From: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Fri, 17 Dec 2021 17:14:59 +0000 (+0000)
Subject: aarch64: Add setcontext support for SME
X-Git-Tag: glibc-2.39~137
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9d30e5cf9687559d942514c780332d53b0617f0b;p=thirdparty%2Fglibc.git

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 699c31189fe..ba659438c56 100644
--- 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)