6096f3c 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -189,10 +189,25 @@ static inline int have_cpuid_p(void) static inline void native_cpuid(unsigned int *eax, unsigned int *ebx, unsigned int *ecx, unsigned int *edx) { - /* ecx is often an input as well as an output. */ - asm volatile("cpuid" + /* + * This function can be used from the boot code, so it needs + * to avoid using EBX in constraints in PIC mode. + * + * ecx is often an input as well as an output. + */ + asm volatile(".ifnc %%ebx,%1 ; .ifnc %%rbx,%1 \n\t" + "movl %%ebx,%1 \n\t" + ".endif ; .endif \n\t" + "cpuid \n\t" + ".ifnc %%ebx,%1 ; .ifnc %%rbx,%1 \n\t" + "xchgl %%ebx,%1 \n\t" + ".endif ; .endif" : "=a" (*eax), - "=b" (*ebx), +#if defined(__i386__) && defined(__PIC__) + "=r" (*ebx), /* gcc won't let us use ebx */ +#else + "=b" (*ebx), /* ebx is okay */ +#endif "=c" (*ecx), "=d" (*edx) : "0" (*eax), "2" (*ecx)