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