| Message ID | 20210924005147.1122357-1-oupton@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | selftests: KVM: Explicitly use movq to read xmm registers | expand |
On Fri, Sep 24, 2021 at 12:51:47AM +0000, Oliver Upton wrote: > Compiling the KVM selftests with clang emits the following warning: > > >> include/x86_64/processor.h:297:25: error: variable 'xmm0' is uninitialized when used here [-Werror,-Wuninitialized] > >> return (unsigned long)xmm0; > > where xmm0 is accessed via an uninitialized register variable. > > Indeed, this is a misuse of register variables, which really should only > be used for specifying register constraints on variables passed to > inline assembly. Rather than attempting to read xmm registers via > register variables, just explicitly perform the movq from the desired > xmm register. > > Fixes: 783e9e51266e ("kvm: selftests: add API testing infrastructure") > Signed-off-by: Oliver Upton <oupton@google.com> > --- > .../selftests/kvm/include/x86_64/processor.h | 34 +++++++++---------- > 1 file changed, 17 insertions(+), 17 deletions(-) > > diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h > index 242ae8e09a65..eba8bd08293e 100644 > --- a/tools/testing/selftests/kvm/include/x86_64/processor.h > +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h > @@ -312,37 +312,37 @@ static inline void set_xmm(int n, unsigned long val) > } > } > > -typedef unsigned long v1di __attribute__ ((vector_size (8))); > +#define GET_XMM(__xmm) \ > +({ \ > + unsigned long __val; \ > + asm volatile("movq %%"#__xmm", %0" : "=r"(__val) : : #__xmm); \ > + __val; \ > +}) > + > static inline unsigned long get_xmm(int n) > { > assert(n >= 0 && n <= 7); > > - register v1di xmm0 __asm__("%xmm0"); > - register v1di xmm1 __asm__("%xmm1"); > - register v1di xmm2 __asm__("%xmm2"); > - register v1di xmm3 __asm__("%xmm3"); > - register v1di xmm4 __asm__("%xmm4"); > - register v1di xmm5 __asm__("%xmm5"); > - register v1di xmm6 __asm__("%xmm6"); > - register v1di xmm7 __asm__("%xmm7"); > switch (n) { > case 0: > - return (unsigned long)xmm0; > + return GET_XMM(xmm0); > case 1: > - return (unsigned long)xmm1; > + return GET_XMM(xmm1); > case 2: > - return (unsigned long)xmm2; > + return GET_XMM(xmm2); > case 3: > - return (unsigned long)xmm3; > + return GET_XMM(xmm3); > case 4: > - return (unsigned long)xmm4; > + return GET_XMM(xmm4); > case 5: > - return (unsigned long)xmm5; > + return GET_XMM(xmm5); > case 6: > - return (unsigned long)xmm6; > + return GET_XMM(xmm6); > case 7: > - return (unsigned long)xmm7; > + return GET_XMM(xmm7); > } > + > + /* never reached */ > return 0; > } > > -- > 2.33.0.685.g46640cef36-goog > Reviewed-by: Ricardo Koller <ricarkol@google.com>
On 24/09/21 06:56, Ricardo Koller wrote:
> Reviewed-by: Ricardo Koller<ricarkol@google.com>
Queued, thanks for the patch and the review!
Paolo
diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h index 242ae8e09a65..eba8bd08293e 100644 --- a/tools/testing/selftests/kvm/include/x86_64/processor.h +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h @@ -312,37 +312,37 @@ static inline void set_xmm(int n, unsigned long val) } } -typedef unsigned long v1di __attribute__ ((vector_size (8))); +#define GET_XMM(__xmm) \ +({ \ + unsigned long __val; \ + asm volatile("movq %%"#__xmm", %0" : "=r"(__val) : : #__xmm); \ + __val; \ +}) + static inline unsigned long get_xmm(int n) { assert(n >= 0 && n <= 7); - register v1di xmm0 __asm__("%xmm0"); - register v1di xmm1 __asm__("%xmm1"); - register v1di xmm2 __asm__("%xmm2"); - register v1di xmm3 __asm__("%xmm3"); - register v1di xmm4 __asm__("%xmm4"); - register v1di xmm5 __asm__("%xmm5"); - register v1di xmm6 __asm__("%xmm6"); - register v1di xmm7 __asm__("%xmm7"); switch (n) { case 0: - return (unsigned long)xmm0; + return GET_XMM(xmm0); case 1: - return (unsigned long)xmm1; + return GET_XMM(xmm1); case 2: - return (unsigned long)xmm2; + return GET_XMM(xmm2); case 3: - return (unsigned long)xmm3; + return GET_XMM(xmm3); case 4: - return (unsigned long)xmm4; + return GET_XMM(xmm4); case 5: - return (unsigned long)xmm5; + return GET_XMM(xmm5); case 6: - return (unsigned long)xmm6; + return GET_XMM(xmm6); case 7: - return (unsigned long)xmm7; + return GET_XMM(xmm7); } + + /* never reached */ return 0; }