x86: Properly disable XSAVE related features [BZ #27605]

1. Support GLIBC_TUNABLES=glibc.cpu.hwcaps=-XSAVE.
2. Disable all features which depend on XSAVE:
   a. If OSXSAVE is disabled by glibc tunables.  Or
   b. If both XSAVE and XSAVEC aren't usable.

diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index d7248cbb4545b3ac056bc7aa7491bb2958f10e22..e99e67f34d81de4027d3feb3d8592657cd01fe61 100644 (file)
--- a/sysdeps/x86/cpu-features.c
+++ b/sysdeps/x86/cpu-features.c
@@ -654,6 +654,61 @@ no_cpuid:
 
 #if HAVE_TUNABLES
   TUNABLE_GET (hwcaps, tunable_val_t *, TUNABLE_CALLBACK (set_hwcaps));
+
+  bool disable_xsave_features = false;
+
+  if (!CPU_FEATURE_USABLE_P (cpu_features, OSXSAVE))
+    {
+      /* These features are usable only if OSXSAVE is usable.  */
+      CPU_FEATURE_UNSET (cpu_features, XSAVE);
+      CPU_FEATURE_UNSET (cpu_features, XSAVEOPT);
+      CPU_FEATURE_UNSET (cpu_features, XSAVEC);
+      CPU_FEATURE_UNSET (cpu_features, XGETBV_ECX_1);
+      CPU_FEATURE_UNSET (cpu_features, XFD);
+
+      disable_xsave_features = true;
+    }
+
+  if (disable_xsave_features
+      || (!CPU_FEATURE_USABLE_P (cpu_features, XSAVE)
+         && !CPU_FEATURE_USABLE_P (cpu_features, XSAVEC)))
+    {
+      /* Clear xsave_state_size if both XSAVE and XSAVEC aren't usable.  */
+      cpu_features->xsave_state_size = 0;
+
+      CPU_FEATURE_UNSET (cpu_features, AVX);
+      CPU_FEATURE_UNSET (cpu_features, AVX2);
+      CPU_FEATURE_UNSET (cpu_features, AVX_VNNI);
+      CPU_FEATURE_UNSET (cpu_features, FMA);
+      CPU_FEATURE_UNSET (cpu_features, VAES);
+      CPU_FEATURE_UNSET (cpu_features, VPCLMULQDQ);
+      CPU_FEATURE_UNSET (cpu_features, XOP);
+      CPU_FEATURE_UNSET (cpu_features, F16C);
+      CPU_FEATURE_UNSET (cpu_features, AVX512F);
+      CPU_FEATURE_UNSET (cpu_features, AVX512CD);
+      CPU_FEATURE_UNSET (cpu_features, AVX512ER);
+      CPU_FEATURE_UNSET (cpu_features, AVX512PF);
+      CPU_FEATURE_UNSET (cpu_features, AVX512VL);
+      CPU_FEATURE_UNSET (cpu_features, AVX512DQ);
+      CPU_FEATURE_UNSET (cpu_features, AVX512BW);
+      CPU_FEATURE_UNSET (cpu_features, AVX512_4FMAPS);
+      CPU_FEATURE_UNSET (cpu_features, AVX512_4VNNIW);
+      CPU_FEATURE_UNSET (cpu_features, AVX512_BITALG);
+      CPU_FEATURE_UNSET (cpu_features, AVX512_IFMA);
+      CPU_FEATURE_UNSET (cpu_features, AVX512_VBMI);
+      CPU_FEATURE_UNSET (cpu_features, AVX512_VBMI2);
+      CPU_FEATURE_UNSET (cpu_features, AVX512_VNNI);
+      CPU_FEATURE_UNSET (cpu_features, AVX512_VPOPCNTDQ);
+      CPU_FEATURE_UNSET (cpu_features, AVX512_VP2INTERSECT);
+      CPU_FEATURE_UNSET (cpu_features, AVX512_BF16);
+      CPU_FEATURE_UNSET (cpu_features, AVX512_FP16);
+      CPU_FEATURE_UNSET (cpu_features, AMX_BF16);
+      CPU_FEATURE_UNSET (cpu_features, AMX_TILE);
+      CPU_FEATURE_UNSET (cpu_features, AMX_INT8);
+
+      CPU_FEATURE_UNSET (cpu_features, FMA4);
+    }
+
 #elif defined SHARED
   /* Reuse dl_platform, dl_hwcap and dl_hwcap_mask for x86.  The
      glibc.cpu.hwcap_mask tunable is initialized already, so no

diff --git a/sysdeps/x86/cpu-tunables.c b/sysdeps/x86/cpu-tunables.c
index 126896f41b14bb289eee3c2c7f5f3aec7ccce7d0..61b05e5b1d56179470d03db8933e5d48257867fe 100644 (file)
--- a/sysdeps/x86/cpu-tunables.c
+++ b/sysdeps/x86/cpu-tunables.c
@@ -168,6 +168,7 @@ TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp)
              CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, MOVBE, 5);
              CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SHSTK, 5);
              CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSSE3, 5);
+             CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, XSAVE, 5);
            }
          break;
        case 6: