Revert "[FMV][AArch64] Add initial AT_HWCAP3 / AT_HWCAP4 support (#161595)" (#171071)

Crashing with older glibc.

This reverts commit edb4319,
57b5ba0 and
9715cca.

Author: brad0

compiler-rt/lib/builtins/cpu_model/aarch64.c

@@ -19,13 +19,15 @@
 #error This file is intended only for aarch64-based targets
 #endif
 
+#if __has_include(<sys/ifunc.h>)
+#include <sys/ifunc.h>
+#else
 typedef struct __ifunc_arg_t {
   unsigned long _size;
   unsigned long _hwcap;
   unsigned long _hwcap2;
-  unsigned long _hwcap3;
-  unsigned long _hwcap4;
 } __ifunc_arg_t;
+#endif // __has_include(<sys/ifunc.h>)
 
 // LSE support detection for out-of-line atomics
 // using HWCAP and Auxiliary vector

compiler-rt/lib/builtins/cpu_model/aarch64/fmv/android.inc

@@ -27,14 +27,10 @@ void CONSTRUCTOR_ATTRIBUTE __init_cpu_features(void) {
 
   unsigned long hwcap = getauxval(AT_HWCAP);
   unsigned long hwcap2 = getauxval(AT_HWCAP2);
-  unsigned long hwcap3 = getauxval(AT_HWCAP3);
-  unsigned long hwcap4 = getauxval(AT_HWCAP4);
 
   __ifunc_arg_t arg;
   arg._size = sizeof(__ifunc_arg_t);
   arg._hwcap = hwcap;
   arg._hwcap2 = hwcap2;
-  arg._hwcap3 = hwcap3;
-  arg._hwcap4 = hwcap4;
   __init_cpu_features_constructor(hwcap | _IFUNC_ARG_HWCAP, &arg);
 }

compiler-rt/lib/builtins/cpu_model/aarch64/fmv/elf_aux_info.inc

@@ -7,21 +7,17 @@ void __init_cpu_features_resolver(unsigned long hwcap,
 }
 
 void CONSTRUCTOR_ATTRIBUTE __init_cpu_features(void) {
-  unsigned long hwcap, hwcap2, hwcap3, hwcap4 = 0;
+  unsigned long hwcap, hwcap2 = 0;
   // CPU features already initialized.
   if (__atomic_load_n(&__aarch64_cpu_features.features, __ATOMIC_RELAXED))
     return;
 
   elf_aux_info(AT_HWCAP, &hwcap, sizeof hwcap);
   elf_aux_info(AT_HWCAP2, &hwcap2, sizeof hwcap2);
-  elf_aux_info(AT_HWCAP3, &hwcap3, sizeof hwcap3);
-  elf_aux_info(AT_HWCAP4, &hwcap4, sizeof hwcap4);
 
   __ifunc_arg_t arg;
   arg._size = sizeof(__ifunc_arg_t);
   arg._hwcap = hwcap;
   arg._hwcap2 = hwcap2;
-  arg._hwcap3 = hwcap3;
-  arg._hwcap4 = hwcap4;
   __init_cpu_features_constructor(hwcap | _IFUNC_ARG_HWCAP, &arg);
 }

compiler-rt/lib/builtins/cpu_model/aarch64/fmv/getauxval.inc

@@ -12,14 +12,10 @@ void CONSTRUCTOR_ATTRIBUTE __init_cpu_features(void) {
 
   unsigned long hwcap = getauxval(AT_HWCAP);
   unsigned long hwcap2 = getauxval(AT_HWCAP2);
-  unsigned long hwcap3 = getauxval(AT_HWCAP3);
-  unsigned long hwcap4 = getauxval(AT_HWCAP4);
 
   __ifunc_arg_t arg;
   arg._size = sizeof(__ifunc_arg_t);
   arg._hwcap = hwcap;
   arg._hwcap2 = hwcap2;
-  arg._hwcap3 = hwcap3;
-  arg._hwcap4 = hwcap4;
   __init_cpu_features_constructor(hwcap | _IFUNC_ARG_HWCAP, &arg);
 }

compiler-rt/lib/builtins/cpu_model/aarch64/hwcap.inc

@@ -2,7 +2,7 @@
 #define _IFUNC_ARG_HWCAP (1ULL << 62)
 #endif
 #ifndef AT_HWCAP
-#define AT_HWCAP 16 // Linux value
+#define AT_HWCAP 16
 #endif
 #ifndef HWCAP_CPUID
 #define HWCAP_CPUID (1 << 11)
@@ -90,7 +90,7 @@
 #endif
 
 #ifndef AT_HWCAP2
-#define AT_HWCAP2 26 // Linux value
+#define AT_HWCAP2 26
 #endif
 #ifndef HWCAP2_DCPODP
 #define HWCAP2_DCPODP (1 << 0)
@@ -185,19 +185,3 @@
 #ifndef HWCAP2_CSSC
 #define HWCAP2_CSSC (1UL << 34)
 #endif
-
-#ifndef AT_HWCAP3
-#ifdef __linux__
-#define AT_HWCAP3 29 // Linux value
-#else
-#define AT_HWCAP3 38 // BSD value
-#endif
-#endif
-
-#ifndef AT_HWCAP4
-#ifdef __linux__
-#define AT_HWCAP4 30 // Linux value
-#else
-#define AT_HWCAP4 39 // BSD value
-#endif
-#endif