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/*
* arm linux replacement vdso.
*
* Copyright 2023 Linaro, Ltd.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include <asm/unistd.h>
#include "vdso-asmoffset.h"
/*
* All supported cpus have T16 instructions: at least arm4t.
*
* We support user-user with m-profile cpus as an extension, because it
* is useful for testing gcc, which requires we avoid A32 instructions.
*/
.thumb
.arch armv4t
.eabi_attribute Tag_FP_arch, 0
.eabi_attribute Tag_ARM_ISA_use, 0
.text
.macro raw_syscall n
.ifne \n < 0x100
mov r7, #\n
.elseif \n < 0x1ff
mov r7, #0xff
add r7, #(\n - 0xff)
.else
.err
.endif
swi #0
.endm
.macro fdpic_thunk ofs
ldr r3, [sp, #\ofs]
ldmia r2, {r2, r3}
mov r9, r3
bx r2
.endm
.macro endf name
.globl \name
.type \name, %function
.size \name, . - \name
.endm
/*
* We must save/restore r7 for the EABI syscall number.
* While we're doing that, we might as well save LR to get a free return,
* and a branch that is interworking back to ARMv5.
*/
.macro SYSCALL name, nr
\name:
.cfi_startproc
push {r7, lr}
.cfi_adjust_cfa_offset 8
.cfi_offset r7, -8
.cfi_offset lr, -4
raw_syscall \nr
pop {r7, pc}
.cfi_endproc
endf \name
.endm
SYSCALL __vdso_clock_gettime, __NR_clock_gettime
SYSCALL __vdso_clock_gettime64, __NR_clock_gettime64
SYSCALL __vdso_clock_getres, __NR_clock_getres
SYSCALL __vdso_gettimeofday, __NR_gettimeofday
/*
* We, like the real kernel, use a table of sigreturn trampolines.
* Unlike the real kernel, we do not attempt to pack this into as
* few bytes as possible -- simply use 8 bytes per slot.
*
* Within each slot, use the exact same code sequence as the kernel,
* lest we trip up someone doing code inspection.
*/
.macro slot n
.balign 8
.org sigreturn_codes + 8 * \n
.endm
.macro cfi_fdpic_r9 ofs
/*
* fd = *(r13 + ofs)
* r9 = *(fd + 4)
*
* DW_CFA_expression r9, length (7),
* DW_OP_breg13, ofs, DW_OP_deref,
* DW_OP_plus_uconst, 4, DW_OP_deref
*/
.cfi_escape 0x10, 9, 7, 0x7d, (\ofs & 0x7f) + 0x80, (\ofs >> 7), 0x06, 0x23, 4, 0x06
.endm
.macro cfi_fdpic_pc ofs
/*
* fd = *(r13 + ofs)
* pc = *fd
*
* DW_CFA_expression lr (14), length (5),
* DW_OP_breg13, ofs, DW_OP_deref, DW_OP_deref
*/
.cfi_escape 0x10, 14, 5, 0x7d, (\ofs & 0x7f) + 0x80, (\ofs >> 7), 0x06, 0x06
.endm
/*
* Start the unwind info at least one instruction before the signal
* trampoline, because the unwinder will assume we are returning
* after a call site.
*/
.cfi_startproc simple
.cfi_signal_frame
.cfi_return_column 15
.cfi_def_cfa sp, 32 + 64
.cfi_offset r0, -16 * 4
.cfi_offset r1, -15 * 4
.cfi_offset r2, -14 * 4
.cfi_offset r3, -13 * 4
.cfi_offset r4, -12 * 4
.cfi_offset r5, -11 * 4
.cfi_offset r6, -10 * 4
.cfi_offset r7, -9 * 4
.cfi_offset r8, -8 * 4
.cfi_offset r9, -7 * 4
.cfi_offset r10, -6 * 4
.cfi_offset r11, -5 * 4
.cfi_offset r12, -4 * 4
.cfi_offset r13, -3 * 4
.cfi_offset r14, -2 * 4
.cfi_offset r15, -1 * 4
nop
.balign 16
sigreturn_codes:
/* [EO]ABI sigreturn */
slot 0
raw_syscall __NR_sigreturn
.cfi_def_cfa_offset 160 + 64
/* [EO]ABI rt_sigreturn */
slot 1
raw_syscall __NR_rt_sigreturn
.cfi_endproc
/* FDPIC sigreturn */
.cfi_startproc
cfi_fdpic_pc SIGFRAME_RC3_OFFSET
cfi_fdpic_r9 SIGFRAME_RC3_OFFSET
slot 2
fdpic_thunk SIGFRAME_RC3_OFFSET
.cfi_endproc
/* FDPIC rt_sigreturn */
.cfi_startproc
cfi_fdpic_pc RT_SIGFRAME_RC3_OFFSET
cfi_fdpic_r9 RT_SIGFRAME_RC3_OFFSET
slot 3
fdpic_thunk RT_SIGFRAME_RC3_OFFSET
.cfi_endproc
.balign 16
endf sigreturn_codes
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