[8/8] aarch64: Allow overriding HWCAP_CPUID feature check using HWCAP_MASK
Commit Message
Now that LD_HWCAP_MASK (or glibc.tune.hwcap_mask) is read early enough
to influence cpu feature check in aarch64, use it to influence
multiarch selection. Setting LD_HWCAP_MASK such that it clears
HWCAP_CPUID will now disable multiarch for the binary.
* sysdeps/unix/sysv/linux/aarch64/cpu-features.c
(init_cpu_features): Use glibc.tune.hwcap_mask.
Change-Id: Ia801ed6b8166b79a0cae184ee7417272f2f60593
---
sysdeps/unix/sysv/linux/aarch64/cpu-features.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
@@ -18,18 +18,25 @@
#include <cpu-features.h>
#include <sys/auxv.h>
+#include <elf/dl-tunables.h>
static inline void
init_cpu_features (struct cpu_features *cpu_features)
{
- if (GLRO(dl_hwcap) & HWCAP_CPUID)
+#if HAVE_TUNABLES
+ uint64_t hwcap_mask = TUNABLE_GET (glibc, tune, hwcap_mask, uint64_t);
+#else
+ uint64_t hwcap_mask = GLRO (dl_hwcap_mask);
+#endif
+
+ uint64_t hwcap = GLRO (dl_hwcap) & hwcap_mask;
+
+ if (hwcap & HWCAP_CPUID)
{
register uint64_t id = 0;
asm volatile ("mrs %0, midr_el1" : "=r"(id));
cpu_features->midr_el1 = id;
}
else
- {
- cpu_features->midr_el1 = 0;
- }
+ cpu_features->midr_el1 = 0;
}