144 lines
3.3 KiB
C
144 lines
3.3 KiB
C
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASMARM_TLS_H
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#define __ASMARM_TLS_H
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#include <linux/compiler.h>
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#include <asm/thread_info.h>
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#ifdef __ASSEMBLY__
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#include <asm/asm-offsets.h>
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.macro switch_tls_none, base, tp, tpuser, tmp1, tmp2
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.endm
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.macro switch_tls_v6k, base, tp, tpuser, tmp1, tmp2
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mrc p15, 0, \tmp2, c13, c0, 2 @ get the user r/w register
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@ TLS register update is deferred until return to user space
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mcr p15, 0, \tpuser, c13, c0, 2 @ set the user r/w register
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str \tmp2, [\base, #TI_TP_VALUE + 4] @ save it
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.endm
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.macro switch_tls_v6, base, tp, tpuser, tmp1, tmp2
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#ifdef CONFIG_SMP
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ALT_SMP(nop)
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ALT_UP_B(.L0_\@)
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.subsection 1
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#endif
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.L0_\@:
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ldr_va \tmp1, elf_hwcap
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mov \tmp2, #0xffff0fff
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tst \tmp1, #HWCAP_TLS @ hardware TLS available?
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streq \tp, [\tmp2, #-15] @ set TLS value at 0xffff0ff0
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beq .L2_\@
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mcr p15, 0, \tp, c13, c0, 3 @ yes, set TLS register
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#ifdef CONFIG_SMP
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b .L1_\@
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.previous
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#endif
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.L1_\@: switch_tls_v6k \base, \tp, \tpuser, \tmp1, \tmp2
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.L2_\@:
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.endm
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.macro switch_tls_software, base, tp, tpuser, tmp1, tmp2
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mov \tmp1, #0xffff0fff
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str \tp, [\tmp1, #-15] @ set TLS value at 0xffff0ff0
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.endm
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#else
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#include <asm/smp_plat.h>
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#endif
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#ifdef CONFIG_TLS_REG_EMUL
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#define tls_emu 1
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#define has_tls_reg 1
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#define defer_tls_reg_update 0
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#define switch_tls switch_tls_none
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#elif defined(CONFIG_CPU_V6)
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#define tls_emu 0
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#define has_tls_reg (elf_hwcap & HWCAP_TLS)
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#define defer_tls_reg_update is_smp()
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#define switch_tls switch_tls_v6
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#elif defined(CONFIG_CPU_32v6K)
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#define tls_emu 0
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#define has_tls_reg 1
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#define defer_tls_reg_update 1
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#define switch_tls switch_tls_v6k
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#else
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#define tls_emu 0
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#define has_tls_reg 0
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#define defer_tls_reg_update 0
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#define switch_tls switch_tls_software
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#endif
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#ifndef __ASSEMBLY__
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static inline void set_tls(unsigned long val)
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{
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struct thread_info *thread;
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thread = current_thread_info();
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thread->tp_value[0] = val;
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/*
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* This code runs with preemption enabled and therefore must
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* be reentrant with respect to switch_tls.
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*
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* We need to ensure ordering between the shadow state and the
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* hardware state, so that we don't corrupt the hardware state
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* with a stale shadow state during context switch.
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*
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* If we're preempted here, switch_tls will load TPIDRURO from
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* thread_info upon resuming execution and the following mcr
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* is merely redundant.
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*/
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barrier();
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if (!tls_emu) {
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if (has_tls_reg && !defer_tls_reg_update) {
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asm("mcr p15, 0, %0, c13, c0, 3"
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: : "r" (val));
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} else if (!has_tls_reg) {
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#ifdef CONFIG_KUSER_HELPERS
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/*
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* User space must never try to access this
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* directly. Expect your app to break
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* eventually if you do so. The user helper
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* at 0xffff0fe0 must be used instead. (see
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* entry-armv.S for details)
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*/
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*((unsigned int *)0xffff0ff0) = val;
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#endif
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}
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}
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}
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static inline unsigned long get_tpuser(void)
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{
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unsigned long reg = 0;
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if (has_tls_reg && !tls_emu)
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__asm__("mrc p15, 0, %0, c13, c0, 2" : "=r" (reg));
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return reg;
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}
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static inline void set_tpuser(unsigned long val)
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{
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/* Since TPIDRURW is fully context-switched (unlike TPIDRURO),
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* we need not update thread_info.
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*/
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if (has_tls_reg && !tls_emu) {
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asm("mcr p15, 0, %0, c13, c0, 2"
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: : "r" (val));
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}
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}
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static inline void flush_tls(void)
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{
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set_tls(0);
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set_tpuser(0);
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}
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#endif
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#endif /* __ASMARM_TLS_H */
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