Files
Adhemerval Zanella 712676ea2b arm64: vDSO: Wire up getrandom() vDSO implementation
Hook up the generic vDSO implementation to the aarch64 vDSO data page.
The _vdso_rng_data required data is placed within the _vdso_data vvar
page, by using a offset larger than the vdso_data.

The vDSO function requires a ChaCha20 implementation that does not write
to the stack, and that can do an entire ChaCha20 permutation.  The one
provided uses NEON on the permute operation, with a fallback to the
syscall for chips that do not support AdvSIMD.

This also passes the vdso_test_chacha test along with
vdso_test_getrandom. The vdso_test_getrandom bench-single result on
Neoverse-N1 shows:

   vdso: 25000000 times in 0.783884250 seconds
   libc: 25000000 times in 8.780275399 seconds
syscall: 25000000 times in 8.786581518 seconds

A small fixup to arch/arm64/include/asm/mman.h was required to avoid
pulling kernel code into the vDSO, similar to what's already done in
arch/arm64/include/asm/rwonce.h.

Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2024-09-13 17:28:36 +02:00

117 lines
2.4 KiB
ArmAsm

/* SPDX-License-Identifier: GPL-2.0-only */
/*
* GNU linker script for the VDSO library.
*
* Copyright (C) 2012 ARM Limited
*
* Author: Will Deacon <will.deacon@arm.com>
* Heavily based on the vDSO linker scripts for other archs.
*/
#include <linux/const.h>
#include <asm/page.h>
#include <asm/vdso.h>
#include <asm/vdso/vsyscall.h>
#include <asm-generic/vmlinux.lds.h>
#include <vdso/datapage.h>
OUTPUT_FORMAT("elf64-littleaarch64", "elf64-bigaarch64", "elf64-littleaarch64")
OUTPUT_ARCH(aarch64)
SECTIONS
{
PROVIDE(_vdso_data = . - __VVAR_PAGES * PAGE_SIZE);
PROVIDE(_vdso_rng_data = _vdso_data + __VDSO_RND_DATA_OFFSET);
#ifdef CONFIG_TIME_NS
PROVIDE(_timens_data = _vdso_data + PAGE_SIZE);
#endif
. = VDSO_LBASE + SIZEOF_HEADERS;
.hash : { *(.hash) } :text
.gnu.hash : { *(.gnu.hash) }
.dynsym : { *(.dynsym) }
.dynstr : { *(.dynstr) }
.gnu.version : { *(.gnu.version) }
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
/*
* Discard .note.gnu.property sections which are unused and have
* different alignment requirement from vDSO note sections.
*/
/DISCARD/ : {
*(.note.GNU-stack .note.gnu.property)
}
.note : { *(.note.*) } :text :note
. = ALIGN(16);
.text : { *(.text*) } :text =0xd503201f
PROVIDE (__etext = .);
PROVIDE (_etext = .);
PROVIDE (etext = .);
. = ALIGN(4);
.altinstructions : {
*(.altinstructions)
}
.dynamic : { *(.dynamic) } :text :dynamic
.rela.dyn : ALIGN(8) { *(.rela .rela*) }
.rodata : {
*(.rodata*)
*(.got)
*(.got.plt)
*(.plt)
*(.plt.*)
*(.iplt)
*(.igot .igot.plt)
} :text
_end = .;
PROVIDE(end = .);
DWARF_DEBUG
ELF_DETAILS
/DISCARD/ : {
*(.data .data.* .gnu.linkonce.d.* .sdata*)
*(.bss .sbss .dynbss .dynsbss)
*(.eh_frame .eh_frame_hdr)
}
}
/*
* We must supply the ELF program headers explicitly to get just one
* PT_LOAD segment, and set the flags explicitly to make segments read-only.
*/
PHDRS
{
text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
note PT_NOTE FLAGS(4); /* PF_R */
}
/*
* This controls what symbols we export from the DSO.
*/
VERSION
{
LINUX_2.6.39 {
global:
__kernel_rt_sigreturn;
__kernel_gettimeofday;
__kernel_clock_gettime;
__kernel_clock_getres;
__kernel_getrandom;
local: *;
};
}
/*
* Make the sigreturn code visible to the kernel.
*/
VDSO_sigtramp = __kernel_rt_sigreturn;