linux/arch/tile/kernel/entry.S
Chris Metcalf 4a556f4f56 tile: implement gettimeofday() via vDSO
This change creates the framework for vDSO calls, makes the existing
rt_sigreturn() mechanism use it, and adds a fast gettimeofday().
Now that we need to expose the vDSO address to userspace, we add
AT_SYSINFO_EHDR to the set of aux entries provided to userspace.
(You can disable any extra vDSO support by booting with vdso=0,
but the rt_sigreturn vDSO page will still be provided.)

Note that glibc has supported the tile vDSO since release 2.17.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
2013-08-13 16:26:21 -04:00

72 lines
2.3 KiB
ArmAsm

/*
* Copyright 2010 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program 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, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*/
#include <linux/linkage.h>
#include <linux/unistd.h>
#include <asm/irqflags.h>
#include <asm/processor.h>
#include <arch/abi.h>
#include <arch/spr_def.h>
#ifdef __tilegx__
#define bnzt bnezt
#endif
STD_ENTRY(current_text_addr)
{ move r0, lr; jrp lr }
STD_ENDPROC(current_text_addr)
STD_ENTRY(dump_stack)
{ move r2, lr; lnk r1 }
{ move r4, r52; addli r1, r1, dump_stack - . }
{ move r3, sp; j _dump_stack }
jrp lr /* keep backtracer happy */
STD_ENDPROC(dump_stack)
STD_ENTRY(KBacktraceIterator_init_current)
{ move r2, lr; lnk r1 }
{ move r4, r52; addli r1, r1, KBacktraceIterator_init_current - . }
{ move r3, sp; j _KBacktraceIterator_init_current }
jrp lr /* keep backtracer happy */
STD_ENDPROC(KBacktraceIterator_init_current)
/* Loop forever on a nap during SMP boot. */
STD_ENTRY(smp_nap)
nap
nop /* avoid provoking the icache prefetch with a jump */
j smp_nap /* we are not architecturally guaranteed not to exit nap */
jrp lr /* clue in the backtracer */
STD_ENDPROC(smp_nap)
/*
* Enable interrupts racelessly and then nap until interrupted.
* Architecturally, we are guaranteed that enabling interrupts via
* mtspr to INTERRUPT_CRITICAL_SECTION only interrupts at the next PC.
* This function's _cpu_idle_nap address is special; see intvec.S.
* When interrupted at _cpu_idle_nap, we bump the PC forward 8, and
* as a result return to the function that called _cpu_idle().
*/
STD_ENTRY(_cpu_idle)
movei r1, 1
IRQ_ENABLE_LOAD(r2, r3)
mtspr INTERRUPT_CRITICAL_SECTION, r1
IRQ_ENABLE_APPLY(r2, r3) /* unmask, but still with ICS set */
mtspr INTERRUPT_CRITICAL_SECTION, zero
.global _cpu_idle_nap
_cpu_idle_nap:
nap
nop /* avoid provoking the icache prefetch with a jump */
jrp lr
STD_ENDPROC(_cpu_idle)