diff options
Diffstat (limited to 'src/thread')
| -rw-r--r-- | src/thread/aarch64/__set_thread_area.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/src/thread/aarch64/__set_thread_area.c b/src/thread/aarch64/__set_thread_area.c index a348ee77..2ec788e8 100644 --- a/src/thread/aarch64/__set_thread_area.c +++ b/src/thread/aarch64/__set_thread_area.c @@ -1,5 +1,27 @@ +#include <elf.h> +#include "libc.h" + +#define BITRANGE(a,b) (2*(1UL<<(b))-(1UL<<(a))) + int __set_thread_area(void *p) { __asm__ __volatile__ ("msr tpidr_el0,%0" : : "r"(p) : "memory"); + + /* Mask off hwcap bits for SME and unknown future features. This is + * necessary because SME is not safe to use without libc support for + * it, and we do not (yet) have such support. */ + for (size_t *v = libc.auxv; *v; v+=2) { + if (v[0]==AT_HWCAP) { + v[1] &= ~BITRANGE(42,63); /* 42-47 are SME */ + } else if (v[0]==AT_HWCAP2) { + v[1] &= ~(BITRANGE(23,30) + | BITRANGE(37,42) + | BITRANGE(57,62)); + } else if (v[0]==AT_HWCAP3 || v[0]==AT_HWCAP4) { + v[0] = AT_IGNORE; + v[1] = 0; + } + } + return 0; } |