aarch64: Add setcontext support for SME

For the ZA lazy saving scheme to work, setcontext has to call
__libc_arm_za_disable.

Also fixes swapcontext which uses setcontext internally.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

diff --git a/sysdeps/unix/sysv/linux/aarch64/setcontext.S b/sysdeps/unix/sysv/linux/aarch64/setcontext.S
index 699c311..ba65943 100644 (file)
--- a/sysdeps/unix/sysv/linux/aarch64/setcontext.S
+++ b/sysdeps/unix/sysv/linux/aarch64/setcontext.S
@@ -49,6 +49,25 @@ ENTRY (__setcontext)
        cbz     x0, 1f
        b       C_SYMBOL_NAME (__syscall_error)
 1:
+       /* Disable ZA of SME.  */
+#if HAVE_AARCH64_PAC_RET
+       PACIASP
+       cfi_window_save
+#endif
+       stp     x29, x30, [sp, -16]!
+       cfi_adjust_cfa_offset (16)
+       cfi_rel_offset (x29, 0)
+       cfi_rel_offset (x30, 8)
+       mov     x29, sp
+       bl      __libc_arm_za_disable
+       ldp     x29, x30, [sp], 16
+       cfi_adjust_cfa_offset (-16)
+       cfi_restore (x29)
+       cfi_restore (x30)
+#if HAVE_AARCH64_PAC_RET
+       AUTIASP
+       cfi_window_save
+#endif
        /* Restore the general purpose registers.  */
        mov     x0, x9
        cfi_def_cfa (x0, 0)