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/* Libc internal support routine for SME.
Copyright (C) 2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
#include <rtld-global-offsets.h>
#define HWCAP2_SME_BIT 23
/* Disable ZA. Call ABI:
- Private ZA, streaming-compatible.
- x0-x13, x19-x29, sp and fp regs are call preserved.
- On return tpidr2_el0 = 0, ZA = 0.
- Takes no argument.
- Does not return a value.
- Can abort on failure (then registers are not preserved). */
ENTRY (__libc_arm_za_disable)
/* Check if SME is available. */
#ifdef SHARED
/* In libc.so. */
adrp x14, :got:_rtld_global_ro
ldr x14, [x14, :got_lo12:_rtld_global_ro]
ldr x14, [x14, GLRO_DL_HWCAP2_OFFSET]
#else
/* In libc.a, may be PIC. */
adrp x14, _dl_hwcap2
ldr x14, [x14, :lo12:_dl_hwcap2]
#endif
tbz x14, HWCAP2_SME_BIT, L(end)
.inst 0xd53bd0ae /* mrs x14, tpidr2_el0 */
cbz x14, L(end)
/* Check reserved bytes, abort on unknown extensions. */
ldrh w15, [x14, 10]
ldr w16, [x14, 12]
orr w15, w15, w16
cbnz w15, L(fail)
ldr x16, [x14]
cbz x16, L(end)
ldrh w17, [x14, 8]
cbz w17, L(end)
/* x14: tpidr2, x15: 0,
x16: za_save_buffer, x17: num_za_save_slices. */
L(save_loop):
.inst 0xe1206200 /* str za[w15, 0], [x16] */
.inst 0xe1206201 /* str za[w15, 1], [x16, 1, mul vl] */
.inst 0xe1206202 /* str za[w15, 2], [x16, 2, mul vl] */
.inst 0xe1206203 /* str za[w15, 3], [x16, 3, mul vl] */
.inst 0xe1206204 /* str za[w15, 4], [x16, 4, mul vl] */
.inst 0xe1206205 /* str za[w15, 5], [x16, 5, mul vl] */
.inst 0xe1206206 /* str za[w15, 6], [x16, 6, mul vl] */
.inst 0xe1206207 /* str za[w15, 7], [x16, 7, mul vl] */
.inst 0xe1206208 /* str za[w15, 8], [x16, 8, mul vl] */
.inst 0xe1206209 /* str za[w15, 9], [x16, 9, mul vl] */
.inst 0xe120620a /* str za[w15, 10], [x16, 10, mul vl] */
.inst 0xe120620b /* str za[w15, 11], [x16, 11, mul vl] */
.inst 0xe120620c /* str za[w15, 12], [x16, 12, mul vl] */
.inst 0xe120620d /* str za[w15, 13], [x16, 13, mul vl] */
.inst 0xe120620e /* str za[w15, 14], [x16, 14, mul vl] */
.inst 0xe120620f /* str za[w15, 15], [x16, 15, mul vl] */
add w15, w15, 16
.inst 0x04305a10 /* addsvl x16, x16, 16 */
cmp w17, w15
bhi L(save_loop)
.inst 0xd51bd0bf /* msr tpidr2_el0, xzr */
.inst 0xd503447f /* smstop za */
L(end):
ret
L(fail):
#if HAVE_AARCH64_PAC_RET
PACIASP
cfi_window_save
#endif
stp x29, x30, [sp, -32]!
cfi_adjust_cfa_offset (32)
cfi_rel_offset (x29, 0)
cfi_rel_offset (x30, 8)
mov x29, sp
.inst 0x04e0e3f0 /* cntd x16 */
str x16, [sp, 16]
cfi_rel_offset (46, 16)
.inst 0xd503467f /* smstop */
adrp x0, L(msg)
add x0, x0, :lo12:L(msg)
bl HIDDEN_JUMPTARGET (__libc_fatal)
END (__libc_arm_za_disable)
.section .rodata
.align 3
L(msg):
.string "FATAL: __libc_arm_za_disable failed.\n"
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